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One-step FeCl 3 -mediated pyrolysis/activation was developed for preparation of bermudagrass (BG)-derived FeCl 3 -activated biochars (FA-BCs) from bermudagrass (BG) as a heterogenous Fenton catalyst for heterogeneous Fenton oxidation of sulfamethoxazole (SMX) in water. The FA-BC prepared at the FeCl 3 to BG mass ratio of 2 (FA-BC) exhibited higher adsorption and Fenton oxidation of SMX than other mass ratios of the FeCl 3 to BG. FA-BC presented the great surface area (835 m 2 /g) and high SMX adsorption capacity (195 mg SMX/g BC), which was higher than various BCs in the previous studies. Additionally, the surface of FA-BC was attached with Fe 2 O 3 , Fe 0 , and Fe 3 O 4 after the FeCl 3 activation. Under the optimal conditions for Fenton reaction (SMX concentration, 100 mg/L; loading of FA-BC, 0.1 g/L; dose of H 2 O 2 , 200 mg/L; temperature, 20 °C; pH 3; reaction time, 12 h), SMX and COD removal efficiencies reached 99.94% and 65.19%, respectively. Increasing reaction temperature from 20 to 50 °C significantly improved the SMX oxidation rate from 0.46 to 1.04 h -1 . The HO· radicals were proved to play a major role during the Fenton oxidation of SMX. In addition, the SMX solution treated by Fenton oxidation showed much less toxicity than the initial SMX solution. Additionally, the reusability tests of FA-BC indicated that 89.58% removal efficiency for SMX was still achieved after 3 cycles of Fenton oxidation under the optimal conditions. Furthermore, FA-BC can also efficiently remove SMX from the dairy wastewater. Therefore, FA-BC showed a high potential to eliminate aqueous SMX through adsorption and heterogeneous Fenton oxidation., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

In this study, a cyclic process of adsorption and persulfate (PS) oxidation-driven regeneration using FeCl 3 -activated biochar (FA-BC) was suggested as a novel remediation process to remove microcystin-LR (MC-LR) from water. For enhancing overall treatment efficiency and cost effectiveness, the impacts of temperature on adsorption and PS oxidation-driven regeneration were investigated. The increase of temperature resulted in the increase of MC-LR adsorption rate on FA-BC due to the enhanced MC-LR diffusivity in water. Moreover, the MC-LR oxidation and PS reaction rates during the PS regeneration on FA-BC were remarkably improved by factors of 3.4 and 3.5 with increasing temperature from 20 °C to 50 °C. Both diffusion and desorption of MC-LR from FA-BC were thought to be the key factors for controlling the MC-LR oxidation rate during the PS regeneration of MC-LR. In addition, the decrease of pH (from 10 to 4) and increase of PS concentration (from 100 to 400 mg/L) enhanced the regeneration efficiency for MC-LR-spent FA-BC. The four cycles of adsorption-PS regeneration (200 mg/L PS, pH 6, and 50 °C) resulted in 92.81% regeneration efficiency in DI water and 82.89% in lake water. However, the four cycles of adsorption-PS regeneration led to the reduction of surface area (from 835 to 413 m 2 /g), oxidation of carbon surface and slight reduction of Fe 0 on FA-BC. In overall, the cyclic adsorption-PS regeneration at higher temperature could provide practical reuse of FA-BC for cost-effective treatment of aqueous MC-LR., (Copyright © 2021. Published by Elsevier Ltd.)