Fabrication and Characterization of Carbon Nanotube Filled PDMS Hybrid Membranes for Enhanced Ethanol Recovery.

Ethanol separation via the pervaporation process has shown growing application potential in solvent recovery and the bioethanol industry. In the continuous pervaporation process, polymeric membranes such as hydrophobic polydimethylsiloxane (PDMS) have been developed to enrich/separate ethanol from dilute aqueous solutions. However, its practical application remains largely limited due to the relatively low separation efficiency, especially in selectivity. In view of this, hydrophobic carbon nanotube (CNT) filled PDMS mixed matrix membranes (MMMs) aimed at high-efficiency ethanol recovery were fabricated in this work. The filler K-MWCNTs was prepared by functionalizing MWCNT-NH2 with epoxy-containing silane coupling agent (KH560) to improve the affinity between fillers and PDMS matrix. With K-MWCNT loading increased from 1 wt % to 10 wt %, membranes showed higher surface roughness and water contact angle was improved from 115° to 130°. The swelling degree of K-MWCNT/PDMS MMMs (2 wt %) in water were also reduced from 10 wt % to 2.5 wt %. Pervaporation performance for K-MWCNT/PDMS MMMs under varied feed concentrations and temperatures were evaluated. The results supported that the K-MWCNT/PDMS MMMs at 2 wt % K-MWCNT loading showed the optimum separation performance (compared with pure PDMS membranes), with the separation factor improved from 9.1 to 10.4, and the permeate flux increased by 50% (40-60 °C, at 6 wt % feed ethanol concentration). This work provides a promising method for preparing a PDMS composite with both high permeate flux and selectivity, which showed great potential for bioethanol production and alcohol separation in industry.

Exploring the Dehydrogenation Reaction Pathway of Perhydro-Polycyclic Aromatic Hydrocarbons over the Pt/Al2O3 Catalyst as Liquid Organic Hydrogen Carriers by In Situ DRIFT.

Polycyclic aromatic hydrocarbons (PAHs) have been paid more attention as liquid organic hydrogen carriers (LOHCs) because of their high hydrogen storage, easy transportation, low price, and other advantages. Dehydrogenation is the key point of the PAH hydrogen storage. However, the dehydrogenation reaction rate of perhydro-PAHs is slow, and their pathway is still not clear. To clarify the PAH dehydrogenation pathway, three kinds of perhydro-PAHs containing six-membered rings (methylcyclohexane, perhydro-diphenylmethane, and perhydro-dibenzyltoluene) are selected, and their dehydrogenation processes over the Pt/Al2O3 catalyst are carried out by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFT). It was found that the dehydrogenation in the six-membered ring started in the para position of the -CH3 group, and then, the six-membered ring was transformed into a benzene ring gradually. Between the six-membered rings, dehydrogenation started from the side ring, which has fewer groups.

Synergistic Effect of TMSPi and FEC in Regulating the Electrode/Electrolyte Interfaces in Nickel-Rich Lithium Metal Batteries.

Nickel-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) with respect to Li metal can enhance the energy density of lithium batteries effectively. However, the unstable Li deposition, together with the dissolution and migration of transition metal (TM) ions toward the anode deteriorate the cycle performance of NCM811||Li battery, especially when commercial carbonate electrolyte is used. Herein, tris(trimethylsilyl)phosphite (TMSPi) and fluoroethylene carbonate (FEC) are used to construct a dual-additive electrolyte, by which both electrodes can be protected. It is found that TMSPi can be preferentially adsorbed on the cathode surface through its strong coordination with Ni4+, playing the role as a HF scavenger and suppressing TM ions dissolution, as well as mitigating the structural degradation of the cathode effectively. When it comes to the lithium anode, the presence of TMSPi may lead to side reactions with Li metal, accompanied by fast dendrite growth. The introduction of FEC could facilitate the formation of stable electrode/electrolyte interfaces on both sides. Particularly, reduce the direct contact between TMSPi and Li anode, thus ameliorate the incompatibility issue. Consequently, the NCM811||Li cell with dual-additive demonstrates excellent capacity retention of 81.2% after 500 cycles at 1 C rate. As a sharp contrast, it only retains 13.9% in the one with blank electrolyte. The findings of this work provide a new insight into enhancing the cycle performance of NCM811||Li system via the synergistic effect between additives.

