Equilibrium and isotherm studies of sludge based activated carbon

摘要

Activated carbon was prepared from the digested sludge of tannery industry and investigated the possibility of the removal of reactive red dye from aqueous solution. The adsorption of dye through this activated carbon was studied under various conditions such as dosage of carbon, equilibrium time and concentration of dye solution, particle size of the carbon, different pH and temperature of dye solution. The equilibrium time was obtained after 120 minutes for the concentrations of 10 mg/L, 20 mg/L, 30 mg/ L, 40 mg/L> 50 mg/L and 60 mg/L. The optimum dosage of carbon was found to be 3.5 g to treat 250 ml of dye solution on all concentrations with the percent dye removal in the range of 88.93% to 100%. The effect of concentration of dye solution on adsorption was studied on all dosages of carbon at 120 minutes. An effect of particle size of carbon was tried with 150-300, 300-425, 425-600 and 600-1000 micron sizes and found that the adsorption capacity of carbon increased with decrease in particle size The pH of the dye solution was taken in the range of 2 to 11 and the results showed that dye removal efficiency of carbon decreased from 100% to 83 53% with the increase in pH of dye solution. Effect of the temperature of the dye solution was also studied in the range of 30°C to 60°C and found that the dye removal efficiency of carbon decreased from 95.84% to 73.06% with the increase in temperature. The Langmuir, Freundlich and Temkin equilibrium isotherms fitted the data well, with the value of R2=0.9724. 0.8515, 08663 respectively. As the data ar^ fitted the isotherms and the performance of carbon under various test conditions was good, the activated carbon prepared from the digested sludge of tannery industry may be effectively used in dye wastewater treatment.