Study On Preparation Of Biochar Adsorbent With Sludge And Its Adsorption Of VOCs Toluene

The excess sludge from sewage plant was used as raw material to prepare biochar for adsorption of VOCs toluene.Its recyclable raw materials are cheap and easy to obtain,which could achieve the environmental idea of "using waste to treat waste".This will bring potentially significant economic,social and environmental benefits.The moisture,volatile matter,ash content,and organic matter content in raw sludge were determinated with 84.4%,37.14%,62.73%and 52.53%,respectively.SBA was prepared at different pyrolysis time and pyrolysis temperature,would result in,volatile of 12.57?4.97%,ash of 64.81?87.20%and fixed carbon of 0.001%?0.018%.SBA-551 made at 550? for 60 mins will have its maximum adsorption capacity both in iodine and methylene,reaching 163.9mg/g and 79.7mg/g respectively.Through the experiment,we found that both sludge and SBA contained heavy metals,including in Zn,Mn,Cu,Cr,Ni,Pb,As,Co,Cd and Hg etc.In addition,the Zn content was at 1889.44 mg/kg.TG analysis showed that sludge weight loss was most obvious when sludge was pyrolysied at the temperature of 300?550?,indicated that it was most obvious the weight loss of organic matter in sludge.The results of SEM showed that SBA-551 exhibited more pores than that of sludge.The results of FTIR showed that the nitrogenous substances and-OH of sludge would exhaust after pyrolysis,and their surface were taken up by the-COOH and a small amount of phenolic hydroxy.Under the condition of 30?,the static saturated adsorption capacity of toluene was 156.0mg/g with SBA-551 as raw material.When the particle size of SBA-551 was 30?50 mesh,the saturated adsorption capacity increased to 175.3mg/g.Therefor,SBA-551M35 was prepared with 30 to 50 mesh of SBA-551 modified by 5%ZnCl2 at 40? for 270mins,and its saturated adsorption capacity was 203.34 mg/g at the concentration of 5500mg/m3 toluene for 48h.TG analysis showed that ZnC12 could effectively reduce the loss of carbon and help the generation of ash,playing the role of carbon sequestration,corrosion.SBA-551 M35 had a richer microporous structure compared with SBA-551 by SEM.After modification,the specific surface area increased from 42.549 m2/g to 66.612 m2/g,while the pore volume increased from 0.2335 cm3/g to 0.2608 cm3/g,and the average pore size decreased from 21.95 nm to 15.66 nm.The dynamic adsorption experiment showed that the saturated adsorption capacity of SBA-551M35 to toluene was 126.0mg/g,which indicated that it had the feasibility of application and provided some theoretical basis for future industrial application.