聚羟基丁酸酯(PHB)对水中微量多环芳烃的仿生吸附

Biomimetic adsorption of trace amounts of polycylic aromatic hydrocarbons from aqueous solution by poly-3-hydroxybutrate

基于生物体组织可对水体中低浓度有机污染物的高倍富集现象,以一种微生物细胞内广泛合成的聚羟基丁酸酯(PHB)为吸附剂,对水溶液中微量的多环芳烃(PAHs)进行仿生吸附研究.实验选取萘、菲和芘为模型污染物,考察了温度、时间、溶液pH和吸附剂用量等因素对吸附效果的影响,并分别以经典的吸附动力学模型、等温吸附模型和吸附热力学模型对吸附过程的机理进行了分析.结果表明,PHB对微量的萘(<1500μg.L-1)、菲(<1000μg.L-1)和芘(<130μg.L-1)具有较高的吸附速率,分别在60、120、80 min即可基本达到平衡,吸附动力学符合拟二级动力学模型;3种多环芳烃的等温吸附曲线用Henry、Langmuir和Freundlich方程进行拟合,线性关系良好,反映出PHB仿生吸附剂与PAHs之间存在着"吸溶"作用而非通常的位点吸附;考察分配系数Kd与Kow、温度的关系,发现Kd与Kow呈正相关,与温度呈负相关;低温有利于吸附,PHB对菲和芘的吸附为自发过程,而对萘的吸附为非自发过程.上述仿生吸附原理的阐明对微污染水处理技术的研究具有重要指导作用.

As some trace organic contaminants can be bioaccumulated in organisms,poly-3-hydroxybutyrate（PHB）,composition of many microorganisms,was used as biomimetic adsorbent to remove polycyclic aromatic hydrocarbons（PAHs） from wastewater.In this study,naphthalene,phenanthrene and pyrene were selected as model compounds.The effects of temperature,reaction time,pH and adsorbent dosage on adsorption capacity and removal efficiency were studied in batch reactors.The adsorption mechanism was investigated by kinetic,adsorption equilibrium isotherms and thermodynamic model.The results showed that the adsorption balance of trace naphthalene（1500 μg · L-1）,phenanthrene（1000 μg · L-1） and pyrene（130 μg · L-1） can be achieved in a short time（60,120 and 80 min,respectively）.Kinetic data can be fitted well by the pseudo second order model.The adsorption equilibrium isotherms can be fitted by the Henry,Freundlich and Langmuir models,which indicated that there was absorption solution force between PHB and PAHs rather than site adsorption.The results also showed that Kd has a positive correlation with Kow while it has a negative correlation with temperature.Therefore,lower temperature would be helpful to adsorption process.The adsorption of phenanthrene and pyrene by PHB was spontaneous while it was non-spontaneous for naphthalene.In all,the biomimetic adsorption mechanism found in this study might be useful and important to others studies of removing trace contaminants from wastewater.