Upcycling iron-rich industrial sludge into Fe-enriched biochar for triggering Fenton-like reaction is proposed as a ‘waste control by waste’ idea. However, the structure-activity relationship between biochar and its decontamination performance remains largely unclear. Herein, with primary sludge (from a textile dyeing industry) derived biochar (PSDB) as a representative, we unveil that the activation of H₂O₂ (6 mM) by PSDB (1 g L⁻¹) for 4-chlorophenol (4-CP) removal highly depends on the iron speciation and carbon phase. With rising pyrolysis temperature, Fe minerals in PSDB undergo valence change from amorphous tri- and divalent Fe oxides (PSDB-400) to crystalline Fe₃O₄ (PSDB-600), Fe⁰ (PSDB-800), and partially evolve to iron phosphide and sulfide (PSDB-1000). Correspondingly, aliphatic labile fraction and dissolved carbon phase in PSDB-400 evolve into aromatic stable fraction and undissolved phase in PSDB-1000, as suggested by 83.5% reduction in dissolved organic carbon, and 50.1% increase in aromatic carbon proportion. PSDB-400/PSDB-600 tends to degrade 4-CP by leached Fe²⁺-mediated homogeneous Fenton reaction, while PSDB-800/PSDB-1000 achieves rapid 4-CP adsorption and subsequent oxidation through homogeneous/heterogeneous H₂O₂ activation. Reusability test confirms the potential of PSDB-400 as sustaining Fe²⁺ donors for H₂O₂ activation, and the robustness of PSDB-1000 for multiple adsorption-oxidation cycles. This study provides guidance on designing sludge-derived engineered biochar for wastewater purification.

中文翻译：

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富铁工业污泥衍生生物炭引发的 Fenton 样反应中铁形态和碳相的共控


将富含铁的工业污泥升级回收成富含铁的生物炭以触发 Fenton 反应被提议为“废物控制废物”的想法。然而，生物炭与其去污性能之间的结构-活性关系在很大程度上仍不清楚。在本文中，以初级污泥（来自纺织印染工业）衍生的生物炭 （PSDB） 为代表，我们揭示了 PSDB （6 g L ⁻¹ ） 对 H ₂ O ₂ （1 mM） 的活化以去除 4-氯苯酚 （4-CP） 在很大程度上取决于铁形态和碳相。随着热解温度的升高，PSDB 中的 Fe 矿物发生从无定形三价和二价 Fe 氧化物 （PSDB-400） 到结晶 Fe ₃ O ₄ （PSDB-600）、Fe ⁰ （PSDB-800） 的价态变化，并部分演变为磷化铁和硫化物 （PSDB-1000）。相应地，PSDB-400 中的脂肪族不稳定馏分和溶解碳相在 PSDB-1000 中演变为芳香族稳定馏分和未溶解相，溶解有机碳减少 83.5%，芳烃比例增加 50.1%。PSDB-400/PSDB-600 倾向于通过浸出 Fe ²⁺ 介导的均相 Fenton 反应降解 4-CP，而 PSDB-800/PSDB-1000 通过均相/非均相 H ₂ O ₂ 活化实现快速 4-CP 吸附和随后的氧化。可重用性测试证实了 PSDB-400 作为 H ₂ O ₂ 活化的维持 Fe ²⁺ 供体的潜力，以及 PSDB-1000 在多个吸附-氧化循环中的稳健性。本研究为设计用于废水净化的污泥衍生工程生物炭提供了指导。