引用本文:王佳怡,毕二平.羧酸类药用活性化合物在生物碳质上的吸附特性[J].环境科学研究,2017,30(8):1278-1286.
WANG Jiayi,BI Erping.Sorption Characteristics of Pharmaceutically Active Carboxyl Acid Compounds to Biochar[J].Reserrch of Environmental Science,2017,30(8):1278-1286.]
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羧酸类药用活性化合物在生物碳质上的吸附特性
王佳怡, 毕二平
中国地质大学(北京)水资源与环境学院, 水资源与环境工程北京市重点实验室, 北京 100083
摘要:
为研究生物碳质吸附在处理水土环境中羧酸类PhACs(药用活性化合物)的作用,通过比表面积、红外光谱、元素分析及电镜扫描对商业水稻秸秆生物碳质的结构与性质进行了讨论,同时研究了生物碳质对不同初始pH及不同初始质量浓度的五种羧酸类PhACs〔KTP(酮洛芬)、IBP(布洛芬)、NPX(萘普生)、ASP(阿司匹林)、SYA(水杨酸)〕吸附特征的影响. 结果表明:吸附过程包括前期快速吸附和后期缓慢吸附至平衡两个阶段;在第一阶段,外表面吸附与大孔及中孔扩散是控制吸附的机制,在第二阶段,生物碳质内表面吸附及基质在微孔中的扩散是影响吸附的主要机制. 初始pH为6.0~7.0时,等温吸附数据符合Freundlich吸附等温方程,反映了非均匀性表面的吸附特性. 五种羧酸类PhACs在生物碳质上的吸附能力〔通过Kd,0.01(特定液相浓度下的单点分配系数)表达〕表现为NPX(24.30 g/L)>IBP(15.82 g/L)>KTP(10.44 g/L)>SYA(2.64 g/L)>ASP(1.24 g/L). 溶液初始pH变化对所选PhACs的吸附量有显著影响,初始溶液pH处于pKa±1.0范围内时,所选吸附质的吸附量达到最大值,随着初始pH的升高,所选PhACs主要以阴离子形式存在,同时生物碳质表面负电性增加,增强的静电斥力减弱了氢键作用. 研究显示,氢键作用在生物碳质吸附PhACs过程中起到主要促进作用,除此之外,还受到范德华力及π-π电子供受体等多种作用驱动.
关键词:  羧酸类药用活性化合物  生物碳质  吸附  溶液pH  氢键作用
DOI:
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基金项目:国家自然科学基金项目(41472231)
Sorption Characteristics of Pharmaceutically Active Carboxyl Acid Compounds to Biochar
WANG Jiayi, BI Erping
Beijing Key Laboratory of Water Environmental Engineering, School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, China
Abstract:
Abstract: In order to evaluate the role of biochar sorption in treatment of pharmaceutically active compounds (PhACs) in water and soil environments, the structure and properties of commercial rice straw biochar (carbonization temperature:400-500 ℃, 200 mesh/0.0075 mm) were characterized by BET, Fourier transform infrared spectroscopy, elemental analysis and scanning electron microscopy. Meanwhile, five carboxyl acid PhACs (i.e., NPX (naproxen), ibuprofen (IBP), ketoprofen (KTP), aspirin (ASP) and salicylic acid (SYA)) were selected as model sorbates. The mechanisms of these sorbates sorbing to biochar were investigated through batch experiments under different initial sorbate concentrations and initial solution pH values. The results showed that the overall sorption process included two stages, i.e., fast sorption in the beginning followed by slow sorption. In the first stage, the outside surface adsorption and sorbate diffusion into macro and mesopores were the main mechanisms. In the second stage, inner surface sorption and sorbate diffusion into micropores dominated the sorption process. The isotherm data were well fitted by the Freundlich isotherm when initial solution pH was in the range of 6.0 to 7.0, which indicates sorption to a non-uniform biochar surface. The sorption coefficients Kd,0.01(Cw/Sw=0.01) of the five PhACs were in the order:NPX (24.30 g/L) > IBP (15.82 g/L) > KTP (10.44 g/L) > SYA (2.64 g/L)> ASP (1.24 g/L). Initial solution pH played a crucial role in PhACs sorption. The maximum sorption capacity was observed at the solution pH range of pKa±1.0 for the five PhACs. With increasing initial solution pH, the species of five sorbates were mainly in anion forms, and the surfaces of biochar became more negatively charged. Therefore, the enhanced electrostatic repulsion between sorbate anions and the negatively charged biochar reduced the possibility of hydrogen bonding. The results showed that hydrogen bonding was the main driving force in the sorption process; the other forces included van der Waals and π-π electron-donor-acceptor interactions.
Key words:  carboxyl acid pharmaceutically active compounds  biochar  sorption  solution pH  hydrogen bonding