碳基吸附剂对典型有机防晒剂二苯甲酮-3的吸附性能及热力学研究

针对环境水体中药物及个人护理用品(PPCPs)的污染问题,选择在环境水体中存在的有机紫外防晒剂二苯甲酮-3(BP-3)作为典型污染物,以颗粒活性炭(GAC)、粉末活性炭(PAC)和碳纳米管(CNT)作为吸附剂,考察吸附剂对BP-3的吸附性能、吸附特性和吸附热力学.结果表明:吸附性碳材料对BP-3具有良好的吸附性能,3种碳材料的最大吸附容量排列为:PACGACCNT,其中,PAC的单层最大吸附容量为450.36mg·g-1.Freundlich、Redlich-Peterson和Temkin吸附等温线方程能够较好地拟合吸附数据,Langmuir吸附等温线方程对PAC的吸附拟合效果较好,而对粒径较大的吸附剂(GAC、CNT)的拟合效果不理想.PAC、GAC的吸附过程可以采用一级动力学或者二级动力学模型拟合,而CNT适合采用一级动力学模型来描述.吸附热力学分析表明,PAC、GAC和CNT对BP-3的吸附过程都是自发进行的,其中,PAC和GAC的吸附过程是吸热的,升高温度有利于吸附反应的进行;而CNT的吸附过程是放热的.

Adsorption characteristics and adsorption thermodynamics of typical UV sunscreen oxybenzone(BP-3)at trace level in water by carbon-based adsorption materials

In view of the aquatic environment pollution caused by pharmaceutical and personal care products (PPCPs), three carbon-based materials, including granular activated carbon (GAC), powered activated carbon (PAC), and carbon nanotube (CNT), were selected to remove the typical UV sunscreen oxybenzone (BP-3) in water. The adsorption characteristics and adsorption thermodynamics of three selected adsorbents were investigated. The results showed that three carbon-based materials showed good adsorption capacity on BP-3, and the rank order for adsorption capacity was:PAC> GAC> CNT. PAC presented the highest monolayer adsorption capacity of 450.36 mg·g^-1. Freundlich, Redlich-Peterson and Temkin adsorption isotherm equation could fit adsorption data well. The adsorption of PAC was more easily fitted by Langmuir adsorption isotherm model. The adsorption process of PAC and GAC could be fitted by first-order kinetic model or second-order kinetic model, while the adsorption process of CNT was only fitted by first-order kinetic model. The adsorption thermodynamics parameters showed that the adsorption processes of three carbon-materials were all spontaneous. The adsorption processes of GAC and PAC were endothermic in nature. Increase in temperature could promote the adsorption reaction. However the adsorption process of CNT was exothermic in nature.