AUTHOR=Attri Pankaj , Okumura Takamasa , Takeuchi Nozomi , Kamataki Kunihiro , Koga Kazunori , Shiratani Masaharu 

TITLE=Plasma-assisted CO2 and N2 conversion to plant nutrient

JOURNAL=Frontiers in Physics

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2023.1211166

DOI=10.3389/fphy.2023.1211166

ISSN=2296-424X

ABSTRACT=<p>Colossal research on CO<sub>2</sub> and N<sub>2</sub> conversion using non-thermal plasma (NTP) technology has been ongoing since many years. The primary focus is on CO and NH<sub>3</sub> production through CO<sub>2</sub> and N<sub>2</sub> conversion, respectively, with high conversion efficiency and low energy consumption with or without catalysts. Although in the present study, we propose that the NTP can assist in converting CO<sub>2</sub> and N<sub>2</sub> to plant nutrients in the form of plasma-treated/activated water. We used a homemade streamer plasma device and produced plasma-activated water (PAW) using CO<sub>2</sub> and N<sub>2</sub> feed gas, CO<sub>2</sub>-activated water (CAW) and N<sub>2</sub>-activated water (NAW). Later, we used CAW and NAW to treat the radish seeds and evaluate the germination rate, germination percentage, and seeding growth. To understand the chemical changes in PAW after the NTP treatment, we performed a chemical analysis to detect NO<sub>2</sub>¯, NO<sub>3</sub>¯, NH<sub>4</sub><sup>+</sup>, and H<sub>2</sub>O<sub>2</sub> along with the PAW pH and temperature shift. Additionally, to understand the other species produced in the gas phase, we simulated chemical reactions using COMSOL Multiphysics<sup>®</sup> software. Our results show that NO<sub>x</sub> and NH<sub>x</sub> species are less produced in CAW than in NAW, but CO<sub>2</sub>-generated PAW offers a significantly more substantial effect on enhancing the germination rate and seeding growth than NAW. Therefore, we suggested that CO and H<sub>2</sub>O<sub>2</sub> formed during CAW production trigger early germination and growth enhancement. Furthermore, the total plasma reactor energy consumption, NO<sub>3</sub>¯ and NH<sub>4</sub><sup>+</sup> selective production percentage, and N<sub>2</sub> conversion percentage were calculated. To our best knowledge, this is the first study that uses plasma-assisted CO<sub>2</sub> conversion as a nutrient for plant growth.</p>