Preparation and characterization of La(III) encapsulated silica gel/chitosan composite and its metal uptake studies

► LaSiCS composite is biodegradable, nontoxic and regenerateable. ► Maximum sorption capacity with the minimum 60 min contact time. ► -OH and -NH2 groups in the composite reduce toxic Cr(VI) to less toxic Cr(III). ► The Cr(VI) removal is via., adsorption coupled reduction/ion-exchange.