College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China; Beijing Key Laboratory of Biodiversity and Organic Farming, China Agricultural University, Beijing, 100193, China.
College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China; Beijing Key Laboratory of Biodiversity and Organic Farming, China Agricultural University, Beijing, 100193, China.
Environ Pollut. 2022 Aug 15;307:119490. doi: 10.1016/j.envpol.2022.119490. Epub 2022 May 17.
Cadmium (Cd) is one dangerous and widespread heavy metal that of great environmental concern. To cost-efficiently adsorb aqueous Cd under influence of various factors, this study succeeded in fabricating goethite-modified biochar (GBC) derived from distillers' grains (DGs) for Cd sorption of different concentrations (10-100 mg L) at pH of 3, 6 and 8 with and without microcystin-LR (MC-LR). Sorption kinetics and isotherms data revealed that Cd sorption capacity of GBC and unmodified BC increased as pH elevated from 3 to 6 but stabilized when pH further elevated to 8. Pseudo-second-order and Langmuir models more accurately fitted to sorption data for both BCs, implying monolayer chemisorption of Cd onto BCs. GBC exhibited more robust sorption for each Cd concentration than unmodified BC, with the maximum sorption capacity of around 28 mg g at neutral and weak alkaline pH. Notably, goethite-modification obviously increased bulk polarity, specific surface area, porosity and surface oxygenic group abundance of BC, thus strongly enhancing Cd sorption by creating more sorption sites mainly via pore-filling, electrostatic attraction, and also via complexation and cation exchange. Co-existing MC-LR of 100 μg L did not obviously affect Cd sorption by both BCs for most Cd levels at each pH, mostly because sorption mechanisms diverged between MC-LR and Cd to largely avoid their competition for sorption sties. Thus, goethite could modify DG-BC as promising and cost-efficient sorbent for Cd even with co-existing MC-LR, especially at neutral and weak alkaline pH that common in the nature. This study was greatly implicated in modifying and applying DG-BC for Cd immobilization in MC-LR laden waters with various pH circumstances.
镉 (Cd) 是一种危险且广泛存在的重金属，对环境有很大的影响。为了在各种因素的影响下，以经济有效的方式吸附水溶液中的 Cd，本研究成功地制备了由酒糟 (DG) 衍生的针铁矿改性生物炭 (GBC)，用于在 pH 值为 3、6 和 8 时吸附不同浓度 (10-100 mg L) 的 Cd，同时存在和不存在微囊藻毒素-LR (MC-LR)。吸附动力学和等温线数据表明，GBC 和未改性生物炭的 Cd 吸附容量随着 pH 值从 3 升高到 6 而增加，但当 pH 值进一步升高到 8 时稳定下来。准二级和 Langmuir 模型更准确地拟合了两种生物炭的吸附数据，这表明 Cd 以单分子层化学吸附到生物炭上。GBC 对每种 Cd 浓度的吸附能力均强于未改性生物炭，在中性和弱碱性 pH 下，最大吸附容量约为 28 mg g。值得注意的是，针铁矿改性明显增加了生物炭的整体极性、比表面积、孔隙率和表面含氧基团丰度，从而通过孔填充、静电吸引以及通过络合和阳离子交换，创造更多的吸附位点，从而强烈增强 Cd 的吸附。共存的 100μg L MC-LR 对大多数 pH 下每种 Cd 水平的两种生物炭的 Cd 吸附没有明显影响，这主要是因为 MC-LR 和 Cd 的吸附机制不同，从而在很大程度上避免了它们对吸附位点的竞争。因此，针铁矿可以改性 DG-BC 作为一种有前途且经济有效的 Cd 吸附剂，即使共存 MC-LR，特别是在自然中常见的中性和弱碱性 pH 条件下。本研究对于在各种 pH 条件下，用 DG-BC 固定含 MC-LR 的水中的 Cd 具有重要意义。
