The role of silica and chlorine in cupric hydroxide aging

摘要

Experiments were conducted to investigate fundamental reactions between silica and cupric hydroxide solids at pH 7-10.5 and silica concentrations between 0-30 mg/L. The sorption density ranged from 0-0.77 M Si/M Cu depending on solids age and initial silica concentration, but was not a strong function of pH if the silica was present in excess. At all pHs studied, sorption of silica to Cu(OH){sub}2 slowed its aging as noted by color changes and surface chemistry. On the other hand, chlorine concentrations between 5-65 mg/L hastened transitions from Cu(OH){sub}2 at pH 6 and pH 7 with concurrent loss of free chlorine. This reaction was not anticipated and is deserving of additional research.