Preface

In an ever-expanding world of innovation and technology, the significance of environmental sustainability is increasingly important for life and survival of mankind on planet Earth. The material and structure of a product and the processes it undergoes are now checked to know whether the effects are supportive to our natural environment and its sustainability. It would be unwise to compromise the good effects. The materials that can offer the desired performance without harming the natural environment are obviously viable for the sustainable growth of the industry. Consequently, montmorillonite (MMT) clay becomes an attractive material in making various products and composite structures.

The book chapters are written to provide scientific understanding and knowledge to scholars, students, faculty members, and laboratory and industry workers of the subject of montmorillonite clay, including its structure and properties, use in composite, industrial application, and testing and evaluation. The introduction provides a useful discussion on the current consumption trend in the industrial market. This is to signify how important montmorillonite clay is as a material in the modern and emerging market of product development and industrial applications.

In the chapter on the purification of montmorillonite, the process of removing non-clay minerals (gangue), such as calcite, feldspar, quartz, opal-CT, and mica, from montmorillonite ore is introduced. Physical and chemical purification processes are discussed. Such purification is important for applications in pharmaceutical, cosmetic, food, and advanced materials for nanotechnology. The chapter on using bentonite in wastewater treatment presented the efficiency of bentonite and modified bentonite to purify aqueous solutions containing organic pollutants, such as phenol.

Montmorillonite composite is presently an important subject that is covered in the chapter *Reinforcement of Montmorillonite Clay in Epoxy/Unsaturated Polyester Blended Composite: Effect on Composite Properties*. This chapter discusses the montmorillonite clay dissemination into unsaturated polyester (UP) and epoxy blend systems in diverse weight ratios to prepare epoxy/UP/ MMT clay composite. The prepared specimens were characterized by thermal and chemical analysis.

An analytical study of using activated bentonite is presented in the chapter *Study of Adsorption Properties of Bentonite Clay*. This is an important chapter to learn the physicochemical properties of bentonite in adsorption using analytical techniques, such as chemical composition, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Brunauer–Emmett–Teller surface area (SBET). The bentonite was intercalated by aluminum poly-cation solution and cetyltrimethylammonium bromide. The acid activation of natural bentonite was done by treatment with hydrochloric acid. The surface water pollutants removed by the prepared bentonite were BEMACID YELLOW E-4G and reactive MX-4R dye and fungicide chlorothalonil.

Optimistically, concerned readers will find the content of the book useful in knowing and understanding montmorillonite clay.

Finally, I am grateful to all the authors, commissioning editor, and the supporting staff at the IntechOpen team for their valuable contribution and for making this book project successful.

> **Dr. Faheem Uddin** Professor, Asian Institute of Fashion Design (AIFD), Iqra University, Karachi, Pakistan

Section 1 Introduction

### **Chapter 1**

## Introductory Chapter: Montmorillonite Clay Consumption Trend in Industry

*Faheem Uddin*

### **1. Introduction**

Clay is the material of choice in the 21st century. The value of natural environment and sustainability is now recognized as more demanding at social, political, and public levels. The realization of these two prime influencers has resulted in an increased demand for montmorillonite consumption. The performance features in montmorillonite clay in meeting the application requirement for a variety of materials is the foundation for the continual interest in production, consumption, and research studies.

Clay utilization from grave flooring to pottery and construction of bricks, with origin traced several thousand years back, is breathing to date in human society. Increasing interest and realization in saving the natural environment, through using environment-friendly material, will apparently capture the motivation and attention of researchers and industrialists to value the clay consumption in products and structure of materials.

The earliest examples of clay consumption as a product or constituent material can be seen in the oldest human civilization. The abundant presence of clay in the natural environment is a vital source of directing the interest in using the clay as a product and as an effective material component in a composite structure.

Presently, the study of montmorillonite clay structure and properties [1], industrial applications, composite materials, and testing and evaluation are active areas for research and development studies.

More importantly, the sustainability, environment-friendly character, costeffectiveness, and ease of processing are continually supporting an enhanced interest in consuming clay for the development of a variety of products (**Figure 1**).

The study can be seen presenting an overview of montmorillonite clay structure and properties, and addressing its effects in selected materials [2]. Important aspects of montmorillonite clay utilization for the industry are discussed in terms of natural sources, chemical structure, and physical and chemical properties. The useful properties for industrial application include, however, not limited to, particle size and layered structure, molecular structure and cation exchange effect, barrier property, and water sorption.

It is fascinating to see clay as the oldest material consumed in human civilization, and in the 21st century, it appears to be the latest material in modern human society.

Clay as a material has an extensive variety of uses and application [3–6]. Many of the uses of clay are traditional; however, an increasing interest in clay research and innovation is providing continuous breathing to its global market consumption.

**Figure 1.** *Important driving factors leading the clay consumption in the industry.*

The interesting clay consumption in traditional sectors including civil structure, paint, construction products, plastic, etc., coupled with more specialized uses in medical, healthcare, and industrial applications demonstrate the current and future viability of clay consumption.

The study of clay consumption in the research studies can be seen for particular application materials and products. However, any quantified information available on clay consumption in the industrial market is mainly seen in the progress studies of industrial products. This chapter provides an overview of the montmorillonite clay consumption mainly based on the reports produced by the market studies, where necessary reference is made to the research studies that direct the particular use or consumption of montmorillonite.

### **2. Montmorillonite clay producers**

The consumption of clay in the industry is presented in reports by various study groups on a commercial basis. These reports demonstrate the clay consumption in various industrial sectors in terms of quantity and value. Montmorillonite clay is generally represented by sodium bentonite and calcium bentonite in the industrial sector.

Undoubtedly, commercially available industrial clay is a chemical composition that generally comprises minerals, metal oxide, and organic traces [7]. The industrial market studies are showing the growth in montmorillonite clay consumption over the period of 2012–2030. The main known producers of montmorillonite clay around the world are apparently the same; they can be seen in **Table 1**. The influence of the COVID-19 pandemic has not affected the presence of producers; however, depending upon the country or region, the variation in production is obviously possible.

It can be seen that for the last almost two decades, the main montmorillonite clay producers for the industry are there in different study reports. These producers are mainly located in the USA, China, India, and Turkey (countries with more than


### **Table 1.**

*The main producers of montmorillonite clay around the world over the period 2012–2030.*

one producing company). Countries severely affected by the COVID-19 pandemic including Italy, India, Spain, and the USA may be having some variation in the production capacity. The main influence of the COVID-19 pandemic is possible on the demand, production, and supply chain of montmorillonite clay.

### **3. Variety of industrial clay**

Naturally occurring bentonite is essentially comprising montmorillonite. Bentonite contains exchangeable cations including Ca2+, Mg2+, Na+ , or Li+ . The dominant presence of a particular cation in bentonite provided important application properties. Sodium bentonite can swell in water. It has good binding property and is generally used in its natural state. However, calcium bentonite has a nonswelling character. The binding property in calcium bentonite is achievable through a chemical reaction with soda ash to introduce sodium-exchanged bentonite at outer and inner surfaces, resulting in an increased ability to bind water. Calcium bentonite can also be treated with acid to obtain bleaching clay. Li bentonite is called hectorite; however, it is not mined at a commercial level like sodium or calcium bentonite [12].

