Pd–In bimetallic nanoparticles supported on chelating resin for nitrate removal from water: high efficiency and low NH4+ selectivity

Abstract

Nitrate pollution in groundwater and surface water is a worldwide challenge. Reduction of nitrate to nitrogen gas according to electrocatalysis or hydrogenation catalysis is a prospective way to remove nitrate from water. A Pd/In bimetallic catalyst supported on chelating resin was prepared by a chemical reduction method in aqueous solution. SEM-EDS, TEM, XRD and XPS analyses revealed that the Pd/In nanoparticles with particle sizes ranging from 10 nm to 200 nm showed a uniform distribution in resin. The prepared M-Pd/In composites showed high nitrate removal efficiency (96%) and low NH₄⁺ selectivity (<2%) when the initial concentration of NO₃⁻-N was 100 mg N per L. The coexisting anion, organic matter and initial pH value showed little influence on the nitrate removal ability of the prepared M-Pd/In composites. H_ads and NaBH₄ could be stored during the preparation process of the Pd/In bimetallic composites, and acted as reducing agents in the nitrate removal process. The prepared M-Pd/In composites showed good nitrate removal ability after recycling 5 times. When they were used to treat actual wastewater, nearly all of the nitrate, nitrite and ammonium were removed from municipal WWTP effluent.