Alkali treated Foumanat tea waste as an efficient adsorbent for methylene blue adsorption from aqueous solution

The adsorption of methylene blue (MB) from aqueous solution by alkali treated Foumanat tea waste (ATFTW) from agriculture biomass was investigated. The adsorbent was characterized by Scanning Electron Microscopy (SEM), Fourier Transform-Infrared Spectroscopy (FT-IR) and nitrogen physisorption. FTIR results showed complexation and ion exchange appear to be the principle mechanism for MB adsorption. The adsorption isotherm data were fitted to Langmuir, Sips, Redlich-Peterson and Freundlich equations, and the Langmuir adsorption capacity, Qmax was found to be 461 mgg−1. It was found that the adsorption of MB increases by increasing temperature from 303 to 323 K and the process is endothermic in nature. The removal of MB by ATFTW followed pseudo-second order reaction kinetics based on Lagergren equations. Mechanism studies indicated that the adsorption of MB on the ATFTW was mainly governed by external mass transport where particle diffusion was the rate limiting step.