Effective removal of nitrate by palygorskite-supported nanoscale zero-valent iron from aqueous solution

Nitrate nitrogen (NO 3 - -N) has become an important pollutant in industrial and agricultural production processes in China. In this study, Palygorskite-supported nanoscale zero-valent iron (nZVI/PG) adsorbent was prepared using the liquid-phase reduction method for the removal of NO 3 - -N from water. Benefiting from the good dispersion uniformity of nZVI on the Palygorskite carrier, the prepared nZVI/PG exhibited a significantly increased specific surface area compared to nZVI, with a noticeable reduction in nZVI aggregation. The Fe/PG mass ratio of 2:1 was found to be the optimal loading ratio for the removal of NO 3 - -N by nZVI/PG, with a removal capacity of 24.36 mg/g and a removal efficiency of 81.23 %, with a nitrogen gas conversion rate of 40.92 %. The removal process of NO 3 - -N by nZVI/PG followed a pseudo-second-order kinetic model, with the removal rate inversely proportional to the initial concentration of NO 3 - -N and directly proportional to the dosage. nZVI/PG exhibited high removal efficiency for NO 3 - -N within the pH range of 2 to 9, with the highest selectivity for NO 3 - -N conversion to N 2 observed at pH 5. The main mechanism for the removal of NO 3 - -N by nZVI/PG was found to be adsorption and reduction, with the main products being NH 4 + -N, NO 2 - -N, and N 2 .