High-performance clay and K2CO3-Modified sludge biochar for efficient reactive black-5 Removal: Mechanistic insights and alleviation of phytotoxicity

作者：Muhammad Arif, Guijian Liu, Muhammad Zia‐ur‐Rehman, Qumber Abbas, Aniqa Ashraf, Muhammad Rashid, Krzysztof Pikoń, Balal Yousaf · 发表于：Biomass and Bioenergy · 年份：2025 · DOI：10.1016/j.biombioe.2025.108235 · 被引用次数：10 · 研究领域：Adsorption and biosorption for pollutant removal、Heavy metals in environment、Microbial bioremediation and biosurfactants

Sewage sludge, an unavoidable byproduct of wastewater treatment plants, requires effective valorization to achieve environmental sustainability. Herein, we produced a set of sludge biochar (BC) including the pristine and the modified BC by clay and potassium carbonate (K 2 CO 3 ) integration, pyrolyzed at 300, 500, and 650 °C, for the removal of reactive black 5 (RB-5). The characterization of adsorbents and investigation of the adsorption mechanism confirmed that clay modification and K2CO3 activation altered the properties of BC, significantly influencing their adsorption ability. Among the fifteen adsorbents, K 2 CO 3 modified BC produced at 650 °C (PBC-650) was the most effective to remove up to 96 % of RB-5 in 6h, whereas pristine BC-650 removed only 62 % RB-5. Under the optimum conditions, PBC-650 showed much higher adsorption capacity of RB-5 (30.33 mg g −1 ) compared to pristine BC (15.65 mg g −1 ). The experimental data were more consistent with Elovich isotherm model and the Sips kinetic model. The main adsorption mechanisms were H-bonding, electrostatic interaction, ion exchange, pore-filling, and π-π interaction. Moreover, phyto-toxicity assay was performed to assess the toxicity of RB-5 (0–1000 mg L −1 ) to wheat. At 1000 mg RB-5 L −1 , root and shoot dry biomass decreased by 62 and 43 %, respectively, compared to control. The shoot dry weight of wheat decreased by 31 % under 300 mg RB-5 L −1 , whereas the application of PBC-650 at 2 and 5 g L −1 alleviated the t...