In order to investigate the feasibility of sequential removal NO and SO_2 using non-thermal plasma and adsorbent simultaneously,the removal of NO and SO_2 from dry gas stream(NO/SO_2/N_2/O_2)with very little O_2 using non-thermal plasma was investigated using a coaxial dielectric barrier discharge.Comparative experiments were carried out in the dry gas stream with and without Ar respectively at O_2 concentration of 0.1%.The results showed that NO could be removed remarkably and it would be enhanced in the presence of Ar in the dry gas stream.It seems that SO_2 could not be removed unless there is Ar in the dry gas stream.The mechanism of removal of NO and SO_2 in the dry gas stream was discussed. 相似文献
Two challenges persist in the applications of nanoscale zero-valent iron(nZVI) for environmental remediation and waste treatment: limited mobility due to rapid aggregation and short lifespan in water due to quick oxidation. Herein, we report the nZVI incorporated into mesoporous carbon(MC) to enhance stability in aqueous solution and mobility in porous media. Meanwhile, the reactivity of nZVI is preserved thanks to high temperature treatment and confinement of carbon framework. Small-sized(~16 nm) nZVI nanoparticles are uniformly dispersed in the whole carbon frameworks. Importantly, the nanoparticles are partially trapped across the carbon walls with a portion exposed to the mesopore channels. This unique structure not only is conductive to hold the nZVI tightly to avoid aggregation during mobility but also provides accessible active sites for reactivity. This new type of nanomaterial contains ~10 wt% of iron. The nZVI@MC possesses a high surface area(~ 500 m~2/g) and uniform mesopores(~ 4.2 nm) for efficient pollutant diffusion and reactions. Also, high porosity of nZVI@MC contributes to the stability and mobility of nZVI. Laboratory column experiments further demonstrate that nZVI@MC suspension(~4 g Fe/L) can pass through sand columns much more efficiently than bare nZVI while the high reactivity of nZVI@MC is confirmed from reactions with Ni(II). It exhibits remarkably better performance in nickel(20 mg/L) extraction than mesoporous carbon, with 88.0% and 33.0%uptake in 5 min, respectively. 相似文献
Adsorption mechanisms and the role of different porous and crystalline structures on the removal of five haloacetonitriles (HANs) over hexagonal mesoporous silica (HMS), titanium substituted mesoporous silica (Ti-HMS), rod-shaped SBA-15 and microporous zeolite NaY were investigated. In addition, the effect of pH on adsorption mechanism and selective adsorption of five HANs individually and in an equimolar mixed solution were evaluated. The results indicated that the intraparticle diffusion rate constants of the mesoporous adsorbents were higher than that of the microporous NaY. In single solute, the order of adsorption preference (highest to lowest) was mono-HANs?>?di-HANs?>?tri-HAN. However, in mixed solute, the large molecular weight of the tri-HAN and di-HANs are more easily adsorbed than the smaller molecular weight mono-HANs. Except for SBA-15, the order of adsorption capacities in mixed HANs solute was not different compared to that observed for the single HAN solute, which might be caused by the higher accessibility to the active sites due to larger pore size. The ion-dipole electrostatic interaction was likely to be the main adsorption mechanism, and was favored at high pH values due to the high negative surface charge density of the adsorbent. The molecular structure of the HANs and hydrophilic/hydrophobic nature affected the adsorption capacities and their selective adsorption from mixed solutes. 相似文献
Transport of engineered antibiotic resistance plasmids in porous media has been reported to potentially cause significant spreading of antibiotic resistance in the environment. In this work, transport of an indigenous resistance plasmid pK5 in porous media was investigated through packed column experiments. At identical ionic strengths in CaCl2 solutions, the breakthroughs of pK5 from soil columns were very close to those from quartz sand columns, indicating that transport of pK5 in quartz sand and soil was similar. A similarity in transport behavior was also found between pK5 and an engineered plasmid pBR322 that has approximately the same number of base pairs as pK5. The influence of surfactants, a major group of constituents in soil solutions, was examined using an engineered plasmid pcDNA3.1(+)/myc-His A. The impact of an anionic surfactant, sodium dodecyl sulfate (SDS), was negligible at concentrations up to 200 mg·L–1. Cetyltrimethyl ammonium bromide (CTAB), a cationic surfactant, was found to significantly enhance plasmid adsorption at high concentrations. However, at environmentally relevant concentrations (<1 mg·L–1), the effect of this surfactant was also minimal. The negligible impact of surfactants and the similarity between the transport of engineered and indigenous plasmids indicate that under environmentally relevant conditions, indigenous plasmids in soil also have the potential to transport over long distances and lead to the spreading of antibiotic resistance.