Development of low power non-thermal plasma jet and optimization of operational parameters for treating dyes and emerging contaminants

Abstract

Non-thermal plasma has emerged as an effective treatment system against the latest class of highly recalcitrant and toxic environmental pollutants termed emerging contaminants (ECs). In the present work, a detailed experimental study is carried out to evaluate the efficacy of a non-thermal plasma jet with two dyes, Rd. B and Met. Blue, as model contaminants. The plasma jet provided a complete dye decoloration in 30 min with an applied voltage of 6.5 kVp−p •OH, having the highest oxidation potential, acts as the main reactive species, which with direct action on contaminants also acts indirectly by getting converted into H2O2 and O3. Further, the effect of critical operational parameters viz., sample pH, applied voltage (4.5−6.5 kVp−p), conductivity (5−20 mS cm−1), and sample distance on plasma treatment efficacy was also examined. Out of all the assessed parameters, the applied voltage and sample conductivity was found to be the most significant operating parameters. A high voltage and low conductivity favored the dye decoloration, while the pH effect was not that significant. To understand the influence of plasma discharge gas on treatment efficacy, all the experiments are conducted with argon and helium gases under the fixed geometrical configuration. Both the gases provided a similar dye decoloration efficiency. The DBD plasma system with complete dye removal also rendered maximum mineralization of 73% for Rd. B, and 60% for Met. Blue. Finally, the system's efficiency against the actual ECs (four pharmaceutical compounds, viz., metformin, atenolol, acetaminophen, and ranitidine) and microbial contaminant (E. coli) was also tested. The system showed effectivity in the complete removal of targeted pharmaceuticals and a log2.5 E. coli reduction. The present systematic characterization of dye degradation could be of interest to large communities working towards commercializing plasma treatment systems.

Antimicrobial Efficacy of Argon Cold Atmospheric Pressure Plasma Jet on Clinical Isolates of Multidrug-Resistant ESKAPE Bacteria

“…In this study, an increase in inactivation for both drugresistant Gram-negative bacillus (MDR E. coli) and Grampositive cocci (MDR S. aureus) was observed with an increase in CAP exposure time. This result is concordant with previous studies [22], [25], [26], [61]. The prolonged interaction of CAP species (Ar I, OH .…”

“…The thermocouple probe tip was insulated and calibrated for the measurement of plume temperature. The details of the developed CAPJ system can be found elsewhere [22]. All the experiments in this study were performed at a fixed applied voltage of 6.5 kVp-p, 25 kHz frequency, and argon gas at a flow rate of 3 lpm.…”

Effect of Plasma On-Time with a Fixed Duty Ratio on Reactive Species in Plasma-Treated Medium and Its Significance in Biological Applications

“…ROS/RNS have therapeutic effects when administered to cells and tissues either directly from the plasma or by exposure to solutions that have already been plasma-treated. Optimization of the NTAPP treatment remained an active topic of research [ 50 , 51 ].…”

Efficacy of argon cold atmospheric pressure plasma jet on hospital surface decontamination and its impact on the surface property

“…The copious of RONS, ions, electrons, and excited species integrates an antimicrobial nature to the discharge [17,[24][25][26][27][28][29]. The efficacy of CAP in removing the microbial load from nutrient culture media [24,[30][31][32][33][34] or liquid suspensions [24,31,[35][36][37] have been studied. Das et al [24] and Flynn et al [38] showed the efficacy of CAP jet on the inactivation of clinically isolated ESKAPE pathogens.…”