不同作物原料热裂解生物质炭对溶液中Cd2+和Pb2+的吸附特性

选择由小麦秸秆、玉米秸秆和花生壳经350~500℃热裂解制成的生物质炭,研究生物黑炭对水溶液中Cd2+和Pb2+的吸附特性,分析了pH值、吸附时间、溶液初始质量浓度、生物质炭粒径和投加量对吸附效果的影响。结果表明:生物质炭对Cd2+和Pb2+的吸附约10 min即达平衡;3种生物质炭对Cd2+和Pb2+的等温吸附均可用Langmuir方程和Freundlich方程拟合,玉米秸秆炭对Cd2+和Pb2+的最大吸附量远大于小麦秸秆炭和花生壳炭;在生物黑炭投加量为150 mg(6 g.L-1)时,3种生物黑炭对溶液Cd2+的去除率均在90%以上,玉米秸秆炭对溶液Pb2+的去除率达90.30%,而小麦秸秆炭和花生壳炭的去除率仅为52%和47%,玉米秸秆炭有望成为处理重金属污染废水的新型吸附材料。

Adsorption of Cd2+ and Pb2+ in aqueous solution by biochars produced from the pyrolysis of different crop feedstock

Biochars were produced from the pyrolysis of wheat,corn straw and peanut husk respectively,at 350-500 ℃.The adsorpents of Cd2+ and Pb2+in aqueous solution by three biochars were investigated.The effect of pH,contract time,initial solution concention,adsorbent particlesize and adsorbent dose on the adsorption of Cd2+and Pb2+on biochars were also estimated.The results indicated that adsorption equilibrium of Cd2+ and Pb2+on biochars almost reached in 10 minutes.The equilibrium adsorption data fitted well to the Langmiur and Freundlich equation.The maximum adsorption capacities of Cd2+ and Pb2+on biochar from corn straw was much larger than wheat straw and peanut shell.When 150mg(6 g.L-1)biochar were used,adsorption capacity of Cd2+on three biochars was 90%,and Pb2+on biochar from corn straw was 90.30% while 52% and 47% on biochar from wheat straw and peanut shell respectively.It suggested that biochar from corn straw was expected to be good adsorbents for heavy metals removal from contaminated water: