Faculty Materials Science and Chemistry, China University of Geosciences, Wuhan, 430074, Hubei, China.
School of Environment Studies, China University of Geosciences, Wuhan, 430074, Hubei, China.
Water Res. 2019 Mar 1;150:473-487. doi: 10.1016/j.watres.2018.11.085. Epub 2018 Dec 12.
Waste activated sludge (WAS) contains many anionic functional groups which can interact with heavy metal ions through electrostatic action and complexation reactions. The transition metals adsorbed in WAS can catalyze sludge pyrolysis in anaerobic conditions and improve structural properties of organic matter. In this work, a multistage WAS utilization process for preparing the carbon-based Fenton-like catalysis materials is proposed. More specifically, WAS is firstly used as an adsorbent for heavy metals (Cu and Ni) removal, and then complexes are converted into heterogeneous Fenton-like carbon-based catalysts through oxygen-free pyrolysis. The mechanisms of interactions between extracellular polymeric substances (EPS) and metals are investigated, and the physicochemical properties of sludge-based carbons (SBC) are comprehensively characterized using varies techniques. It is found that WAS is an excellent adsorbent for Cu and Ni removal, which is mainly due to the coordination and electrostatic interactions between EPS and heavy metals. Cu and Ni adsorbed in WAS significantly improved the porous structure of SBC. Both adsorption and catalytic oxidization of Cu/Ni-SBC contribute the removal of E2 in real wastewater. The E2 removal mechanism is explored by electron-spin resonance spectroscopy (ESR) analysis, and it is found that both of O and OH radicals are responsible for E2 degradation in Cu(II)-SBC-HO, while O radicals contributes to E2 degradation in Ni(II)-SBC-HO system, so the former performed better than the latter in total removal of E2. Besides, Cu(II) and Cu(I) are both formed in Cu(II)-SBC during the oxidation process, while only Ni(II) is found in the Ni(II)-SBC-HO process, confirming that different catalytic oxidation reactions are occurred in the Cu(II)-SBC-HO and Ni(II)-SBC-HO processes. This study facilitates a great strategy to the sludge multi-stage circulating utilization and a better understanding about the role of the Cu/Ni existed in SBC during the estrogens removal process.
剩余活性污泥（WAS）含有许多阴离子官能团，可通过静电作用和络合反应与重金属离子相互作用。吸附在 WAS 中的过渡金属可以在厌氧条件下催化污泥热解，并改善有机物的结构性能。在这项工作中，提出了一种多阶段 WAS 利用工艺来制备基于碳的类芬顿催化材料。更具体地说，首先将 WAS 用作重金属（Cu 和 Ni）去除的吸附剂，然后通过无氧热解将配合物转化为非均相类芬顿碳基催化剂。研究了细胞外聚合物（EPS）与金属之间的相互作用机制，并采用多种技术对基于污泥的碳（SBC）的物理化学性质进行了全面表征。结果发现，WAS 是 Cu 和 Ni 去除的优良吸附剂，这主要归因于 EPS 与重金属之间的配位和静电相互作用。吸附在 WAS 中的 Cu 和 Ni 显著改善了 SBC 的多孔结构。Cu/Ni-SBC 的吸附和催化氧化都有助于实际废水中 E2 的去除。通过电子顺磁共振光谱（ESR）分析探讨了 E2 的去除机制，发现 Cu(II)-SBC-HO 中 O 和 OH 自由基都参与了 E2 的降解，而 Ni(II)-SBC-HO 体系中 O 自由基则促进了 E2 的降解，因此前者在 E2 的总去除方面优于后者。此外，在氧化过程中，Cu(II)-SBC 中形成了 Cu(II)和 Cu(I)，而 Ni(II)-SBC-HO 过程中仅发现了 Ni(II)，这证实了在 Cu(II)-SBC-HO 和 Ni(II)-SBC-HO 过程中发生了不同的催化氧化反应。这项研究为污泥多阶段循环利用提供了一种很好的策略，并深入了解了 SBC 中存在的 Cu/Ni 在雌激素去除过程中的作用。
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