Study of Application of Layered Double Hydroxide Derived from Zinc-Plating Wastewater to Boron Adsorbent

Layered double hydroxides (LDH) were synthesized from zinc-plating wastewater and its applicability to boron adsorbent was investigated. Since the high concentration of sulfate ions in zinc-plating wastewater is assumed to inhibit the boron adsorption capacity, we searched for optimal synthesis conditions using simulated wastewater with sulfate ions added. It was suggested that the boron adsorption capacity of LDH decreases when large amounts of sulfate ions are present in wastewater. However, in case carbonated-LDH was synthesized with sodium carbonate and the interlayer carbonate ions were removed by calcination at 450 degrees C, oxidized LDH (LDO) was obtained, and the amount of sulfate ion contained in LDO was reduced, thereby boron adsorption capacity was improved. LDO obtained by calcination at 450 degrees C had the same boron adsorption capacity as that of the simulated wastewater, even when using zinc-plating wastewater, so the influence of foreign substances other than sulfate ions was negligible. Therefore, this study is expected to be an effective method of utilizing zinc-plating wastewater.