Development, Characterization, and Applications of Capsaicin Composite Nanofiltration Membranes

Biofouling in reverse osmosis (RO) membranes is a severe problem, causing a decrease in both permeate flux and salt rejection and increasing transmembrane pressure. Capsaicin extract inhibits bacterial growth and is therefore used in this study to prepare a thin-film composite membrane and membrane support. Four types of nanofiltration (NF) membranes were prepared by interfacial polymerization onto a porous support prepared by the phase inversion method. Membrane A was the control membrane with no capsaicin extract, membrane B contains capsaicin in the polyamide thin film, membrane C contains capsaicin in the porous support, and membrane D contains capsaicin in both the thin film and support layers. Three different salts (Na2SO4, MgSO4, and NaCl) were used at different concentrations (1000, 3000, and 5000 ppm) to test the performance of the membranes in terms of salt rejection and permeate flux. Membrane B showed the highest rejection for all the salts and concentrations tested. For 5000 ppm NaCl, the permeate flux for membrane B was 14.81% higher, and salt rejection was 19.6% higher than membrane A. Future work will evaluate the anti-biofouling properties of the membranes prepared with capsaicin, when exposed to seawater microorganisms

Evaluation of cobalt nanoparticle deposited graphene oxide and carbon nanotube supports as supercapacitor electrodes

Cobalt nanoparticles were deposited on multi-wall carbon nanotubes (CNT) and graphene oxide (GO) carbon supports and evaluated as a potential supercapacitor electrodes. The structure and morphology of the cobalt nanoparticles deposited on carbon supports were studied using XRD, TGA, and Raman spectroscopy. Cyclic voltammetry was used to measure the electrical charge of the electrode based on the materials and their specific capacitance (Csp) were calculated. GO based electrode showed a higher Csp than CNT electrode which is attributed to a larger surface area of the GO carbon support. Interestingly, the deposition of Co nanoparticles promoted an enhanced Csp in the both GO and multi-wall CNT supports.Las nanopartículas de cobalto se depositaron en soportes de carbono, nanotubos de carbono de pared múltiple (CNT) y óxido de grafeno (GO), y se evaluaron como potenciales electrodos de supercondensadores. La estructura y la morfología de las nanopartículas de cobalto depositadas sobre los soportes de carbono se estudiaron mediante XRD, TGA y espectroscopía Raman. La voltametría cíclica se utilizó para medir la carga eléctrica del electrodo en función de los materiales y se calculó su capacitancia específica (Csp). El electrodo basado en GO mostró un Csp mayor que el electrodo CNT, lo cual se atribuye a un área de superficie mayor del soporte de carbono GO. Curiosamente, el depósito de nanopartículas de Co promovió una Csp mejorada en los soportes GO y en los CNT de pared múltiple

Ultra-Low Pt Loading in PtCo Catalysts for the Hydrogen Oxidation Reaction: What Role Do Co Nanoparticles Play?

The effect of the nature of the catalyst on the performance and mechanism of the hydrogen oxidation reaction (HOR) is discussed for the first time in this work. HOR is an anodic reaction that takes place in anionic exchange membrane fuel cells (AEMFCs) and hydrogen pumps (HPs). Among the investigated catalysts, Pt exhibited the best performance in the HOR. However, the cost and the availability limit the usage. Co is incorporated as a co-catalyst due to its oxophylic nature. Five different PtCo catalysts with different Pt loading values were synthesized in order to decrease Pt loading. The catalytic activities and the reaction mechanism were studied via electrochemical techniques, and it was found that both features are a function of Pt loading; low-Pt-loading catalysts (Pt loading < 2.7%) led to a high half-wave potential in the hydrogen oxidation reaction, which is related to higher activation energy and an intermediate Tafel slope value, related to a mixed HOR mechanism. However, catalysts with moderate Pt loading (Pt loading > 3.1%) exhibited lower E1/2 than the other catalysts and exhibited a mechanism similar to that of commercial Pt catalysts. Our results demonstrate that Co plays an active role in the HOR, facilitating Hads desorption, which is the rate-determining step (RDS) in the mechanism of the HOR