Study on Phosphorus Adsorption Properties by Layered Double Hydroxides with Different Preparation Methods
Magnesium-aluminum layered double hydroxides(LDH)were prepared by hydrothermal(LDH-H)and co-pre-cipitation(LDH-C)methods to study the effect of LDH's preparation method on its adsorption properties.The effects of initial pH,adsorption time,initial concentration,and co-existing ions on the adsorption of phosphate ions(PO43-)were investi-gated.The pH experiments showed that the adsorption performance of LDH-H was more stable at pH 3～6.The adsorption behaviors of PO43-on LDH-H and LDH-C were more fitted to the pseudo-second-order and Langmuir model,indicating a monolayer chemisorption process.Alternatively,the fitted adsorption rate constant(k2)of PO43-adsorption on LDH-H was 7.2 times higher than that on LDH-C,and the corresponding maximal adsorption capacity of LDH-H and LDH-C were 41.003 mg/g and 22.179 mg/g,respectively.Additionally,the PO43-adsorption by LDH-H and LDH-C was slightly affected by low concentrations of coexisting ions(Cl-,NO3-,CO32-,SO42-).X-ray diffraction and Fourier transform infrared spectrosco-py results implied that the superior adsorption performance of LDH-H was attributed to the stronger interlayer ion ex-change.This study could provide technical support for mitigating the eutrophication of water and developing efficient adsor-bents for phosphorus removal.
layered double hydroxideshydrothermal methodcoprecipitation methodadsorption of phosphorus
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