Application of chitosan padded rice and wheat husk for the removal of reactive dye from aqueous solution

Abstract

Industrial waste especially textile effluents contain many harmful ingredients, which cause environmental problems. In the present study, the removal of reactive red 195 dye was carried out using chitosan padded wheat husk (CWH) and rice husk (CRH) adsorbents. Chitosan was prepared in the laboratory from chitin which was obtained from crab shells by adopting reported method. The removal of dye was carried out by batch adsorption method under the optimized conditions of amount of adsorbent, stay time, temperature and dye concentration. Spectrophotometric technique was adopted for the measurement of concentration of dye before and after adsorption. Adsorption data was fitted in Freundlich and Dubinin-Radushkevich adsorption isotherm equations. The values of the corresponding constants were evaluated from the slope and intercept of their respective plots. Thermodynamic parameters such as free energy (ΔG o ), enthalpy (ΔH o ), and entropy (ΔS o ) of the system were also calculated by using distribution coefficient K D . From the percent removal data, it was concluded that chitosan-rice husk (CRH) and chitosan- wheat husk (CWH) systems showed about 83 and 79% removal tendency respectively. Chitosan itself act as a good adsorbent and its derivative with rice and wheat husk (mainly cellulose) show high removal tendency and may be used as low cost biosorbents for the removal of pollutants from the industrial effluent. Keywords: Adsorption, reactive red 195 dye, chitosan, rice husk, wheat husk