Rice husk as a low cost adsorbent for removal of malachite green and nylosan blue from aqueous solutions

Abstract

Colored dye waste water arises as results of the production of dye and also as a consequence of its use in textile industry. Many types of dyes are used in the textile industries such as direct, reactive, acid and basic dyes. Most of them are toxic and non biodegradable which impede light penetration. Therefore it can affect the photosynthetic activity of aquatic plants and raise the chemical oxygen demand (COD) of the effluent. From various methods use to remove dye from waste water, adsorption technology is considered to be the most effective and proven technology. The most common adsorbent used is activated carbon. However, it is quite expensive and regeneration cost is high. So there is a need for low cost and readily available material for adsorption of dyes from waste water. Rice husk is widely available in Sri Lanka at low or no cost. Sometimes this agricultural waste causes disposal problems. Rice husks consist of ligno cellulose materials and they can easily adsorb cationic substances in aqueous medium. Chemically and thermally activated rice husk can be used to adsorb not only cationic substances but also anionic substances.