玉米秸秆生物炭对磷酸三(2-氯异丙基)酯的吸附特性及机理

Adsorption characteristics and mechanisms of tris(2-chloroisopropyl) phosphate from corn straw biochar

为探究生物炭对磷酸三(2-氯异丙基)酯(TCIPP)的吸附机理及pH、温度和吸附剂添加量对吸附效果的影响,以玉米秸秆为原料,经500℃限氧热解制备生物炭,通过元素分析、FTIR及XPS等方法分析了生物炭吸附前后表面官能团及元素的变化。结果表明,生物炭对TCIPP的吸附过程更符合准二级动力学(R^(2)=0.964 1)和Temkin(R^(2)=0.994 8)方程,吸附过程以化学吸附为主且存在分子间作用力;生物炭对TCIPP的吸附过程包括液膜扩散、表面吸附及颗粒内部扩散三个过程。pH值和吸附剂添加量对吸附效果的影响较大,而温度对吸附过程的影响较小。生物炭吸附前后的FTIR和XPS表明,生物炭表面的—OH、C=O及芳环上的C—H等官能团以π-π、配位作用参与了吸附过程。研究表明,生物炭对TCIPP的吸附受多个因素的影响,因此在使用生物炭去除污染物时要综合考虑其本身理化性质及外界环境因素的影响。

In this study,we investigated the mechanisms through which tris(2-chloroisopropyl) phosphate(TCIPP) is absorbed on biochar and the effects of pH,temperature,and adsorbent addition on this adsorption effect.We prepared biochar from corn straw through oxygenlimited pyrolysis at 500 ℃,and we analyzed the changes in the surface functional groups and the elemental composition of biochar before and after adsorption of TCIPP by elemental analysis,FTIR,and XPS.The results showed that the adsorption of TCIPP on biochar was more consistent with the quasi-secondary kinetics(R^(2)=0.964 1) and Temkin(R^(2)=0.994 8) models.The adsorption of TCIPP on biochar was mainly achieved through chemisorption and intermolecular forces.The adsorption process included liquid-film diffusion,surface adsorption,and internal particle diffusion.The pH and adsorbent addition had a stronger effect,whereas the temperature had a weaker effect on the adsorption process.The results of FTIR and XPS before and after the adsorption of TCIPP on biochar showed that the functional groups on the surface of biochar,such as—OH,C=0,and C—H on the aromatic ring,participated in the adsorption process viaπ-π interactions and coordination bonds.Our findings show that the adsorption of TCIPP onto biochar is influenced by several processes and factors.Therefore,the influence of physical and chemical properties and external environmental factors should be considered when using biochar to remove target pollutants.