Project Abstract

Abstract
The synthesis of a novel organokaolinite with improved sorption characteristics was achieved through the modification of kaolinite with cetyl trimethyl ammonium bromide (CTAB). Kaolinite, a naturally occurring clay mineral, was selected for its abundance and low cost. The modification with CTAB aimed to enhance the sorption properties of kaolinite for potential applications in environmental remediation and water purification processes. The synthesis process involved the intercalation of CTAB within the kaolinite layers through ion exchange reactions. The resulting organokaolinite material exhibited increased surface area and enhanced hydrophobicity compared to pristine kaolinite. Characterization techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and nitrogen adsorption-desorption analysis confirmed the successful modification of kaolinite with CTAB. The sorption characteristics of the organokaolinite were evaluated using various model dyes and heavy metal ions. The results showed improved sorption capacities for organic dyes and metal ions compared to pristine kaolinite. The enhanced sorption performance was attributed to the increased surface area and the presence of hydrophobic CTAB moieties on the organokaolinite surface, which facilitated the adsorption of target pollutants. The potential application of the organokaolinite material in wastewater treatment was explored, demonstrating its effectiveness in removing contaminants from aqueous solutions. Batch sorption experiments revealed high removal efficiencies for various pollutants, highlighting the promising sorption capabilities of the synthesized material. The environmental implications of the organokaolinite material were also considered, with a focus on its eco-friendly synthesis process and sustainable use in water treatment applications. The use of abundant and inexpensive raw materials, coupled with the improved sorption properties of the organokaolinite, presents a cost-effective and environmentally friendly solution for water remediation processes. Overall, the synthesis of the novel organokaolinite material through the modification of kaolinite with CTAB offers a promising approach to developing efficient sorbents for water treatment applications. The enhanced sorption characteristics of the organokaolinite, along with its eco-friendly synthesis route, position it as a viable candidate for addressing water pollution challenges and advancing sustainable environmental management practices.

Project Overview

INTRODUCTION AND LITERATURE REVIEW

1.0     General Introduction

            Clay is a naturally occurring material composed primarily of fine-grained minerals, which show plasticity through a variable range of water content, and which can be hardened when dried or fired. Clay deposits are mostly composed of clay minerals (phyllosilicate minerals) and variable amounts of water trapped in the mineral structure by polar attraction. Organic materials which do not impart plasticity may also be a part of clay deposits.   Clay is a widely distributed, abundant mineral resource of major industrial importance for an enormous variety of uses (Ampian, 1985). In both value and amount of annual production, it is one of the leading minerals worldwide. In common with many geological terms, the term “clay” is ambiguous and has multiple meanings: a group of fine-grained minerals which show plasticity through a variable range of water content, and which can be hardened when dried or fired i.e., the clay minerals; a particle size (smaller than silt); and a type of rock i.e., a sedimentary deposit of fine-grained material usually composed largely of clay minerals (Patterson & Murray, 1983; Bates & Jackson, 1987). Clays find wide range of applications, in various areas of science, due to their natural abundance and the propensity with which they can be chemically and physically modified to suit practical technological needs (Xi et al., 2005).

Clays are distinguished from other fine-grained soils by various differences in composition. Silts, which are fine grained soils which do not include clay minerals tend to have large particle sizes than clays but there is some overlap in both particle size and other physical properties, and there are many naturally occurring deposits which include both silts and clays. The distinction between silts and clay varies by discipline.Geologists and soil scientists usually consider the separation to occur at a particle size of 2µm (clays being finer than silts), sedimentologists often use 4-5µm, and colloid chemists use 1um. Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, ISO 14688 grades; clay particles as being smaller than 0.063mm and silts one larger.

There are three or four main groups of clays; kaolinite, montmorillonite-smecite, illite and chlorite. Chlorites are not always considered clay, sometimes being classified as a separate group within the phyllosilicates. There are approximately thirty different types of “pure” clays in these categories but most “natural” clays are mixtures of these different types along with other weathered minerals (Lagaly, 1984).

1.1                    Clay Minerals

Clay minerals likely are the most utilized minerals not just as the soils that grow plants for foods and garment, but a great range of applications, including oil absorbants, iron casting, animal feeds, pottery, china, pharmaceuticals, drilling fluids, waste water treatment, food preparation, paint e.t.c.

Clay minerals are hydrous aluminium phyllosilicates, sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations. Clays form flat hexagonal sheets similar to the micas. Clay minerals are common weathering products (including weathering of feldspar) and low temperature hydrothermal alteration products. Clay minerals are very common in fine grained sedimentary rocks such as shale, mudstone, and siltstone and in fine grained metamorphic slate and phyllite. Clay minerals are usually (but not necessarily) ultrafine-grained (normally considered to be less than 2µm in size on standard particle size classifications) and so may require special analytical techniques for their identification/study. These include x-ray diffraction, electron diffraction methods, various spectroscopic methods such as Mössbauer spectroscopy, infrared spectroscopy, and SEM-EDX or automated mineralogy solutions. These methods can be enlarged by polarized light microscopy, a traditional technique establishing fundamental occurrences or petrologic relationships.

Clay minerals can be classified as 1:1 or 2:1clays; this originates from the fact that they are fundamentally built of tetrahedral silicate sheets and octahedral hydroxide sheets, as described in Figure 1 below. A 1:1 clay would consist of one tetrahedral sheet and one octahedral sheet, for example, kaolinite and serpentine. A2:1 clay consists of an octahedral sheet sandwiched between two tetrahedral sheets, for example, talc, vermiculite and montmorillonite.

Clay minerals include the following groups:

Other 2:1 clay types exist such as sepiolite or attapulgite, which areclays with long water channels internal to their structure.

Typically, the structural formula for kaolinite is Al4Si4O10(OH)8 and the theoretical chemical composition given in Table 1.