Preparation of cobalt/hydrochar using the intrinsic features of rice hulls for dynamic carbamazepine degradation via efficient PMS activation

Strategy exploration for tailored conversing bio-wastes into valuable functional matrices with varied potentiality is a hotspot in the field of environmental remediation and green chemistry. As is known, the direct combustion of rice hulls has led to serious atmospheric pollution. Accordingly, how to controllably convert rice hulls into catalytic functional materials for water remediation is highly demanded yet remains a great improvement. Herein, low-cost and environmentally friendly surface-loaded cobalt/ hydrochar composites (Co-RHs) were successfully synthesized by hydrothermal carbonizing cobalt-impregnated rice hull waste. The Co-RH-130 exhibited prominent performance in efficiently activating peroxymonosulfate (PMS) to degrade carbamazepine (CBZ), which could remove 95.78% of CBZ within 60 min. Additionally, the Co-RH-130 in recyclability tests maintained high stability and recyclability from the synergy of cobalt oxides and hydrochar, and the inherent mechanically stable of the rice hulls. Based on quenching tests and EPR analysis, SO4•−and O2•− were proved as the predominant reactive species for the CBZ degradation and the reaction mechanism was elucidated. Most importantly, the degradation experiment of the fixed-bed column was used to simulate the degradation process under actual conditions to evaluate the efficiency and practical application value, which showed that the continuous degradation rate of 97.06% of CBZ could still be reached in the Co-RH-130/PMS system at 720 min. This work might provide a contributing solution for the controllable conversion of rice hull waste and practical treatment for continuous organic wastewater. [Display omitted] •Rice hulls were reused to synthesize catalyst (Co-RH-130) for PMS activation.•The Co-RH-130 showed excellent performance and practicability for CBZ degradation.•Both radical and non-radical processes contributed to the oxidation reaction.•Possible degradation pathways were discussed in detail.•The fixed bed reaction was systematically researched.