Novel bamboo-derived composites for the efficient adsorption of a methylene blue pollutant

The application of low-cost biosorbent of bamboo in methylene blue (MB) removal treatment is limited by its poor adsorption performance. In this study, bamboo parenchyma cell (BP) was isolated from bamboo powder by facile method of water separation and then incorporated with natural non-toxic vermiculite (VE) to prepare bamboo parenchyma cell-vermiculite (VEBP) composites. Much more nanopores were formed and more active adsorbed sites were introduced by filling with VE in BP lumen, which is favorable for improving the MB adsorption capacity. The MB adsorption isotherm of VEBP was preferably fitted with Langmuir model, yielding the highest equilibrium MB adsorption capacity of approximately 422 mg/g. As-obtained adsorption capacity is much higher than that of BP and various kinds of biosorbents in previous researches. Besides, the adsorption kinetics was closer to the pseudo-second-order model, indicating the dominant chemisorption process. Thermodynamic parameters implied the endothermic and spontaneous as well as entropy-governed adsorption process. Based on the analysis of adsorption behavior together with characterizations of VEBP, it can be confirmed that the predominant mechanisms for MB adsorption may involve electrostatic attraction, ion exchange, hydrogen bonding, pore filling, complexation reaction, and π-π interactions. Furthermore, the VEBP exhibited excellent reusability with MB removal efficiency of more than 80% after five cycles. Therefore, this study successfully provides a facile method for preparation of bamboo-based adsorbent with efficient MB adsorption performance.