Zhang Zeyuan, Tang Liangjie, Luo Jing, Tan Jinfang, Jiang Xiaoqian
School of Agriculture and Biotechnology, Sun Yat-Sen University, Shenzhen, Guangdong, 518107, People's Republic of China.
Adv Biotechnol (Singap). 2025 Jan 21;3(1):4. doi: 10.1007/s44307-024-00055-3.
Low efficiency and high surface runoff of 2,4-dichlorophenoxyacetic acid (2,4-D) from agricultural field threaten crop yield severely. Layered double hydroxides (LDH) have shown promising adsorption properties for 2,4-D. However, the comparison of two environmentally friendly LDHs (i.e. Mg/Al-LDH vs Mg/Fe-LDH) on adsorption of 2,4-D and corresponding intrinsic mechanisms are still unclear, and the studies on the leaching control of 2,4-D by LDHs in soil environment are particularly limited. In this study, Mg/Al-LDH and Mg/Fe-LDH were selected to conduct their adsorption kinetics experiment for 2,4-D combined with the characterization technology. The results showed that the adsorption capacity of Mg/Al-LDH and Mg/Fe-LDH for 2,4-D was up to 242 mg kg and 64 mg kg, respectively, which were negatively correlated with pH. Adsorption mechanisms of both Mg/Al-LDH and Mg/Fe-LDH for 2,4-D are dominated by chemical adsorption, including electrostatic attraction and inner sphere complexation, but no interlayer adsorption mechanism. Mg/Al-LDH contains smaller metal ion radius, which provides greater surface charge density, resulting in greater electrostatic attraction and inner sphere complexation to 2,4-D compared to Mg/Fe-LDH. The greater adsorption capacity of Mg/Al-LDH for 2,4-D was driven by the higher adsorption energy (E) and lower electron density, as corroborated by density functional theory (DFT) calculation. The soil column experiment further verified that Mg/Al-LDH could control the loss of 2,4-D more effectively, and the leaching amount could be significantly reduced by 61.7%, while the effect of Mg/Fe-LDH was only 24.2%. This study provides theoretical guidance for screening more potential LDH types to solve the leaching loss of 2,4-D from soil and improve its effectiveness in agricultural production.
农田中2,4-二氯苯氧乙酸（2,4-D）的低效率和高地表径流严重威胁作物产量。层状双氢氧化物（LDH）对2,4-D显示出良好的吸附性能。然而，两种环境友好型LDH（即Mg/Al-LDH与Mg/Fe-LDH）对2,4-D的吸附比较及相应的内在机制仍不明确，且关于LDH在土壤环境中对2,4-D淋溶控制的研究尤为有限。本研究选取Mg/Al-LDH和Mg/Fe-LDH结合表征技术开展其对2,4-D的吸附动力学实验。结果表明，Mg/Al-LDH和Mg/Fe-LDH对2,4-D的吸附量分别高达242 mg/kg和64 mg/kg，且均与pH呈负相关。Mg/Al-LDH和Mg/Fe-LDH对2,4-D的吸附机制均以化学吸附为主，包括静电吸引和内层络合，但不存在层间吸附机制。Mg/Al-LDH所含金属离子半径较小，提供了更大的表面电荷密度，相较于Mg/Fe-LDH，对2,4-D具有更强的静电吸引和内层络合作用。密度泛函理论（DFT）计算证实，Mg/Al-LDH对2,4-D更强的吸附能力是由更高的吸附能（E）和更低的电子密度驱动的。土柱实验进一步验证了Mg/Al-LDH能更有效地控制2,4-D的流失，淋溶量可显著降低61.7%，而Mg/Fe-LDH的效果仅为24.2%。本研究为筛选更具潜力的LDH类型以解决土壤中2,4-D的淋溶损失并提高其在农业生产中的有效性提供了理论指导。
