磁性生物炭对水体中对硝基苯酚的吸附特性

为了制备同时具备磁分离和优良吸附性能的环境友好吸附材料，以棉花秸秆为生物质原料制备生物炭（CSBC），采用共沉淀法制得磁性棉花秸秆生物炭（MCSBC）.通过元素分析、SEM、XRD、XPS、FTIR和VSM等对MCSBC进行表征，研究了CSBC和MCSBC对水中对硝基苯酚（PNP）的吸附特性.结果表明，溶液pH值对CSBC和MCSBC吸附PNP的影响较大，在酸性条件下的吸附量更大.CSBC和MCSBC对PNP的吸附动力学过程可被准二级动力学模型很好地描述，吸附过程包括液膜扩散和颗粒内扩散两个阶段.Langmuir、Freundlich和Sips模型都可以很好地描述PNP在CSBC和MCSBC上的吸附行为，最大吸附量分别为44.54和48.94mg/g，MCSBC相较于CSBC对PNP的吸附具有更好的效果.热力学研究结果表明，CSBC和MCSBC对PNP的吸附过程为熵增加的自发吸热过程.再生试验结果表明，经6次吸附-解吸循环后，MCSBC对PNP的吸附容量仍能达到初始吸附量的82%.

Adsorption characteristics of p-nitrophenol removal by magnetic biochar

In order to obtain environmentally friendly adsorbent with magnetic separation and excellent adsorption characteristics, biochar (CSBC) was prepared from cotton straw, and magnetic cotton straw biochar (MCSBC) was prepared by co-precipitation method. CSBC and MCSBC were characterized by SEM, XRD, XPS, FTIR, VSM, and element analysis. The adsorption characteristics of PNP in aqueous solution using CSBC and MCSBC were investigated. The results showed that the pH value of the solution had a great influence on the adsorption of PNP by CSBC and MCSBC, and the adsorption capacity was greater under acidic conditions. Adsorption process of PNP by CSBC and MCSBC can be well fitted by the pseudo-second-order kinetic model. The adsorption process includes two stages:liquid film diffusion and intra-particle diffusion. Langmuir, Freundlich, and Sips models described the adsorption behavior well. The maximum adsorption capacity of CSBC and MCSBC for PNP were 44.54 and 48.94mg/g, respectively. The adsorption capacity of MCSBC was higher than that of the CSBC. Thermodynamic parameters indicated that the adsorption process of PNP onto CSBC and MCSBC was spontaneous with increased entropy and endothermic. The regeneration studies indicated that MCSBC kept 82% of its initial PNP adsorption capacity at the sixth adsorption/desorption cycle.