Study On Ligand Exchanged Materials And Methods For Arsenic Removal

Though nature functions as well as the well drilling weathering, erosion, dissolution, and artificial activity such as water wells, irrigation, mining, chemical industry, arsenic in lithosphere has released into the natural water ,mainly into the groundwater, followed by access to surface water. The arsenic concentration has gone beyond 0.1 ~ 2 mg / L. Arsenide is easily accumulated in the human body, causing acute or chronic poisoning. It is one of the major threats caused human suffering from lung cancer, skin cancer and other cancers visceral. The arsenic quantity standard in drinking water has been dropped from 0.05mg/L to 0.01mg/L in China, the US, Japan and the WTO. Therefore, in order to strictly control the content of arsenic in drinking water, protect people's health, it is imperative to find a new method of removing arsenic from water. At present, a lot of study has been done in this area. Nevertheless, the method has limited used in practice for its shortcomings in varying degrees. Therefore, it is a subject of great value to investigate the cost-effective materials and methods for arsenic removal.In this paper, a detail analyzing and discussion of the existing arsenic removal methods is made in foundation of much reading and lots of experiments. Taking advantage of porous, easily modified molecular sieve or similar to the skeleton on the cage-like structure, it can be obtained by loading Fe3+ on the skeleton of the material. By the complexation of Fe3+ and H2AsO4—or HAsO42- , arsenate can be removed from high arsenic containing water.The optimum condition of synthesis, modification, and the carrier behavior have been discussed in this study , separately from modified zeolite, modified activated carbon and modified kaolin. In-depth research has been carried on in arsenic removal conditions, disturbed conditions, technological conditions and adsorption mechanism. All of the three arsenic removal materials have the advantages of simple operation, less interference and non-secondary pollution the environment. The modified zeolite and the modified activated carbon could be separated from the water easily. The modified kaolin has the maximum arsenical absorption capacity in water among three materials. The water can meet the state drinking water standards or even lower after treatment by it. In addition, It has the vital significance and high practical value to arsenic removal. The mechanism of arsenic removal is a process of ligand exchange. The process can been described as three steps: scatter- react- scatter. Finally, through the design parameters, centralized water equipment of arsenic removal has been designed. It takes a new depth-solid-liquid separation method to arsenic removal both in theory and practice.