TiO2 nanoparticles were successfully fabricated on electrospun polyacrylonitrile (PAN) nanofibers via the coupling of electrospinning and hydrothermal pathway. A straightforward photocatalysis oxidation process has been developed for simultaneous desulfurization and denitrification of flue gas using the TiO2-PAN photocatalyst. Also, the influences of some important operating parameters, such as titanium loading content of catalyst, flue gas humidity, flue gas flow, and inlet flue gas temperature on removal efficiencies of SO2 and NO were investigated. The results demonstrated that removal efficiencies of 99.3% for SO2 and 71.2% for NO were attained under the following optimal experiment conditions: titanium loading content, 6.78 At %; gas flow rate, 200 mL/min; flue gas humidity, 5%; inlet flue gas temperature, 40 °C. Furthermore, the presumed reaction mechanism of SO2 and NO removal using TiO2-PAN photocatalyst under UV light was proposed.
Increasing attention has been given to nanobiocatalysis for commercial applications. In this study, laccase was immobilized on polyacrylonitrile (PAN) nanofibrous membranes through ethanol/HCl method of amidination reaction and successfully applied for removal of 2,4,6-trichlorophenol (TCP) from water. PAN membranes with fiber diameters from 200 nm to 300 nm were fabricated via electrospinning and provided a large surface area for enzyme immobilization and catalytic reactions. Images of scanning electron microscope demonstrated the enzyme molecules were aggregated on the nanofiber surface. The immobilized laccase exhibited 72% of the free enzyme activity and kept 60% of its initial activity after 10 operation cycles. Moreover, the storage stability of the immobilized laccase was considered excellent because they maintained more than 92% of the initial activity after 18 days of storage, whereas the free laccase retained only 20%. The laccase-PAN nanofibrous membranes exhibited high removal efficiency of TCP under the combined actions of biodegradation and adsorption. More than 85% of the TCP was removed under optimum conditions. Effects of various factors on TCP removal efficiency of the immobilized laccase were analyzed. Results suggest that laccase-PAN nanofibrous membranes can be used in removing TCP from aqueous sources and have potential for use in other commercial applications.
Novel mesoporous poly(vinyl alcohol)/SiO(2) composite nanofiber membranes functionalized with mercapto groups with diameters of 300-500 nm have been fabricated by a sol-gel electrospinning process; they were highly effective at absorbing Cu(ii) ions from waste water. These nanofiber membranes could be regenerated through acidification.
Semiconductor nanostructures have received considerable attention in the field of photocatalytic hydrogen evolution. However, eco-friendly, high efficiency, and low-cost semiconductor materials are still desired. In consideration of this, herein, we design a new and economic noble-metal-free CdS/ZnCoO (CdS/ZCO) nanohybrid photocatalyst using a metal-organic framework (MOF) template, which is a framework structure composed of organic ligands and metal ion nodes with different numbers of connections. The as-prepared CdS/ZCO composites with a large specific surface area and porous hollow structure exhibit remarkable catalytic activity and high stability for hydrogen generation. The hydrogen evolution rate is about 3978.6 μmol g h with lactic acid as the sacrificial agent when the optimized amount of CdS nanoparticles (30 wt%) is decorated on the ZCO frame, and the production efficiency of H for CdS/ZCO is 4 times higher than that for CdS nanospheres or CdS/CoO. The significantly enhanced photocatalytic activity of CdS/ZCO is attributed to the efficient charge separation and transfer between the phase boundary of CdS and ZCO. In addition, the composites exhibit better hydrogen production in lactic acid than in methanol, and the remarkable catalytic activity and high stability of the CdS/ZCO composites for hydrogen evolution indicate that MOF-based composite materials have potential application prospects in energy conversion.
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