Synthesis of magnetite/lanthanum hydroxide composite and magnetite/aluminum hydroxide composite for removal of phosphate

Qixuan Song; Suzhen Huang; Li Xu; Ning Wang; Zhongda Hu; Xingzhang Luo; Zheng Zheng

doi:10.1016/j.scitotenv.2020.137838

Synthesis of magnetite/lanthanum hydroxide composite and magnetite/aluminum hydroxide composite for removal of phosphate

Sci Total Environ. 2020 Jun 25:723:137838. doi: 10.1016/j.scitotenv.2020.137838. Epub 2020 Mar 10.

Authors

Qixuan Song¹, Suzhen Huang¹, Li Xu¹, Ning Wang¹, Zhongda Hu¹, Xingzhang Luo¹, Zheng Zheng²

Affiliations

¹ Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, PR China.
² Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, PR China. Electronic address: zzhenghj@fudan.edu.cn.

PMID: 32217398
DOI: 10.1016/j.scitotenv.2020.137838

Abstract

Two magnetic adsorbents, magnetite/aluminum hydroxide composite (MAC) and magnetite/lanthanum hydroxide composite (MLC), were successfully synthesized by a simple one-pot method and their phosphate adsorption process was investigated. The properties of synthesized adsorbents were studied using Fourier transform infrared spectroscopy (FTIR), zeta potential, vibrating sample magnetometry (VSM) and X-ray photoelectron spectroscopy (XPS). The adsorption isotherms, adsorption kinetics and the effects of solution pH and dissolved organic carbon (DOC) on the adsorption of phosphate in aqueous solution by MAC, MLC-2, MLC-10 and LMB were investigated to evaluate the difference in phosphate removal efficiency of the magnetic adsorbents and non-magnetic adsorbent. According to the results of this study, MLC-10 had a higher phosphate adsorption capacity (19.34 mg P g^-¹) than LMB (11.55 mg P g^-1), MAC (10.48 mg P g^-1) and MLC-2 (8.89 mg P g^-¹). MLC-10 showed a relative higher partition coefficient (PC) (1.74 mg g^-1 μM^-1) than other three adsorbents at initial P concentration of 15 mg L^-1. Also, MLC-10 was less pH dependent than MAC and had higher phosphate adsorption capacities under different DOC concentrations (0-72 mg L^-1) than LMB, MAC and MLC-2. Further, MLC-10 had excellent recyclability due to high magnetism. Electrostatic interaction and the inner-sphere surface complexation were the potential phosphate adsorption mechanisms employed by MLC-10. In summary, MLC-10 is a promising adsorbent for phosphate removal from eutrophication water.

Keywords: Adsorption mechanism; Magnetite/aluminum hydroxide composite; Magnetite/lanthanum hydroxide composite; Phosphate removal.