Research on the Surface Functional Groups of Oxidative Modified Activated Carbon and Its Adsorption Behaviour of Methylene Blue

This article focused on methylene blue (MB) as a typical dye, used oxidative modified activated carbon (MAC) for adsorption, and obtained the adsorption capacities of different activated carbon (AC) samples through isothermal adsorption fitting using Langmuir, Freundlich and Temkin isotherm equations, respectively. The relationship between functional groups of MACs and their adsorption behaviour was analyzed through the study of surface functional groups by Boehm titration experiment and Fourier transform infrared spectroscopy analysis. The results showed that the adsorption behaviours are monolayer adsorption and obey the Langmuir isotherm well, and the calculated maximum adsorption capacity of MB onto AC is 284.1 mg/g. However, the adsorption capacity of MAC for MB decreases to varying degrees. After oxidation modification, the number of oxygen-containing functional groups on the surface of AC significantly increases, which forms water clusters and hinders the diffusion of MB into the particle aperture, resulting in a decreasing of MB removal efficiency.