Department of Analytical Chemistry and Chemical Metallurgy, Wroclaw University of Science and Technology, 27 Wybrzeze St. Wyspianskiego, 50-370 Wroclaw, Poland.
Department of Process Engineering and Technology of Polymer and Carbon Materials, Wroclaw University of Science and Technology, 27 Wybrzeze St. Wyspianskiego, 50-370 Wroclaw, Poland.
Int J Mol Sci. 2024 Oct 21;25(20):11319. doi: 10.3390/ijms252011319.
Yearly, thousands of tons of wasted coffee grounds are produced according to high coffee consumption. Still, after the coffee brewing, wasted coffee grounds contain some amounts of caffeine (CAF). CAF, in turn, contains multiple O and N chelating atoms in its structure. These have a potential to be reductors for complexes of metals. In this context, within the present study, a set of CAF extracts derived from coffee beans and coffee grounds were obtained and then used for the one-step reduction of ReO ions with no additional toxic chemicals. Within this approach, CAF was applied as a secondary, green resource for the synthesis of unique rhenium nanoparticles (ReNPs) containing Re species at 0 and +6 oxidation states. The obtained ReNPs were identified and characterized with the use of X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Further, the capping and stabilization of ReNPs by CAF were verified with the aid of Fourier transformation infrared spectroscopy (FT-IR). The so-obtained "green" ReNPs were then used as a homogenous catalyst in the catalytic hydrogenation of 4-nitrophenol (4-NP). This new nanomaterial revealed a superior catalytic activity, leading to the complete reduction of 4-NP to 4-aminophenol within 40-60 min with a first-order rate constant of 0.255 min.
每年，由于咖啡消耗量高，都会产生数千吨的废咖啡渣。然而，在冲泡咖啡后，废咖啡渣中仍含有一定量的咖啡因（CAF）。CAF 在其结构中含有多个 O 和 N 螯合原子，这些原子有可能成为金属配合物的还原剂。在这种情况下，本研究中获得了一组从咖啡豆和咖啡渣中提取的 CAF 提取物，然后将其用于一步还原 ReO 离子，而无需添加额外的有毒化学物质。在这种方法中，CAF 被用作二次、绿色资源，用于合成含有 Re 物种的独特铼纳米粒子（ReNPs），其氧化态为 0 和 +6。使用 X 射线粉末衍射（XRD）和高分辨率透射电子显微镜（HRTEM）对获得的 ReNPs 进行了鉴定和表征。此外，通过傅里叶变换红外光谱（FT-IR）证实了 CAF 对 ReNPs 的包覆和稳定作用。然后，将获得的“绿色”ReNPs 用作 4-硝基苯酚（4-NP）催化加氢反应的均相催化剂。这种新型纳米材料表现出优异的催化活性，可在 40-60 分钟内将 4-NP 完全还原为 4-氨基酚，一级反应速率常数为 0.255 min。
