Asam nitrat atau HNO3 merupakan salah satu produk penting bagi pelaku industri, karena dapat digunakan untuk bahan baku proses pembuatan pupuk, industri tekstil, bahan peledak dan sebagai bahan pemurnian logam. Salah satu proses pembuatan asam nitrat yaitu dengan menggunakan proses ostwald, akan tetapi proses ini menghasilkan berbagai macam limbah yang merugikan untuk lingkungan. Pada percobaan ini, reaktor plasma discharge berbahan baku udara bebas diberikan variasi parameter yaitu jarak antar elektroda 0,5 cm dan 1 cm, tegangan 4,8 kV dan 6 kV, serta laju aliran udara 0,2 L/m, 0,4 L/m, dan 1 L/m.  Semakin besar jarak elektroda, tegangan, dan waktu akan menurunkan pH dan meningkatkan konsentrasi nitrat di air penampungan. Lain halnya dengan laju alir yang semakin besar akan memperoleh konsentrasi nitrat lebih sedikit. Nilai konsentrasi nitrat tertinggi sebesar 21,94 ppm (pH=2,9) diperoleh dengan perlakuan berupa jarak elektroda 1 cm,  laju aliran udara 0.2 L/m, tegangan 6kV dan waktu treatment selama 40 menit. Reaktor plasma dapat menghasilkan nitat cair yang asam sehingga berpotensi dalam pembentukan asam nitrat, namun perlu penelitian lebih lanjut.

Nitrogen-based fertilizer production mainly involves the Haber-Bosch process, which synthesizes Ammonia via a chemical reaction of N2 from the air and H2 under high temperature and pressure conditions in the presence of a catalyst. However, the environmental concern for greenhouse gas emissions and high energy consumption triggers other Nitrogen fixation method development. The non-thermal plasma oxidation of N2 into Nitrate is a promising method since it has lower energy consumption and a more suitable process condition with a better environmental profile. This study tested the designed plasma discharge reactor tube to produce nitrate from air N2 with varying voltage, time, and airflow rate operating conditions. Nitrate concentration was analyzed using a UV-Vis spectrophotometer. The results show that nitrate concentration changes linearly with the applied voltage in a constant airflow rate and length of treatment time. The highest performance of the plasma discharge reactor was achieved on a 6 kV applied voltage with a flow rate of 0.2 L/min and a treatment time of 40 minutes where the obtained nitrate concentration was 7.7 ppm, which indicated the potential plasma discharged nitrate production for green fertilizer application. Further study shall be carried out to enhance the performance.

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Ozonizer is a method used for sterilization and food preservation by utilizing ozone produced from plasma discharge. The effective way of obtaining ozone is to use dielectric barrier discharge (DBD) plasma. The manufacture of a controlled ozonizer chamber system is important to result in effective and efficient performance. The aim of this study is to design and optimize the ozone chamber parameter using pulse width modulation (PWM). The system design is added with the Arduino Mega 2560 microcontroller and the L296N motor driver as an ozone generator radiation controller by changing the pulse width modulation to determine the ozone levels produced. The experimental results show that the ozone concentration increases by 50 % on average with increasing variations of the 10 % duty cycle (PWM) and the ignition time length. The optimum value is achieved on a 70 % duty cycle for 60 - 300 seconds, where the ozone level of 3 ppm is obtained and sustained for fruits/vegetables sterilization and preservation application.