Multi-spark discharge system for preparation of nutritious water

Abstract

Abstract. The nitrogen compound concentration in water is increased by atmospheric-pressure plasma discharge treatment. A rod-to-water electrode discharge treatment system using plasma discharge has been developed by our group to obtain water with a high concentration of nitrogen compounds, and this plasma-treated water improves the growth of chrysanthemum roots. However, it is difficult to apply the system to the agriculture because the amount of treated water obtained by using the system too small. In this study, a multi-spark discharge system (MSDS) equipped multiple spark plugs is presented to obtain a large amount of plasma-treated water. The MSDS consisted of inexpensive parts in order to reduce the system introduction cost for agriculture. To suppress the temperature increase of the spark plugs, the 9 spark plugs were divided into 3 groups, which were discharged in order. The plasma-treated water with a NO 3 -concentration of 50 mg/L was prepared using the MSDS for 90 min, and the treatment efficiency was about 6 times higher than that of our previous system. It was confirmed that the NO 2 -, O 3 , and H 2 O 2 concentrations in the water were also increased by treating the water using the MSDS.

Comparative study of discharge schemes for production rates and ratios of reactive oxygen and nitrogen species in plasma activated water

“…There are only a few previous data explicitly reporting the RONS energy-yield. As examples, we can estimate the energy yield from the information given in original literature to be around a few g kWh −1 in pin-to-water discharge and packed-bed DBD schemes [29,44]. Those are in consistent with our present results shown above.…”

“…Various kinds of plasma sources have been used for the production of RONS. Plasma jets are the most commonly used ones [10, 15-17, 19-21, 24-33], but there are various other methods which use, for example, dielectric barrier discharge (DBD) [13,14,29,[34][35][36], pin-to-plane (or water) corona or spark discharge [37][38][39][40][41][42][43][44], pin-in-water discharge with gas bubbling [45][46][47][48], gliding arc discharge [37] and other methods [12,48]. Product species have been inspected using various methods.…”

“…Product species have been inspected using various methods. For instance, methods such as laserinduced fluorescence (LIF) or absorption spectroscopy [25,27,[49][50][51][52][53], Fourier-transform infrared spectroscopy [16,29,38,[53][54][55], mass-spectrometry [17,31,56] and gas sensors or analysers [29,42,55] are used for products in the gas phase, and UV-absorption spectroscopy [28,57], liquid chromatography [12,29] and electron spin resonance spectroscopy [15,24] are used for products in the liquid phase in addition to the usually employed chemical colorization methods [14,15,30,35,44,55,58]. Selective production methods have also been investigated for the preferable composition of specific products by adjusting the operating conditions of each plasma source [17,20,30,31,33,48,56,[59][60][61].…”

“…Since our aim is mainly directed toward applications of those sources for the agricultural and/or food industries, we preferably use nitrogen and air as low cost feed gases with and without water vapour mixing. As has been tried in a few previous studies [36,37,44,58], we also use tap water in comparison with pure water for a systematic investigation into the buffer action of impurity comp onents in variations of the products, and the pH change with changes in composition and concentrations.…”

Efficient Ammonia Production Beginning from Enhanced Air Activation

“…A series of plasma experiments at different concentrations of NaOH (0.2–2 m ) have also been explored, and the result shows that the optimal concentration of NaOH is 1 m , with which the highest NO x − yield rate (55.29 mmol h −1 , Equation S4, Supporting Information) and the lowest specific energy consumption (11.18 kW h mol −1 , Equation S5, Supporting Information) can be simultaneously obtained (Figure S4, Supporting Information), and is superior to most of the reported ones referring to plasma‐generated NO x − (Figure 1d). [ 34–36 ] The yield of NO x − gradually accumulates with the increase of plasma operation time, and the total NO x − concentration reaches 0.11 m after 60 min, in which NO 2 − dominates 97.25% molar ratio in the final product (Figure 1e). The as‐prepared NO x − (0.11 m ) in NaOH (1 m ) aqueous solution is directly used as the electrolyte for the following eNO x RR.…”