美國麥克儀器公司研究人員近期在《Journal of Materials Chemistry A》與《ACS Sustainable Chem. Eng》上分別發表題為“ Enhanced reactive adsorption of H2S on Cu–BTC/ S- and N-doped GO composites”和“Adsorption Properties of Activated Carbons Prepared from Waste CDs and DVDs”文章,兩篇文章的摘要分別如下:
New composites containing Cu–BTC and S- and N-doped graphite oxides (GOs) were synthesized. The composites were evaluated as adsorbents of H2S under ambient conditions. The texture and chemistry of the initial samples and those exposed to H2S were analyzed using a wide range of analytical techniques (XRD, SEM-EDX, FTIR, thermal analysis-MS, and nitrogen adsorption). The performance of the new composites as H2S adsorbents was much better than that of the parent MOFs. It was owing to the formation of new microporosity as a result of linkages between the sulfonic acids and amine groups of modified GO and copper centers Cu–BTC. The presence of moisture in the pore system increased the amount adsorbed. Physical adsorption and reactive adsorption play an important role in the mechanism of retention. The removal of H2S is favored on the composites with a higher degree of surface heterogeneity, which facilitates the retention of H2S molecules mostly in the form of sulfides. Given the differences in the chemistry of the N- and S-containing groups in the composites, distinct mechanisms of adsorption occur, which result in sulfides/sulfates of unique morphologies. Nitrogen functional groups catalyze the formation of superoxide ions on the graphene phase, resulting in the partial oxidation of H2S and in the release of SO2.
Two sets of activated carbons have been prepared from waste CDs and DVDs by carbonization and subsequent activation with either KOH or CO2. The resulting activated carbons had specific surface area in the range of 500–2240 m2g–1, total pore volume in the range of 0.18–1.36 cm3g–1, volume of micropores and small mesopores (w< ~2.9 nm) in the range of 0.17–1.25 cm3g–1, and volume of small micropores (w< ~1.2 nm) in the range of 0.14–0.71 cm3g–1. Both KOH and CO2activation resulted in 5–45-fold improvement in the structural properties, depending on the conditions used. The resulting carbons showed good adsorption properties toward carbon dioxide, hydrogen, and benzene. The best uptakes for these adsorptives were 5.8 mmol g–1of CO2at 0 °C and 800 mmHg, 3.3 mmol g–1of CO2at 25 °C and 850 mmHg, 13.9 mmol g–1of H2at –196 °C and 850 mmHg, and 15.4 mmol g–1of C6H6at 20 °C and saturation pressure. The excellent adsorption properties of the prepared carbons render them as potential adsorbents in CO2capture and storage, VOCs adsorption/separation, and hydrogen storage.