Influence of various experimental parameters on the capacitive removal of phosphate from aqueous solutions using LDHs/AC composite electrodes

Zhou, Enhao, Hong, Xiaoting, Ye, Zhuoliang, Hui, K. S. and Hui, K. N. (2019) Influence of various experimental parameters on the capacitive removal of phosphate from aqueous solutions using LDHs/AC composite electrodes. Separation and Purification Technology, 215. pp. 454-462. ISSN 1873-3794

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    Abstract

    The efficient uptake of phosphate from aqueous solutions was achieved on layered double hydroxides (LDHs)-based electrodes via capacitive desalination in our previous study. The current follow-up work was mainly carried out to study the influence of various experimental parameters on the capacitive removal of phosphate using LDHs/activated carbon (LDHs/AC) composite electrodes. A series of batch experiments were implemented to investigate the experimental factors, including Mg2+/Al3+ ratios (2, 3, and 4), trivalent metal cations (Al3+, Fe3+, Cr3+), initial solution pH (from 3 to 10), coexisting anions (NO3-, Cl-, SO42-), and ion strengths, in capacitive deionization. The electrode materials before and after capacitive deionization were characterized to reinforce the analysis of the adsorption mechanisms by X-ray powder diffraction, scanning electron microscopy, energy dispersive X-ray, cyclic voltammetry, and electrochemical impedance spectroscopy. Results indicated that the Mg-Al LDHs/AC electrodes exhibited higher phosphate adsorption capacity (80.43 mg PO43-/g), more regular morphology, and higher degree of crystallinity than that of Mg-Fe LDHs/AC and Mg-Cr LDHs/AC. Increasing Mg2+/Al3+ ratios enhanced the adsorption capacity of phosphate. The uptake of phosphate by Mg-Al LDHs/AC under circumneutral pH and low ion strength reached the maximum level. Furthermore, the presence of coexisting anions lowered the adsorption capacity of phosphate mainly due to the occurrence of a compressed electrical double layer. Therefore, the influence of different experimental parameters on phosphate removal via capacitive deionization by Mg-Al LDHs/AC necessitates a systematic investigation to optimize the preparation conditions of LDHs-based electrodes and several important operating parameters.

    Item Type: Article
    Uncontrolled Keywords: capacitive deionization,layered double hydroxide,phosphate removal,coexisting anion,ion strengths
    Faculty \ School: Faculty of Science > School of Mathematics
    Depositing User: LivePure Connector
    Date Deposited: 11 Jan 2019 16:30
    Last Modified: 13 Feb 2019 14:30
    URI: https://ueaeprints.uea.ac.uk/id/eprint/69563
    DOI: 10.1016/j.seppur.2019.01.004

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