KOH-mediated structural modification of activated charcoal by heat treatment for the efficient adsorption of organic dyes

IF 7.5 Q1 CHEMISTRY, PHYSICAL
Indujalekshmi J, Arsha M S, Biju V
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Abstract

Modification of the structural features of activated charcoal by KOH-mediated heat treatment is reported. Improved adsorption of rhodamine B (RhB) and methyl orange (MO) is observed, which is dependent on the KOH/precursor ratio. At the optimum ratio of 2:1, the removal of RhB is (92 ± 2)% and that of MO is (82 ± 1)% in 15 min. The influence of contact time, adsorbent dose, adsorbate concentration and temperature on the adsorption are analyzed. The kinetics and equilibrium studies are also carried out. The process follows pseudo-second-order kinetics for both the dyes. The Langmuir isotherm results in the best linear fit with a monolayer adsorption capacity of 312.5 mg g-1 in the case of RhB adsorption and 188.7 mg g-1 for MO adsorption. Thermodynamic studies reveal the predominance of chemisorption in the removal of RhB, whereas in the case of MO, physisorption is favoured. The versatility in removing various organic dyes is evident from the ∼100% removal of methylene blue (MB), malachite green (MG), crystal violet (CV) dyes as well as a 1:1 mixture of RhB and MO. The structure and chemical composition before and after activation is analyzed. The activation results in a significant improvement in specific surface area from 787.9 to 975.4 m2 g-1 and an enhancement in the number of nanopores. The mechanism of adsorption is discussed in terms of the improved specific surface area, surface functionalization and the resultant adsorbent-adsorbate interactions.

Abstract Image

通过热处理对活性炭进行 KOH 介导的结构改性,以高效吸附有机染料
据报道,通过 KOH 介导的热处理可以改变活性炭的结构特征。结果表明,活性炭对罗丹明 B(RhB)和甲基橙(MO)的吸附效果有所改善,这与 KOH/前驱体的比例有关。当最佳比例为 2:1 时,15 分钟内对 RhB 的去除率为 (92 ± 2)%,对 MO 的去除率为 (82 ± 1)%。分析了接触时间、吸附剂剂量、吸附剂浓度和温度对吸附的影响。此外,还进行了动力学和平衡研究。两种染料的吸附过程都遵循伪二阶动力学。Langmuir 等温线的线性拟合效果最佳,RhB 的单层吸附容量为 312.5 mg g-1,MO 的吸附容量为 188.7 mg g-1。热力学研究表明,在去除 RhB 的过程中,化学吸附占主导地位,而在去除 MO 的过程中,物理吸附占优势。对亚甲基蓝(MB)、孔雀石绿(MG)、水晶紫(CV)染料以及 RhB 和 MO 的 1:1 混合物的去除率都达到了 100%,由此可见该物质在去除各种有机染料方面的多功能性。对活化前后的结构和化学成分进行了分析。活化后,比表面积从 787.9 m2 g-1 显著提高到 975.4 m2 g-1,纳米孔的数量也有所增加。从比表面积的提高、表面功能化以及由此产生的吸附剂与吸附剂之间的相互作用等方面讨论了吸附机理。
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来源期刊
CiteScore
8.10
自引率
1.60%
发文量
128
审稿时长
66 days
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