Jia Ruize, Man Ronghao, Shang Liannan
School of Architecture and Engineering, Xinjiang University, Urumqi, 830017, China; MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing, 100083, China.
Graduate School, Hebei GEO University, Shijiazhuang, 050031, China.
Environ Res. 2025 Sep 12;286(Pt 2):122852. doi: 10.1016/j.envres.2025.122852.
The rapid development of mineral resources exploitation and industries has brought a large amount of wastewater containing cadmium (Cd) and arsenic (As) to the environment. Among these, the mining industry has become a major challenge in wastewater treatment due to the coexistence of both pollutants at high concentrations. Developing a sustainable and low-cost adsorbent capable of simultaneously adsorbing both anionic and cationic pollutants is a key breakthrough direction for solving this practical problem. In this study, chitosan-grafted Fe-pillared bentonite (CS@Fe@Bt) was synthesized using natural bentonite, aiming to provide an efficient material for treating Cd and As co-contaminated wastewater (especially mining industry wastewater). Results suggested that the specific surface area (SSA) and total pore volume of Fe-pillared bentonite increased by 1.85 and 1.32 times, respectively, compared with the raw bentonite. Pillaring the bentonite also significantly enhanced its chitosan loading capacity, improving both the structural stability and adsorption performance of CS@Fe@Bt. Kinetic and isothermal adsorption experiments revealed that CS@Fe@Bt possessed a multilayer heterogeneous surface, with Cd and As adsorption following the Pseudo-second-order kinetic model. CS@Fe@Bt showed strong adsorption capacity for both Cd(II) and As(III) when the initial pH of the solution ranged from 6 to 8. The maximum adsorption capacities (Q) for Cd(II) and As(III) were 80.79 mg g and 34.90 mg g, respectively, surpassing most comparable adsorbents. The primary adsorption mechanisms of CS@Fe@Bt in Cd(II) and As(III) co-polluted water included oxidation (57.81 % of As(III) was converted to low-toxicity As(V)), electrostatic interactions, and the formation of B-type ternary surface complexes (CS@Fe@Bt-As-Cd). Additional mechanisms included ion exchange, pore adsorption. These findings highlight the potential of CS@Fe@Bt as an effective adsorbent for Cd(II) and As(III) adsorption, providing technical support for addressing practical wastewater treatment challenges.
矿产资源开采和工业的快速发展给环境带来了大量含镉（Cd）和砷（As）的废水。其中，采矿业由于这两种污染物高浓度共存，已成为废水处理中的一项重大挑战。开发一种能够同时吸附阴离子和阳离子污染物的可持续且低成本的吸附剂，是解决这一实际问题的关键突破方向。在本研究中，以天然膨润土为原料合成了壳聚糖接枝铁柱撑膨润土（CS@Fe@Bt），旨在为处理镉和砷共污染废水（特别是采矿业废水）提供一种高效材料。结果表明，与原膨润土相比，铁柱撑膨润土的比表面积（SSA）和总孔体积分别增加了1.85倍和1.32倍。对膨润土进行柱撑还显著提高了其壳聚糖负载量，改善了CS@Fe@Bt的结构稳定性和吸附性能。动力学和等温吸附实验表明，CS@Fe@Bt具有多层异质表面，镉和砷的吸附遵循准二级动力学模型。当溶液初始pH值在6至8范围内时，CS@Fe@Bt对Cd（II）和As（III）均表现出较强的吸附能力。Cd（II）和As（III）的最大吸附容量（Q）分别为80.79 mg/g和34.90 mg/g，超过了大多数同类吸附剂。CS@Fe@Bt在Cd（II）和As（III）共污染水中的主要吸附机制包括氧化（57.81%的As（III）转化为低毒性的As（V））、静电相互作用以及形成B型三元表面络合物（CS@Fe@Bt-As-Cd）。其他机制包括离子交换、孔隙吸附。这些发现突出了CS@Fe@Bt作为Cd（II）和As（III）吸附有效吸附剂的潜力，为解决实际废水处理挑战提供了技术支持。
