Kumar Aditya, Das Triparna, Thakur Ravindra Singh, Fatima Zeenat, Prasad Satgur, Ansari Nasreen G, Patel Devendra K
Analytical Chemistry Laboratory, Regulatory Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhawan, 31, Mahatma Gandhi Marg, Lucknow226001, Uttar Pradesh, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad201002, India.
ACS Omega. 2022 Nov 8;7(46):41997-42011. doi: 10.1021/acsomega.2c03786. eCollection 2022 Nov 22.
Low-cost alginate gels of activated carbons were prepared, which were derived from the peels of banana and sweet lime. The synthesized carbon was activated and immobilized on alginate, producing its gel. These gels were categorized according to their methods of drying, in which air drying, freeze drying, and supercritical drying led to the formation of xerogels, cryogels, and aerogels, respectively. The gels were used for adsorption of heavy metals from their aqueous solution. The heavy metals that were targeted for removal were Pb(II), Cd(II), Cr(VI), As(III), and Hg(II). Among all the adsorbents, the alginate cryogel of sweet lime-derived activated carbon (SLACC) showed the highest removal percentage of heavy metals, and thus, it was used for batch study. The adsorption of heavy metals by SLACC was checked at different times, pH values, adsorbent doses, temperatures, and adsorbate concentrations. The study revealed that the pseudo-second-order model best described the kinetic study, while the adsorption followed the Freundlich isotherm. SLACC showed maximum adsorption capacities ( ) of 3.71, 4.22, 20.04, 7.31, and 4.37 mg/g for Cr, Cd, Pb, As, and Hg, respectively, when 20 mg of SLACC was used for the removal of 4 ppm concentration of the targeted heavy metals from their 20 mL solution. Based on the thermodynamic study, it was found that the adsorption was spontaneous and exothermic. Furthermore, the adsorbent was also used on real water samples and showed up to 90% removal efficiency for these targeted heavy metals. SLACC was regenerated with 0.1 M ethylenediaminetetraacetic acid (EDTA) solution and reused for five cycles, in which the percentage removal of heavy metals was more than 50% till the fourth cycle. Furthermore, the leaching study showed that no toxic elements had leached from SLACC into water, making it a safe adsorbent.
制备了由香蕉皮和甜橙皮衍生而来的低成本活性炭藻酸盐凝胶。合成的碳被活化并固定在藻酸盐上，形成其凝胶。这些凝胶根据干燥方法进行分类，其中空气干燥、冷冻干燥和超临界干燥分别导致干凝胶、冷冻凝胶和气凝胶的形成。这些凝胶用于从水溶液中吸附重金属。目标去除的重金属为Pb(II)、Cd(II)、Cr(VI)、As(III)和Hg(II)。在所有吸附剂中，甜橙衍生活性炭（SLACC）的藻酸盐冷冻凝胶对重金属的去除率最高，因此用于批量研究。在不同时间、pH值、吸附剂剂量、温度和吸附质浓度下检查了SLACC对重金属的吸附。研究表明，伪二级模型最能描述动力学研究，而吸附遵循弗伦德里希等温线。当使用20 mg SLACC从20 mL溶液中去除4 ppm浓度的目标重金属时，SLACC对Cr、Cd、Pb、As和Hg的最大吸附容量分别为3.71、4.22、20.04、7.31和4.37 mg/g。基于热力学研究，发现吸附是自发的且放热的。此外，该吸附剂还用于实际水样，对这些目标重金属的去除效率高达90%。SLACC用0.1 M乙二胺四乙酸（EDTA）溶液再生并重复使用五个循环，直到第四个循环，重金属的去除率仍超过50%。此外，浸出研究表明，没有有毒元素从SLACC中浸出到水中，使其成为一种安全的吸附剂。
