In this study, fuller’s earth (FE) modified with sodium dodecylbenzene sulphonic acid was used for adsorptive removal of fenoxaprop-p-ethyl (FPE) herbicide from water samples and statistical validation of the experimental observations was accomplished. All the adsorption experiments were conducted in batch mode. The effect of pH, agitation time, adsorbent dose and initial herbicide concentration on adsorption process was studied. About 98.5% adsorption efficiency was achieved at initial analyte concentration of 1000 mg L-1 at pH 6 within 60 min at adsorbent dose of 0.1 g. The adsorption kinetics were studied and pseudo-second-order kinetic model was found to follow the adsorption kinetics with R2=0.998. The isotherm studies show that the adsorption data fit well to the Freundlich isotherms. In statistical evaluation, the individual as well as the interaction effect of various factors on adsorption was investigated and it was found that concentration, pH and adsorbent dose are the significant factors with p values of 0.0001, 0.004 and 0.006 respectively, while contact time was found statistically insignificant having p value greater than 0.05. The coefficient of determination (R2=0.930) shows that % adsorption is highly dependent on the studied factors and their interactions. Under the optimized set of conditions, high absorption capacity of 200.22 mg g-1 was achieved.

Jasmin Shah, Muhammad Rasul Jan, Mian Muhammad, Behisht Ara and Changeez Ahmad