Kinetic, isotherm and thermodynamic studies on the adsorption of Methylene blue dye using Moringa oleifera pods and kernels

The low availability of water resources and the difficulty of access to drinking water are of increasing concern. To face this problem, it is important to improve the quality and quantity of this resource by fighting mainly against its pollution. Thus, it has become necessary to treat the wastewater of industries. In this work we studied the adsorption of methylene blue onto waste of the Moringa oleifera seeds with the aim of valorizing the natural biomass. To understand the adsorption process of Moringa oleifera pods powder and Moringa oleifera kernels powder various studies were performed. Most characterizations of adsorbent like Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electronic microscopy (SEM), specific surface by BET and pHpzc were investigated. The effects of parts of adsorbent, pH of solution, adsorbent dose, initial dye concentration, temperature and contact time on the batch adsorption of methylene blue on Moringa oleifera pods powder (MOPP) and Moringa oleifera kernels powder were studied. The Kinetic, isotherms and thermodynamic studies were done. The adsorption results of methylene blue onto Moringa oleifera pods powder and Moringa oleifera kernels powder showed that the pseudo-second order is the best model with a good correlation. The adsorption isotherm data for the two adsorbents was best correlated with Freundlich isotherm. The values of thermodynamic parameters show that adsorption is an exothermic process for MOPP and MOKP. However, the negative value of the increment G degrees indicated that the adsorption of methylene bleu on adsorbents was thermodynamically feasible and spontaneous.