Engineered adsorptive materials for water remediation - Development, characterization, and application

Engineering alternative eco-friendly techniques for water remediation is a global aim due to the serious contaminations of water sources and strict standards of water quality. Engineered polymer-based adsorptive materials have emerged as new alternatives to activated carbon. Engineered adsorptive materials with embedded inorganic constituent(s) in polymeric matrix provide an opportunity to remove a diverse range of contaminants. Combining the advantages of inorganic and polymeric materials, these engineered materials exhibit enhanced properties e.g., porous structure and easy separation. Particularly, engineered adsorptive materials containing nano-sized titanium dioxide (n.TiO2) exert simultaneous adsorption and photocatalysis. These newly raised materials are new alternatives with a bright prospect in environmental remediation. This dissertation introduces new-engineered adsorptive materials for water remediation. It highlights the fundamental challenges of engineering adsorptive materials from well-known initial materials, chitosan, n.TiO2, and feldspar, for the remediation of water polluted with arsenic, Acid Black 1 dye, and phosphate in laboratory-scale. It focuses on preparing the engineered adsorptive materials, charactering them via common methods e.g., Fourier Transform Infrared Spectroscopy and X-ray Diffraction, and applying them for adsorptive (photoactive) removal of the target pollutants. The adsorption process is explored via kinetic, isotherm, and thermodynamic studies. The adsorptive materials are engineered considering the strengths and drawbacks of initial materials; e.g., n.TiO2 provides high surface area and photo-oxidation, chitosan supplies support matrix and gravity separation, and feldspar lowers the cost and improves the surface texture. The engineered materials showed improved structures and removal performances. The study of material properties revealed their functional groups, compositions, and porosity. The engineered materials embedding n.TiO2 showed enhanced UV-assisted adsorption of the dye and arsenic. UV irradiation enhanced the removal from 33% to 73% for arsenate (5 mg/L), from 23% to 84% for arsenite (5 mg/L), and from 86% to 97% for the dye (50 mg/L). Zinc-functionalized chitosan showed an improved phosphate uptake from 1.45 to 6.55 mg/g compared with plain chitosan. Adsorption kinetics indicated fast removal rates. Modeling of adsorption isotherm and kinetics via theoretical models provided fundamental information about the adsorptive surface properties and adsorption reactions. The adsorption reactions were thermodynamically spontaneous and favorable. The correspondence between the theory behind the models and properties of the engineered materials along with removal mechanisms are discussed. This dissertation provides fundamental knowledge e.g., in designing water treatment units. In summation, the experimental data and theoretical considerations support the applicability of the engineered adsorptive materials for water remediation.