### **4. Montmorillonite clay applications**

The variety of montmorillonite clay applications is significantly diverse. It is applied in areas of catalysis, wastewater treatment, food additive, antibacterial function, polymer, sorbent, etc. Some more specific applications include pelletizing (production of iron-ore pellets, civil engineering and construction work, drilling, impurities removal in oils, animal feed, producing paste composition in pharmaceutical, cosmetics and medical products, detergents, papers, etc. [13].

The significant development in the use and application of montmorillonite is seen in recent times. This chapter provides an overview of montmorillonite's structure and properties and particularly discusses its recent utilization in important materials. Montmorillonite is introduced in terms of its natural sources, chemical structure, physical and chemical properties, and functional utilization. The important physical and chemical properties are summarized as particle and layered structure, molecular structure and cation exchange effect, barrier property, and water sorption. This is followed by the important functional utilizations of montmorillonite based on the effects of its chemical structure. The important functional utilization of montmorillonite includes use as food additive for health and stamina, for antibacterial activity against tooth and gum decay, as sorbent for nonionic, anionic, and cationic dyes, and the use as a catalyst in organic synthesis. In terms of healthcare, the effects of montmorillonite clay are observed for body detoxification, resisting skin allergy and dermatitis, treatment of organism leading to diarrhea, antibacterial effects (killing large spectrum of bacteria), assisting renal health, providing drug delivery for cancer treatment, etc. [14].

The environmental concerns, to date, do not indicate the adversity for particles used as additives. Studies will be useful that are clearly based on any montmorillonite structure to describe environmental effects.

The broader application categories described in the market studies include molding sands, iron-ore pelletizing, pet litter, drilling mud, civil engineering, and agriculture.

### **5. Montmorillonite market**

For the last two decades, the trend in the industrial consumption of montmorillonite clay is progressive, and there are reports indicating the continuity of this trend for the next decade.

Montmorillonite clay market is divided into the United States, Mexico, Canada, Germany, Singapore, the U.K., Italy, Russia, France, Spain, China, India, Japan, South *Introductory Chapter: Montmorillonite Clay Consumption Trend in Industry DOI: http://dx.doi.org/10.5772/intechopen.101362*

**Figure 2.** *Sources for the study of industrial market study.*

Korea, Australia, Brazil, Colombia, Paraguay, Saudi Arabia, South Africa, Egypt, the UAE, and ASEAN countries. The details info and data can be seen in the market study reports, covering the worldwide montmorillonite clay (bentonites) market, the competitiveness of suppliers, market share, size, development rate, future patterns, etc. The discussion for future market trends and the factors that are driving the montmorillonite clay market are provided [15].

The study of the industrial market is based on research methodology that covers three important sources including primary research, secondary research, and expert panel reviews. Where secondary research utilized the sources including press releases, company annual reports, and research papers of the concerned industry. The study is refined using the associated sources of industry magazines, trade journals, websites of related government departments, and the trade associations [10].

The worldwide montmorillonite clay market, for period of 2020–2027, is estimated to move from USD 1238.7 million (2020) to USD 1630 million by 2027; the growth is forecasted at a CAGR of 4.0% (**Figure 2**) [16].

Reducing consumption trend in montmorillonite clay was seen in 2008–2009. However, start recovering the market in 2010. For example, global production of bentonite was reduced by a further 5% in 2010 relative to 2009, and a reduction of 9% in 2009 relative to 2008. The fall was perceived as the decreased demand by the end-user market.

In the following year, the consumption was recovering. Therefore, bentonite production of more than 11 million tons was globally observed in 2011. US Geological Survey estimated the worldwide reserves to be over 10 billion tons [17].

### **6. Conclusion**

Montmorillonite clay is an important material to produce a large variety of products for the industrial consumption around the world. In addition to meeting the requirement for the environment and sustainability, the montmorillonite clay is known for its inexpensive, abundance, and natural character. It is fascinating to see

### *Montmorillonite Clay*

clay as the oldest material consumed in human civilization, and in the 21st century, it appears to be the latest material in modern human society.

Clay as a material has an extensive variety of uses and application. Many of the uses of clay are traditional; however, an increasing interest in clay research and innovation is providing continuous breathing to its global market consumption. The interesting clay consumption in traditional sectors including civil structure, paint, construction products, plastic, etc., coupled with more specialized uses in medical, healthcare, and industrial applications demonstrate the current and future viability of clay consumption.

The reported research literature introduced the use of montmorillonite clay in particular application, or demonstrate its effect in specific material. The data on the consumption of montmorillonite clay is based on products categorized by the industrial application. Therefore, this chapter provides an overview of montmorillonite clay consumption using the market research reports. It indicates the important market regions, suppliers, industrial product areas and applications of montmorillonite clay. If necessary the discussion is supported with the particular research study.

### **Conflict of interest**

There is no conflict of interest in the publication of this manuscript.

### **Author details**

Faheem Uddin Asian Institute of Fashion Design, Iqra University, Karachi, Pakistan

\*Address all correspondence to: dfudfuca@yahoo.ca

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Introductory Chapter: Montmorillonite Clay Consumption Trend in Industry DOI: http://dx.doi.org/10.5772/intechopen.101362*

### **References**

[1] Uddin F. Clay, nanoclay and montmorillonite minerals. Metallurgical and Materials Transactions A. 2008;**39**(12):2804-2814

[2] Uddin F. Montmorillonite: An introduction to properties and utilization. In: Zoveidavianpoor M, editor. Current Topics in the Utilization of Clay in Industrial and Medical Applications. Mansoor Zoveidavianpoor, ed.; London, UK: IntechOpen; 2018. DOI: 10.5772/ intechopen.77987

[3] Agarwal A, Raheja A, Natarajan TS, Chandra TS. Effect of electrospun montmorillonite-nylon 6 nanofibrous membrane coated packaging on potato chips and bread. Innovative Food Science and Emerging Technologies. 2014;**26**:424-430

[4] Robinson A, Johnson NM, Strey A, Taylor JF, Marroquin-Cardona A, Mitchell NJ. Calcium montmorillonite clay reduces urinary biomarkers of fumonisin B1 exposure in rats and humans. Food Additives and Contaminants: Part A. 2012;**29**(5):809- 818. DOI: 10.1080/19440049.2011. 651628

[5] Maria HJ, Lyczko N, Nzihou A, Joseph K, Mathew C, Thomas S. Stress relaxation behavior of organically modified montmorillonite filled natural rubber/nitrile rubber nanocomposites. Applied Clay Science. 2014;**87**:120-128. DOI: 10.1016/j.clay.2013.10.019

[6] Ma J, Lei Y, Khan MA, Wang F, Chu Y, Lei W, et al. Adsorption properties, kinetics & thermodynamics of tetracycline on carboxymethylchitosan reformed montmorillonite. International Journal of Biological Macromolecules. 2019;**124**:557-567

[7] Anon. 2021. Available from: https:// www.transparencymarketresearch.com/ industrial-clay-market.html [Accessed: 2 September 2021]

