Retention of pesticide Endosulfan by nanofiltration: Influence of organic matter-pesticide complexation and solute-membrane interactions

WATER RESEARCH

卷:47

Article

De Munari, Annalisa¹  Semiao, Andrea Joana Correia²  Antizar-Ladislao, Blanca¹ 

[1] Univ Edinburgh, Inst Infrastruct & Environm, Sch Engn, Edinburgh EH9 3JL, Midlothian, Scotland

[2] Univ Coll Dublin, Sch Chem & Bioproc Engn, Dublin 4, Ireland

关键词: Nanofiltration;    Micropollutant;    Natural organic matter;    Solute-solute interactions;    Solute-membrane interactions;   

DOI  :  10.1016/j.watres.2013.03.055

来源: Elsevier

【 摘 要 】

Nanofiltration (NF) is a well-established process used in drinking water production to effectively remove Natural Organic Matter (NOM) and organic micropollutants. The presence of NOM has been shown to have contrasting results on micropollutant retention by NF membranes and removal mechanisms are to date poorly understood. The permeate water quality can therefore vary during operation and its decrease would be an undesired outcome for potable water treatment. It is hence important to establish the mechanisms involved in the removal of organic micropollutants by NF membranes in the presence of NOM. In this study, the retention mechanisms of pesticide Endosulfan (ES) in the presence of humic acids (HA) by two NF membranes, TFC-SR2 and TFC-SR3, a loose and a tight membrane, respectively, were elucidated. The results showed that two mechanisms were involved: (1) the formation of ES HA complexes (solute solute interactions), determined from solid-phase micro-extraction (SPME), increased ES retention, and (2) the interactions between HA and the membrane (solute-membrane interactions) increased membrane molecular weight cut-off (MWCO) and decreased ES retention. HA concentration, pH, and the ratio between micropollutant molecular weight (MW) and membrane MWCO were shown to influence ES retention mechanisms. In the absence of HA-membrane interactions at pH 4, an increase of HA concentration increased ES retention from 60% to 80% for the TFC-SR2 and from 80% to 95% for the TFC-SR3 due to ES HA complex formation. At pH 8, interactions between HA and the loose TFC-SR2 increased the membrane MWCO from 460 to 496 g/mol and ES retention decreased from 55% to 30%, as HA-membrane interactions were the dominant mechanism for ES retention. In contrast, for the tight TFC-SR3 membrane the increase in the MWCO (from 165 to 179 g/mol), was not sufficient to decrease ES retention which was dominated by ES HA interactions. Quantification of the contribution of both solute solute interactions and solute-membrane interactions is hence fundamental in understanding the removal mechanisms of micropollutant by NF membranes in the presence of NOM in order to optimize the treatment process. (C) 2013 Elsevier Ltd. All rights reserved.

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