The kinetic theory of liquid indicates that diffusion coefficient for the dilute liquid at ordinary pressure is essentially independent of mixture composition. Mass transfer is important in separation and adsorption process. However, diffusion may also be caused by other features. Because of the complex nature of mass diffusion, the diffusion coefficients are usually determined experimentally. The mass transfer resistance controls the kinetic adsorption rate, but there is only limited understanding of the adsorption of a solute onto porous material from surface water. Thus, this study was conducted to further enhance the understanding of the mass transfer and adsorption processes of micropollutants. The objectives of this study are to analyze the difference, examine the adsoprtion diffusion of mass transfer and evaluate the variation of total, internal and external mass transfer. This study also used the transformed equation to analyze the rate of adsorption during adsorption process onto different GACs. Five (5) micropollutants namely Hg, Cd, As, DDT and chlordane have been chosen to be adsorbed onto three (3) granular activated carbon which are SIG (shell industrial grade), SAG (shell analytical grade) and BAG (bitumen analytical grade). The micropollutants (Hg, Cd, As, DDT and chlordane) were prepared using standard stock solution in deionized water. Adsorption of pollutants onto SIG, SAG, and BAG were started at different percentages of outflow. Although the samples were taken at the same time, the outcome showed that a significant competition between adsorbates and adsorbents. From the analysis, SIG and SAG displayed excellent performance in adsorbing inorganic micropollutants while BAG for organic micropollutants. Before adsorption takes place, the morphology of the SAG indicated pore abundance compared to SIG and BAG. BAG pores are more structured than SIG and SAG. After adsorption occurs, more of the organic micropollutants are being adsorbed onto BAG and SAG. Meanwhile, SIG proved to be the best adsorbent for inorganic micropollutants. It takes 72 hours for Hg
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and As to saturate SIG whilst Cd take a longer time of 80 hours. SAG was also a good adsorbent for organic elements, with DDT taking 52 hours and chlordane taking 48 hours to be adsorbed. The [KLa]f value for the adsorption of Hg onto SIG was significant and the [KLa]d value for the adsorption of Hg onto SIG was higher onto SAG and BAG. The value of [KLa]f for SIG at 6% outflow was 0.6862 h-1, with values of [KLa]d at -0.4142 h-1 and [KLa]g at 0.2721 h-1, while for the adsorption of Cd it was shown that the [KLa]f values for the adsorption of Cd onto BAG was the most significant and the [KLa]d values for the adsorption of Cd onto SIG was higher than SAG and BAG at 2% outflow, with values of 0.7044 h-1, [KLa]d at -0.3687 h-1, and [KLa]g at 0.3356 h-1. In contrast, for As the [KLa]f for the adsorption of As onto BAG at 4% outflow was 0.6722 h-1 and [KLa]g was 0.3103 h-1. For DDT, the [KLa]f value of DDT for BAG at 0.5% outflow was 1.6662 h-1, [KLa]d was -1.2702 h-1 and [KLa]g was 0.3959 h-1. In the case of DDT, the value of [KLa]f for the adsorption of chlordane onto BAG at 2% outflow was 0.7330 h-1 and [KLa]d was started to activate the adsorption -0.5567 h-1. [KLa]g at 2% outflow was 0.1763 h-1. From these values we can conclude that for the adsorption of inorganic substances, SIG proved to be the best, while for organic substances BAG is the best adsorbent
