Heated kaolinite-La(III) hydroxide complex for effective removal of phosphate from eutrophic water

Eutrophication has long been a serious environmental problem in global water bodies, and phosphate has been considered as one of the key factors causing water eutrophication. Aiming to develop a low-cost and eco-friendly absorbent for phosphate removal, a type of heated kaolinite-lanthanum hydroxide complex (HKL-LaOH) was prepared via an in-situ synthesis method. In the complex, a large number of nanoscale lanthanum hydroxide flakes were observed on the heated kaolinite surface. The HKL-LaOH with a relatively low lanthanum oxide content (4.42 wt%) exhibited a high phosphate adsorption capacity of 26.15 mg g-1. Such a high utilization rate of lanthanum in HKL-LaOH was attributed to the unique two-dimensional flake shape of heated kaolinite, which achieved the effective dispersion of La(OH)3 on the complex. Furthermore, a great quantity of LaPO4 nano -particles on the heated kaolinite surface of the HKL-LaOH complex were observed, which indicated chemical adsorption of phosphate followed by precipitation of LaPO4. In summary, the high dispersion of La(OH)3 in HKL-LaOH and the resulted formation of LaPO4 nanoparticles leads to high phosphate removal from eutrophic water bodies, which shows excellent application potential in the treatment of eutrophic water.

Automated summary

A low-cost and eco-friendly absorbent for phosphate removal was developed using an in-situ synthesis method. The high phosphate adsorption capacity of the absorbent was attributed to the presence of nanoscale lanthanum hydroxide flakes on the heated kaolinite surface. Chemical adsorption of phosphate followed by the precipitation of LaPO4 on the absorbent surface was observed.