Bhushan Divya, Gupta Renuka
Department of Environmental Sciences, J.C. Bose University of Science & Technology, YMCA, Faridabad, Haryana, India.
Environ Geochem Health. 2025 Jun 23;47(7):279. doi: 10.1007/s10653-025-02586-7.
This study investigates the potential of a biogenic iron oxide-graphene oxide nanocomposite modified with Eucalyptus globulus leaf extract, in comparison with its chemically synthesized counterpart, for efficient removal of Cd(II) and Pb(II) ions from aqueous solutions. The nanocomposites were synthesised using two routes via co-precipitation: conventional chemical method (MGO) and green synthesis method using Eucalyptus leaf extract (MGOE), showcasing a novel, sustainable approach. The leaf extract, rich in phytochemicals such as polyphenols and flavonoids, served as a natural reducing and stabilizing agent, enhancing surface functionality and adsorption efficiency. The structural, functional and surface properties were characterized by FESEM-EDX, TEM, XRD, FTIR, BET and pH. Both nanocomposites had rough, mesoporous surfaces with FeO nanoparticles as bright flakes. MGOE demonstrated an increased surface area (156.45 m/g) compared to MGO (116.20 m/g), confirming successful modification by biogenic extract. MGOE had a smaller mean pore diameter (12.574 nm) and reduced pore volume (0.2768 cm/g) than MGO (16.353 nm and 0.3309 cm/g, respectively). The point of zero charge (pH) was 4.6 for MGOE and 3.8 for MGO, exhibiting acidic surface properties. Batch adsorption experiments were conducted across varying pH (2-10), metal concentration (10-60 mg/L), adsorbent dose (0.1-2.5 g/L) and contact time (10-180 min). For Cd(II), the adsorption capacities achieved were 37.52 mg/g (MGO, 1.0 g/L, 120 min) and 42.10 mg/g (MGOE, 0.8 g/L, 90 min), while for Pb(II) removal, maximum adsorption capacities were 90.99 mg/g (MGO, 0.6 g/L, 90 min) and 105.15 mg/g (MGOE, 0.4 g/L, 30 min), at optimum pH 6 and 25 °C. The adsorption behaviour followed Langmuir isotherm model (0 < R < 1) and kinetics analysis indicated pseudo-second-order chemisorption with rate constant (k) between 0.01 and 0.05 g/mg.min. The process was spontaneous and endothermic. Both nanocomposites retained adsorption efficiency up to eight adsorption-desorption cycles. MGOE, enhanced via a green synthesis route, emerged as a cost-effective, efficient, and superior adsorbent than MGO, offering viable and sustainable options for heavy metal remediation in water treatment applications.
本研究调查了用蓝桉叶提取物改性的生物源氧化铁 - 氧化石墨烯纳米复合材料及其化学合成对应物从水溶液中有效去除Cd(II)和Pb(II)离子的潜力。通过共沉淀法使用两种途径合成了纳米复合材料：传统化学方法（MGO）和使用桉树叶提取物的绿色合成方法（MGOE），展示了一种新颖、可持续的方法。富含多酚和黄酮类等植物化学物质的叶提取物用作天然还原剂和稳定剂，增强了表面功能和吸附效率。通过场发射扫描电子显微镜 - 能谱仪（FESEM - EDX）、透射电子显微镜（TEM）、X射线衍射仪（XRD）、傅里叶变换红外光谱仪（FTIR）、比表面积分析仪（BET）和pH测定对其结构、功能和表面性质进行了表征。两种纳米复合材料都具有粗糙的中孔表面，FeO纳米颗粒呈明亮薄片状。与MGO（116.20 m²/g）相比，MGOE的表面积增加（156.45 m²/g），证实了生物源提取物成功改性。MGOE的平均孔径（12.574 nm）和孔体积（0.2768 cm³/g）比MGO（分别为16.353 nm和0.3309 cm³/g）更小。MGOE的零电荷点（pH）为4.6，MGO为3.8，呈现酸性表面性质。在不同的pH（2 - 10）、金属浓度（10 - 60 mg/L）、吸附剂剂量（0.1 - 2.5 g/L）和接触时间（10 - 180分钟）下进行了批量吸附实验。对于Cd(II)，在最佳pH 6和25°C条件下，吸附容量分别为37.52 mg/g（MGO，1.0 g/L，120分钟）和42.10 mg/g（MGOE，0.8 g/L，90分钟）；对于Pb(II)去除，最大吸附容量分别为90.99 mg/g（MGO，0.6 g/L，90分钟）和105.15 mg/g（MGOE，0.4 g/L，30分钟）。吸附行为遵循朗缪尔等温线模型（0 < R < 1），动力学分析表明为拟二级化学吸附，速率常数（k）在0.01至0.05 g/mg·min之间。该过程是自发的且吸热的。两种纳米复合材料在多达八个吸附 - 解吸循环中都保持了吸附效率。通过绿色合成路线增强的MGOE成为一种比MGO更具成本效益、高效且优越的吸附剂，为水处理应用中的重金属修复提供了可行且可持续的选择。
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