School of Physics and Electronic Engineering, Fuyang Normal University, Fuyang, 236037, China.
School of Resources and Environment, Anhui Agricultural University, Hefei, 230036, China.
Environ Sci Pollut Res Int. 2018 Mar;25(9):8688-8700. doi: 10.1007/s11356-017-1189-2. Epub 2018 Jan 10.
The biochars were produced from wheat straw (WSBC) at different pyrolytic temperatures. Biochars were characterized by multiple instrumental techniques and were applied to remove Cd from aqueous solution. The removal mechanism was explored, and the quantitative information regarding the relative contribution of related mechanisms to Cd sorption on biochars was provided. The results showed that pseudo-second-order kinetic model, TC (two-compartment) model, and Freundlich isotherm could well fit the process of Cd sorption on biochars. The sorption could be divided into fast and slow adsorption stages. The order of the Cd removal capacity by biochar was WSBC700 > WSBC500 > WSBC300. Adsorption amount of Cd by biochar reduced when the biochar was rinsed with 1.0 M HCl, which indicated that acid-soluble minerals in biochar played an important role during the Cd removal process, especially for the biochar obtained at high pyrolytic temperature. Various equipments were used to investigate the interaction mechanism between biochar and Cd. Mineral precipitation, surface complexation, and cation-π interaction were the main mechanisms of Cd sorption on the biochars. The contribution of cation-π mechanism was in the range of 25.42-48.58%, 2.18-19.30% for surface complexation and 32.12-72.41% for mineral precipitation, respectively. The pyrolytic temperature significantly influenced the removal capacity and mechanism of Cd on biochars. The cation-π mechanism was predominant for biochar obtained at lower pyrolytic temperature. However, mineral precipitation mechanism played a crucial role for biochar obtained at high pyrolytic temperature. These results are helpful for the design or screening of "engineered biochar" to act as sorbents to remove or immobilized Cd in polluted soil or water. Graphical abstract ᅟ.
生物炭是由不同热解温度下的小麦秸秆（WSBC）制成的。通过多种仪器技术对生物炭进行了表征，并将其应用于从水溶液中去除 Cd。探讨了去除机制，并提供了有关相关机制对生物炭上 Cd 吸附贡献的定量信息。结果表明，准二级动力学模型、TC（双室）模型和 Freundlich 等温线可以很好地拟合 Cd 在生物炭上的吸附过程。吸附过程可以分为快速和缓慢吸附阶段。生物炭对 Cd 的去除能力顺序为 WSBC700 > WSBC500 > WSBC300。用 1.0 M HCl 冲洗生物炭后，Cd 的吸附量减少，这表明生物炭中酸溶性矿物质在 Cd 去除过程中起着重要作用，特别是对于在高温下获得的生物炭。各种设备被用来研究生物炭与 Cd 之间的相互作用机制。矿物沉淀、表面络合和阳离子-π 相互作用是 Cd 吸附在生物炭上的主要机制。阳离子-π 机制的贡献范围分别为 25.42-48.58%、2.18-19.30%用于表面络合和 32.12-72.41%用于矿物沉淀。热解温度显著影响生物炭对 Cd 的去除能力和机制。对于较低热解温度下获得的生物炭，阳离子-π 机制占主导地位。然而，对于在较高热解温度下获得的生物炭，矿物沉淀机制起着至关重要的作用。这些结果有助于设计或筛选“工程生物炭”作为吸附剂，以去除或固定污染土壤或水中的 Cd。
