Abstract：Dyes are widely used in industries and their removal from industrial wastewater poses an important issue. A new type of treating agent, chitosan modified bentonite, was prepared. Bentonite had been proven to be a promising material for the removal of contaminants from wastewater, which belongs to the 2:1 clay family. Not only bentonite is abundant in nature, but also it is really an efficient and economic adsorbent for adsorption of pollutants including dyes, oil and heavy-metals. Conventional methods for the removal of dyes from wastewater include adsorption to solid substrates, chemical coagulation, oxidation, filtration and biological treatment. Adsorption is one of the easiest and most effective techniques to remove dilute pollutants among conventional methods. In this paper, the enffluent factors of absorption of acid scarlet in dyeing wastewater on modified bentonite are investigated, including pH value, ratio of modified bentonite mass to wastewater, mixing time and centrifugating time to obtain optimal treatment conditions. The removal rate of chromacity is found to be 97% under the conditions of 30 g/L ratio of modified bentonite mass to wastewater, pH value of 4, 6 min of mixing time and 17 min of centrifugating time. In addition, for better explanation of these results, the natural bentonite and chitosan modified bentonite were critically examined in specific surface area, and with SEM and IR analyses. Results show that structure of bentonite is not changed by adding chitosan, except an increased specific surface area and improved adsorptive capability. It is concluded that chitosan modified bentonite has a promising application in removing acid scarlet from wastewater using adsorption methods.
2009, Vol. 27 
