Optimization of process parameters for sorption of p-Nitrophenol from aqueous solution by hexadecyltrimethylammonium chloride-treated bentonite (HDTMA-bentonite)

Abstract

Sorption of p-Nitrophenol from aqueous solution using hexadecyltrimethylammonium chloride treated bentonite (HDTMA-bentonite) clay was investigated using a batch system. The combined effect of four independent variables: contact time, pH, adsorbate concentration and solid:liquid ratio on the sorption process was studied and optimized using the Central Composite Design-Response Surface Methodology. The development of the experimental design as well as the interpretation of results was carried-out using the statistical software MINITAB 16 (Stasoft, USA). It was observed from this investigation that the percentage removal efficiency was influenced by process parameters in the following order: solution pH ˃ Adsorbate concentration ˃ solid:liquid ratio ˃ contact time. Optimum values for pH, adsorbate concentration, solid:liquid ratio and contact time were found to be 7.97, 2.01mg/dm³, 2.86 and 99 minutes respectively for the maximum p-nitrophenol removal (99.79%). It was also observed that both experimental and predicted values were in good agreement and the model developed was significant. These results indicate the suitability of HDTMA-bentonite for the removal of p-nitrophenol from aqueous solution.