Removal of mercury species with dithiocarbamate-anchored polymer/organosmectite composites

Abstract

Mercury is one of the most toxic heavy metals found in solid and liquid waste disposed by chloro-alkali, paint, paper/pulp, battery, pharmaceutical, oil refinery and mining companies. Any form of mercury introduced to nature through any means is converted into a more toxic form such as methylmercury chloride (as produced by aquatic organisms) which usually accumulates in the tissue of fish and birds. The primary aim of this study was to investigate performance of dithiocarbamate-anchored polymer/organosmectite composites as sorbents for removal of mercury from aqueous solution. The modified smectite nanocomposites then were reacted with carbondisulfide to incorporate dithiocarbamate functional groups into the nanolayer of the organoclay. These dithiocarbamate-anchored composites were used for the removal of mercury species [Ha(II), CH3Hg(I) and C6H5Hg(I)]. Mercury adsorption was found to be dependent on the solution pH, mercury concentration and the type of mercury species to be adsorbed. The maximum adsorption capacities were equal to 157.3 mg g(-1) (782.5 mu mol g(-1)) for Hg(II); 214.6 mg g(-1) (993.9 mu mol g(-1)) for CH3Hg(I); 90.3 mg g(-1) (325 mu mol g(-1)) for C6H5Hg(I). The competitive adsorption capacities (i.e. adsorption capacities based on solutions containing all three mercuric ions) are 7.7 mg g(-1) (38.3 mu mol g(-1)), 9.2 mg g(-1) (42.6 mu mol g(-1)) and 12.7 mg g(-1) (45.7 mu mol g(-1)) for Hg(II), CH3Hg(I) and C6H5 Hg(I), respectively, at 10 ppm initial concentration. The adsorption capacities on molar basis were in order of C6H5 Hg(I) > CH3 Hg(I) > Hg(II)