Design and Characterization of Electrospun Polyamide Nanofiber Media for Air Filtration Applications

Electrospun polyamide 6 (PA 6) and polyamide 6/6 (PA 6/6) nanofibers were produced in order to investigate their experimental characteristics with the goal of obtaining filtration relevant fiber media. The experimental design model of each PA nanofibers contained the following variables: polymer concentration, ratio of solvents, nanofiber media collection time, tip-to-collector distance, and the deposition voltage. The average diameter of the fibers, their morphology, basis weight, thickness, and resulting media solidity were investigated. Effects of each variable on the essential characteristics of PA 6/6 and PA 6 nanofiber media were studied. The comparative analysis of the obtained PA 6/6 and PA 6 nanofiber characteristics revealed that PA 6/6 had higher potential to be used in filtration applications. Based on the experimental results, the graphical representation—response surfaces—for obtaining nanofiber media with the desirable fiber diameter and basis weight characteristics were derived. Based on the modelling results the nanofiber filter media (mats) were fabricated. Filtration results revealed that nanofiber filter media electrospun from PA6/6 8% (w/vol) solutions with the smallest fiber diameters (62–66 nm) had the highest filtration efficiency (PA6/6_30 = 84.9–90.9%) and the highest quality factor (PA6/6_10 = 0.0486–0.0749 Pa−1)

Biogas combustion with various oxidizers in a nanosecond DBD microplasma burner

This study concerns the effect of non-thermal plasma discharges on simulated biogas (mixture of CH4 with 80–20 vol% CO2) combustion at atmospheric pressure in synthetic air or synthetic air enriched by oxygen. The plasma-assisted, premixed combustion was performed in a porous-plate burner with dielectric barrier discharge microplasmas driven by nanosecond high-voltage pulses at 3 kHz and 10 kHz repetition rates in the burner holes. The characteristics of the plasma-assisted flames and the role of reactive oxygen species in the plasma-assisted combustion process supplying various oxidizers were determined using a spatial flame chemiluminescence scanning technique acquiring OH*, C2* and CH* emission intensities. From the obtained results, the pathways of combustion enhancement by the plasma were established. During plasma-assisted combustion, the biogas flame stability has improved. The highest plasma impact on the flame stability was observed for the biogas mixture (CH4-60%/CO2-40%). The flame lift-off for a stoichiometric mixture was reduced by 54% with the discharge at 10 kHz repetition rate, but a decrease of fuel–air ratio φ resulted in reduced effect of plasma and the lift-off was reduced only by 38–10% with 10 kHz discharge and by 22–7% with 3 kHz discharge. The experiments with oxygen-enriched synthetic air showed that the oxygen addition increases the flammability limit of biogas mixtures (CH4 with 50–20 vol% in CO2), and allowed to burn mixtures which were not able to combust under normal conditions. However, the plasma-assisted combustion with oxygen enrichment showed a lower effect on the combustion enhancement than without. During experiments of plasma-assisted combustion, the plasma impact on NOX emissions was also determined, showing that NOX concentrations increased with increasing plasma power

Atmospheric Plasma Supported by TiO2 Catalyst for Decolourisation of Reactive Orange 16 Dye in Water

Purpose Every advanced oxidation process (AOP) has its limitations in water purification. Novel designs with simultaneous application of different AOPs can offer better solutions for cleaner water. Methods We have comparatively studied two advanced oxidation processes (AOPs) on decolourisation of Reactive Orange 16 (RO 16) azo dye pollutant from water: gas plasma treatment by low power atmospheric pressure plasma using novel plasma needle configuration, and semiconductor heterogeneous photocatalysis using titanium dioxide (TiO2) nanopowders. Additionally, simultaneous application of two advanced oxidation processes on azo dye decolourisation was studied. Results It was found that plasma treatment is very efficient system for the dye removal even for low flow rates (1 slm) of the Ar as feed gas. The presence of 10% of O-2 in Ar flow intensified dye oxidation process and shortened required time for total decolourisation. When plasma and catalyst were simultaneously applied, TiO2 was activated with a few Watts plasma source as well as 300 W UV lamp source. The synergic effect of two AOPs was more pronounced for higher feed gas flow rates, resulting in improved decolourisation efficiency. Conclusion Plasma needle can efficiently remove Reactive Orange 16 azo dye from water with a power consumption of only few Watts. With the addition of TiO2 the removal efficiency is significantly improved. [GRAPHICS]