Acta Scientiarum Naturalium Universitatis Pekinensis

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Study on Adsorption Behavior of Pb2+ and Cd2+ by Extracellular Polymeric Substances

ZHANG Jiangshui1, LIU Wen1,2, SUN Weiling2, XU Nan1, NI Jinren2   

  1. 1. Key Laboratory for Urban Habitat Environmental Science and Technology, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen 518055; 2. Department of Environmental Engineering, Peking University, Key Laboratory of Water and Sediment Sciences MOE, Beijing 100871;
  • Received:2012-05-12 Online:2013-05-20 Published:2013-05-20

胞外聚合物对Pb2+和Cd2+吸附行为研究

张江水1,刘文1,2,孙卫玲2,许楠1,倪晋仁2   

  1. 1. 北京大学深圳研究生院环境与能源学院, 城市人居环境科学与技术重点实验室, 深圳 518055; 2. 北京大学环境工程系, 教育部水沙科学重点实验室, 北京 100871;

Abstract: As a kind of new biosorbent, aerobic granular sludge which has the advantages of strong adsorption capacity and easily-desorbing property, was paid great attention in the area of heavy metal waste water treatment. In this research, the adsorption behaviors of Pb2+ and Cd2+ by extracellular polymeric substances (EPS) which extracted from aerobic granular sludge using improved centrifugation methods were studied. The results showed that the adsorption capacity of Pb2+ and Cd2+ on EPS was considerably large. The experimental results were fit well with the Langmuir iostherms model. The maximum adsorption capacity for Pb2+ and Cd2+ by EPS was up to 534.76 mg/g and 478.47 mg/g, respectively. Furthermore, the competitive adsorption experiments presented that EPS exhibited a selective adsorption for Pb2+. Specially, there was a minor inhibition for Pb2+ adsorption in presences of Cd2+, while the adsorption capacity of Cd2+ was greatly decreased when Pb2+ co-existed in solutions. FT-IR and EEM analysis revealed that EPS was rich in hydrophilic groups and hydrophobic groups, which was benefit to combine heavy metals by complexation, ions exchange and chelation. The adsorption of Pb2+ and Cd2+ by EPS was mainly attributed to the ?COOH, ?NH2, ?CH, ?OH and ?C=O groups from protein fractions of them. The main adsorption mechanism of Pb2+ by EPS was ion exchange and complexation, while for Cd2+ was mainly took effect by complexation.

Key words: extracellular polymeric substances, Pb2+, Cd2+, adsorption mechanism

摘要: 利用改良离心法从好氧颗粒污泥中提取胞外聚合物(EPS), 并研究其对重金属废水中Pb2+和Cd2+的吸附行为。结果表明, EPS对Pb2+和Cd2+具有很强的吸附能力, 吸附行为符合Langmuir等温式, 拟合得到的最大吸附量分别可达534.76 和478.47 mg/g。Pb2+和Cd2+在EPS上存在竞争吸附, EPS对Pb2+的吸附选择性更强。Cd2+对EPS吸附Pb2+有一定的抑制作用, 但Pb2+的存在对EPS吸附Cd2+具有显著的抑制作用。傅立叶红外光谱(FT-IR)和三维荧光光谱(EEM)测定表明, 实验提取的EPS含有大量疏水和亲水性基团, 因此可通过络合作用、离子交换、螯合等多种作用与重金属发生强结合。对重金属起主要吸附作用的是存在于EPS蛋白质组分中的?COOH, ?NH2, ?CH2?, ?OH及?C=O官能团。研究表明, EPS吸附Pb2+的主要机理为离子交换和络合作用, 而对Cd2+的吸附则主要通过络合作用完成。

关键词: 胞外聚合物, Pb2+, Cd2+, 吸附机理

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