Efficient natural organic matter removal from water using nano-MgO coupled with microfiltration membrane separation

[Display omitted] •MgO performs abnormally high NOM removal capacity.•MgO serves as a two-in-one coagulant and adsorbent.•Dissolved Mg2+ removes 92% NOM via coagulation.•Mg(OH)2 is responsible for the adsorption removal of residue NOM.•MgO can be regenerated for more than 10 times without generating...

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Bibliographic Details
Published in:The Science of the total environment 2020-04, Vol.711, p.135120-135120, Article 135120
Main Authors: Zhou, Juanjuan, Xia, Yan, Gong, Yanyan, Li, Wanbin, Li, Zhanjun
Format: Article
Language:English
Subjects:
Adsorption
Annealing regeneration
Membrane separation
MgO
Natural organic matter
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Summary:[Display omitted] •MgO performs abnormally high NOM removal capacity.•MgO serves as a two-in-one coagulant and adsorbent.•Dissolved Mg2+ removes 92% NOM via coagulation.•Mg(OH)2 is responsible for the adsorption removal of residue NOM.•MgO can be regenerated for more than 10 times without generating any solid waste. Excess natural organic matter (NOM) in water not only lead to unpleasant black color and dissolved oxygen depletion in wastewater and natural water body but also causes carcinogenic chlorinated organic byproduct during drinking water chlorine disinfection. We try to develop a novel cost-effective and green technology for water NOM removal. In our simulated NOM removal process using humic acid (HA) as typical organic matter, we find that mesoporous nano-MgO performs an abnormally high NOM removal capacity (1260 mg-HA/g-MgO, or 446 mgC/g-MgO) when coupled with microfiltration membrane separation, which can’t be illustrated by traditional adsorption mechanism. Actually, Mg2+ from dissolved Mg(OH)2 contributes ∼ 92% NOM removal via coagulation while Mg(OH)2 is responsible for the residue ∼ 8% via adsorption. MgO serves as a two-in-one coagulant and adsorbent. The MgO treatment process is highly pH sensitive and weak acidic condition is favored for high NOM removal efficiency. MgO can be regenerated for more than 10 circulations by annealing Mg(OH)2/Mg-NOM composite at 500 °C, so that our MgO recycling process will be sustainable without the need of continuous chemical purchase. More importantly, no solid waste is generated in this novel process. This MgO-recycling NOM-removal process is simple, efficient, and sustainable for water NOM removal and will be significant in promoting novel sustainable technologies for NOM- or HA-related water remediation and treatment while minimizing the generation of solid waste.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2019.135120