**4. Applications**

Organoclays have been used in various applications. These applications include adsorbents, rheological control agents, paints, grease, cosmetics, personal care products, and oil well drilling fluids. Currently, an important application of the organoclays is in pollutant adsorption. In fact, a view of the literature shows that various studies have shown that replacing the inorganic exchange cations of clay

minerals with organic cations can result in greatly enhanced abilities to remove various contaminants from water:

#### **4.1 Application of organoclay to remove fluoride, phosphate and nitrate**

Phosphate, fluoride and nitrate are essential nutrients in the aquatic environment, but excessive phosphate (above 0.02 mg/L), nitrate (above 0.02 mg/L) and Fluoride (above 1.5 mg/L) input may lead to eutrophication (causing degradation of water quality) respectively. Nowadays, the presence of fluoride, phosphate and nitrate in the environment has been identified as one of the acute problems worldwide. Organoclay has been successfully utilized for the removal of nitrate, phosphate and fluoride:

Gammoudi et al. prepared organoclay with smectite using two cationic surfactants (HDPy and HDTMA) for fluoride removal from wastewaters. The optimal condition suitable for defluoridation consists of low fluoride concentration, contact time equal to 6 h and acidic pH. These organoclays showed high removal capacities for fluoride ions [45].

Xi et al. prepared various Organoclays with on halloysite, kaolinite and bentonite for removal of nitrate. The results showed that all these raw clays showed poor adsorption amounts for nitrate. However, when these clays were modified with surfactant HDTMA in 2 or 4 CEC, the removal amounts of these clays were greatly improved. Thus, among all these organoclays, HDTMA modified bentonite showed the best result [30].

Ma and Zhu [48] used inorganic–organo-bentonite which is prepared by replacing the exchangeable inorganic cations with cetyltrimethylammonium bromide (CTMAB) to phosphures from water. The results of this study reveal that inorganic– organo-bentonite can act as a successful adsorbent for removing the phosphures from contaminated water. More than 95% phosphate and 99% phenanthrene were removed from the water within 30 min. The amount of sorbed phosphate increased as pH decreased and the sorption amount increased slightly with an increase in temperature [48].

#### **4.2 Application of organoclay to remove dye**

Dyes and pigments are widely used by several industries like plastics, textile, cosmetics…etc. Textile dyeing process is an important source of contamination responsible for the continuous pollution of the environment. In recent years Organoclays have been attractive for use as selective sorbents for dyes:

Tabak et al. [49] studied the adsorption of the Reactive Red 120 by cetylpyridinium modified Resadiye bentonite (CP-bentonite) prepared by ion exchange at different temperature, force ionique and pH levels. Their results showed that the structural arrangement of cetylpyridinium ions in the CP-bentonite sample, as well as the pH, temperature and ionic strength of the bulk solution, influenced the adsorption of RR 120 dye from aqueous solutions by CP-bentonite [49].

Ma et al. [46] showed that bentonite modified with hexadecyltrimethylammonium bromide could be used as a highly efficient adsorbent for the removal of acid dyes from an aqueous solution. The study reveals that the adsorption capacity of organobentonites is affected by the surfactant alkyl chain length [46].

Gammoudi and Srassra [50] studied the removal of three dyes (methyl orange (MO), indigo carmine (IC) and phenol red (PR) on the surface of Tunisian

HDPy-modified; the maximum adsorption capacity from the Langmuir equation was calculated at 227.27, 326.40, and 344.82 mg/g, respectively. The results revealed that the kinetics uptake was fast and equilibrium was attained within 30 min for IC, PR and 60 min for MO.

#### **4.3 Application of organoclay to remove pesticides and herbicide**

Shirzad-Siboni et al. [42] were prepare surfactant-modified pillared montmorillonites using cetyltrimethylammonium bromide and used them as adsorbents to remove bentazon from aqueous solutions. Results showed that the maximum adsorption capacity was estimated to be 500 mg/g at pH 3 and room temperature. The removal efficiency at optimum pH 3 was found to increase with the increase in contact time and adsorption dosage, but to decrease with an increase in initial bentazon concentration [42].

Carrizosa et al. [41] examined the adsorption of the herbicide dicamba by organoclays at various concentrations and pH levels. Their results showed that the adsorption capacity of organoclays is favored for high-layer charge and saturation with bulky organic cations close to the CEC.

