College of Environmental Science and Engineering, Hunan University, Changsha, 410082, People's Republic of China.
Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 410082, People's Republic of China.
Environ Sci Pollut Res Int. 2023 Mar;30(13):39154-39168. doi: 10.1007/s11356-022-24952-z. Epub 2023 Jan 3.
Numerous studies have explored the adsorption of cadmium (Cd) and arsenic (As) by iron (Fe)-modified biochar, but few studies have examined in-depth the similarities and differences in the adsorption behavior of different iron types on Cd and As. In this study, sewage sludge biochar (BC) was co-pyrolyzed with self-made Fe minerals (magnetite, hematite, ferrihydrite, goethite, and schwertmannite) to treat Cd and As co-contaminated water. The adsorption of Cd and As on the Fe-modified biochar was further analyzed by adsorption kinetics, adsorption isotherms, and adsorption thermodynamics combined with a series of characterization experiments. Both SEM-EDX and XRD results confirmed the successful loading of iron minerals onto BC. Both adsorption kinetics and adsorption isotherms experiments showed that the adsorption of Cd and As by BC and the other five Fe-modified biochar was mainly controlled by chemical interactions. The results also indicated that goethite biochar (GtBC) was the most effective for the adsorption of Cd among the five Fe-modified biochar. Ferrihydrite biochar (FhBC) formed more diverse complexes, coupled with the relatively stronger electrons accepting ability, thus making it more effective for As adsorption than the others. Additionally, GtBC and hematite biochar (HmBC) were found effective for the adsorption of both Cd and As, whereas MBC was not found effective for either metal. Furthermore, combined with XPS results, the adsorption of Cd by the materials was mainly governed by Cd-π interactions, complexation precipitation, and co-precipitation, while oxidation reactions also existed for As.
许多研究都探讨了铁（Fe）改性生物炭对镉（Cd）和砷（As）的吸附，但很少有研究深入研究不同铁类型对 Cd 和 As 的吸附行为的异同。本研究采用自制的 Fe 矿物（磁铁矿、赤铁矿、水铁矿、针铁矿和纤铁矿）与污水污泥生物炭（BC）共热解，处理 Cd 和 As 共存污染水。通过吸附动力学、吸附等温线和吸附热力学结合一系列表征实验，进一步分析了 Cd 和 As 在 Fe 改性生物炭上的吸附。SEM-EDX 和 XRD 结果均证实了 Fe 矿物成功负载到 BC 上。吸附动力学和吸附等温线实验表明，BC 和其他五种 Fe 改性生物炭对 Cd 和 As 的吸附主要受化学相互作用控制。结果还表明，在五种 Fe 改性生物炭中，针铁矿生物炭（GtBC）对 Cd 的吸附效果最佳。水铁矿生物炭（FhBC）形成了更多样的配合物，再加上相对较强的电子接受能力，因此对 As 的吸附效果比其他的要好。此外，GtBC 和赤铁矿生物炭（HmBC）对 Cd 和 As 的吸附均有效，而 MBC 对这两种金属均无效。此外，结合 XPS 结果，材料对 Cd 的吸附主要受 Cd-π 相互作用、络合沉淀和共沉淀控制，而 As 的吸附还存在氧化反应。
