Facile design of UiO-66-NH2@La(OH)3 composite with enhanced efficiency for phosphate removal

Abstract

Excessive phosphate in wastewater can cause eutrophication of water body, which will worsen the ecological environment and threaten human health and biological life safety. Adsorption of phosphate is the most effective way to remove phosphate, and efficient adsorbent is the key. Amorphous La(OH)3 has been deemed as a potential phosphate adsorbent on account of high adsorption capacity and environmentally friendly property. However, it also shows some disadvantages such as easy agglomeration, poor water dispersion. In this study, UiO-66-NH2 was used as carrier to load amorphous lanthanum hydroxide as an adsorbent for phosphate removal. The adsorbent (UiO-66-NH2@La(OH)3, ULCs) has good water dispersibility and it is easy to be separated and recovered. At the same time, the maximum phosphate adsorption capacity can reach 140.7 mg P/g. The adsorption process accords with pseudo second order kinetic model and Freundlich isotherm model. The thermodynamic results showed that the adsorption process was spontaneous and endothermic. In addition, in the presence of coexisting anions (such as Cl−, SO42−, NO3−), it also exhibited high selectivity and phosphate removal efficiency. Meanwhile, the adsorption capacity keeps at a high level in the range of pH 3–11. By the merit of above-mentioned properties, the prepared material is expected to be an ideal candidate for phosphate removal from contaminated water.