A systematic comparison between batch and continuous microfluidics systems was conducted for the synthesis of ZnWO 4 nanoparticles . A series of ZnWO 4 nanoparticles were prepared by different operating modes, initial concentration of reactants and residence time. The features of ZnWO 4 nanoparticles including microscopic morphology, particle size distribution and chemical structure were systematically characterized. The results showed that the continuous microfluidics system could obtain ZnWO 4 nanoparticles with a more uniform particle size compared with batch system. The size of ZnWO 4 are reduced from 92.6 to 65.2 nm by changing the reaction system. Besides, a low concentration of reactants is more suitable for preparing smaller particles ZnWO 4 nanoparticles. The average diameters of prepared ZnWO 4 nanoparticles was reduced to 50 nm in the condition that the residence time was 20 s and the concentration of reactants was 0.1 mol/L. Afterward, the degradation of dimethyl sulfoxide (DMSO) in the wastewaters was used as a probe reaction to evaluate the catalysis performance of prepared ZnWO 4 nanoparticles. This work indicates the potential opportunity of versatile continuous microfluidics technique for the fabrication of various multifunctional metal tungstates nanoparticles.
Lidong Wang,Xiaohan Guo,Qingying Ye,Juanjuan Qi,Ping Li,Fei Yan
Dimethyl sulfoxide (DMSO) is a widely used solvent in many industries. The biodegradation of DMSO is difficult, resulting in large amounts volatile and noxious compounds emitted into the atmosphere, including dimethylsulfide, methyl mercaptan, and H2S. Therefore, it is necessary to deal with DMSO-containing wastewater using chemical methods. Here, supported niobia catalysts were prepared and characterized, and their catalytic performances was evaluated by the oxidative degradation of DMSO via H2O2 activation. The product of DMSO oxidation is dimethylsulfone which is a biodegradable and environmentally benign compound. The most active catalyst, 20%Nb2O5/SiO2, can remove 178.6 mmol/L DMSO within 2 h at 25 °C following a pseudo-first-order reaction. EPR spectroscopic studies and scavenging experiments confirms that O2•– and 1O2 are the active species for DMSO degradation. Although the catalytic activity of Nb2O5/SiO2 drops significantly after use, its reusability improved conspicuously after calcination, and the catalyst can be reused for 5 times with an 82.2% DMSO conversion.
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