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Huan Jing Ke Xue. 2019 Feb 8;40(2):658-668. doi: 10.13227/j.hjkx.201806232.

[Influence of Calcium Ion Pre-treatment on Phosphate Adsorption onto Magnetic Zirconium/Iron-modified Bentonite].

[Article in Chinese]

Author information

1
College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China.
2
College of Environment, Zhejiang University of Technology, Hangzhou 310032, China.
3
College of Municipal and Environmental Engineering, Shandong Jianzhu University, Ji'nan 250101, China.

Abstract

Two kinds of magnetic zirconium/iron-modified bentonites (ZrFeBTs), including magnetic zirconium/iron modified raw bentonite (ZrFeRBT) and magnetic zirconium/iron-modified Ca2+-pretreated bentonite, (ZrFeCaBT) were prepared and characterized. Their phosphate adsorption characteristics were compared to determine the effect of the Ca2+ pre-treatment on the adsorption of phosphate onto ZrFeBTs. The results showed that the as-prepared ZrFeBTs contained Fe3O4 and Zr, and the content of exchangeable Ca2+ in ZrFeCaBT was much higher than that in ZrFeRBT. The adsorption isotherm data exhibited good agreement with the Langmuir isotherm model, with maximum monolayer phosphate adsorption capacities of 8.70 mg·g-1 and 11.5 mg·g-1 for ZrFeRBT and ZrFeCaBT, respectively. The isotherm and kinetics studies showed that the adsorption of phosphate on ZrFeBTs was a chemisorption process. The phosphate adsorption capacities for ZrFeBTs decreased with increasing solution pH. The ZrFeBTs exhibited a high selective adsorption for phosphate in the presence of anions and cations, including Cl-, HCO3-, SO42-, NO3-, Na+, K+, Mg2+, and Ca2+. Furthermore, coexisting Ca2+ greatly enhanced the adsorption of phosphate onto ZrFeBTs. The pre-treatment of raw bentonite with Ca2+ significantly improved the adsorption of phosphate onto ZrFeBTs.

KEYWORDS:

adsorption; calcium ion pre-treatment; effect; magnetic zirconium/iron-modified bentonite; phosphate

PMID:
30628328
DOI:
10.13227/j.hjkx.201806232

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