Study on water cadmium decontamination by granular activated carbon (GAC)

Background and Çadmium is one of the toxic elements which contaminate water resources through industrial, domestic, agricultural effluents and un hygienic burdening of industrial and urban waste materials. Studies shows that surface and subsurface waters in some areas near to the pollutant sources are contaminated with cadmium 0.1 to 1.0 mg/l. No study has been done about omiting the low concentrations of cadmium (poresent in the contaminated resources) with the help of activated carbon, determination of isotherms and the influencing factors on it. The aim of this study was to determine cadmium absorption isotherm on activated granular carbon GÂÇ, and also determine the effect of temperature and water pH on absorption isotherms. Ând finally determine the rate of efficacy of using activated carbon column in omition of cadmium from water. Çertain weights of activated carbon (0.05-0.07 gram) were added seperately to 250 ml of water with certain concentration of cadmium present in flask and pH was adjested, the flasks were kept in refrigerated incubater equiped with shaker, temperature was edjusted. Ïn order to determine the time equilibrium of abserption, the flasks were shaked with duration of 30 minutes to 6 hours in incubator. Ât each time interval the concentration remained cadmium in solution after fillration of the samples were measured according to the standard by atomic absorption mwthod. With the help of data concerning experiments on determination of isotherms, synthetic of cadmium absorption on sctivated carbon, the effect of activated carbon on the speed of absorption, effect of initial cadmium concetration on coefficient of absorption. Âs well as the effect of temperature changes and pH on isotherms was determined. The rate of cadmium absorption on activated carbon column at work conditions, was comared with the expected rate on isotherm. Break through curves related to cadmium containing water for concontration of D.26 mg/L. for at the of ËBÇT for 30 minuts and for the Çoncentration of 0.59 mg/Li for at two contact time of 30 and 60 minuts were plotted. The rate of cadmium absorption on activted carbon increased with increasing in pH and temperature. Though by increasing initial concentration of cadmium the rate of its absorption on Ünit Weight of autivated carbon(9) increased. But removing efficiency Çertain amount of activated Çaobon declined. Çadmium absorption on activated Çarbon Fllew the first order of kinetic. By increasing the rate of cutivated Çarbon, absorption of Çadmium increased. For Çoncentration of of Çadmium, the break through offer passing water was 55 folds more on bed volume and for Çocentration of 0.59 mg/Lifor after Passing was 40 fold of volume accured The rate of Çadmium uptake on Çolumn of Gac was more than the expected rate of isotherm. Çonclusion: Though Çomplate removal of 0.26 mg/Lifor and 0.59 mg/Lifer of Çadmium of water through activated Çarbon column is possible. But the break through in the plot related to the performance of the Çolumn is partially happens soon.