Interference effects of oxyanions commonly found in natural waters on the catalytic reduction of nitrate in water

SACCO, NICOLÁS ALEJANDRO; ZOPPAS, FERNANDA MIRANDA; BELTRAME, THIAGO FAVARINI; MIRÓ, EDUARDO ERNESTO; MARCHESINI, FERNANDA ALBANA

ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH

SPRINGER HEIDELBERG

Año: 2022 p. 1 - 13

0944-1344

In this work, the influence of oxyanions on the catalytic reduction of nitrates using formic acid as the reducing agent wasstudied as well as the influence of bicarbonate, sulfate, and phosphate co-anions on the catalytic nitrate reduction with Pd:In/Al2O3 (1:0.25 wt.%). A negative effect on nitrate conversion was observed in the following order: phosphate > sulfate > bicar-bonate, showing a strong influence of electrostatic adsorption on the catalytic reduction of nitrate. However, no direct trendwas observed relating the levels of interferents to the impact on the selectivity of the bimetallic catalyst using formic acidas a reducing agent. For both bicarbonate and phosphate, at lower levels, higher selectivity to nitrogen was obtained thanfor the reaction in the absence of interferents. On the other hand, increasing sulfate concentration led to a decrease in nitrateconversion. The mixtures of co-anions also showed a decrease in the catalytic activity. At 120 min, a N 2 selectivity higherthan 95% was obtained, except for the C50-S20 (bicarbonate 50 ppm–sulfate 20 ppm) mixture which showed the lowestselectivity to N 2 value (87.3%). The loss of catalyst activity was found to be reversible and not permanent.