Microwave-assisted preparation of cotton stem-derived activated carbon for dye removal from synthetic wastewater.

Cotton stem is used to produce the high-efficient adsorbent (CSA) for Rhodamine B (RB) dye removal from wastewater, and hydrogen rich fuel gas via on-pot method using microwave heating. The adsorption data indicate that RB adsorption behavior follows the Langmuir model with the maximum adsorption capacity of 265.96 mg/g, whereas the adsorption kinetics follows the pseudo-second-order model. Thermodynamic calculations indicate that RB adsorption on CSA is spontaneous and endothermic process. The adsorption data are fitted to the Thomas and Yoon-Nelson model to predict the breakthrough curve in the column experiment. The RB removal could still be maintained at 71.22% of the original value after five cycles, demonstrating the reusability of CSA. The chemical functional groups, electrostatic interaction, and pore filling of CSA are found to be responsible for high RB adsorption capability. CSA exhibits excellent RB removal efficiency in treating actual water. The major components of byproduct gases collected from activation process are H and CO.