Novel Method of Treatment of Wastewater Containing Cr(VI) by Synthesizing Layer Double Hydroxide in Situ

摘要

Wastewater containing Cr(VI), known to be toxic and carcinogenic, maybe cause seriously environmental pollution, so it is urgent to work out economical and credible treatment methods for the wastewater. Layer double hydroxides (LDHs) are important materials for anions exchange and have revealed immense applications in treatment of wastewater. The objective of this work was to investigate the efficiency and factors impacting of Cr(VI) removal from wastewater by layer double hydroxide synthesized in situ. Principle of the method may be described as follow: Mg~(2+) and Al~(3+) hydrolyze and form Mg/Al-LDH by adding Mg~(2+), Al~(3+) and NaOH into wastewater containing Cr(VI), Cr(VI) anions are selectively intercalated into interlayer of LDH to balance the positive structural charge While Mg~(2+) and Al~(3+) coprecipitate and form LDH, the Cr(VI) in wastewater is removed by settling of LDH synthesized in situ, which is confirmed by analysis of X-ray diffraction on settlings and chemical analysis on aqueous samples. The results indicate that factors of impacting on efficiency of Cr(VI) removal include amount of adding Mg~(2+) and Al~(3+), Mg/Al ratio, pH and concentration of Cr(VI) in wastewater. This technology has present extraordinary efficiency of treatment and great potential application.