Preparation Of Sludge-based Activated Carbon For Adsorption Of Dimethyl Sulfide And Dimethyl Disulfide During Sludge Aerobic Composting

Aerobic composting is an effective method to treat sludge,which can realize the resource utilization of sludge.In this process,it will produce malodorous gases such as dimethyl sulfide（DMS）and dimethyl disulfide（DMDS）,which has a negative impact on the environment and restricts the widespread use of this technology.Therefore,sludge-based activated carbon is used to treat these two malodorous gases in this study.In this paper,sludge was used as the main raw material,and five kinds of sludge-based activated carbon（SAC,named SAC-0 to 4）were successfully prepared by chemical activation method with HNO₃ and KOH as activators.The physicochemical properties of SAC were analyzed by means of characterization.The results showed that the SAC-2activated by KOH had a higher specific surface area and a better pore structure.Besides,there were abundant functional groups on the surface of SAC.The adsorption results showed that SAC-2 had the best adsorption effect for DMS and DMDS,with the saturated adsorption capacities of 53.45 and 151.28 mg·g^-1,respectively.The experiment of influencing factors showed that the adsorption capacity of SAC-2 for DMS and DMDS gradually decreased with the increase of temperature and air intake flow,and increased with the increase of initial concentrations.At the same time,SAC-2 also had a better adsorption performance for DMS and DMDS mixed gas.In this paper,the adsorption isotherms and kinetics were used to analyze the adsorption mechanism of SACs for DMS,DMDS and mixed gases.The results showed that the adsorption isotherms of SAC-2 for DMS,DMDS and mixed gas were fitted better with the Freundlich,BET and Freundlich models,respectively which indicated that the three adsorption processes were multi-layer adsorption.The isometric heat of adsorption was both less than 40 k J·mol^-1,indicating that the three adsorption processes was physical adsorption,and the kinetics fitting results further confirmed this conclusion.The regeneration study of SAC-2 showed that after four cycles of regeneration,the adsorption capacity of SAC-2 for DMS and DMDS was reduced,but there was still 70%-80%of the original adsorption performance,indicating that SAC-2 was a highly efficient adsorbent with good recyclability.