Nano Carbons for Removal of Arsenic and Bacterial Pathogens and Their Characterization

Abstract

In this work batch adsorption phenomenon of arsenite and gram-negative Escherichia coli on commercially produced nano carbons like fullerene, multi-walled carbon nanotube (MWCNT) and graphite was investigated in laboratory experiments. Also filters were developed using these nano carbons for the removal of arsenic and Escherichia coli bacteria from contaminated water. Both removal methods were carried out under different conditions like varying the amount of materials, dispersion time, contaminant concentration and the type of materials in order to evaluate the suitability of carbon nano particles. During the batch adsorption studies or mixing method pH of the contaminated water observed to remain within the range of 7.1 to 7.3. It was observed that percentage removal of arsenic and E. coli was increased with dispersion time and amount of nano carbon materials. Using column technique better removal was obtained both for arsenic and E. coli contaminated water. In batch adsorption experiment using 542 ppb arsenic contaminated solution, maximum percentage removal was found about 38.37% using MWCNT. In column experiments, removal were improved for all the adsorbents and general trend of increasing percentage filtration was observed for increased column height. Maximum percentage of filtration in column technique using 70 mg SWCNT was found to be 97.80% for arsenic removal. For E. coli removal only using 25 mg of SWCNT in the column technique removed almost all the E. coli. From these results it was evident that batch removal technique using these nano carbons could not bring the contaminated water into safe limit. But under certain conditions in column technique a remarkable result was found using SWCNT. Optical microscopy studies were also conducted. It was found that the nano carbon aggregates adsorbed the arsenic and E. coli from the contaminated water.