Study Of Modified Ca-bentonite And Applied On Adsorption Of Congo Red Dye

Adsorption has already been used widely in wastewater treatment because it is simple and efficient. There are many types of naturally occurring clays such as bentonite that have shown promises in adsorption applications. The wide usefulness of this kind of clay is a result of its high specific surface area, its high chemical and mechanical stability, and a variety of surface and structural properties. The adsorption of Congo red dye in wastewater on nature Ca-bentonite and CaCl2 modified bentonite was investigated in this thesis.The ability of Ca-bentonite to remove Congo red dye from aqueous solutions has been carried out as function of contact time. An amount of 0.2g of Ca-bentonite could remove more than 90.0% of the dye from 100ml of 100mg/L Congo red solution. The amount of dye adsorbed per unit weight of Ca-bentonite increased from 23.25 to 85.29mg/g with increasing concentration from 50 to 200mg/L, but it had a little change with temperature and decreased slightly with increasing pH. The pseudo-second-order kinetic model described the adsorption of Congo red on Ca-bentonite very well. Analysis of adsorption results obtained at 20oC showed that the adsorption pattern on Ca-bentonite not only followed the Freundlich isotherms, but also followed Freundlich isotherms. From thermodynamic studies, it was seen that the adsorption was spontaneous and endothermic.The adsorption of Congo red dye onto CaCl2 modified bentonite (BCa2+) was also investigated in aqueous solutions in a batch system. An amount of 0.1g of BCa2+ could remove more than 95.0% of the dye from 100ml of 100mg/L Congo red solution. The pseudo-second-order kinetic model described the adsorption of Congo red on BCa2+ very well. Adsorption isotherms indicated that sorption took place at specific homogeneous sites within the adsorbent. Furthermore, BCa2+ showed higher sorption capacity compared with other common materials used as adsorbents for Congo red dye.As a result, it can be said that Ca-bentonite and BCa2+ would be as low-cost and effective adsorbents for removal of Congo red from wastewater instead of active carbon.