Nanometer lanthanum hydroxide modified anionic polymer for deep fluoride removal: Adsorption properties and mechanism study

Abstract

The development of chemical industry has brought about serious fluoride pollution, and there is an urgent need to develop an adsorbent with high efficiency and stability for fluoride removal. Despite the remarkable adsorption capacity of lanthanum hydroxide hydrate for fluoride ions, its industrial application is limited by powder leaching and strict pH requirements.In this study, lanthanum-containing anionic resin (HLO-D201) was synthesized by the method of precursor introduction and in-situ deposition, mainly by introducing La3+ into the resin, adding sodium hydroxide to precipitate it in the resin pore, forming hydrated lanthanum oxide.The characterization analysis showed that hydrated lanthanum oxide (HLO) was successfully introduced into the porous matrix of the resin and existed in the form of crystalline hydrated oxide.Static adsorption experiments demonstrated that HLO-D201 could effectively adsorb fluoride ions in a wide pH range (2–10). Since nano La (OH) 3 was encapsulated in the resin pore, the loss of La (OH) 3 was greatly reduced, and under the condition of competitive adsorption of several coexisting ions, Only phosphoric acid group interferes obviously with the adsorption of F-. The synthesized HLO-D201 still showed good adsorption capacity after regenerated by NaOH–NaCl composite solution for six times. The removal mechanism of fluoride by HLO-D201 is mainly electrostatic attraction and ligand exchange.Overall, HLO-D201 is a kind of fluorine removal adsorbent with excellent performance and wide application prospects.