Extraction Remediation Technologies of Arsenic Contaminated Soils Using Citric Acid

With the development of the arsenic industry, major environmental pollution accidents caused by arsenic chemicals has been occurring. It is necessary to find a quick and effective method to remedy arsenic contaminated soils, because the soil generally is the most direct casualty after arsenic pollution event occurs. This article discusses the extraction effects of arsenic contaminated soils using citric acid, aiming at providing measures against arsenic contaminated soils. Citric acid concentration, liquid-soil ratio, extraction time and soil coexisting ions are studied in order to discuss their effects on the extraction effects. The results shows that citric acid is a highly effective extractant for arsenic. After the extraction of citric acid, arsenic contaminated soils could met Identification standards for hazardous wastes -Identification for extraction toxicit. Arsenic extraction efficiency increases with the increasing of citric acid concentration, liquid soil ratio, and extraction time. When citric acid concentration is 0.25 mol/L, liquid-soil ratio was 20 mL/g, extraction time was 21 hours, arsenic extraction efficiency achieves the maximum 74.84%. Because of the existence of competitive actions, the soil coexistence ions of PO43-, Zn2+ and Fe2+ could lead to much poorer extraction effects for citric acid.