Abstract: Chrome shavings were used as raw materials to prepare the Cr-containing biochar (Cr₂O₃-BC) via a pyrolysis process under the nitrogen atmosphere, and its performance for persulfate (PS) activation was studied using methylene blue (MB) as the model pollutant. Results illustrated that high removal rate (99.9%) and high mineralization efficiency (92.1%) of MB could be achieved within 30 min with PS concentration of 10 mmol/L and Cr₂O₃-BC dosage of 0.03 g/L. Besides, the coexisting substances (e.g. Cl^-, NO₃^-, HCO₃^- and humic acid) played a little effect on the MB removal, and more than 80% of MB still could be degraded in the Cr₂O₃-BC/PS system. In addition, the MB removal rate still reached 84.6% after six cycles of Cr₂O₃-BC/PS. Quenching experimental results indicated that both SO₄^·- and ·OH were responsible for the MB removal in the Cr₂O₃-BC/PS system, but SO₄^·- played the dominant role. Hence, this work not only provided a feasible strategy for the high-value use of chrome shavings, but also developed an efficient catalyst for PS activation to remove MB, which is in line with the concept of circular economy.