Inthawong Supawan, Wongkoblap Atichat, Intomya Worapot, Tangsathitkulchai Chaiyot
School of Chemical Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand.
Molecules. 2023 Jul 15;28(14):5433. doi: 10.3390/molecules28145433.
Activated carbon derived from longan seeds in our laboratory and commercial activated carbon are used to investigate the adsorption of methane (CH) and carbon dioxide (CO). The adsorption capacity for activated carbon from longan seeds is greater than commercial activated carbon due to the greater BET area and micropore volume. Increasing the degree of burn-off can enhance the adsorption of CO at 273 K from 4 mmol/g to 4.2 and 4.8 mmol/g at 1000 mbar without burn-off, to 19 and 26% with burn-off, respectively. This is because an increase in the degree of burn-off increases the surface chemistry or concentration of functional groups. In the investigation of the effect of the hydroxyl group on the adsorption of CO and CH at 273 K, it is found that the maximum adsorption capacity of CO at 5000 mbar is about 6.4 and 8 mmol/g for cases without and with hydroxyl groups contained on the carbon surfaces. The opposite behavior can be observed in the case of methane, this is due to the stronger electrostatic interaction between the hydroxyl group and carbon dioxide. The simulation results obtained from a Monte Carlo simulation method can be used to support the mechanism in this investigation. Iron oxide is added on carbon surfaces with different concentrations to reveal the effects of ferric compounds on the adsorption of CO. Iron at a concentration of about 1% on the surface can improve the adsorption capacity. However, excessive amounts of iron led to a limited adsorption capacity. The simulation result shows similar findings to the experimental data. The findings of this study will contribute to the progress of gas separation technologies, paving the way for long-term solutions to climate change and greenhouse gas emissions.
我们实验室用龙眼籽制备的活性炭和商业活性炭被用于研究甲烷（CH）和二氧化碳（CO）的吸附情况。由于具有更大的比表面积和微孔体积，龙眼籽活性炭的吸附容量大于商业活性炭。提高烧失程度可增强在273K、1000毫巴条件下CO的吸附量，未烧失时从4毫摩尔/克提高到4.2和4.8毫摩尔/克，烧失时分别提高到19%和26%。这是因为烧失程度的增加提高了表面化学性质或官能团浓度。在研究273K时羟基对CO和CH吸附的影响时发现，在5000毫巴下，碳表面不含和含有羟基时，CO的最大吸附容量分别约为6.4和8毫摩尔/克。对于甲烷则观察到相反的情况，这是由于羟基与二氧化碳之间更强的静电相互作用。从蒙特卡罗模拟方法获得的模拟结果可用于支持本研究中的机理。在碳表面添加不同浓度的氧化铁以揭示铁化合物对CO吸附的影响。表面铁浓度约为1%时可提高吸附容量。然而，过量的铁会导致吸附容量受限。模拟结果与实验数据显示出相似的结果。本研究的结果将有助于气体分离技术的进步，为气候变化和温室气体排放的长期解决方案铺平道路。
