Recovery of Hg(II) from aqueous solution by complexation-ultrafiltration using rotating disk membrane and shear stabilit
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Recovery of Hg(II) from aqueous solution by complexation-ultrafiltration using rotating disk membrane and shear stability of PMA-Hg complex ZHOU Han(周韩), QIU Yun-ren(邱运仁), CHEN Yu-xin(陈雨欣) School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China © Central South University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract: Copolymer of acrylic acid and maleic acid (PMA) was used to remove Hg2+ from aqueous solution by complexation-ultrafiltration (C-UF) through rotating disk membrane (RDM). The effects of P/M (mass ratio of PMA to metal ions), pH and rotation speed (N) on the interception of Hg2+ were investigated. The interception could reach 99.7% at pH 7.0, P/M 6 and N less than 1890 r/min. The shear stability of PMA-Hg complex was studied by RDM. The critical rotation speed, at which the interception starts to decrease, was 1890 r/min, and the critical shear rate, the smallest shear rate at which PMA-Hg complex begins to dissociate, was 2.50×105 s−1 at pH 7.0. Furthermore, the critical radii were obtained at different rotation speeds and pHs. The results showed that the critical radius decreased with the rotation speed and increased with pH. Shear induced dissociation coupling with ultrafiltration (SID-UF) was efficiently used to recover Hg2+ and PMA. Key words: complexation-ultrafiltration; shear induced dissociation; rotating disk membrane; shear stability; wastewater treatment Cite this article as: ZHOU Han, QIU Yun-ren, CHEN Yu-xin. Recovery of Hg(II) from aqueous solution by complexation-ultrafiltration using rotating disk membrane and shear stability of PMA-Hg complex [J]. Journal of Central South University, 2020, 27(9): 2507−2514. DOI: https://doi.org/10.1007/s11771-020-4471-2.
1 Introduction Large amount of wastewater containing Hg2+ is produced from various chemical industries, such as chloralkali, oil refining and rubber processing [1]. Even trace amounts of Hg2+ may cause serious physiological complications to human as prenatal brain damage and motion disorders for its high biological toxicity [2]. Mercury as a highly toxic metal has aroused widespread attention for researchers to recover it from wastewater. Previous methods for removing Hg2+ from wastewater, such as ion exchange, chemical flocculation, sulfide precipitation, reduction and adsorption, almost possess the defects of high operation cost, limited
raw materials, especially not suitable for treating low concentration wastewater and not helpful for the recovery [3−8]. Complexation–ultrafiltration (C-UF), a promising method with low energy requirements and high removal efficiency, is of great significance in treating wastewater containing heavy metals [9]. In the process of C-UF, metals are bounded with polymers to form macromolecular complexes that can be trapped by ultrafiltration membrane so as to achieve the purpose of removing metals from wastewater [10]. Nevertheless, the traditional C-UF method needs to consume large amounts of acids and alkalis in the subsequent dissociation
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