The Effect of Sodium Chloride (NaCl) on Reactive Oxygen and Nitrogen Species(RONS) in Plasma-Activated Water (PAW)
123
31,2,3A.G. Yahaya , T. Kato , J. Kristof , M. Blajan , K. Shimizu

Organization for Innovation and Social Collaboration Shizuoka University,Nakaku, Johoku, Hamamatsu, 432-8561, Japane-mail: goojy_93@yahoo.com, shimizu@cjr.shizuoka.ac.jp

Introduction

PAW Generation

Previous studies have shown that ordinary
saline solution provides a more suitable living
environment for most bacteria than deionizedwater. However, plasma-activated normal
saline has been found to have a stronger
bactericidal effect than the plasma-activateddeionized water.

Sodium chloride (NaCl) solutions wereprepared using NaCl from (Wako, TSN1081,Japan) and fresh distilled water from a water
distillation apparatus (RFD260NC, Advantec,Tokyo, Japan). 0, 1, 5 and 10% NaCl solutions
were prepared by dissolving 0, 1, 5, and 10 gof NaCl per 100 mL final volume.

Dissolved H2O2, NO2− and NO3− play a key rolein the bactericidal properties of plasma
activated water (PAW). In this work, 1 - 10%sodium chloride (NaCl) PAW was generatedusing cold atmospheric dielectric barrierdischarge (DBD) microplasma at a discharge
voltage of 1.2 kV (0–p), AC-sine frequency of 20
kHz using a 2 L/min room air working gas.
The effect of varying NaCl concentrations on
NO2− and NO3− in PAW was investigated using
ion chromatography (IC).

2 mL of these samples were treated withmicroplasma for 2 min. to generate PAW. The
samples were diluted 2 times serially in
preparation for ion chromatography analysis.
The reactive nitrogen species (NO2−, NO3−)
with chloride Cl− dissolved in the PAW werecharacterized by the standard solution ofNaNO2, KNO3, and NaCl analysis in Fig. 2 ataround 9, 12, and 18 min. respectively.

Results

Methods

1. Experimental setup

Range of Cl-, NO2- & NO3- in Standard Solutions

Fig. 3 Shows the concentration of NO2- & NO3and Cl- in PAW with increase in NaCl
concentration from 0 - 10%.

Discussion
The concentration of NO2− and NO3−
decreased from 32.9 to 5.2 µmol/L and 126.8
to 24.6 µmol/L respectively with increase inNaCl concentration. On the other hand, theconcentration of Cl− increased from 0 to1070.2 µ mol/L with increase in NaCl
concentration.
Overall, NO3− was more
dominant over NO2−. This could be due thescavenging properties of Cl− towardshydroxyl radicals as shown below by(Jayson et al. 1973) and (Klaning et al., 1985)

HO• + Cl– ↔ HOCl –(1)HOCl•–+ H+ ↔ Cl• + H2O(2)

Cl• + HOCl → H+ + Cl– + ClO• (3)Fig. 1 Shows the chromatogram of Cl-, NO2- &NO3- in standard solutions of NaCl, NaNO2 andKNO3 at 8, 11 and 18 min. respectively.
The power
consumption of thissetup was recorded at
2.7 W

Cl• + ClO– → Cl– + ClO•

(4)

Cl• + Cl– ↔ Cl2•–(5)KI Starch Experiments physically confirmed
less oxidation in PAW with increase in NaCl
concentration (0 – 0.1 %) in PAW as shown
below.

2. Experimental conditions
Discharge voltage

1.2 kV (0-p)

SINE frequency

20 kHzCarrier gas

Room air at

Gas flow rate

2 L/min

Treatment time

3 min

Sample volume2 mL

Distance between electrodeand samples

2 mmHumidity±60 %Fig. 2 Shows the chromatogram of Cl-, NO2- &NO3- in PAW at 9, 11 and 18 min. respectively.

Dark Colour
More oxidation

Light Colour
Less oxidation

Conclusion

Tab.1 Experimental conditions for microplasma PAW generation

 Ion chromatography was used to investigate the influence of NaCl concentration (0-10%) onNO2− and NO3− in PAW.
0

 It was observed that increase in NaCl concentration in PAW had a drastic effect in reducing
the concentration of NO2− and NO3− from 32.9 to 5.2 µmol/L and 126.8 to 24.6 µmol/L

0respectively with increase in Cl− concentration from 0 to 1070.2 µ mol/L.
 The decrease NO2− and NO3− could be attributed to the scavenging properties of Cl− towards
Voltage and current waveform

3219 ˚C

The temperature of theelectrode was recorded
by a thermal infrared
camera at 31.2 ˚COH radicals.
 As a result, various chlorine-based active species including chlorine radical anions (Cl2˙−)
could be formed.
 These newly formed species are less active and are not as powerful as OH radicals.
 These findings could contribute in tailoring the composition of PAW for specific use.

Temperature of the electrode during discharge