MERCURY ADSORPTION STOICHIOMETRY OF CERAMIC AND ACTIVATED CARBON FROM AQUEOUS PHASE UNDER DIFFERENT pH AND TEMPERATURE

Experiment was performed to draw a mercury adsorption stoichiometry of ceramic and activated carbon from aqueous phase in two parts first part dealt with the effect of three different pH 4, 7 and 10, whereas second part was designed to determine the effect of three temperatures 15, 25 and 35°C. SEM-EDS analysis of adsorbents clearly showed highly uneven and porous surface structure of activated carbon compared to ceramic that contains SiO2 (73.65%) as a major constituent with negligible amount of metals, whereas C (98.46%) is the only constituent in activated carbon. Activated carbon exhibited 15 to 52% (experiment of pH effect) and 49 to 70% (experiment of temperature effect) higher adsorption efficiency than that of the ceramic, which inferred that the activated carbon is a proficient Hg adsorbent compared to the ceramic because of having greater available Hg adsorptive total surface area than ceramic and in contrary, high ionic competition on the surface of ceramic prevents more Hg adsorption from aqueous phase which is entirely absent in activated carbon. PH 7 and pH 4 revealed the highest Hg adsorption in ceramic and activated carbon, respectively. It also signified that pH 7 facilitates Hg adsorption reducing positive ions competition on the ceramic surface which is higher in rest of the pH levels, whereas pH 4 may be optimum to reduce HgCl2 into Hg (I) over the remaining pH in activated carbon for adsorbing maximum Hg. In the experiment of temperature effects, highest temperature (35°C) exhibited a higher rate of adsorption (ceramic 32 35% and activated carbon 0.13 0.84%) than the remaining temperatures. Therefore, it may also be concluded that highest temperature (35°C) of the medium promotes the used adsorbents to remove higher quantity of Hg from water phase because surface group activity of adsorbents, ionization and movements of Hg ions increases with increasing temperature that leads to the higher rate of Hg adsorption.