Study On Preparation Of Sewage Sluge-based Activated Carbon And Its Application In Adsorption Of Pb²⁺

With the increasing of waste water treatment plant and discharge standards were more and more stern, more and more sewage sluge were produced.In consideration of the fact that the sewage sluge had high moisture content and was dangerous to the environment, it was hard to be disposed. Sanitary landfills, sluge farm application, ocean disposal and other traditional ways existed different problems. So sewage sluge treatment and disposal had become a focussed issue in global. Preparation of sewage sluge-based activated carbon was a new method of utilization of sewage sluge.The sewage sluge of municipal wastewater treatment plant in Harbin was taken as the raw sluge. The sewage sluge-based activated carbon was prepared through chemical activating by zinc chloride(ZnCl2) as activating agent. And the activation agent concentration, dipping temperature, the activation temperature and activation time were chosen as four impact factors, and the adsorption capacity of iodine as the evaluation index. The effects of the four factors above on the sewage sluge-based activated carbon were in the following order:activation temperature>activation agent concention>dipping temperature>activation time, we got the the optmium preparation condition just as following:the ZnCl2concention was45%, the dipping temperature was45℃, the activation temperature was600℃, the activatin time was40～50min. And the iodine value of the sewage sluge-based activated carbon was415～427mg/g. BET surface area was about330m2/g. Its macropore, mesopore and micropore volume was0.1469～0.1959cm3/g,0.1200～0.1405cm3/g,0.1330～0.1553cm3/g. The average pore diameter was3.623～3.953nm. FTIR, XRD, SEM photography, thermogravimetry and boehm titration were analyzed to evaluate the performance of sludge activated carbon.The adsorption action of sewage sluge-based activated carbon (SSBAC-Ⅱ) absorbing waste water containing Pb2+had been studied in this paper. The effect of activated carbon dosage, pH, Pb2+initial mass concentration and adsorption time on the adsorption action were studied. When the dosage was lOg/L, adsorption time was4h, the removal rate of was about68%. Pb2+sorption kinetics curve was linear fitted by Pseudo first-order equation, Pseudo second-order equation, intra-particle diffusion equation and Modified pseudo-first-order equation. Result indicated that the adsorption of Pb2+followed the Pseudo second-order equation. The adsorption isotherm of Pb2+on sewage sluge activated carbon was linear fitted by the Langmuir adsorption isotherm and the Freundlich adsorption isotherm. Result indicated the Langmuir adsorption isotherm was better than Freundlich adsorption isotherm to fit the The adsorption isotherm of Pb2+, R2was0.9985. The SSBAC-Ⅱ sewage sluge-based activated carbon calculated adsorption capacity of Pb2+was about4.8mg/g.