Removal of Nitrate from Wastewater by Nanoscale Zero-Valent Iron Synthesized from Polyhydroxy Alcohols

Nanoscale zero-valent iron (nZVI) has been widely used to remove pollutants from water. However, nZVI particles are easily exposed to air during preparation and consequently undergo oxidative aggregation, which affects the reactivity. In this study, nZVI particles were prepared for nitrate removal from wastewater using different polyhydroxy alcohols (glycerol, butanetetrol, and pentaerythritol) as the liquid phase reduction medium. The NO3- removal ability and anti-aggregation ability of the prepared nZVI particles were evaluated in different pH environments. The specific reaction pathways that occurred during the NO3- removal process for three materials were determined at different dosages. In addition, SEM, BET, FTIR, and XRD were used to characterize the nZVI particles and analyze their nitrate removal mechanism. The experimental results showed that the nZVI prepared with polyhydroxy alcohols exhibited overall higher nitrate removal efficiency than the pure aqueous medium. The nitrate removal rate reached 94.73% at the initial solution pH=2 and the dosage of 3.0 g/L. Polyhydroxy alcohols can replace the iron oxide layer and form a shell of alcohol hydroxyl groups during the core–shell structure formation of the nZVI reduction process, and this shell improves the dispersion performance and reactivity of nZVI particles in the nitrate reduction process.