Effective adsorption of pyridine (Py)-onto mesoporous silica derived from de-oiled mustard cake (DOMC): Experimental and theoretical study

Effective adsorption of pyridine (Py)-a major pollutant present in various industrial wastewaters onto silica derived from de-oiled mustard cake (DOMC) was evaluated. Fourier transform infrared spectroscopy (FT-IR) and SEM were used to characterized the adsorbent. The paper describes data on the chemical composition of the DOMC, kinetics and equilibrium adsorption of Py as well as the effect of different operational parameters (temperature, pH, ionic strength and effect of urea) on the effective removal of Py from its aqueous solution. Adsorption data were modeled with the Freundlich, Langmuir, Redlich-Peterson (R-P) and Temkin isotherm. The adsorption data are found suitable for the studied models quite reasonably. However, the results describe the best representation of the Langmuir isotherm model (non-linear R-2 = 0.99). The adsorption process followed Lagergren first order kinetics. The experimental findings were complemented using density functional theory (DFT) to have more understanding at atomistic level. The possible adsorption interactions were discussed. The effects of process parameters such as pH, urea and ionic strength on the adsorption suggested that the adsorption of Py was attributed to hydrogen bonding; however, hydrophobic interactions and charge transfer interactions are also believed to be responsible for the observed adsorption in the present case. The experimental data were subsentiated by employing a silica model based on DFT. Experimental and theoretical modeling of the adsorption phenomenon suggest hydrogen bonding to be a dominant force for Py adsorption onto silica. (C) 2016 Elsevier Ltd. All rights reserved.