Tracking metal ion-induced organic membrane fouling in nanofiltration by adopting spectroscopic methods: Observations and predictions

Zhaoyang Su; Ting Liu; Xing Li; Nigel J D Graham; Wenzheng Yu

doi:10.1016/j.scitotenv.2019.135051

Tracking metal ion-induced organic membrane fouling in nanofiltration by adopting spectroscopic methods: Observations and predictions

Sci Total Environ. 2020 Mar 15:708:135051. doi: 10.1016/j.scitotenv.2019.135051. Epub 2019 Nov 2.

Authors

Zhaoyang Su¹, Ting Liu², Xing Li³, Nigel J D Graham⁴, Wenzheng Yu⁵

Affiliations

¹ Key Laboratory of Drinking Water Science and Technology, Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK; College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100024, China. Electronic address: zysu@rcees.ac.cn.
² Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK; School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China. Electronic address: liuting@bit.edu.cn.
³ College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100024, China. Electronic address: lixing@bjut.edu.cn.
⁴ Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK. Electronic address: n.graham@imperial.ac.uk.
⁵ Key Laboratory of Drinking Water Science and Technology, Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK. Electronic address: wzyu@rcees.ac.cn.

PMID: 31796279
DOI: 10.1016/j.scitotenv.2019.135051

Abstract

Natural organic matter (NOM) with the size approaching to membrane pore size is commonly considered as the crucial component leading to severe pore blocking and superfluous energy consumption. Aquatic metal ions coexisting with this NOM constituent (target NOM) exert a significant influence on membrane filtration performance; however, little work elucidated their interactions and the impacts on nanofiltration (NF). Therefore, we systematically investigated this issue by titrating three environmentally-relevant metal ions (Al³⁺, Fe³⁺ and Cu²⁺) into the target NOM sample obtained by pre-filtering using NF membrane. Fast spectrophotometric techniques were employed to observe the interactive performance. Results suggested that all metal ions at their critical concentrations caused severe flux decline; Cu²⁺ at a very low concentration of 5 μM, Al³⁺ and Fe³⁺ at 20 μM. NF performance recovered when the concentrations were beyond their critical values, and was improved at excessive concentration when flocs formed. Relationship between spectroscopic characteristics and NF performance was particularly addressed. UV-vis spectrum can be expected to be useful and predictive in membrane fouling control when Al³⁺ or Fe³⁺ presented. However, fluorescence fingerprint was not likely that effective since fluorescence intensity continuously reduced with the increasing metal ion concentration, attributed to their quenching effect on NOM fluorophores.

Keywords: Complexation; Metal ions; Nanofiltration; Natural organic matter; Spectrophotometric method.