Petrochemical wastewater is generated as a result of many processes carried out in facilities, from extraction to processing of oil. These petrochemical wastewaters, which contain many substances harmful to both human health and the environment. As a solution to this problem, we designed a plasma water treatment system that can simultaneously apply all advanced oxidation processes such as O3, H2O2 and UV, and accordingly, the Fe3O4/CuO-TiO2/rGO photocatalyst, which will contribute to the formation of free radicals by absorbing the light emitted by the plasma between 200-800 nm has been synthesized. Afterwards, we treated the petrochemical waste sludge that we received from the refinery in the hybrid AOP water treatment system we created with a plasma reactor and photocatalyst, purifying it from basic pollutants such as phenol, copper sulphate and ammonia with an efficiency of almost 100%.

This is how I came up with the idea for this project:

While developing an alternative "plasmotherapy" method to traditional cancer treatment methods such as chemotherapy and radiotherapy, I discovered that plasma creates various reactive oxygen species as a result of air interactions. I found that these reactive species can also break down complex molecules into smaller molecules likewise "Advanced Oxidation Processes".

New Method in Treatment of Petrochemical Wastewater

Petroleum and its derivative products are widely used in many areas, especially in the energy sector. Refinery, borehole etc. Petrochemical wastewater is generated as a result of many processes carried out in facilities, from extraction to processing of oil. These petrochemical wastewaters, which contain many substances harmful to both human health and the environment, such as hydrocarbons, micropollutants and heavy metals, are released into nature by many facilities due to high treatment costs. This leads to ecological disasters. As a solution to this problem, we designed a plasma water treatment system that can simultaneously apply all advanced oxidation processes such as O3, H2O2 and UV, and accordingly, the Fe3O4/CuO-TiO2/rGO photocatalyst, which will contribute to the formation of free radicals by absorbing the light emitted by the plasma between 200-800 nm has been synthesized. Afterwards, we treated the petrochemical waste sludge that we received from the refinery in the hybrid AOP water treatment system we created with a plasma reactor and photocatalyst, purifying it from basic pollutants such as phenol, copper sulphate and ammonia with an efficiency of almost 100%. Likewise, hydrocarbon purification was carried out, although it was not as efficient. Additionally, the plasma apparatus is integrated into the water purification system. Thus, all processes can be followed in real time. Afterwards, the system was purified as a whole, and it was observed that the system worked with a high purification efficiency through general concentration measurements. Heavy metals such as copper, iron and zinc were also removed in the system, and 82% of the resulting sludge was fragmented, but there was an artificial increase in the pollutant concentrations in the activated sludge due to the decrease in the sludge volume as a result of the precipitation of the separated pollutants. It is planned to integrate this system into oil wells and ships in the future. Not only petrochemical wastewater but also wastewater from different sources can be treated in our system. In addition, photocatalysts have magnetic properties and can be recovered through magnets after the purification process. Advanced oxidation processes, in its broadest definition, is a water treatment process that involves the decomposition of pollutants into smaller molecules that do not have toxic effects as a result of oxidation of water by creating free OH- radicals as a result of various chemical processes in order to treat organic and inorganic pollutants in wastewater. For this purpose, similar chemical processes such as O3, H2O2, UV are used. Accordingly, we saw that the cold plasma we used in our studies has the ability to create all three processes. At high electrical discharges, a cold plasma structure forms, and as a result of its interaction with air, reactive oxygen species (ROS) are formed. This means obtaining the chemical compounds which necessary for oxidation. Additionally, as a result of our spectrum measurements, we found that the plasma emitted in a wide spectrum from 200 nm to 800 nm. With this knowledge, special photocatalyst nanocomposite that would absorb both UV and visible lights has been synthesized and with this way hydrocarbons and solid pollutants such as phenol, copper sulphate and ammonia were treated by increasing efficiency of OH- creation. In addition, it has been observed in our system that the proven properties of AOP significantly reduce the concentrations in water of parameters such as total oxygen demand (COD) and total organic carbon (TOC). While individual plasma and photocatalysis analyzes are very efficient, there is a certain decrease in treatment efficiency due to a continuous water flow in system integration, but this will be compensated with future developments. Fe3O4/CuO-TiO2/rGO nanocomposite was synthesized to have high photocatalytic properties. Reduced graphene oxide (rGO) increased the surface area and number of electron-hole pairs of the nanocomposite. Semiconductor Titanium dioxide (TiO2) increased the absorbance of UV light and photocatalytic properties. Copper oxide (CuO) provided the absorbance of visible lights and prevented the rGO layers from oxidizing during the photocatalysis reaction with unpaired copper atoms. In addition, rGO was synthesized in a two-step process, different from the literature, and the number of layers was increased. This has created an advantageous situation for our nanocomposite in terms of both photocatalytic and surface chemistry. As a result of the experiments, it was observed that 20 kV – 20 kHz plasma and 30 mg/L photocatalyst configuration gave the best results in the treatment of petrochemical wastewater. It is planned to develop the system in terms of software and hardware in the future.