Novel Na-zeolite covalently bonded with quaternary ammonium for simultaneous removal of phosphate, ammonium and nitrate

摘要

Phosphate and ammonium, along with nitrate, have been regarded as the main control indicators in the treatment of municipal sewage. However, no promising material has yet been developed for the simultaneous removal of phosphate, ammonium and nitrate. Natural zeolite was modified for the first time by quaternary ammonium group-containing silane coupling agent and sodium chloride. The quaternary ammonium groups were covalently attached to the surface of zeolite. This modified zeolite (QaNaZ) could remove not only phosphate and ammonium but also nitrate from sewage efficiently, with removal efficiency of 94.18%, 48.84%, and 91.11% respectively. The results showed that chemical adsorption was the main mechanism in this spontaneous and endothermic process. The coexisting ions in sewage had no significant effect on the adsorption of QaNaZ. The exhausted QaNaZ could be regenerated easily using dilute sodium chloride solution. QaNaZ would have broad applications in simultaneous removal of nitrogen and phosphate from wastewater.