The current investigation aimed on harnessed agricultural waste derived from Aloe vera as an efficient adsorbent to adsorb heavy metals such as Mn(II) and Fe(II) ions from water. The Acid Modified Aloe vera adsorbent (AMA), underwent a thorough characterization process such as point of zero charges, Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis depicted an uneven and highly porous surface, and BET analysis, respectively. The utilization of the low-cost AMA adsorbent yielded noteworthy outcomes, showcasing a remarkable adsorption capacity. Specifically, the adsorbent exhibited a maximum adsorption capacity of 45.120 mg/g for Mn(II) ions and 41.282 mg/g for Fe(II) ions. These results were observed under conditions of 298 K temperature, a pH of 7, an AMA dose of 0.1 g/L, 100 mg/L initial concentration, and contact duration of 130 min. Various kinetic models were explored, including the pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich, and intra-particle diffusion models. Among these, the PFO model exhibited the best association with the experimental data, with a high R² value of 0.997. Similarly, Langmuir and Freundlich isotherm analyses were conducted. From the observed experimental, it was found that the Langmuir isotherm displayed superior fitting with an R² value of 0.997. Considering these outcomes, the AMA adsorbent emerges as a viable candidate for treating water contaminated predominantly with Fe(II) and Mn(II) ions.

Graphical abstract

中文翻译：

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用于去除水处理中的 Fe(II) 和 Mn(II) 的生物质低成本吸附剂：批量和柱吸附研究

目前的研究旨在利用芦荟提取的农业废物作为有效的吸附剂来吸附水中的重金属，例如锰（II）和铁（II）离子。酸改性芦荟吸附剂 (AMA) 经过彻底的表征过程，例如零电荷点、扫描电子显微镜 (SEM) 和能量色散 X 射线光谱 (EDS) 分析，描绘出不均匀且高度多孔的表面，以及 BET分别分析。低成本 AMA 吸附剂的使用取得了显着的成果，显示出卓越的吸附能力。具体而言，该吸附剂对Mn(II)离子的最大吸附容量为45.120 mg/g，对Fe(II)离子的最大吸附容量为41.282 mg/g。这些结果是在温度298 K、pH 7、AMA剂量0.1 g/L、初始浓度100 mg/L、接触时间130 min的条件下观察到的。探索了各种动力学模型，包括伪一级（PFO）、伪二级（PSO）、Elovich 和粒子内扩散模型。其中，PFO模型与实验数据的关联性最好，R ²值高达0.997。类似地，进行了 Langmuir 和 Freundlich 等温线分析。从观察到的实验发现，Langmuir等温线表现出良好的拟合效果，R ²值为0.997。考虑到这些结果，AMA 吸附剂成为处理主要受 Fe(II) 和 Mn(II) 离子污染的水的可行候选者。

图形概要