[8] Anon. 2021. Available from: https:// www.marketwatch.com/press-release/ montmorillonite-clay-marketconsumption-companies-and-industryreport-2021-2030-marketbiz-2021-06-18 [Accessed: 2 September 2021]

[9] Anon. 2021. Available from: https:// www.wboc.com/story/43563723/ montmorillonite-clay-market-2021-isestimated-to-clock-a-modest-cagr-of-40nbspduring-the-forecast-period-2021-2026-with-top-countries-data [Accessed: 2 September 2021]

[10] Anon. 2021. Available from: https:// www.marketresearchintellect.com/ product/global-montmorillonite-claybentonites-consumption-market-sizeand-forecast/ [Accessed: 2 September 2021]

[11] Anon. 2021. Available from: https:// www.marketresearch.com/QYResearch-Group-v3531/Global-Montmorillonite-Clay-Bentonites-Research-11763149/ [Accessed: 2 September 2021]

[12] Anon. 2021. Available from: https:// www.absolutereports.com/enquiry/ request-sample/13870613 [Accessed: 2 September 2021]

[13] EUBA (European Bentonite Association). What is Bentonite. Available from: www.ima-europe.eu [Accessed: 2 September 2021]

[14] Moosavi M. Bentonite clay as a natural remedy: A brief review. Iranian Journal of Public Health. 2017;**46**(9): 1176-1183

[15] Anon. 2021. Available from: https:// www.ktvn.com/story/44226362/ Montmorillonite-Clay-(Bentonites)- Market-Size-2021-with-Top-Countries-Analysis,-COVID-19-Impact-on-Players,-Industry-by-Share,-Global-Trends,-Demand-and-Future-Scope-Forecast-to-2025 [Accessed: 2 September 2021]

[16] Anon. 2021. Available from: https:// www.americanrodeo.com/story/ 44616387/global-montmorillonite-claymarket-to-reach-usd-1630-milliongrowing-at-cagr-of-4-forecastperiod-2021-2027 [Accessed: 2 September 2021]

[17] Hughes E. Bentonite: A swelling market. 2012. Available from: https:// www.indmin.com/Article/3122191/ Bentonite-a-swelling-market.html [Accessed: 2 September 2021]

Section 2

## Structure and Properties

### **Chapter 2**

## Study of Adsorption Properties of Bentonite Clay

*Reda Marouf, Nacer Dali, Nadia Boudouara, Fatima Ouadjenia and Faiza Zahaf*

### **Abstract**

The clay used in this study was the bentonite from Mostagnem, Algeria. This material is used in many fields such as drilling, foundry, painting, ceramics, etc. It can also be applied in the treatment of wastewaters from chemical industries by means of adsorption. In this chapter the physicochemical properties of bentonite were determined by using several analyses techniques such as chemical composition, XRD, FTIR and SBET. The bentonite was intercalated by aluminum polycations solution and cethytrimethyl ammonium bromide. The acid activation of natural bentonite was performed by treatment with hydrochloric acid at different concentrations. The surface water pollutants removed by the modified bentonites are bemacid yellow E-4G and reactive MX-4R dyes, and fungicide chlorothalinil. The Langmuir and Freundlich adsorption models were applied to describe the related isotherms. The pseudo-first order and pseudo-second order kinetic models were used to describe the kinetic data. The changes of enthalpy, entropy and Gibbs free energy of adsorption process were also calculated.

**Keywords:** montmorillonite, bentonite, adsorption, dyes, fungicide

### **1. Introduction**

Bentonite clay is a volcanic rock that was deposited as volcanic ash in fresh or salt water millions of years ago. It was first discovered in 1890 in Wyoming (Montana, USA) near the Fort Benton site, hence its name. Currently there are a large number of bentonite deposits in the world, in USA, in Europe, in North Africa, in Japan, in China … In Algeria, the most economically important bentonite deposits are found in the west. We note in particular the quarry of Maghnia (Tlemcen) with reserves estimated at one million tons and that of M'zila (Mostaganem) with reserves of two million tons [1, 2].

Bentonite is very soft plastic clay composed mainly of montmorillonite, a clay mineral 2: 1 type of phyllosilicate family formed of fine particles. Montmorilonite consists of two tetrahedral layers (SiO4) separated by an octahedral layer (Al(OH)6), its chemical formula is (Al, M2+)2 Si4 O10 (OH)2, n H2O with M2+ = Mg, Fe, … (**Figure 1**) [3]. The total thickness of the sheet is approximately 14 Å. Montmorillonites has a negative charge on the surface, neutralized by compensating cations, the main origin of this surface charge comes from isomorphic substitutions resulting from the replacement of the metal cations of the lattice by cations of the same size but of lower charge (the substitution Al3 + by Mg2 + or Fe2+ and the substitution of Si4 + by Al3 +).

**Figure 1.** *Montmorillonite structure.*

Bentonite has a privileged place in the purification of water [4, 5]. High specific surface area, chemical and mechanical stabilities, layered structure, high cation exchange capacity (CEC), tendency to hold water in the interlayer sites, and the presence of Brønsted and Lewis acidity have made clays excellent adsorbent materials [6, 7]. The chemical nature and pore structure of bentonite generally determine their adsorption ability [8, 9].

The adsorption properties of natural clay minerals can often be improved either by intercalation of organic, inorganic, or organometallic molecules in the interlamellar space, or by heat or acid treatments [10, 11]. XRD measurements show that intercalation increases the spacing between layers. Among these modifications, the insertion of clays by poly cationic solutions has been used widely in recent years [12, 13]. In addition to their catalytic power, they are presented as excellent adsorbents. The main qualities that these pillared clays can develop are a high specific surface area and a large pore volume.

For the poly cation intercalation pillars to execute correctly, the synthesis protocol must pass through three steps: the first is to prepare the pillaring solution based on multivalent cation such as Al3+, Fe3+ or Cr3+. The second is the impregnation of the polycationic solution within the interlayer space [10, 14]. The last step is the calcination at temperature between 400 and 500 °C in order to solidify the pillars [15]. Some examples for montmorillonite intercalating by polycations cited in literature are the following: china montmorillonite was pillared by solution of Al13 polycations to eliminate cadmium [16], the bentonite of Turkish origin pillared with Fe and Cr was applied as adsorbent for carbon oxide (CO2) and hydrogen H2 [17], the Al/Ti and Al/Zr- pillared montmorillonites from Brazilian Amazon was used for zinc cation removal [18] and Fe/Zr-pîllared montmorilointe (Guangdong, China) was tested for Cr(VI) removal [19].

The organic intercalation of montmorillonite can significantly enhance the organophilicity of the resultant product. Cationic organic compounds, such as surfactant cations, exchange the interlayer cations of montmorillonite [20], and the resulting organoclay is excellent for diverse organic pollutants, e.g. phenol [21], dye [22], and VOCs [23, 24]. Quaternary alkylammonium compounds (bromides or chlorides) are the most commonly employed for intercalation into bentonites. Due to their long-chain they offered to the clays a larger interlayer spacing. The most quaternary ammonium surfactants used are cethyltrimethyl ammonium bromide

### *Study of Adsorption Properties of Bentonite Clay DOI: http://dx.doi.org/10.5772/intechopen.96524*

(CTMAB), tetramethyl ammonium (TMA), trimethyl-phenyl ammonium (TMPA), dodecyl trimethyl ammonium and dimethyl sulfoxide (DMSO).

