Microwave Method Of Preparation And Application Of The Sludge Carbon Adsorbent

With the development of wastewater, sewage sludge was produced in an ever increasing amount. Without proper treatment and disposal, sewage sludge would be cause a secondary pollution problem, because it was rich in not only organic materials and dangerous substance but also pathogenic germs. Making full use of available component in sludge and converting waste into valuable substance was the final disposal way in the future. Sewage sludge was carbonaceous in nature and rich in organic materials, hence it had the potential to be changed to activated carbonaceous adsorbent. It was proposed that sewage sludge was converted into carbonaceous adsorbent through microwave radiation in the exist of chemical agent. Compared with traditional electrical heating, microwave heating had outstanding excellence, that is, high efficiency and quickly reaction speed. The time of disposing sample was shortened largely.In the experiment of making carbonaceous adsorbent from sewage sludge, these conclusions obtained are as follows: with chlorination zinc as activated agent, the largest influence factor to iodine value of product was microwave power, the secondary was concentration of chlorination zinc, and the smallest influence factor was radiation time; the largest influence factor to adsorptive value of methylene blue was microwave power, the secondary factor was radiation time, and concentration of ZnCl₂ was the last one. The optimum condition was microwave power 595W, radiation time 4.0 min, and concentration of ZnCl₂ 40% for carbonaceous adsorbent derived from sewage sludge. With H₃PO₄ as activated agent, the sequence of influence factors to iodine value was microwave power > radiation time > the concentration of H3PO4, and the sequence of influence factors to adsorptive value of methylene blue was microwave power > the concentration of H₃PO₄ > radiation time. The best condition of carbonaceous adsorbent made from sewage sludge was microwave power 462W, radiation time 3.5min, the concentration of H3PO4 40%.The carbonaceous adsorbent made from sewage sludge was used to adsorb Cr⁶⁺and methyl orange in aqueous solution. The static way was adopted in the adsorptive experiment. The effects of adsorbent's amount, contacted time, pH value on the removalefficiency of experimental pollution were studied. The adsorption isotherm was also discussed. We could draw the conclusions as follows: in the adsorptive experiment of Cr⁶⁺, the best adsorptive conditions were that the using amount of adsorbent was not less than 0.7g, the adsorptive equilibrium time is 90min, the pH value was less than 2, and the initial concentration of Cr⁶⁺ was not more than 20mg/L. The adsorption isotherm was more fit Langmuir model than Freundlich model, and the saturated adsorption was 8.285mg/g. For the adsorptive experiment of menthyl orange, the optimum of adsorptive conditions were that the using amount of adsorbent was not less than 0.3g, the adsorptive equilibrium time is 150min, and the pH value was less than 5.1. The Langmuir model was more suitable than Freundlich model for the adsorption of menthyl orange on carbon form sewage sludge.Sewage sludge was made into carbonaceous adsorbent by microwave in the exist of chemical agent, which proposed a new way for utilization of sewage sludge, and built foundation for further development of carbonaceous adsorbent derived from sewage sludge by microwave radiation.