Preface

Strong technological development and increasing population over the past few decades have led not only to a dramatic increase in the demand for raw materials and energy but also to the need for recycling and process intensification. Since recycling is seen as the most promising and cost-effective option to reduce the use of fossil energy and non-regenerable raw materials, in industry and oxidic materials applications, geopolymers seem to meet all the criteria to replace conventional materials and contribute to a sustainable future. By applying innovative technologies, the coefficient of use of waste for developing new materials can be increased simultaneously along with a decrease in carbon footprint and ecological impact. Accordingly, these eco-friendly materials will participate in cutting-edge research and applications due to their tailored properties, which include superabsorbent capacity, heavy metals encapsulation, flame retardancy, mechanical performance, electrokinetic behaviour, corrosion resistance, and thermal properties.

Geopolymer–zeolite composites and zeolite-like geopolymers are two different categories of adsorptive materials that have recently attracted increased interest. Geopolymer–zeolite composites are hybrid materials and unite the advantages of both constituents. The geopolymer serves as durable support, while the zeolite provides a high surface area, porosity, and adsorption capacity. The report clearly shows the beneficial influence of the use of zeolitic tuff in the starting mixture on the microstructure and adsorption potential of geopolymers.

This book joins activities and knowledge of researchers from multiple fields to present a comprehensive overview of the advances in synthesis and characterization of geopolymers, including base chemistry concepts, nanoscale characterization, and applications in top-level industry. It is organized into two sections on "Geopolymers" and "Zeolites" and includes eight chapters containing information about the theoretical approach to geopolymers and their applications in civil engineering, medicine, and other areas.

Chapter 1 discusses the regeneration of exhausted materials and available resource recovery options that the regeneration approach opens. It describes new forms of geopolymer adsorbents such as foams or core-shell structures and provides a short economic evaluation of resource recovery models.

Nowadays, globalization generates large amounts of waste that significantly affects storage areas and the surrounding environment. At the same time, the civil engineering sector is experiencing an exponential development process, which increases the demand for building materials and usable space. Therefore, the need to obtain new materials with lower exploitation costs and natural resources consumption became primary. Chapter 2 describes one solution that has been intensively studied in the past year, especially in this sector, consisting of the development of environmentally friendly materials through a mechanism called geopolymerisation.

Geopolymers are being studied extensively due to their potential applications in the construction sector. Chapter 3 is a study of a variety of geopolymer ingredients, including fly ash, bottom ash, high-carbon ferrochrome (HCFC) slag, sodium hydroxide, sodium silicate, plasticizer, and others that are used to synthesize geopolymers with improved mechanical properties such as compressive strength. Geopolymers are developed from HCFC slag by treating with sodium silicate, sodium hydroxide, and water-soluble plasticizers.

Geopolymer concrete (GPC) has significant potential as a more sustainable alternative for ordinary Portland cement concrete. Chapter 4 explains how GPC was introduced to reduce carbon footprints and thereby safeguard the environment. This emerging eco-friendly construction product finds application in precast and prefabricated structures due to the special curing conditions required. Sustained research efforts are being undertaken to make the product suitable for in situ applications. The developed technology will certainly address issues of huge energy consumption as well as reduce water usage.

Several new technologies are emerging to help achieve the aim of reducing energy usage in building sectors, eliminating greenhouse gas emissions, and recycling waste. Chapter 5 describes some of these technologies, including the development of a geopolymer binder that may be used as an alternative to ordinary cement Portland, the adoption of three-dimensional (3D) printing methods in civil engineering, and the integration of phase-change materials (PCMs) in cementitious materials to increase the energy efficiency of buildings. Most investigations in this area focus on the addition of microencapsulated PCM (MPCM) to standard concrete recipes.

Chapter 6 discusses zeolite-like analogies to natural aluminosilicate minerals that may be synthesized in the cement matrices of the Na(K)-Al2O3-SiO2-H2O system. The structure formation and properties of the alkali-activated aluminosilicate cement-based materials at low temperatures may be regulated by changing cement composition, curing conditions, type and concentration of the alkaline activator solution, and solution-to-solid ratio. Directed regulation of the low-temperature structure formation process is a key instrument allowing to obtain a wide range of special materials using various types of alkali-activated aluminosilicate cement and curing conditions.

Chapter 7 critically reviews the studies related to structural and photophysical properties of metal clusters within zeolite matrices and summarizes the progress made in understanding host-guest interactions. The goal is to provide useful insight into the nature of such interactions and experiments used in identifying the excited-state dynamics and reaction mechanisms leading to the emitting species. Especially interesting are the combined experimental and computational approaches used to elucidate the structures and electronic transition of clusters inside the cavity.

The last chapter explains the three-dimensional structure of zeolites, composed of AlO4 and SiO4, which are related to each other by sharing electrons from oxygen and are arranged tetrahedrally. Zeolites have been widely used in industrial processes as environmentally friendly heterogeneous catalysts, for ion exchange, and

**V**

as adsorbents due to their high specific surface area, large pore volume, uniform micropore channels, and excellent thermal and hydrothermal stability. The use of

**Petrica Vizureanu**

Iasi, Romania

Kyiv, Ukraine

**Pavel Krivenko**

The "Gheorghe Asachi" Technical University,

Kyiv National University of Construction and Architecture,

zeolite as a catalyst in various industries is limited due to its narrow pores.

as adsorbents due to their high specific surface area, large pore volume, uniform micropore channels, and excellent thermal and hydrothermal stability. The use of zeolite as a catalyst in various industries is limited due to its narrow pores.

> **Petrica Vizureanu** The "Gheorghe Asachi" Technical University, Iasi, Romania

**Pavel Krivenko** Kyiv National University of Construction and Architecture, Kyiv, Ukraine

Section 1 Geopolymers
