Factors controlling arsenic adsorption in the environment

Recent epidemiological studies on arsenic report that the cancer risk associated with arsenic at the current maximum contaminant level (MCL) of 50 {mu}g/L is much greater than previously believed. In response to these findings, the U.S. Environmental Protection Agency intends to decrease the MCL to between 2 and 20 {mu}g/L. The efficiency of arsenic removal in water treatment and the ambient levels of arsenic in source waters are both strongly influenced by the extent of arsenic adsorption to oxide surfaces. An investigation of ft factors controlling arsenic adsorption is crucial to evaluate properly the effectiveness of arsenic removal technologies such as enhanced coagulation. This study examined the effects of the following parameters on arsenic adsorption to preformed hydrous ferric oxide: arsenic oxidation state, initial arsenic concentration, pH and the presence of sulfate. The studies were carried out over initial arsenic concentrations between 2.5 and 100 {mu}g/L (0.33 and 1.34 {mu}M).