Effective purification of phosphate from water using ultra-small hydrated cerium oxides encapsulated inside gel-type polymer

[Display omitted] •A novel gel-type nanocomposite HCO@N201 contained sub-5 nm HCO NPs is prepared.•The sub-5 nm nature endows HCO@N201 with more Ce(III) and surface hydroxy groups.•HCO@N201 shows superior reactivity, selectivity and stability in phosphate removal.•The depleted HCO@N201 could be fully refreshed by the simple alkali treatment.•HCO@N201 column steadily produces >1100 bed volumes clean water during cyclic runs. Deep removing phosphate from waters is crucial in managing eutrophication, and adsorption has been widely regarded as an effective option. However, it is still lack of adsorbents with high reactivity and applicability. Herein, a novel nanocomposite HCO@N201 was introduced by impregnating hydrated cerium oxides (HCO) NPs inside a gel-type polymer N201. Due to the unique pore structure of N201 that contained plenty of micropores of