Adsorption of chlorophenols from aqueous solution over amino-modified ordered nanoporous silica materials

The capability of the adsorption of 2-chlorophenol (2-CPh) and 2,4-dichlorophenol (2,4-DCPh) from aqueous solutions with mesoporous silica material MCM- 48 after functionalizing with amine groups, such as 3-(trimethoxysilyl)propyl amine and tetraethylenepentamine, was investigated in this study. It was found that amino-modified ordered mesoporous silica materials show significant adsorption for 2-CPh and 2,4-DCPh. This is possible due to the alkaline and acid interactions among the amine functional groups and chlorophenols. The adsorbents were characterized by X-ray diffraction, nitrogen adsorption–desorption isotherms and Fourier transform infrared. Batch adsorption studies were done to study the effect of various parameters like chemical modification, pH, contact time, adsorbent dose and initial concentration. It was found that adsorption of 2-CPh and 2,4-DCPh depends upon the solution pH. Adsorption data were modeled with the Langmuir and Freundlich adsorption isotherms. The data fitted the Freundlich isotherm model better than Langmuir. The kinetics analysis revealed that the overall adsorption process was successfully fitted with the pseudo-first-order kinetic model.