Waste valorization: Transforming the fishbone biowaste into biochar as an efficient persulfate catalyst for degradation of organic pollutant

Fishbone is a major by-product of fishing processing and how to deal with the increasingly generated fishbone has been a big challenge. In an effort to convert the low-value waste into valuable material, this research explores the valorization of fishbone biowaste, which can be transformed into biochar as a persulfate activator for phenol removal. The fishbone derived biochar (FBBC) was prepared by one-step pyrolysis without additional template. The catalytic efficiency of FBBC increases with pyrolysis temperature, with FBBC-800 (pyrolyzed at 800 °C) exhibiting the best performance of 100% phenol (20 mg/L) removal within 60 min at the catalyst dosage of 0.1 g/L, which is comparable to other recently reported carbon-based catalysts but with the advantage of easy preparation, low cost and wastes valorization. The high efficacy of FBBC-800 is related to its large surface area (758.44 m 2 /g), carbonyl group and defective structure. In the FBBC-800/peroxydisulfate/phenol system, both radical and non-radical pathways are involved, among which hydroxyl radical is more important in radical pathway while singlet oxygen dominates in non-radical pathway. Electron transfer plays a key role in this process through electron capture experiment and electrochemical characterization. This study proposes a new strategy for the valorization of fishbone, and provides the guidance for the structure design of carbon-based catalyst for persulfate activation. • A new strategy for fishbone valorization was developed. • The fishbone derived biochar is cost effective and easy to prepare. • High surface area, carbonyl group and defective structure contribute to the catalytic activity. • SO 4 · − , · OH, O 2 · − and 1 O 2 were identified in the catalytic reaction. • Electron transfer mechanism for pollutant degradation was proposed.