Chitosan-derived three-dimensional porous carbon for fast removal of methylene blue from wastewater

Despite much progress in modifying chitosan as an absorbent for wastewater treatment, it is still difficult for current chitosan-based adsorbents to achieve the desired removal effects towards basic dyes. In this study, chitosan-derived three-dimensional porous carbon (CTC) consisting of large-diameter channels and mesopores was prepared to remove methylene blue (MB) from wastewater. The results indicate that CTC has excellent performance for MB removal, and the maximum adsorption capacity was 925.93 mg g^-1 at 318 K. The adsorption isotherm and kinetics models of MB on CTC could be described well by the Langmuir isotherms and the pseudo-second-order rate model. An experiment to study the CTC removal of MB from a flowing aqueous solution was performed using a homemade device. The water treatment rate of CTC reached 250 L g^-1 h^-1, with high MB removal efficiency (>93.4%). Furthermore, the desorption-adsorption experiments indicate that CTC is also a reusable adsorbent that can be applied to recover MB from wastewater. The obtained CTC is a promising alternative for the current expensive absorbents and provides a concept for designing the three-dimensional (3D) structures of raw materials to improve adsorption capability.