Arsenic Contaminated Groundwater Remediation by Entrapped Nanoscale Zero-Valent Iron

摘要

The use of NZVI entrapped in Ca-alginate beads shows great promise as an advanced treatment technique for arsenic removal from groundwater. As clean water sources around the world become scarce, the ability to remediate contaminated water is becoming increasingly critical. Millions of people are forced to consume water contaminated by arsenic daily, jeopardizing their health and quality of life. In batch studies with initial As~(5+) concentrations of 1, 5, 10 mg/L, ～ 85-100% removal of arsenic was achieved within 2 h. At each concentration level bare particle performance exceeds that of the entrapped for the initial 15 to 60 min of the reaction. However, after this initial phase most of the bare NZVI particles are exhausted while entrapped particles are more steadily consumed allowing for consistently lower arsenic levels in the latter reaction stages. Entrapment also controls the dispersibility by containing particles to larger polymer structures while we still benefit from the unique properties of nanomaterials (e.g. increased surface area). Furthermore, Ca-alginate polymer is non-toxic, biodegradable and has little to no solubility in water making it ideal for treatment purposes. After treatment entrapped particles can be more easily separated from liquid stream as well.