Unfortunately, sometimes the insertion of a surfactant weakens the specific surface of an organo-clay. To remedy this disadvantage, it's preferable to combine the intercalation of organic pillar with another mineral. For example, Jiang et al. used hexadecyltrimethyl ammonium bromide added to Al/Fe-pillared montmorillonite [25]. Zhu's group prepared an intercalated montmorillonite with both hexadecyltrimethyl ammonium bromide and Al13 cations, and discussed the influence of the addition sequence of these two modifiers on the final products [26].

Another method applied to improve adsorption capacity of bentonite consists of the reaction of clay minerals with a strong mineral acid solution, usually hydrochloric acid (HCl) or sulfuric acid (H2SO4). Acid activation leads to modification of Mt. with improved properties such as enhanced surface area, pore diameters, number of acid sites, and catalytic activities. The treatment of the naturally occurring and purified Mt. with hot mineral acid replaces exchangeable cations with H<sup>+</sup> ions. Gradual leaching of Al3+ out of both tetrahedral and octahedral sites occurs, but the silicate groups remain largely intact [27, 28].

Dyes released into wastewaters of different industrial plants such as dye manufacturing, textile, paper and food, are toxic, not degradable and stable. The presence of these substances in the surface waters can be carcinogenic and causes damage to human beings, such as dysfunction of kidneys and central nervous system [29, 30].

Pesticides are synthesized substances or biological agents used for attracting any pest. They are mainly applied in agriculture to protect crops from insects, weeds, and bacterial or fungal diseases during growth [31]. Some pesticides, like fungicides are used to kill or inhibit growth of fungi or insects that parasitize crops [32]. Pesticides originating from human activity can also enter water bodies through surface runoff, leaching, and/or erosion. Pesticides can cause endocrine disruptions and neurological disturbancies, influence immune system, reproduction and development [33].

Wastewaters containing dyes or pesticides are often treated by conventional methods as ozonation, membrane filtration, reverse osmosis, oxidation, ion exchange coagulation and adsorption [34–38]. Adsorption is considered as an attractive and favorable alternate for the removal of dyes and other organic molecules from wastewater streams. Many efforts have been made to find an appropriate adsorbent. Clay adsorbents enable to adsorb anionic and cationic pollutants such as dyes, pesticides and metal ions.

In this context, the present chapter focused in the application of Mostaganem bentonite in the treatment of natural water contaminated by dyes and pesticide. We will also study the phenomenon of adsorption of these pollutants through the use of mathematical models to determine the reaction mechanism, kinetics and thermodynamics of adsorption.

### **2. Materials and methods**

Bentonite used in this investigation was purchased from M'zila deposit (Mostaganem, Algeria). This material is commercialized as industrial charge bentonite without additives by ENOF Company. The physicochemical properties of bentonite are resumed in chemical composition, point of zero charge, cation exchange capacity (CEC) and different analyses techniques such as XRD, FTIR, SEM and Specific surface area (BET).

The aim of the present study was the adsorption of two dyes, acid yellow E-4G and reactive yellow MX-4R. For this purpose two adsorbents were used: (i) bentonite intercalated by hydroxy-aluminum cations, (ii) bentonite pillared by cethyltrimethyl ammonium cation.

Bemacid Yellow E 4G (C.I. acid Yellow 49) and reactive Procion Yellow MX 4R (C.I. Reactive Yellow 14) were supplied by SOITEX textile society (Tlemcen, Algeria). The chemical formula and molecular weight of E-4G and MX-4R are C16H13Cl2N5O3S; 426.24 g/mol and C20H19ClN4Na2O11S3; 669.02 g/mol, respectively. A stock solution (1.0 g/L) of dye was prepared by dissolving accurate weight amount in deionized water and the other concentrations were obtained by dilution of this stock dye solution.

The product chlorothalonil (Chl) fungicide was removed by acid activated bentonite from aqueous solution. Chl was obtained by Syngenta Protection of Plants S.A, Bale, Switzerland. It contains 400 g/L of chlorothalonil in the form of concentrated suspension with some impurities. The Chl is an inhibitor of spore germination, which acts on various enzymes and on the metabolism of fungi. The chemical formula of Chl is C8Cl4N2, and its molecular weight is 265.93 g/mol. The solubility of chlorothalonil in water is 0.6 mg/L at 20 °C.

### **2.1 Preparation of pillared bentonite**

The Al(III)-modified bentonite was obtained by mixing AlCl3 solution (0.2 mol/L) with sodium hydroxide solution (0.2 mol/L) at 60 °C, up to the molar ratio OH− /Al3+ = 2 [39]. The solution was aged at room temperature for three days before using. The resulting pillaring solution was added to the bentonite by stirring for 4 h at 70 °C at the ratio of 50 mmol oligomeric cations per gram of bentonite [40]. The slurry was stirred for 24 h at room temperature, filtered, and washed repeatedly with deionized water. The solid was dried at 80 °C and kept in a sealed bottle. The pillared bentonite obtained was designated as B-Al.

### **2.2 Preparation of CTAB-intercalated bentonite**

The surfactant CTAB intercalated bentonite was synthesized as follows: the amount of CTAB (175 mg) corresponding to 1.0 times CEC of bentonite was dissolved in 1 L of distilled water at ambient temperature and stirred for 24 h. A total of 1 g bentonite was added to 100 mL surfactant solution. The dispersion was stirred for 4 h at 60 °C. The separated sample was washed several times and dried at 80 °C. The final product was noted as B-CTAB.

### **2.3 Acid activation of bentonite**

Raw bentonite was treated by hydrochloric acid (HCl) (37% purity, Merck) at different concentrations (0.1, 1 and 6 N) at 70 °C. The amounts of 4 g of each treated sample were added to 400 mL of acid solution [41]. The contact time of the samples with the acid solution was fixed as 4 hours. At the end of treatment, the bentonite was washed several times with distilled water and dried over night at 80 °C [42].

### **2.4 Adsorption experiment**

The adsorption experiments were carried out in a series of Erlenmeyer flasks containing 0.1 g of B-Al or B-CTAB and 20 mL of dyes aqueous solution at the desired concentration and initial pH (adjusted with hydrochloric acid 0.1 N or

0.1 N NaOH) in ambient temperature bath (23 °C). After shaking for 3 h of contact time, the flasks were removed and the concentration of MX-4R and E-4G after the adsorption was analyzed by spectrophotometer at wavelength of 425 and 400 nm, respectively. The adsorbed amount of dye (mg/g) was calculated as follow:

$$q\_{\epsilon} = \left(\mathbf{C}\_{0} - \mathbf{C}\_{\epsilon}\right) \cdot \frac{V}{m} \tag{1}$$

where, *q*e (mg/g) is the equilibrium adsorption capacity, *C*0 the initial dye concentration, *C*e the equilibrium dye concentration (mg/L), *V* the volume of solution (L) *m* is the mass of the adsorbent (g).

