Adsorption Equilibrium, Kinetics, and Thermodynamic Studies of Cefpirome Sulfate by Using Macroporous Resin

The adsorption thermodynamics, kinetics, and isotherm parameters of cefpirome sulfate in aqueous solution on macroporous resin (XAD-16) were studied. Using static equilibrium tests, the fitting of resin adsorption data were calculated by the isothermal adsorption model. The fitting results show that Freundlich equation can adequately fit the adsorption isotherm. Meanwhile, the derived adsorption constants and their temperature dependencies from Freundlich isotherm had been used to calculate the corresponding thermodynamic quantities, such as the free energy of adsorption, heat, and entropy of adsorption. The thermodynamic data indicated that XAD-16 resin adsorption of cefpirome sulfate in aqueous solution was a spontaneous exothermic process, which was characterized by physical adsorption. The influences of initial concentration, bed height, and residence time on the breakthrough curve were examined by dynamic tests and the optimal parameters were defined

Amphiphobic Polytetrafluoroethylene Membranes for Efficient Organic Aerosol Removal

Polytetrafluoroethylene (PTFE) membrane is an extensively used air filter, but its oleophilicity leads to severe fouling of the membrane surface due to organic aerosol deposition. Herein, we report the fabrication of a new amphiphobic 1H,1H,2H,2H-perfluorodecyl acrylate (PFDAE)-grafted ZnO@PTFE membrane with enhanced antifouling functionality and high removal efficiency. We use atomic-layer deposition (ALD) to uniformly coat a layer of nanosized ZnO particles onto porous PTFE matrix to increase surface area and then subsequently graft PFDAE with plasma. Consequently, the membrane surface showed both superhydrophobicity and oleophobicity with a water contact angle (WCA) and an oil contact angle (OCA) of 150° and 125°, respectively. The membrane air permeation rate of 513 (m³ m^–2 h^–1 kPa^–1) was lower than the pristine membrane rate of 550 (m³ m^–2 h^–1 kPa^–1), which indicates the surface modification slightly decreased the membrane air permeation. Significantly, the filtration resistance of this amphiphobic membrane to the oil aerosol system was much lower than the initial one. Moreover, the filter exhibited exceptional organic aerosol removal efficiencies that were greater than 99.5%. These results make the amphiphobic PTFE membranes very promising for organic aerosol-laden air-filtration applications

Electric Field-Controlled Ion Transport In TiO₂ Nanochannel

On the basis of biological ion channels, we constructed TiO₂ membranes with rigid channels of 2.3 nm to mimic biomembranes with flexible channels; an external electric field was employed to regulate ion transport in the confined channels at a high ionic strength in the absence of electrical double layer overlap. Results show that transport rates for both Na⁺ and Mg²⁺ were decreased irrespective of the direction of the electric field. Furthermore, a voltage-gated selective ion channel was formed, the Mg²⁺ channel closed at −2 V, and a reversed relative electric field gradient was at the same order of the concentration gradient, whereas the Na⁺ with smaller Stokes radius and lower valence was less sensitive to the electric field and thus preferentially occupied and passed the channel. Thus, when an external electric field is applied, membranes with larger nanochannels have promising applications in selective separation of mixture salts at a high concentration

High-efficiency, Synergistic ZnO-Coated SiC Photocatalytic Filter with Antibacterial Properties

A new composite ZnO-coated SiC filter with photocatalytic and antibacterial properties was prepared via a simple sol–gel method. The crystallinity, grain size, and ZnO loadings played important roles in the photocatalytic and antibacterial properties of as-prepared materials. The high-efficiency photocatalytic and antibacterial properties resulted from the active oxidizing reagents and released Zn²⁺, respectively. The possible formation of an n–p junction between n-type ZnO and p-type SiC filter support is considered as another reason for enhanced photocatalytic performance (i.e., the effective degradation of methyl orange (MO) solution). Antibacterial activity of as-prepared samples against Escherichia coli and Staphylococcus aureus (without UV light) were also examined; after 30 min sterilization, the samples removed a maximum of 97.6 and 99.9% of these bacteria, respectively

Facile Synthesis of Dual-Layer Organic Solvent Nanofiltration (OSN) Hollow Fiber Membranes

A dual-layer organic solvent nanofiltration (OSN) hollow fiber membrane was prepared by a single-step coextrusion process with polybenzimidazole as the outer selective layer and hyperbranched polyethylenimine cross-linked polyimide as the inner support layer. The OSN membrane shows a rejection of >99% against methylene blue (MW: 319.85 g mol^–1) with good solvent fluxes in water, methanol, and acetonitrile. The newly invented fabrication technology may provide simple, cost-effective, scalable, and high-performance OSN membranes for organic solvent recovery

