Stevens Institute of Technology , USA

Dr. Xiaoguang Meng is a professor of Environmental Engineering at Stevens Institute of Technology in USA ...

... He earned his PhD degree in Environmental Engineering from Syracuse University in 2003. His research is focused on environmental surface chemistry, development of chemical and physical processes for treatment of arsenic and heavy metals, and removal and recovery of phosphate in wastewater. He has published more 90 papers in peer reviewed scientific journals, obtained four US patents, and edited a book. He developed an effective household filtration process and successfully demonstrated it in hundreds of families in Bangladesh. He developed a nanocrystalline titanium dioxide adsorbent and the patented material has been used in filters for treatment of arsenic, lead and other heavy metals worldwide.

 

Abstract


Competing Interactions of Arsenic Adsorption and Fe(III) Precipitation in Arsenic Treatment with Iron

Xiaoguang Meng1, Qiantao Shi1, Chuanyong Jing2

1 Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ, USA

2 State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China

Ferric chloride and sulfate salts and zero valent iron are commonly used for treatment of arsenic in water. Extensive study has been conducted on the adsorption of arsenic by Fe(OH)3. However, there is limited knowledge about the effect of interactions between Fe(III) and arsenic on the formation of Fe(OH)3. The kinetics of As removal using coagulation by iron chloride (FeCl3) was studied using different orders of As and FeCl3 addition. Adding 6.7 mg/L FeCl3 into 325 µg/L As solution (coprecipitation) resulted in more As removal at 2 min than adding As into aged FeCl3 solution (pre-aged) at pH 7. However, soluble As gradually increased in the coprecipitation system and decreased in the pre-aged system to reach similar concentrations after 800 h aging. The particle size of the iron hydroxides increased slower in the coprecipitation than in the pre-aged systems. These results suggest the rapid adsorption of As on Fe polymer during the initial polymerization process, which delays the growth of iron hydroxides. Quantum chemical calculations implied that ferric ion adsorption on iron hydroxide polymer was more stable than As adsorption, which is the main driving force for the As release during aging process. In addition to the FeCl3, zero valent iron powder was used in the experiments to determine the effect of As(V) on the formation of iron hydroxide precipitates. The presence of As(V) resulted in the formation of nano ferric hydroxide precipitates with high specific surface area and high adsorption capacity for As.