Department of Chemical Engineering, Sathyabama Institute of Science and Technology, Chennai, Tamilnadu, 600119, India.
Department of Chemical Engineering, Sri Sivasubramaniya Nadar College of Engineering, Chennai, Tamilnadu, 603110, India; Centre of Excellence in Water Research (CEWAR), Sri Sivasubramaniya Nadar College of Engineering, Kalavakkam, 603110, Tamil Nadu, India; School of Engineering, Lebanese American University, Byblos, Lebanon; Department of Biotechnology Engineering and Food Technology, Chandigarh University, Mohali, 140413, India.
Environ Res. 2023 Nov 1;236(Pt 2):116735. doi: 10.1016/j.envres.2023.116735. Epub 2023 Jul 28.
In the current study, an attempt was made to synthesize coffee husk (CH) activated carbon by chemical modification approach (sulphuric acid-activated CH (SACH) activated carbon) and was used as a valuable and economical sorbent for plausible remediation of Methylene blue (MB) dye. Batch mode trials were carried out by carefully varying the batch experimental variables: SACH activated carbon (SACH AC) dosage, pH, initial dye concentration, temperature, and contact time. The optimum equilibrium time for adsorption by SACH activated carbon was obtained as 60 min, and the maximum adsorption took place at 30 °C. Morphological and elemental composition, crystallinity behaviour, functional groups, and thermal stability were examined using SEM with EDX, XRD, FTIR, BET, TGA, and DTA and these tests showed successful production of activated carbon. The outcomes showed that chemical activation enhanced the number of pores and roughness which possibly maximized the adsorptive potential of coffee husk. The Box-Benken design (BBD) was used to optimize the MB dye adsorption studies and 99.48% MB dye removed at SACH AC dosage of 4.83 g/L at 30 °C for 60 min and pH 8.12, and the maximum adsorption was yielded for sulphuric acid-activated coffee husk carbon carbon with 88.1 mg/g maximum MB adsorption capacity. Langmuir- Freundlich model deliberately provided a better fit to the equilibrium data. The SACH AC-MB dye system kinetics showed a high goodness-of-fit with pseudo second order model, compared to other studied models. Change in Gibbs's free energy (ΔG) of the system indicated spontaneity whereas low entropy value (ΔS) suggested that the removal of MB dye on the SACH activated carbon was an enthalpy-driven process. The exothermic nature of the sorption cycle was affirmed by the negative enthalpy value (ΔH). The adsorptive-desorptive studies reveal that SACH AC could be restored with the maximum adsorption efficiency being conserved after the fifth cycles. Overall, the outcomes revealed that sulphuric acid-activated coffee husk activated carbon (SACH AC) can be used as prompt alternative for low-cost sorbent for treating dye-laden synthetic wastewaters.
在本研究中，尝试通过化学修饰方法（硫酸活化咖啡壳（SACH）活性炭）合成咖啡壳活性炭，并将其用作有价值且经济的吸附剂，以合理修复亚甲蓝（MB）染料。通过仔细改变批处理实验变量进行批量模式试验：SACH 活性炭（SACH AC）剂量、pH 值、初始染料浓度、温度和接触时间。通过 SACH 活性炭吸附的最佳平衡时间为 60 分钟，最大吸附发生在 30°C。使用 SEM 结合 EDX、XRD、FTIR、BET、TGA 和 DTA 检查形态和元素组成、结晶行为、官能团和热稳定性，这些测试表明成功生产了活性炭。结果表明，化学活化增加了孔和粗糙度的数量，这可能最大限度地提高了咖啡壳的吸附潜力。使用 Box-Benken 设计（BBD）优化 MB 染料吸附研究，在 SACH AC 剂量为 4.83 g/L、温度为 30°C、pH 值为 8.12 的条件下，99.48%的 MB 染料被去除，最大吸附量为 88.1 mg/g 的硫酸活化咖啡壳活性炭。Langmuir-Freundlich 模型故意为平衡数据提供了更好的拟合。与其他研究模型相比，SACH AC-MB 染料体系动力学显示出与伪二阶模型高度拟合。系统吉布斯自由能（ΔG）的变化表明该过程是自发的，而低熵值（ΔS）表明 MB 染料在 SACH 活性炭上的去除是一个焓驱动过程。吸附循环的放热性质得到负焓值（ΔH）的证实。吸附-解吸研究表明，SACH AC 可以通过最大吸附效率恢复，并且在第五个循环后保持吸附效率。总的来说，结果表明，硫酸活化咖啡壳活性炭（SACH AC）可用作处理含染料合成废水的低成本吸附剂的快速替代品。