The chlorothalonil was prepared in the range of initial concentrations 100–500 mg/L, in order to know the maximum amount of fungicide that bentonite can adsorb. For each experiment, 20 mL of pesticide solution was added to 0.1 g of the solid. The suspension was shaken at room temperature (23 °C) for 3 h. The chlorothalonil was detected by spectrophotometer at wavelength of 360 nm.

### **3. Results and discussions**

### **3.1 Characterization of raw and modified bentonite**

The chemical analysis of raw bentonite was performed by X-fluorescence XRF 9900. Thermo Instrument. The result of this analysis revealed that the silica (64.22%), alumina (11.62%) and lime (9.33%) are the main oxides of the bentonite with the existence of the others oxides in the small amounts such as Fe2O3 (4.88%), TiO2 (1.06%), Na2O (3.38%) and P2O5 (0.03%). The elementary analysis of M'zila bentonite gives the formula Na0.13, Ca0.01, K0.10, (Al1.24 Mg0.2 Fe0.17 Ti0.01) (Si4.24) O10 (OH)2 with mass molar 368.68 g/mol [43].

The pHPZC value purified bentonite was found as 6.8. This value informs us about the electric charge on the solid surface. At pH value below than pHPZC the electrical charge on the surface is positive, it will be negative at pH higher than pHPZC. Cation exchange capacity of natural bentonite was determined to be 112 meg/100 g by applying the conductimetric titration method [44]. The BET specific surface area measured via Quantachrome instrument was found 59.02 m<sup>2</sup> /g.

The diffractogram of raw bentonite was shown in **Figure 2**. The bentonite sample contains some mineral phases such as the Montmonrillonite (M), Kaolinite (K), Calcite (C), Quartz (Q ) and Dolomite (D). The characteristic peak d001 of montmorillonite appears at 2θ = 5.5°, the kaolinite is observed at 2θ = 10° and the peak of calcite appears at 2θ = 31°.

The FT-IR spectrum of raw bentonite was performed with Agilent Cary 630 Spectrometer in range of 4000–400 cm−1. The FT-IR analysis illustrated in **Figure 3** shows an intensive band at 1000 cm−1 which is attributed to the Si-O in plan stretching vibration and other bands at 520 and 470 cm−1 assigned to Al- O- Si (octahedral Al) and Si- O-Si bending vibrations, respectively [45]. The small band at 1620 cm−1 is attributed to the deformation vibrations of the O–H bond of the constitution water. The band at 3620 cm−1 is assigned to hydroxyl groups Al3+ is partially replaced by Fe3+ and Mg2+.

The images of scanning electron microscope were made by microscope JSM-6360 to observe the morphology of bentonite particles. According to the **Figure 4** the particles were formed by heterogeneous aggregates of different shape and size. It appears that these grains constitute a stack of sheets probably representing the

**Figure 2.** *XRD pattern of raw bentonite.*

**Figure 3.** *FT-IR spectra of raw bentonite.*

clay layers. On the surface of the sample, a small luminous crystallite settles, may be of free silica (quartz).

According to the XRD analysis realized with INEL CPS 120 instrument employing cobalt radiation (λ = 0.178 nm), the hydroxy-aluminum polycations exchange increases the *d*001 value to 14.3 Å, but the peak was much less intense compared to that of natural bentonite (**Figure 5**). The reduction in diffractogram might be caused by collapsing of the Mt. layers due to partial incongruent phase transition of hydroxy-Al into Fe/Al oxides and their interactions during aging and drying, as suggested by Thomas et al. [46].

The addition of surfactant causes the increasing of basal spacing of the bentonite around 18 Å, indicating location of CTA+ ions between layers of montmorillonite. In order to increase more again the basal spacing, it must be increase in CTA+ concentration, because as known, the amount of added surfactant has a direct effect on the interlayer expansion of Mt.

The pillaring bentonite with hydroxy-aluminum and CATB generated an enhancement of specific surface area where the values found were 110 and 194.4 m<sup>2</sup> /g for B-Al and B-CTAB, respectively. These values were very higher than that of untreated bentonite (59.02 m<sup>2</sup> /g). In the case of Al-modified bentonite the specific surface area was increased significantly but a slight increase was noted

#### **Figure 4.**

*SEM images of natural bentonite extension 3000 and 9000.*

**Figure 5.** *XRD patterns of natural and pillared bentonitew.*

through the basal spacing. This is due to the existence of electrostatic bonding between the negatively charges layers and pillaring oligocations in uncalcined Al-pillared clay.

The second application deals with the acid activation of Algerian bentonite and testing of his capacity to remove the chlorothalonil fungicide in aqueous solution. The hydrochloric acid solutions were used in the concentration range of 0.1-6 N.

The specific surface area of bentonite treated by 1 N (BA1N) and 6 N (BA 6 N) of hydrochloric acid were determined as 82.22 and 80.55 m<sup>2</sup> /g, respectively. We see that the specific surface areas of both activated bentonites are almost identical, which are much higher than that of the raw bentonite (59.02 m<sup>2</sup> /g). The specific surface area greatly increases at the acid concentration of 1 N, but slightly decreases at the concentrations higher than this value and then does not change much. Similar results were found by activating bentonite with sulfuric acid [47, 48].

The XRD patterns of raw and activated bentonites at various concentrations (0.1, 1 and 6 N) were shown in **Figure 6**. We note that there is no difference between the spectra of BN and BA 0.1 N. The concentration of 0.1 N of hydrochloric solution seems not be sufficient to make significant changes in the structure of

**Figure 6.** *XRD patterns of raw and activated bentonites.*

bentonite. This means that it is a cation exchange causing the substitution of the exchangeable cations of interlayer space by protons H<sup>+</sup> . In contrast to the sample treated with 0.1 N, the samples BA 1 N and BA 6 N undergo a significant structural modification according to the XRD spectra, where we notice that the peaks of montmorillonite and the kaolinite almost disappeared, while that of the illite is reduced in intensity. So from 1 N concentration of HCl, the clay minerals of bentonite are exposed to the direct effect of acid leading to the destruction of the basic clay sheets.

This process generally increases the surface area and the acidity of the clay minerals [49].

### **3.2 Adsorption isotherms of dyes and models fitting**

The adsorption isotherms are realized at different initial concentrations of dyes, adsorbent dose was 5 g/L, and pH effect was tested and maximum adsorbed amount of dye was noted at pH = 2–3. The isotherms are formed by amount of dye adsorbed by the plot vs. equilibrium concentration. The adsorption isotherms of MX-4R and E-4G by the pillared bentonites are presented in **Figure 7**. The results show that the amount of dye adsorbed increases with the increase in equilibrium concentration of dye. All isotherms are of S-shape according to the classification of Giles et al. [50]. This type of isotherm originates from the cooperative isothermal adsorption, i.e. the adsorbed molecules promote higher adsorption of other molecules and tend to be adsorbed in groups. The maximum adsorbed amounts registered were 93.91 and

*Study of Adsorption Properties of Bentonite Clay DOI: http://dx.doi.org/10.5772/intechopen.96524*

**Figure 7.**

*Adsorption isotherms of (a) MX-4R and (b) E-4G onto B-Al and B-CTAB. (C0 = 200–500 mg/L, pH = 2–3, adsorbent dose 5 g/L, contact time 3 h)*

92.75 mg/g for MX-4R and E-4G respectively, attributed to B-CTAB sample. Those of B-Al adsorbent were 66.08 and 87.72 mg/g, respectively. According to these results, the B-CTAB sample has adsorption capacity most important than that of B-Al for the both dyes, in same operating conditions.

