Hierarchical porous carbons from biowaste: Hydrothermal carbonization and high-performance for Rhodamine B adsorptive removal

Abstract

Hydrothermal carbonization procedure is effective to transform biowaste into coal-like hydrochar, which can be further used as renewable source to produce porous carbons on the use of water treatment. Here, hierarchical porous carbons were produced by shells of bamboo shoot (BSS) based on hydrothermal treatment and KOH activation, under the assistance of melamine. The surface area of carbons was up to 3250 m2/g with multi-level pore architecture, endowing them to be potential adsorbents in dyes removal i.e. Rhodamine B (RhB), where hierarchical mesopores were formed by foaming effect of melamine. Experimental kinetic data had better accordance with pseudo-second-order model, and the equilibrium state reached after contact time of 300 min with equilibrium RhB capacity up to be 3860 mg/g in 500 mg/L solution at 25 °C. Langmuir model was suitable to describe removal behavior of carbons containing well-developed mesopores as an increase of concentration. Importantly, the determined maximum capacity of RhB was highly up to 5398 mg/g, attributing to the synergetic aspects of porosity, pyrrolic-N configurations and hierarchical architecture.