#### **4.4 Application of organoclay to remove heavy metal**

Some heavy metals are notorious water pollutants with high toxicity and carcinogenicity. Heavy metals have been removed from water by adsorption technology using nanoparticles. Organoclay is effective for the removal of various heavy metals. The elimination efficacies of these contaminants are discussed below.

HDTMA modified natural kaolin has been confirmed effective sorbent for Cr (VI) with a maximum adsorption capacity of 27.8 mg/g, while the unmodified natural kaolin was only 0.7 mg/g [60]. Results indicate that most of the adsorption of chromate occurred through the anion exchange of the Br-anion of the HDTMA ion pair [66].

Similarly, the adsorption scheme of oxygen anions of Cr and Mowas studied with bentonite modified by cetylpyridine bromide (CPBr). The equilibrium adsorption capacity of Mo (VI) of 1.4 mmol/g quantity to double the capacity of Cr(VI) (0.7 mmol/g), indicating that Mo (VI) was removed on organic bentonite in the form of polynuclear anions [67].

#### **4.5 Application of organoclay to remove pharmaceutical contaminants**

Various researches have reported the successful elimination of pharmaceutical pollutants using organoclay:

Saitoh and Shibayama synthesized organo-clays: Didodecyldimethylammonium bromide (DDAB)-montmorillonite which was used for the removal of 1β-lactam antibiotics from water. The study showed that the removal of antibiotics increased with increasing the amount of organoclay added and the amount of DDAB sorbed on MT. Thus, the authors postulated that the Didodecyldimethylammonium bromide (DDAB)-montmorillonite (MT) organoclay was a useful sorbent not only for the removal of β-lactam antibiotics from water but for their eco-friendly degradation [54].

Polubesova et al. [68] examined tetracycline and sulfonamide antibiotics sorption by the BDMHDA modified montmorillonite. Their results indicated that BDMHDA

*Organoclay Nano-Adsorbent: Preparation, Characterization and Applications DOI: http://dx.doi.org/10.5772/intechopen.105903*

modified montmorillonite is very efficient for water purification from tetracycline and sulfonamide antibiotics [68].

Guégan and Le Forestier [47] used modified montmorillonite with tetramethyl ammonium (TMA) and hexadecyl trimethyl ammonium (HDTMA) cationic surfactants as adsorbents for the retention of amoxicillin (AMX) [47].

#### **4.6 Application of organoclay to remove hydrocarbons**

Masooleh et al. [53] studied the performance of a organically modified nanoclay for petroleum hydrocarbon adsorption. The obtained results that the adsorption capacity of the organoclay was clearly higher than that of the unmodified clay and the hydrocarbons the adsorption capacity was in the range of 4 to 10 g of adsorbent. Also, adsorption equilibrium was attained within 1 h.

#### **4.7 Application of organoclay to remove phenol**

Park et al. [57] prepared two types of organoclays from different surfactants (DDTMA and DDDMA) for the adsorption of phenolic compounds. This study revealed the potential utility of the organoclays as adsorbents for the uptake of industrial pollutants in environmental applications.

Zhang et al. [64] were prepared organoclays using withdodecyltrimethylammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB); were used as adsorbents for 4-chlorophenol and 2,4-dichlorophenol. This study demonstrates that the adsorption process is affected by the initial solution pH and temperature.

#### **4.8 Application of organoclay to remove radioactive**

Bentonite clay is suggested as a buffer material in various concepts for repositories for high-level radioactive waste. Two different mechanisms have been established to study the importance of the ionic balance between the interlayer space of montmorillonites and an external solution: the Donnan equilibrium and the ion exchange equilibrium [69].

Yang et al. [55] synthesized Hexadecylpyridinium Chloride Monohydrate modified bentonite (HDPy-bent) and used it as an adsorbent to remove-99 (99Tc). Results are demonstrated that the HDPy-bent is a low-cost sorbent which can efficiently eliminate Technetium-99 from wastewaters.

Li et al. [58] examined the efficacy of organoclay as sorbents to bind iodide (I<sup>−</sup>) and iodate (IO3 <sup>−</sup>) from groundwater. Results showed that these sorbents were highly effective at removing I<sup>−</sup> and IO3 from groundwater under oxic conditions, with the adsorption capacity up to 30 mg I/g sorbent.

