One of the world's critical problems is industrial pollution, which is created by a variety of uses. Water pollution is also a major issue. The amount of drinking water utilized and the water exposed to pollutions that are not suitable for the environment, clean water resources reach critical levels with the growing population (Donkadokula et al., 2020). Synthetic dyes with cationic, anionic, and nonionic classification consisting of water-soluble compounds are used very frequently, especially in the textile industry (Shindhal et al., 2021). These types of paints, which are resistant to high thermal environment, can stay in surface waters for a long time since they have high solubility in water (Benjelloun et al., 2021). Cationic dyes have teratogenic and carcinogenic effects on human cells and must be released into the environment without being discharged (Heidari et al., 2021). Many techniques such as membrane (Khoshnevisan et al., 2021), advanced oxidation process (Liu et al., 2021), electrocoagulation (Chanikya et al., 2021), adsorption (Prajapati et al., 2021) and photodegradation (Mousa et al., 2021) are used for the treatment of dye-containing wastewater. Traditional methods can only make organic compounds to another phase because to the high durability of dye compounds, resulting in secondary contamination (Keerthana et al., 2021).
Photocatalytic systems absorb photons and perform redox reactions, breaking complex organic molecules into smaller pieces, using semiconductor oxides or transition metal oxides (Ahuj et al., 2021). In photocatalytic systems, a variety of materials are used. Compounds like TiO2, ZnO, Ag2O and other semiconductors are the most popular. Also with their high oxidation power and resistance to photochemical corrosion, such compounds are chosen. (Cao et al., 2020; Yu et al., 2020; Li et al., 2021). Calcium oxide (CaO) has just been studied for its photoactivity. Due to their thermal stability, mechanical characteristics, and ease of recycling, calcium compounds like CaO have a wide range of uses. Moreover, CaO has the impact of improving the performance of the photocatalytic process in the synthesis of photocatalyst (Song et al., 2010; Nassar et al., 2021). CaO is formed naturally through the decarbonization of calcium carbonate (CaCO3) in the light of sun radiation. As a result of the thermochemical reaction, CaCO3 is broken down into CaO and CO2. CaCO3 calcination should be performed in a high concentration CO2 environment at temperatures greater than 900°C if it is desired to be synthesized in an experimental situation (Sun et al., 2020; Xu et al., 2021). The photocatalytic effect in photocatalytic processes involving photocatalysts made from tomato stems must be understood. After the photocatalysts have been adsorbed, the rays from the light source cause the production of holes and final electrons, which leads to the oxidativereducing reaction. •CO3−, as well as •O2−, plays an active role in tomato stem systems. •OH− causes the oxidation of H2O, which happens in electron-hole pairs as a result of excitation. •CO3− is formed when such radicals combine with carbonate and bicarbonate ions (Baláz et al., 2021). Natural calcium oxide or hydroxide materials are employed for a variety of applications due to their nanometric size, biocompatibility, and bioactive nature. The research's major aim is to inform pure nanocrystalline CaO in a green way and synthesize it with cutting-edge new research methods, so that it may be universally recognized by the scientific community around the world. The synthesis of photocatalysts for use in photocatalytic processes can be produced using a variety of ways. Catalysts created using the green synthesis approach are of particular interest because of their ecologically friendly properties and one-step synthesis process. For this purpose, biomaterials such as chicken egg shells are employed, which are mostly constituted of extremely tiny amounts of calcium carbonate and other organic compounds (Sinha et al., 2021; Chand et al., 2021).
The separation of simple minerals in the soil, microorganisms in the soil, and complicated substances into their simpler components and absorption into the body with the help of the plant's roots is called to as phytoremediation. The quality and development of the harvested product are known to be influenced by the soil content in tomato-growing regions. The kind of fertilizer that will aid in plant development, the content of irrigation water, and the minerals in soil components can all be easily absorbed by the agricultural product thanks to plant roots (Demirer, 2018; Chen et al., 2022). Ertürk (2021) researched tomato production using an aquatic system. She carried out his investigation with only irrigation water and two other additional materials that injected into the system to examine the influence of different supplemental materials in waterless agricultural production on growing farm products. The mineral content of tomato and tomato stem was determined using Inductively Coupled Plasma (ICP) analysis as a result of various agricultural crop production methodologies. Many distinct substances were discovered when the content of tomato stem (TS) was tested as part of the investigation. She came to the conclusion that the calcium (Ca) and phosphorus concentration of the tomato stem was higher in the eggshell experimental sets than in the other experimental sets. Quensafi et al. (2019) investigated the effect of soil characteristics on the production and growth of tomato plants irrigated with treated wastewater. Two different kinds of alkaline soils were employed in the experiment. The CaO content of two soil types was found to be 9.5 g/kg and 7.2 g/kg. The fresh weight and size of the fruits in the plants were reported to be higher as a result of the agricultural production in which the FS solid type was applied. CaO may inhibit fruit growth and limit its utilization in photosynthesis in soils with high CaO content, according to the researchers.
The aim of this study is to convert the CaCO3 in tomato stem wastes from harvested tomatoes to CaO (TS-CaO) using a one-step thermal technique and then use it to remove dye with a photocatalytic process. Both the environmentally friendly green synthesis of nanomaterials and the possibility of reusing waste material for other uses were assisted by the photocatalyst, which was created exclusively at high temperatures without the need of chemical catalysts. The amount of photocatalyst, dye concentration, solution pH value, and light source effects were all studied in photocatalytic experiments.