ADSORPTIVE REMOVAL OF TEXTILE DYE DIRECT BLUE 86 FROM AQUEOUS SOLUTION BY RICE HUSK-BASED ADSORBENT

Adsorption by activated carbon has proven to be most effective method of dye removal. However due to high production and regeneration cost of activated carbon, various studies on low-cost adsorbent have been carried out for alternative. Agricultural waste such as rice husk is seen to be a good adsorbent for dye removal. Moreover, rice husk can be easily obtained in any part of the country. In this study, rice husk-based adsorbents were prepared by chemical and thermal treatment. Standard curve of DB 86 at pH 1-10 were prepared to determine the concentration of unadsorbed dye in adsorption test at different pH. The adsorptive potential of the adsorbent for textile dye DB 86 was evaluated by batch adsorption screening test. The most effective adsorbent, RH6 was selected and the potential of RH6 was evaluated and compared to commercial PAC. The optimum pH for DB 86 removal is pH 2 for both adsorbent. The optimum contact time were observed to be 3 hours with 20 mg/L of dye concentration for RH6 and PAC. The optimum adsorbent dosage is 4 g/L for RH6 and 3 g/L for PAC. Both Langmuir and Freundlich provide high correlation coefficients R2 (>0.97) but Langmuir isotherm is the best to describe the process with correlation coefficients R2 >0.99. Adsorption capacity obtained was 34.4828 mg/g for RH6 and 47.6190 mg/g for PAC. Pseudo second order kinetic model yielded high R2 values (>0.99) to prove that the model is best fit for the adsorption mechanism of RH6 and PAC compared to pseudo first order.