生物炭对铅离子的吸附性能

Adsorption Capability of Biochar to Lead Ion

以废弃松木屑为原料,采用控制热分解法制备了生物炭。运用BET和FTIR等技术对生物炭进行了表征,考察了生物炭对铅离子的吸附效果,并探讨了吸附机理。表征结果显示,700℃氨气处理的生物炭,其比表面积和总孔体积显著增大。实验结果表明：生物炭对铅离子的吸附效果优于普通活性炭,且以700℃氨气处理的生物炭为最佳;随溶液pH的升高生物炭对铅离子的去除率增大,当pH为4-6时去除效果较好;在溶液pH为6、初始铅离子质量浓度为50 mg/L、吸附剂加入量为1 g/L、吸附时间为6 h的条件下,700℃氨气处理的生物炭对铅离子的去除率达99%以上;700℃氨气处理的生物炭的Langmuir吸附常数和Freundlich吸附常数远大于普通活性炭和其他工艺的生物炭;铅离子在生物炭上的吸附过程符合拟二级动力学方程。

Biochar was prepared by controlled thermal decomposition using waste pine sawdust as raw material,and was characterized by BET and FTIR. The adsorption effects of biochar to lead ion were studied and the adsorption mechanism was discussed. The characterization results show that： The specifi c surface area and the total pore volume of the biochar treated with ammonia at 700 ℃ are enlarged signifi cantly. The experimental results show that： The adsorption effects of biochar,especially the biochar treated with ammonia at 700 ℃,are much better than that of the normal activated carbon;The removal rate of lead ion is increased with the increasing of solution pH,and the better values are within the range of pH 4-6;Under the conditions of solution pH 6,initial lead ion mass concentration 50 mg/L,adsorbent dosage 1 g/L and adsorption time 6 h,the removal rate of lead ion on the biochar treated with ammonia at 700 ℃ reaches above 99%;The equilibrium constants of Langmuir and Freundlich isothermal adsorption equations of the biochar treated with ammonia at 700 ℃ is much larger than those of common activated carbon and the biochar treated by other processes;The adsorption of lead ion on biochar follows the pseudo-second-order kinetics equation.