Study On Preparation Of Sludge Activated Carbon And Its Adsorption Characteristics For Lead(?)

Sludge is one of the main by-products of sewage treatment.On the one hand,it contains a large number of nitrogen,phosphorus,potassium and other plant nutrients,on the other hand,it contains a large amount of organic matter,pathogenic bacteria,parasites and harmful substances(such as heavy metals)and often accompanied by odour.So it may cause secondary pollution if stacked or treated unproperly.The process of activated charcoal prepared by sludge pyrolysis has many advantages.First,this process is an effective method to deal with sludge.Secondly,it can make sludge become a better adsorbent through low cost of pyrolysis and activation.Finally,the adsorbent can also adsorb the pollutants in sewage to fight against pollution by means of pollution.Therefore,the prospect of its application is broad.In this study,municipal sludge,as raw material,was first pyrolyzed on a fixed bed pyrolysis activation device,then the biochar was activated(i.e.,the"two step process").The specific surface area,pore structure analysis and Fourier Transform Infrared(FTIR)spectroscopy were used to characterize the physicochemical property of biochar to determine the optimal pyrolysis temperature.The results show that different activation conditions have great influence on the pore structure of the products.The pore structure of activated carbon activated by potassium hydroxide is the best(the activation temperature is700 ~oC and the activation ratio is 2:1)and the maximum BET surface area can reach907.95m~2/g.After the optimum process of activation of different activators was determined,the adsorption experiments on different sludge based activated biochar were carried out.The effect of activation temperature and activation ratio on the adsorption of lead(?)in the optimum preparation conditions was investigated and the adsorption process was fitted by isothermal adsorption and adsorption kinetics equation.The experimental results show that the lead(?)adsorption on activated carbon activated by potassium hydroxide has good adsorption performance.The maximum adsorption capacity is up to 35.81mg/g at the initial concentration of 200 mg/L,while the maximum lead(?)adsorption capacity of activated carbon activated by potassium acetate and carbon dioxide is 26.47mg/g and 16.14mg/g respectively.The adsorption process of three activated carbons accords with the adsorption isotherm equation of Langmuir and Freundlich and the adsorption kinetics is more consistent with pseudo-second order kinetics equation.