The adsorption isotherms were fitted by Langmuir and Freundlich equations expressed in linear forms in relations (2) and (3), respectively:

$$\frac{C\_{\epsilon}}{q\_{\epsilon}} = \frac{C\_{\epsilon}}{Q\mathbf{O}} + \frac{1}{K\_{L}Q\mathbf{O}}\tag{2}$$

where *Q*0 is the maximum adsorption capacity (mg/g), and *K*L(L/mg) is a constant that relates to the heat of adsorption.

$$\log q\_{\epsilon} = \log K\_F + \frac{1}{n} \log Ce \tag{3}$$

*K*F and *n* are the Freundlich constants, indicating the capacity and intensity of adsorption, respectively.

The Langmuir and Freundlich constants and the linear regression correlations (R<sup>2</sup> ) for both isotherms model are listed in **Table 1**. The results reveal that the adsorption isotherms correlate with Freundlich model because the correlation coefficient (R<sup>2</sup> ) values obtained were above 0.98, while the model of Langmuir describes less well the experimental data where the linearization constants were insignificant except in the case of MX-4R. However Freundlich model is well used to describe the adsorption behavior of dyes on the both materials. This can be explained by the fact that the Langmuir equation is valid for monolayer adsorption onto a surface containing a finite number of identical sites, while Freundlich isotherm represents satisfactorily the sorption data on heterogeneous surfaces.

### **3.3 Adsorption kinetics of dyes**

To evaluate the adsorption rate, the adsorption kinetic was examined by pseudo-first order and pseudo-second order models. The evolution of adsorption capacity of MX-4R and E-4G dyes increases over time and attained an equilibrium state around 60 min. The adsorption rates of the E-4G and MX-4R by intercalated bentonites are rapid early in the process and becoming slower over time. The


**Table 1.**

*Linearization constants of Langmuir and Freundlich equations.*

pseudo-first order kinetic using the linear Lagergren equation is generally expressed as follows [51]:

$$\ln\left(q\_{\epsilon} - q\_{\epsilon}\right) = \ln q\_{\epsilon} - k\_{\text{1}}t \tag{4}$$

where *q*t is amount adsorbed of dye at time *t* (mg/g) and *k*1 is the rate constant of the pseudo-first order model (min−1). The *k*1 and *q*e were calculated from the slope and intercept of plots ln(qe-qt) versus *t,* respectively.

The pseudo-second order kinetic is expressed as follows [52]:

$$\frac{t}{q\_t} = \frac{1}{k\_2 q\_e^2} + \frac{t}{q\_e} \tag{5}$$

where *k*2 is the rate constant of the pseudo-second order model for the adsorption process (g/mg.min). Plots of t/qt against *t* have been drawn to obtain the rate parameters.

The calculated qe values agree with the experimental qe values, and the correlation coefficients for the pseudo-second-order kinetic plots were also found to be very high (R<sup>2</sup> = 0.98), indicating that pseudo-second order model fitted very well the kinetic adsorption. The pseudo second order model is based on the assumption that the rate limiting step may be chemisorption which involves valence forces by sharing or electron exchange between the adsorbent and the adsorbate [53]. According to the **Table 2**, the rate constants increase from 0.002 and 0.011 g.mg−1 min−1 (B-CTAB) to 0.922 and 0.912 g.mg−1 min−1 (B-Al). This means that the adsorption of dyes onto B-Al is a fast reaction, and CTABmodified bentonite has a best adsorption capacity due to its high porosity and its large specific surface area.

### **3.4 Adsorption isotherms of chlorothalonil**

The **Figure 8** shows the adsorption of Chl by the activated bentonite. This figure indicates that the adsorbed amount of Chl onto raw and activated bentonite increases in parallel with the equilibrium concentration. The experimental isotherm obtained here may be classified as type S referring to the classification of Giles et al. This type of isotherm originates from the cooperative isothermal adsorption, i.e. the adsorbed molecules promote higher adsorption of other molecules and tend to be adsorbed in groups. We note also that the activated bentonite adsorbs much better than the natural bentonite. When the activated

*Study of Adsorption Properties of Bentonite Clay DOI: http://dx.doi.org/10.5772/intechopen.96524*


### **Table 2.**

*Constants rates of the E-4G and MX-4R adsorption by B-Al and B-CTAB.*

**Figure 8.** *Adsorption isotherms of Chl onto activated bentonite.*


### **Table 3.**

*The constants of Freundlich model.*

samples were compared, it was found that the maximum amount of adsorption (38.42 mg/g) was observed for BA 1 N.

The isotherm model fit the experimental data very well is Freundlich model. The Freundlich equation is an empirical equation that can be used for heterogeneous systems with interaction between the molecules adsorbed. As seen from **Table 3**, the values of regression coefficients R<sup>2</sup> were close to the unit and the 1/n values were less than unity which indicates that the adsorption intensity was favorable and was a physical process. On the other hand, the experimental data fitted by Langmuir model were insignificant in terms of adsorption; this is why they are not mentioned.

### **3.5 Adsorption heats of chlorothalonil**

In the case of adsorption of molecules on a solid surface, the Gibbs energy is composed of two functions, the enthalpy function (*H*), which is measure of the energy of interaction between the molecules and the adsorbent surface, and the entropy function (*S*), which reflects the change and the arrangement of molecules in the liquid phase and on the surface. The free energy *ΔG* was calculated according the following relation:

$$
\Delta \mathbf{G}^0 = \Delta H^0 - T\Delta \mathbf{S}^0 \tag{6}
$$

The distribution coefficient Kd (L/g) is calculated from the following Equations [54, 55]:

$$
\ln K\_d = \frac{\Delta S^0}{R} - \frac{\Delta H^0}{RT} \tag{7}
$$

$$K\_d = \frac{\left(C\_0 - C\_\epsilon\right)}{C\_\epsilon} \cdot \frac{V}{m} \tag{8}$$

where *ΔH°*, *ΔS°*, and *T* are the adsorption enthalpy (kJ/mol), entropy (J/mol.K) and temperature in Kelvin, respectively, and *R* is the gas constant (8.31 J/mol.K). The slope and intercept of the plot of ln Kd versus 1/T correspond to *ΔH°/R* and *ΔS°/R*, respectively.

It can be seen from **Table 4** that the calculated *ΔG°* values have negative signs, indicating that the adsorption process is spontaneous in the experimental conditions and the spontaneity increases with increasing of temperature. All enthalpy values are positive, showing that the adsorption process is endothermic. The magnitude of enthalpy values suggests that the adsorption of Chl onto activated bentonite was physic in nature. The entropy values were positive that means the molecules disorder was located in interface solution/solid.


