https://www.sciencedirect.com/science/article/abs/pii/S2213343718306341

Journal of Environmental Chemical Engineering, 6 (2018) 6904–6915

Abstract

In present work, Post-treatment method was employed to prepare sulfur-doped carbon spheres (CS-S). Moreover, CO2 activation was performed on the products to increase their surface area and enhance their adsorption properties. The structures of products have been characterized using EDS, FE-SEM, TEM, XRD, BET and Raman techniques. Then, the effect of carbon dioxide activation of the morphologies and application of the products were examined. All products (doped and undoped, inactivated and activated by 4 and 8 h) were employed in the adsorption of cationic dye (methylene blue) to investigate and compare their efficiencies in this process. In isotherm experiments, Langmuir model has elucidated experimental data, in comparison with Freundlich and Temkin models. The kinetic investigations showed that pseudo-second-order model well-fitted with the experimental data. Moreover, the external mass transfer and intra-particle diffusion models were controlled the adsorption process and external diffusion was more dominant. Thermodynamic investigations confirmed the endothermic nature of the adsorption and also showed that adsorption occurred spontaneously. The high potencies for dye removal were observed for the most of products.