Some studies, evaluate the efficiency and capability of organoclay to simultaneously remove various pollutants from wastewater:

Yahya et al. [61] used smectitic clay modified using cationic surfactant (hexadecylpyridinium for the removal of fluoride and phosphate single and industrial aqueous solutions. The results show low adsorption ability for fluoride and phosphate ions comparing the case of single solutions. Thus, the selectivity of fluoride is better than phosphate and with coexisting chloride, sulfate ions and other cations.

Xiaoying et al. [36] are studying the possibility of organoclays used to simultaneously remove amoxicillin (AMX) and Cu (II) from wastewater. Results showed that the adsorption of AMX onto organ-bentonite was 6 times higher than that using

**Figure 6.** *Mechanism of pollutant (P) uptake in organoclay.*

bentonite (control), while adsorption of Cu (II) on organ-bentonite showed comparable results as that using bentonite. The simultaneous adsorption of AMX and Cu (II) onto organ-bentonite occurred through partition for AMX and ion-exchange for Cu (II). More than 34.8% AMX and 43.6% Cu (II) were removed from industrial wastewater, indicating its great potential removal of mixed organic and metal contaminants.

Oyanedel-Craver et al. [36] were studying the feasibility of using hexadecyltrimethylammonium bentonite clay (HDTMA-clay) and benzyl triethylammonium bentonite clay (BTEA-clay) for simultaneous sorption of benzene and one of four heavy metals (Pb, Cd, Zn and Hg). Results showed that both organoclays tested had dual sorptive properties for both heavy metals and an organic contaminant. But, sorption of Pb, Cd, and Zn on both BTEA- and HDTMA-clay decreases in the presence of benzene relative to the sorption obtained without benzene present.

Generally, the predominant mechanism of the adsorption of dye, inorganic oxyanions (fluoride, phosphate nitrate) is an ion exchange [46, 51, 61] (**Figure 6**). The mechanisms mainly include electrostatic adsorption of heavy metal, redox, ion exchange, precipitation, coordination (chelation), as well as surface complexation. For heavy metals, the mechanisms mainly include surface complexation, redox, ion exchange, precipitation, coordination (chelation) and electrostatic adsorption (**Figure 7**) [26].

**Table 3** represents various applications of organoclay for the removal of wastewaters pollutants by adsorption.

### **5. Conclusion**

The study of organoclays is a vast field and shows immense potential to be explored. This chapter describes the various ways of preparation of organoclays with the use of cationic surfactants (quaternary alkyl ammonium). Generally, organoclay is obtained by the replacement of the inorganic cations through cation exchange with surfactant. Organoclay can be made using a variety of clay minerals; however,

*Organoclay Nano-Adsorbent: Preparation, Characterization and Applications DOI: http://dx.doi.org/10.5772/intechopen.105903*

**Figure 7.**

*Adsorption mechanisms of functional organoclays for heavy metal ions [26].*

smectite is the most commonly used due to its specific properties. Thus, quaternary ammonium cations are most commonly used as surfactants.

A detailed understanding of the structure of organoclay is of importance in its design and applications. In this chapter, FTIR, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) has been employed to provide insights into the interlayer structure and morphology of organoclay. The details are as follows:


Using SEM and TEM indicate that the raw clay showed rough surface morphology however organoclay showed a smooth surface with large size particles.

Organoclays can be used in various applications including adsorbent systems in the environmental field. These adsorbents display interesting adsorption properties for several organic compounds, especially hydrophobic chemicals.

Despite the potential interest in environmental applications, the use of organoclays appears to be limited to batch experiments but has not yet been explored under dynamic conditions that reduce the efficiency of adsorption.


#### **Table 3.**

*Applications of organoclay for the elimination of water pollutants by adsorption.*

Finley, overall, in this chapter researchers suggest that the Organoclay could be considered a cheap and efficient adsorbent for the removal of most of the chemical pollutants from wastewater that could be of socioeconomic and environmental relevance.

*Organoclay Nano-Adsorbent: Preparation, Characterization and Applications DOI: http://dx.doi.org/10.5772/intechopen.105903*
