Thermodynamics, and kinetics study of physical removal of high concentration sodium dodecayle sulfate during recycling of industrial and household waste water by adsorption at activated charcoal using pH measurements

Adel R. Ismaeel* and Khaled M.

Abstract

The adsorption of sodium dodecyl sulfate (SDS) at activated charcoal (AC) from high concentration aqueous solution as in recycling processes of industrial and household waste water was studied using pH measurements before and after adsorption processes using batch technique. The results is applicable to Langmuir adsorption isotherm at 20, and 40Coshowing inflection of the lines at tow points dividing the isotherm into three concentration ranges, the relation between adsorption rate and SDS concentration was plotted to give straight line divided to the same three concentration ranges of slope equals the rate constant for the three concentration ranges .From Langmuir lines the free energy change ΔG showing spontaneous adsorption for all concentration ranges decreases at the second range due to change of adsorption mode from vertical to hemi cylinder micillar structure, the third range show a little increase of spontaneity due to reach the critical micillar concentration (CMC) at the given temperature where ( CMC) at 20Co is higher than that at 40Co . The values of activation energy Ea was calculated by Arhineous relation to show high positive values reach 37 k J / M.(g. AC) while compeered with corresponding value of ΔG = -15 k J / M.(g. AC) .This high activation energy Ea is used to release a number of water molecules already adsorbed at AC surface to be replaced by one molecule of larger size SDS