ゼオライト－ハイドロタルサイト複合硬化体の鉛およびリン除去特性

抄録

Nutrient salts such as phosphorus and nitrogen compounds contained in wastewater are the causative substances of eutrophication phenomena in lakes and rivers and cause water quality deterioration. Also, heavy metals such as lead and cadmium cause four major pollution diseases. In this study, we prepared composites of zeolite with cation exchange capacity and hydrotalcite with anion exchange capacity and examined the possibility of simultaneous removal of phosphorus and lead. Zeolite-hydrotalcite composite was prepared by geopolymer reaction using silica fume, sodium aluminate and commercial hydrotalcite as starting materials. The effects of aging temperature and water content of the precursor slurry on the formation of zeolite were investigated to determine the optimal solidification conditions. In addition, the effects of zeolite / hydrotalcite mixing ratio and particle size of on phosphorus and lead removal ability were investigated. Zeolite formation and solidification sufficiently proceeded by aging the precursor slurry with a moisture content of 35 mass% at 90 °C. The smaller particle size of composites, the higher both phosphorus and lead removal ratios. The lead removal ratio increased with increasing zeolite content. The phosphorus removal ratio also increased as the hydrotalcite content increased. However, the composite collapse easily as the hydrotalcite content increased. Therefore, the optimum mixing ratio of zeolite / hydrotalcite was probably 6/4 in this experiment.