小麦秸秆生物炭对水中Cd2+的吸附特性研究

摘要

The objective of this work was to investigate adsorptive characteristic of wheat straw biochar (WSBC) for removal of cadmium ions (Cd2+) from aqueous solution. Batch adsorption experiments were carried out to evaluate the effects of pH value of solution, adsorbent dosage, and co-existing cations on the adsorption of Cd2+ using biochar, and the structural characteristics of biochar were analyzed. The results showed that the biochar contained a large amount of oxygen-containing group on the surface. The adsorption efficiency depended on pH value of solution. The adsorption kinetic data were fitted with pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion models. The pseudo-second-order model provided the best fitting for the adsorption kinetics of Cd2+ onto WSBC. In addition, three isotherm models, Langmuir, Freundlich, and Temkin ones were applied to determine the isotherm parameters of adsorption process. The results indicated that the adsorption isotherm was described well with the Freundlich model. Thermodynamics analysis suggested that Cd2+ adsorption onto WSBC was spontaneous and endothermic process.%以小麦秸秆生物炭(WSBC)为吸附剂,研究了WSBC对水中Cd2+的吸附特性,探讨了溶液pH值、投加量和共存阳离子对其吸附Cd2+的影响.WSBC结构表征结果表明,WSBC表面含有大量的含氧官能团.吸附结果表明,溶液pH值会对WSBC吸附Cd2+产生较大影响.吸附动力学数据分别用准一级动力学、准二级动力学、Elovich 和颗粒内扩散方程拟合,结果表明,准二级动力学方程可以很好地描述 Cd2+在WSBC上的吸附.采用Langmuir、Freundlich和Temkin等温吸附模型对吸附数据进行拟合,发现Cd2+在WSBC上的吸附符合Freundlich等温吸附模型.热力学结果表明,WSBC对Cd2+的吸附是一个自发的吸热过程.