Recent Progress in Continuous-Flow Hydrogenation.

To achieve a safe, efficient, and sustainable (even fully automated) production for the continuous-flow hydrogenation reactions, which is among the most often used reactions in chemical synthesis, new catalyst types and immobilization methods as well as flow reactors and technologies have been developed over the last years; in addition, these approaches have been combined with new and transformational technologies in other fields such as artificial intelligence. Thus, attention from academic and industry practitioners has increasingly focused on improving the performance of hydrogenation in flow mode by reducing the reaction times, increasing selectivities, and achieve safe operation. This Minireview aims to summarize the most recent research results on this topic with focus on the advantages, current limitations, and future directions of flow chemistry.

Degradation of organic wastewater by hydrodynamic cavitation combined with acoustic cavitation.

In this paper, the decomposition of Rhodamine B (RhB) by hydrodynamic cavitation (HC), acoustic cavitation (AC) and the combination of these individual methods (HAC) have been investigated. The degradation of 20 L RhB aqueous solution was carried out in a self-designed HAC reactor, where hydrodynamic cavitation and acoustic cavitation could take place in the same space simultaneously. The effects of initial concentration, inlet pressure, solution temperature and ultrasonic power were studied and discussed. Obvious synergies were found in the HAC process. The combined method achieved the best conversion, and the synergistic effect in HAC was even up to 119% with the ultrasonic power of 220 W in a treatment time of 30 min. The time-independent synergistic factor based on rate constant was introduced and the maximum value reached 40% in the HAC system. Besides, the hybrid HAC method showed great superiority in energy efficiency at lower ultrasonic power (88-176 W). Therefore, HAC technology can be visualized as a promising method for wastewater treatment with good scale-up possibilities.

Bimetallic Rh-Fe catalysts for N2O decomposition: effects of surface structures on catalytic activity.

Well-homogenized RhFe alloy nanoparticles and core-shell structured Fe@Rh nanoparticles were highly dispersed on SBA-15 and then applied to N2O catalytic conversion. Compared to RhFe/SBA-15, Fe@Rh/SBA-15 showed a higher catalytic activity for N2O decomposition. This is because the Rh layers covering the Fe core were able to protect against oxidization and so Fe@Rh/SBA-15 was prevented from deactivating. DFT calculations were performed to study the reaction mechanism of N2O decomposition. The rate-determining step, which was found to be the formation of O2 from adsorbed oxygen atoms on the surfaces of RhFe and Fe@Rh, revealed that O atoms prefer to be adsorbed on exposed Fe atoms on the surface of RhFe rather than that of Fe@Rh. The calculation results indicate that the exposed Fe atoms tend to be oxidized on the surface of RhFe, resulting in the deactivation of RhFe/SBA-15 during the experiment.

A novel Ni-WC/AC catalyst with enhanced electroactivity for glucose oxidation.

WC-doped Ni over an active carbon catalyst (Ni-WC/AC), prepared by incipient wetness impregnation, is proposed as an anode for the amplified electrochemical oxidation of glucose in 0.1 M KOH solution. Cyclic voltammetry and morphology characterizations were used to explore these electrocatalysts. It was found that Ni-WC/AC catalysts were nanoparticles with a diameter of 10 nm and the 20%wtNi-20%wtWC/AC catalyst showed superior electrocatalytic activity toward glucose oxidation. The extraordinary activity obtained at the 20%wtNi-20%wtWC/AC modified glass carbon electrode (GCE) is attributed to the synergistic effect between Ni and WC toward glucose electroxidation.