Cellulose Nanocrystals Incorporated Nanocomposites for Water Treatment Applications

Abstract

Water is the elixir of life; however, it is being increasingly contaminated by a wide variety of contaminants from industrial, municipal and agricultural sources like dyes, heavy metal ions, food additives, pharmaceuticals, detergents, agrochemicals, etc. Among the various water treatment technologies employed for the treatment of wastewater, adsorption is a technique which when implemented using well-designed system provides high quality treated water at affordable cost. Activated carbon is the conventionally used adsorbent and its production is energy intensive, expensive and is a contributor to greenhouse gas emission. Hence there is an enormous interest in developing low-cost alternative adsorbents from industrial and agricultural contaminants. In this context, the use of sustainable nanomaterial such as cellulose nanocrystals (CNCs) to prepare sustainable platforms for wastewater treatment is a novel approach that has a negligible carbon footprint. CNCs are rod-like nanomaterials that possess several properties such as high specific surface area, high specific strength, hydrophilicity, biodegradability and surface functionalization capabilities. These properties and their large-scale availability make them attractive candidates for use in water treatment applications. However, the separation of these nanomaterials after use in water treatment is a challenge because of their high colloidal stability and nano-dimensions. Incorporating these CNCs into nanocomposite systems that can be easily separated after use in batch and continuous water treatment processes is an ideal strategy to address this challenge. Also, the selectivity of pristine CNCs towards a wide variety of water contaminants is limited, and it is essential to surface functionalize them to impart this selectivity. Hence, this thesis explores the (i) development of CNC incorporated nanocomposites and evaluation of their adsorption characteristics using batch and fixed bed column adsorption studies, and (ii) evaluation of the selective adsorption characteristics of surface functionalized CNCs and their ability to tailor the characteristics of the nanocomposites, for use in water treatment applications.