Unusual Air Filters with Ultrahigh Efficiency and Antibacterial Functionality Enabled by ZnO Nanorods

Porous membranes/filters that can remove airborne fine particulates, for example, PM2.5, with high efficiency at low energy consumption are of significant interest. Herein, we report on the fabrication of a new class of unusual superior air filters with ultrahigh efficiency and an interesting antibacterial functionality. We use atomic layer deposition (ALD) to uniformly seed ZnO on the surface of expanded polytetrafluoroethylene (ePTFE) matrix, and then synthesize well-aligned ZnO nanorods with tunable widths and lengths from the seeds under hydrothermal conditions. The presence of ZnO nanorods reduces the effective pore sizes of the ePTFE filters at little expense of energy consumption. As a consequence, the filters exhibit exceptional dust removal efficiencies greater than 99.9999% with much lower energy consumption than conventional filters. Significantly, the presence of ZnO nanorods strongly inhibits the propagation of both Gram positive and negative bacteria on the filters. Therefore, the functionalized filters can potentially overcome the inherent limitation in the trade-off effect and imply their superiority for controlling indoor air quality

Novel Synthesis of a High-Performance Pt/ZnO/SiC Filter for the Oxidation of Toluene

In this work, a novel Pt/ZnO/SiC filter was successfully prepared by first coating ZnO nanoparticles on a silicon carbide filter by a sol–gel process and then loading Pt nanoparticles on the ZnO layer through impregnation. The microstructure, crystal morphology, composition and elemental valence of the prepared filter were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). It was found that the ZnO coating layer improved the dispersity of the Pt nanoparticles and significantly enhanced the catalytic performance. Toluene was used as a model volatile organic compound and reached complete conversion of up to 100% over the porous tubular Pt/ZnO/SiC material at a filtration velocity of 0.72 m/min within 240 h at 210 °C. The synthetic ceramic filter presented a good capacity for the catalytic oxidation of volatile organic compounds (VOCs), and accordingly, a simple approach is suggested here for preparing this catalyst on a support to increase the catalytic efficiency

Balancing Osmotic Pressure of Electrolytes for Nanoporous Membrane Vanadium Redox Flow Battery with a Draw Solute

Vanadium redox flow batteries with nanoporous membranes (VRFBNM) have been demonstrated to be good energy storage devices. Yet the capacity decay due to permeation of vanadium and water makes their commercialization very difficult. Inspired by the forward osmosis (FO) mechanism, the VRFBNM battery capacity decrease was alleviated by adding a soluble draw solute (e.g., 2-methylimidazole) into the catholyte, which can counterbalance the osmotic pressure between the positive and negative half-cell. No change of the electrolyte volume has been observed after VRFBNM being operated for 55 h, revealing that the permeation of water and vanadium ions was effectively limited. Consequently, the Coulombic efficiency (CE) of nanoporous TiO₂ vanadium redox flow battery (VRFB) was enhanced from 93.5% to 95.3%, meanwhile, its capacity decay was significantly suppressed from 60.7% to 27.5% upon the addition of soluble draw solute. Moreover, the energy capacity of the VRFBNM was noticeably improved from 297.0 to 406.4 mAh remarkably. These results indicate balancing the osmotic pressure via the addition of draw solute can restrict pressure-dependent vanadium permeation and it can be established as a promising method for up-scaling VRFBNM application

A Side-Stream Catalysis/Membrane Filtration System for the Continuous Liquid-Phase Hydrogenation of Phenol over Pd@CN to Produce Cyclohexanone

A catalysis/membrane filtration system combining a catalytic reaction and a separation process can realize the in situ separation of ultrafine catalysts from the reaction mixture and make the production continuous. In this study, a side-stream catalysis/membrane filtration system was developed for the first time for the continuous liquid-phase hydrogenation of phenol over Pd@CN to produce cyclohexanone. The operating parameters including the reaction and filtration conditions were optimized by balancing their influences on the catalytic and separation properties. It was found that the properties of the side-stream catalysis/membrane filtration system depended strongly on the operating conditions. Continuous phenol hydrogenation over Pd@CN was performed under the optimized operating conditions. A stable operation of 30 h was achieved with both a phenol conversion and a cyclohexanone selectivity of greater than 85%, and the ceramic membrane showed excellent stability. This study is a contribution to the development of green cyclohexanone production processes