**Table 4.**

*Heats adsorption of Chl onto activated bentonite.*

### **4. Conclusions**

In this research we studied the characteristics and the physicochemical properties of an Algerian bentonite which its adsorption capacity was tested to eliminate organic pollutants from aqueous solution.

Before the adsorption experiment, bentonite underwent two different treatments in order to improve its exchange capacity and porosity. The first treatment carried out is that of the pillaring clay with mineral (polycations of Al13) and organic (CTAMB) intercalants. The second is the treatment by acid attack (HCl) at different concentrations (0.1, 1 and 6 N).

The intercalation of the bentonite by Al13 and CTAB increased the basal sheet space up to 14.3 and 18 Å, respectively. The chemical activation with HCl at 6 N concentration enhanced the specific surface area of the bentonite from 59.02 to a value of 82 m<sup>2</sup> /g. The obtained materials from the both treatments were applied for the adsorption of MX-4R, E-4G dyes and the fungicide chlorothalonil.

The adsorption isotherms of these pollutants have shown that the adsorption capacities were very satisfactory and the adsorption phenomenon was physical nature. The adsorption isotherms of all adsorbates were well described by Freundlich model. Kinetic data of dyes adsorption tend to fit well in pseudo-second order rate expression. Moreover the adsorption of chlorothalonil by activated bentonite was spontaneous and this spontaneity increases with increasing temperature.

### **Conflict of interest**

The authors declare no conflict of interest in publishing this chapter.

### **Author details**

Reda Marouf\*, Nacer Dali, Nadia Boudouara, Fatima Ouadjenia and Faiza Zahaf Faculty of Exacts Sciences, Laboratory of Materials, Applications and Environment, University Mustapha Stambouli of Mascara, Algeria

\*Address all correspondence to: r.marouf@univ-mascara.dz

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Section 3

## Montmorillonite Composite

### **Chapter 3**

## Reinforcement of Montmorillonite Clay in Epoxy/Unsaturated Polyester Blended Composite: Effect on Composite Properties

*Chakradhar V.P. Komanduri*

### **Abstract**

Montmorillonite (MMT) clay was disseminated into Unsaturated Polyester (UP) and Epoxy blend systems in diverse weight ratios namely, 0, 1, 2, 3, and 5% to prepare Epoxy/UP/MMT clay composite. The specimen was characterized by thermal and chemical analysis. Homogeneous mixture of blended composites is obtained through mechanical stirring and ultrasonication processes. The testing of thermal and chemical properties was performed. Evidence acquired from the above tests indicate that Epoxy reinforced with UP and further strengthened with MMT clay enhanced the thermal and chemical properties of the composite to a considerable extent. The purpose of this study was to recognize an appropriate composite offering a stronger material with enhanced performance; that is suitable for diverse industrial uses.

**Keywords:** montmorillonite clay, epoxy, unsaturated polyester, thermal properties, chemical properties

### **1. Introduction**

Polymer blending attained an appreciable market, since they save by weight approximately 36–40% of polymer consumption. Epoxy is a flexible, popular resin used for manufacturing state-of-art composites since it has superior binding, thermal, mechanical and aging characteristics [1, 2]. But for enhancement of impact attribute in state-of-art engineering uses, reinforcing epoxy is required. It can be improved through mixing with adaptable polymers and elastomers. Nevertheless, alteration of epoxy with elastomers enhances its toughness property besides drop in few properties of epoxy at elevated temperatures [3–5]. Hence, an apt polymer is needed to improve the toughness of epoxy, by preserving stiffness, glass transition temperature, and heat stability. It is accomplished by an inter cross-linked polymer network of thermoset-thermoset blends [6–10].

A good range of commercial relevance to polyester resins is identified in areas like paints and surface coatings. Several merits of polyester are observed with inclusion of flexibility in properties, reasonable cost and ease of use. But polyester possesses some demerits such as inferior resistance to alkalis and hardness. For overcoming the above-mentioned demerits, blending of polyester with suitable

resins can be performed as it exhibits better compatibility with diverse resins. The technique of blending can be productively applied to eliminate the substandard properties of both components. Blended polymers provide superior composite from lesser superior components.

The merits of nano-particles over conventional macro or micro particles are improved surface area and aspect ratio which could improve binding of nanoparticles and polymers. Presently the most popular clay used for polymer-clay composites is MMT. Various studies were conducted on epoxy-clay composites (ECN) under different curing conditions. The exfoliated clay provides superior properties and offers advantages over other nanofillers in terms of cost and biodegradability [8, 9]. This paper furnishes facts on the property's analysis of the MMT clay reinforced polymer blended composites. The intention of this study was to recognize a composite that offers better strength, providing better performance at minimum cost; applicable for diverse applications.

Composites are influenced by chemical and thermal properties. Thermal and chemical properties of materials play an equally important role as mechanical properties. Polymers are very vulnerable to changes in temperature. Plastics tend to become rigid and brittle at minimal temperatures. The portability of the polymer chain is greatly reduced at low temperatures, which is the reason for the above. The temperature and dimensions of solid increases as it absorbs heat. Further heating melts the solid. Thus, knowledge of heat properties of materials becomes crucial for assessing the performance of polymers and their reaction to thermal changes.

### **2. Experimental procedure**

### **2.1 Materials and methods**


Thermogravimetric analysis (TGA) and Differential scanning calorimetry (DSC-2010 TA Instrument) are employed to assess the heat attributes of the epoxy/ polyester/MMT clay blended composites [11]. The thermal degradation behavior of the composite blend is investigated using TGA. TGA is performed on a 10 mg powdered sample to identify changes in weight to corresponding changes in temperature. The sample is placed in a thermocouple fitted oven for precise temperature measurement. An inert gas atmosphere is used to suppress unwanted reactions. A computer monitors and controls the entire process. Steadily enhancing sample temperature until 1200°C, evaluation is performed. A graph of percentage weight Vs temperature is plotted [12].

Evaluation of Glass transition temperature (Tg) of the material and assessment of thermal deterioration of polymers is carried out using DSC [13]. Studies are performed under an inert atmosphere at 10°C/min scan rate and a temperature ranging from 30°C up to 600°C. A 10 mg powdered specimen is used for each run. Thermograms are plotted recording weight change with respect to temperature change. Weight change results from bond-forming or breaking at elevated

*Reinforcement of Montmorillonite Clay in Epoxy/Unsaturated Polyester Blended Composite… DOI: http://dx.doi.org/10.5772/intechopen.97431*

temperatures. Throughout the experiment identical temperatures are maintained for the sample and reference. Heat capacity over a span of temperatures was examined. When the sample undergoes phase transition, heat is required to flow to it and the reference to sustain them at similar temperatures. Suppose as a solid sample changes phase to liquid it needs more heat flow to enhance its temperature at the same pace as the reference. DSC can estimate quantity of heat taken in and discharged in sample and reference by perceiving variation in heat flow. DSC can also perceive precise change of state, like glass transitions. It is extensively applied in industries as a quality checking instrument to estimate sample clarity and to observe curing of polymers.

