Nitrate removal from aqueous solution using natural zeolite-supported zero-valent iron nanoparticles

Abstract

A report on the synthesis and characterization of nanoscale zero-valent iron in the presence of natural zeolite as a stabilizer is presented. This novel adsorbent (Ze-nZVI) was synthesized by the sodium borohydride reduction method. The scanning electron microscopy (SEM) images revealed that the stabilized nZVI particles were uniformly dispersed across the zeolite surface without obvious aggregation. The synthesized Ze-nZVI material was then tested for the removal of nitrate from aqueous solution. The effect of various parameters on the removal process, such as initial concentration of nitrate, contact time, initial pH, and Ze-nZVI dosage, was studied. Batch experiments revealed that the supported nZVI materials generally have great flexibility and high activity for nitrate removal from aqueous solution. The nitrogen mass balance calculation showed that ammonium was the major product of nitrate reduction by Ze-nZVI (more than 84% of the nitrate reduced); subsequently the natural zeolite in Ze-nZVI removed it completely via adsorption. The kinetic experiments indicated that the removal of nitrate followed the pseudo-second-order kinetic model. The removal efficiency for nitrate decreased continuously with an increase in the initial solution pH value and Ze-nZVI dosage but increased with the increase in the initial concentration of nitrate. The overall results indicated the potential efficacy of Ze-nZVI for environmental remediation application.