Optimization And Preliminary Aplication Of Sludge Based Activated Carbon

This paper is to introduce our study on activated carbon made of sewage sludgevia chemical activation. Some corn straw was added to sewage sludge in order toincrease carbon content and BET surface area. Two kinds of pyrolysis methods wereadopted to prepare activated carbon. Activated carbon was used to adsorpt methyleneblue wastewater, and adsorption dynamics were established.Single factor experiments indicated that the BET surface area was maximized atan activation reagent of ZnCl2and a concentration of activation reagent of4mol/Land an activation temperature of600°C and a dwell time of60min and a solid toliquid ratio of1:2. Under optimal conditions, the BET surface area value of activatedcarbon was475m2/g. Under optimal conditions, one-step pyrolysis method was usedto prepare activated carbon. And when activated temperature was600℃with25%corn straw added in, a BET surface area of769m2/g and a product yield of36.1%were achieved. A BET surface area of756m2/g and a product yield of32.5%wereobtained when two-step pyrolysis method was used at a carbonization temperature of400℃and an activated temperature of500℃. The process of one step pyrolysismethod is simple, at the same time the BET surface area and product yield were high.So one-step method was the better preparation method in this experimental.Activated carbon with a BET surface area of658m2/g prepared by one-steppyrolysis method with10%corn straw added in was used to treat methylene bluewastewater. The results indicated that the adsorption process can be well described byLangmuir isotherms, and the saturated adsorption capacity was167.04mg/g at20℃.Pseudo-second-order rate equation was found to interpret the kinetic data suitably.Nitric acid solution, hydrogen peroxide solution, ammonia was used to modifyactivated carbon based on sludge. Through modification, the BET surface area ofactivated carbon decreased, and activated carbon modified by hydrogen peroxide gota lowest BET surface area. Modified by all three kinds of solution raised the removerate of methylene blue. But activated carbon modified by ammonia owned the highestadsorption remove rate of99%, and the adsorption capacity reached154mg/g.