Nwokem C. O., Gimba C. E., Ndukwe G. I. and Abechi S. E.
Optimization of the removal of p-nitrophenol and p-nitroaniline from single and binary solute systems by Hexadecyltrimethylammonium chloride (HDTMA) bentonite using the response surface methodology (RSM) was studied. Central composite design was used to determine the effect of four independent variables; pH, Adsorbate concentration, solid:liquid ratio (S:L) and Time. Based on the central composite design used, linear and quadratic models were developed for removal of p-nitrophenol and p-nitroaniline from the single- and binary solute systems respectively. The influence of each factor on the process was determined from the analysis of variance (ANOVA). The optimum conditions obtained for the single solute system were pH of 7.99, adsorbate concentration of 2.02mg/dm3, solid: liquid ratio of 5.0, time of 120mins and removal efficiency of 27.07% for p-nitroaniline and pH of 7.97, adsorbate concentration of 2.01mg/dm3, solid: liquid ratio of 2.86, time of 99mins and removal efficiency of 99.79% for p-nitrophenol. The optimum conditions obtained for the binary solute system were pH of 6.10, adsorbate concentration of 1.00mg/dm3, solid: liquid ratio of 5.0, time of 120mins and removal efficiency of 71.33% for pnitroaniline and pH of 7.17, adsorbate concentration of 1.00mg/dm3, solid: liquid ratio of 5.00, time of 120mins and removal efficiency of 94.74% for p-nitrophenol
