College of Ecology and Environment, Xinjiang University, Urumqi, Xinjiang, 830011, PR China.
School of Environment and Energy, Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters (Ministry of Education), Guangzhou, South China University of Technology, Guangzhou, Guangdong, 510006, PR China.
Chemosphere. 2022 Oct;304:135303. doi: 10.1016/j.chemosphere.2022.135303. Epub 2022 Jun 9.
Biochar derived from municipal sludge can be applied to adsorption. But it usually requires activation and pickling due to the generation of impurities such as metal oxide particles, which is uneconomical. Here, a facile strategy, acidification-one-step calcination, was developed and sludge-based Fe-C materials with good Cr(VI) removal effect were obtained by regulating the amount of hydrochloric acid. The results show that the adsorption capacity of Fe/C-5 (the best sample) for Cr(VI) was 150.84 mg g. According to the Langmuir isotherm and pseudo-second-order kinetic model, the removal of Cr(VI) by Fe/C-5 is spontaneous and endothermic chemisorption process. In addition, Fe/C-5 has good ability to remove Cr(VI) under the interference of coexisting ions, and has good cycle stability. The removal of Cr(VI) by Fe/C-5 is considered to be synergistic process of adsorption and reduction. The Fe atoms were highly dispersed in Fe/C-5 and tightly bonded with C atoms, which not only strengthened the Cr(VI) adsorption by electrostatic attraction, but also activated the C atoms in the biochar material, so that the C atoms can reduce Cr(VI) to Cr(III) under acidic conditions. This may be due to the fact that acid pretreatment converted the iron in municipal sludge in the form of Fe-O/OH to free Fe and entered the C lattice during the calcination process. In this work, Fe-C materials with excellent Cr(VI) adsorption capacity were prepared by one-step calcination method, which has important reference significance for the resource utilization of municipal sludge.
生物炭来源于城市污泥，可用于吸附。但由于金属氧化物颗粒等杂质的产生，通常需要进行活化和酸洗，这是不经济的。在这里，开发了一种简便的策略，即酸化-一步煅烧法，并通过调节盐酸的用量获得了具有良好 Cr(VI)去除效果的基于污泥的 Fe-C 材料。结果表明，Fe/C-5（最佳样品）对 Cr(VI)的吸附容量为 150.84 mg g。根据 Langmuir 等温线和准二级动力学模型，Fe/C-5 对 Cr(VI)的去除是自发和吸热的化学吸附过程。此外，Fe/C-5 在共存离子的干扰下具有良好的去除 Cr(VI)的能力，且具有良好的循环稳定性。Fe/C-5 去除 Cr(VI)被认为是吸附和还原的协同过程。Fe 原子在 Fe/C-5 中高度分散并与 C 原子紧密结合，这不仅增强了静电吸引对 Cr(VI)的吸附，而且还激活了生物炭材料中的 C 原子，使得 C 原子在酸性条件下能够将 Cr(VI)还原为 Cr(III)。这可能是由于酸预处理将城市污泥中的铁以 Fe-O/OH 的形式转化为游离铁，并在煅烧过程中进入 C 晶格。在这项工作中，通过一步煅烧法制备了具有优异 Cr(VI)吸附能力的 Fe-C 材料，这对城市污泥的资源化利用具有重要的参考意义。
