Spent Coffee Bioelastomeric Composite Foams for the Removal of Pb²⁺ and Hg²⁺ from Water

Herein we present an interesting approach for the reutilization of coffee waste in water remediation. This is achieved by the development of bioelastomeric foams composed of 60 wt % of spent coffee powder and 40 wt % of silicone elastomer using the sugar leaching technique. In this study, we present the necessary characteristics of the developed “green” foams for the successful removal of Pb²⁺ and Hg²⁺ ions from water, and we identify the involved mechanisms. The capability of the bioelastomeric foams to interact with Pb²⁺ and Hg²⁺ is not affected by the presence of other metal ions in water as tests in real wastewater demonstrate. The incorporation of the spent coffee powder in a solid porous support, without compromising its functionality, facilitates the handling and allows the accumulation of the pollutants into the foams enabling their safe disposal. The fabricated foams can be used for the continuous filtration and removal of metal ions from water, demonstrating their versatility, in contrast to the sole coffee powder utilized so far, opening the way for the reutilization and valorization of this particular waste

Fabrication of Sustainable Hybrid MOF/Silica Electrodes for Current Lithium-ion Batteries and Beyond

Natural abundance and well-explored synthesis of silica are among the main motivations for the impressive evolution of silicon-based electrodes occurring over the last few years. In this work, an effective strategy has been introduced for the realization of silica-based anodes for lithium-ion batteries (LIBs) starting from zeolitic imidazolate framework-67 (ZIF67)/mesopores silica (mSiO2), which has been employed as a precursor. This approach leads to the realization of a hybrid electrode formed by the combination of a carbon nanotube (CNT) grown on the nitrogen-doped graphene-like structure, ultrafine cobalt-based nanoparticles, and silica (SiO2/Co3O4/NGC/CNT). From an electrochemical point of view, the performance of this engineered hybrid silica-based electrode (EHSiE), formed by water and a cellulose-based binder, is evaluated in both LP30 and ether-based electrolyte environments, the latter being particularly attractive in the emerging field of sulfur-based batteries. The EHSiE electrode displays a remarkable stability for 1000 cycles with the high reversible capacity of ∼410 mA h g–1 at 5 A g–1 versus Li/Li+ in the LP30 electrolyte. Moreover, this electrode discloses a good electrochemical behavior when coupled with high mass loading LiFePO4 cathode to design a full LIB. More impressively, a systemic investigation reveals a remarkable compatibility of EHSiE with ether-based electrolytes, providing a specific discharge capacity of 300 mA h g–1 for 500 cycles at 1 A g–1. These results suggest that the engineered electrode can be successfully applied in the field of high-energy and environmentally sustainable lithium-based batteries

Antibacterial Melamine Foams Decorated with <i>in Situ</i> Synthesized Silver Nanoparticles

A new and straightforward single-step route to decorate melamine foams with silver nanoparticles (ME/Ag) is proposed. Uniform coatings of silver nanoparticles with diameters less than 10 nm are formed <i>in situ</i> directly on the struts surface of the foams, after their dipping in an AgNO₃ solution. We prove that the nanoparticles are stably adhered on the foams, and that their amount can be directly controlled by the concentration of the AgNO₃ solution and the dipping time. Following this production route, ME/Ag foams can be obtained with silver content ranging between 0.2 and 18.6 wt % and excellent antibacterial performance, making them appropriate for various applications. Herein we explore the possibility to use them as antibacterial filters for water treatment, proving that they are able to remove completely <i>Escherichia coli</i> bacteria from water when filtered at flow rates up to 100 mL/h·cm² due to the release of less than 1 ppm of Ag⁺ ions by the foams. No bacterial regrowth was observed after further dilution of the treated water, to arrive below the safety threshold of Ag⁺ for drinking water (0.1 ppm), demonstrating the excellent bactericide performance of the ME/Ag filters