Competitive inhibition of catalytic nitrate reduction over Cu–Pd-hematite by groundwater oxyanions
Nurlan N. Akmanova A. Hamid S. Lee W.
March 2022Elsevier Ltd
Chemosphere
2022#290
The presence of various oxyanions in the groundwater could be the main challenge for the successive application of Cu–Pd-hematite bimetallic catalyst to aqueous NO3− reduction due to the inhibition of its catalytic reactivity and alteration of product selectivity. The batch experiments showed that the reduction kinetics of NO3− was strongly suppressed by ClO4−, PO43−, BrO3− and SO32− at low concentrations (>5 mg/L) and HCO3−, CO32−, SO42− and Cl− at high concentrations (20–500 mg/L). The presence of anions significantly changing the end-product selectivities influenced high N2 selectivity. The selectivity toward N2 increased from 55% to 60%, 60%, and 70% as the concentrations of PO43−, SO32−, and SO42− increased, respectively. It decreased from 55% to 35% in the presence of HCO3− and CO32− in their concentration range of 0–500 mg/L. The production of NO2− was generally not detected, while the formation of NH4+ was observed as the second by-product. It was found that the presence of oxyanions in the NO3− reduction influenced the reactivity and selectivity of bimetallic catalysts by i) competing for active sites (PO43−, SO32−, and BrO3− cases) due to their similar structure, ii) blockage of the promoter and/or noble metal (HCO3−, CO32−, SO42−, Cl− and ClO4− cases), and iii) interaction with the support surface (PO43− case). The results can provide a new insight for the successful application of catalytic NO3− reduction technology with high N2 selectivity to the contaminated groundwater system.
Catalytic denitrification , Competitive inhibition , Groundwater anions , N2 selectivity , Nitrate removal
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Green Energy and Environmental Laboratory, National Laboratory Astana, Nazarbayev University, Nur-Sultan, 010000, Kazakhstan
Environmental Sustainability Research Center, Department of Agricultural Engineering, Faculty of Engineering, Khwaja Fareed University of Engineering and Information Technology, Rahim Yar Khan, Pakistan
Department of Civil and Environmental Engineering, School of Engineering and Digital Sciences, Nazarbayev University, Nur-Sultan, 010000, Kazakhstan
Green Energy and Environmental Laboratory
Environmental Sustainability Research Center
Department of Civil and Environmental Engineering
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