To analyze the chemical resistance of the composites, ASTM 543–87 test methodology is employed. Standard reagents are applied to confirm outcomes. In the existing work, tests on epoxy/UP/clay composites are conducted to identify the resistivity to chemicals. The reaction of acids, alkalis and solvents on the composite are studied. In each case, pre-weighed specimens (5 x 5 x 3 mm) of 10 numbers were dipped into the respective chemical reagents for twenty-four-hour duration.

### **2.2 Thermal properties**

The thermal properties analysis like TGA and DSC are performed on clay-filled epoxy/UP blended composite as per ASTM E1131 and ASTM D3418 respectively. The properties like degradation temperature and glass transition temperature are studied. In TGA, the heat stability of composite is studied as % weight loss vs. temperature.

### **2.3 Resistivity to chemicals**

ASTM 543–87 is employed to evaluate the chemical resistivity of the composite. In the present work, chemical resistivity tests on epoxy/UP/clay composites are conducted. In each case, ten specimens are tested. Pre-weighed specimens are dipped in chemical reagents for 24 hours. They are then removed from the chemicals, cleaned in distilled water, and completely dried at room temperature using filter paper. The specimens are again weighed and the % gain/decrease in weight is ascertained as shown below.

$$\% \text{gain} / \text{decrease in specimen weight} = \frac{\text{Original weight} - \text{Final weight}}{\text{Original weight}} \times 100 \tag{1}$$

The chemical reagents used in the study are mentioned below: *Acids:* Acetic acid, Nitric acid and Hydrochloric acid. *Alkalis:* Sodium hydroxide, Sodium carbonate and Ammonium hydroxide. *Solvents:* Benzene, Toluene, Carbon tetrachloride and Water.

### **2.4 Results and discussions**

### *2.4.1 Thermogravimetric analysis*

Heat stability of composites is analyzed using TGA. **Figure 1** indicates the weight loss of five different samples. In pure blend, loss in weight is constant up to 200°C and degradation starts at 400°C. As clay content is increased to 5 wt. % degradation temperature of the composite shifts upwards to higher temperatures. Until 350°C Weight loss is constant for 5 wt. %. Presence of moisture is the cause

### **Figure 1.** *Epoxy/polyester as a function of MMT clay-TGA.*

for drop in weight for 1 wt. % sample. Evidently, the degradation temperature of the composite shifts upwards to elevated temperatures, demonstrating enhanced heat stability for 5 wt. % clay [12, 13]. Presence of inorganic materials like clay is the cause for improved heat stability.

In comparison to pure blend 15% weight loss and a 10° C rise in degradation temperature are observed for 5 wt. % sample. The results indicate that better dispersion of polymer and clay are the reasons for higher heat stability [13].

### *2.4.2 Differential scanning calorimetry*

DSC investigates the thermal transitions of the pure polymer and the composites. A graph indicating glass transition temperatures for diverse clay weight percentages viz. for 0, 1, 2, 3, 4 and 5 wt.% at 430, 432, 433, 433, 431 and 429°C respectively of the composite is presented in **Figure 2**. A fall of 2°C glass transition temperature is noticed for 4 wt%., whereas a fall of 4°C is observed for 5 wt.% in comparison to 3 wt.%. Nil change is perceived for 2 and 3 wt. % samples. Similar changes in Tg are due to: (i) better surface interaction strengthening the interface (ii) enhanced interfacial free volume due to the lower bulk crystallinity of polymer chains. It is also found that the Tg of the Epoxy/UP composite decreases at higher montmorillonite loading.

### *2.4.3 Chemical resistance measurement*

From **Table 1** it is evident that the Epoxy/UP/MMT clay composite exhibits better resistivity to all chemicals considered for the study, except the solvents. In each case, the pre-weighed specimens are immersed in the chemicals, cleaned in distilled water and then dried. Nanocomposite blend specimens show a weight reduction on treatment with solvents. This is understandable as UP, that is present in the blend, dissolves in the solvents under study. These composites prove to be having good resistance to attack from chemicals except solvents. The highly expandable montmorillonite clay has caused maximum swelling in nitric acid in contrast to maximum weight loss in benzene due to its high cation exchange capacity. The increase in weight of the composite is due to the penetration of the liquid chemical resulting due to swelling of composite [14].

*Reinforcement of Montmorillonite Clay in Epoxy/Unsaturated Polyester Blended Composite… DOI: http://dx.doi.org/10.5772/intechopen.97431*

**Figure 2.** *Epoxy/polyester blend as a function of MMT clay-DSC analysis.*


**Table 1.**

*Experimental values, showing percentage change in weight of epoxy/UP/MMT clay composite*

### **2.5 Conclusions**

In the experimental analysis of thermal and chemical resistivity of MMT clay strengthened composite, the following conclusions were made.

From TGA it was observed that clay content does not affect the heat stability at 5 wt.% in comparison to pure and other combinations blends. A weight loss of 15% and rise of 10°C in degradation temperature were noticed in the TGA analysis, while 4°C fall in Tg is noticed in differential scanning calorimetry analysis for 5 wt. % clay combinations. The heat properties of the clay-filled composite are perceived to increase gradually and are observed to be the highest at 5 wt. % in comparison to other variants. The presence of clay, in the composite, improves the heat stability of the composites [11–13].

From DSC analysis it was observed that the glass transition temperature (Tg) of blended nanocomposites varied for 0, 1, 2, 3, 4 and 5 wt% clay contents at 430, 432, 433, 433, 432 and 429°C respectively. A 2°C decrease in glass transition temperature is observed for 4 wt% clay filled samples while 4°C decrease in glass transition temperature is observed for 5 wt% clay filled samples when compared with 3 wt% clay samples, where as no change is observed between the 2 and 3 wt. % clay samples. A 4°C decrease in glass transition temperature is observed for 5 wt% clay when compared with 3 wt% clay samples, where as no change is observed between the 2 and 3 wt% clay samples. The reduction in the values of Tg for unsaturated polyester toughened epoxy system may be due to the flexibility imparted by unsaturated polyester to the epoxy matrix [15].

The composite blend specimens show a weight reduction on treatment with solvents. This is understandable as Unsaturated Polyester (UP), that is present in the blend, dissolves in the solvents under study. The composite has good resistance to attack from acids and alkalis. The highly expandable montmorillonite clay has caused maximum swelling in nitric acid in contrast to maximum weight loss in benzene due to its high cation exchange capacity. The enhancement in weight of the composite is due to the penetration of the liquid chemical in the composite; resulting in swelling [14]. The epoxy/UP/clay composite can be used for applications like a) charge storage containers in vehicles (Nanoclay limits the diffusion of solvents into polymer) b) chemical containers (as the composite has good resistance to chemicals) and c) fire proof cables.

### **Author details**

Chakradhar V.P. Komanduri Department of Mechanical Engineering, Vardhaman College of Engineering, Hyderabad, Telangana, India

\*Address all correspondence to: chakradharkvp@vardhaman.org

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Reinforcement of Montmorillonite Clay in Epoxy/Unsaturated Polyester Blended Composite… DOI: http://dx.doi.org/10.5772/intechopen.97431*

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Section 4
