Recently, the lack of fresh water in the world led to the efficient use of technical water in many areas, including agriculture. Purification and efficient use of wastewater of various compositions helps to solve many problems. To this end, one of the main issues is the treatment of wastewater containing toxic substances of organic origin, especially phenolic compounds. In this case, the authors investigated the purification of phenol from wastewater using photochemical reactions. A photochemical reaction of a phenol solution in the presence of TiO2 nanoparticles 10–30 nm in size and crystalline ethyl 3, 3, 5, 5-tetracyano-2-hydroxy-2-methyl-4, 6-diphenylcyclohexane carboxylate (С26Н22N4O3) synthesized under mild conditions was carried out for the first time. The course of photochemical dissociation was confirmed by the difference in the absorption curves of the reaction product before and after the photolysis process, and the process was also monitored on a “Varian Cary 50.” The photochemical decomposition of phenol was 52%.
TopIntroduction
Pollution of water bodies with toxic organic substances has recently been considered a global environmental issue, and therefore it is important to develop new methods to solve the problem.
In modern times, heterogeneous photocatalytic methods are considered to be the most effective methods in protecting the environment and removing phenol-type compounds from wastewater. On the other hand, due to the development of nanotechnology, the processes involving nanoparticles are very interesting and new.
In this case, it is considered environmentally friendly because of the very small amount of substances consumed. In this regard, in modern times, effective cleaning methods using nanoparticles are becoming more widespread (De Luis et al., 2011; Gumush & Akbal, 2011).
Looking at the world literature, in recent years there have been many methods of effective cleaning based on nano-composites. For example, GO/Al2O3 nano-composite was prepared by spin-closing method for effective removal of phenol from wastewater, and it was possible to remove phenolic organic compounds from wastewater with 99.9% on the basis of composite (Hu et al., 2018).
Phenol is always found in wastewater because it is obtained from petrochemicals, pharmaceuticals, plastics, coal, paints and paper.
In general, phenol is one of the most important hazardous pollutants due to its low biological decomposition, high concentrations and high toxicity in terms of long-term harmful effects on the environment (Santhosh et al., 2016). The gradual reduction of fresh water and the increase in pollution are already important environmental problems in the world.
Today, millions of people around the world suffer from a shortage of fresh water. In general, phenol, the most important of the water pollutants, causes serious environmental problems. So far, many methods have been used to purify phenol from wastewater. The use of physical, chemical and biological methods is less on the agenda today (Mohammadi et al., 2015; Wang, 2017).
As is known, phenol and its derivatives are very toxic and their presence in water is undesirable.
When they exceed the permissible concentration, they become dangerous for all living things. In this regard, it is important to first purify water from such compounds. In the future, such water can be used for technical purposes. It can even be used for irrigation in agriculture (Gosling & Arnell, 2016).
Various methods have been used to treat phenol from industrial wastewater (Raghuvir Singh et al., 2021). The presence of phenolic compounds in petroleum refinery wastewater is a matter of significant environmental concern.
Its removal is achieved through various methods, among which adsorption is an efficient and eco- nomically viable option. This study reports the development of activated biochar (EABC) from Eucalyptus wood pyrolytic biochar (EPBC) to remove phenols from petroleum refinery wastewater.
The best activation strategy involved ball-milling of KOH and EPBC in the ratio 3:1, followed by annealing at 800°C under an N 2 atmosphere.
The activated biochar (EABC-3–800) exhibited high phenol adsorption capacity (308.9 mg/g), attributed to the presence of heterogeneous pores, corroborated by large BET surface area (2048 m2/g). As determined through HPLC, the EABC-3–800 could remove nearly 95% phenol (C0=114 ppm) from the wastewater of the delayed coking unit of a petroleum refinery.
The best-fitting of the adsorption results in the Freundlich isotherm model substantiates the hypothesis of pore-based adsorption of phenol compared to the surface-adsorption-based Langmuir isotherm.
The phenol adsorption kinetics followed the pseudo-second-order model, indicating weak chemical interactions between phenol and activated biochar. The regeneration and reuse of EABC-3–800 for a minimum of five operational cycles demonstrate its potential for industrial wastewater remediation.
The article discusses the approach of TiO2 nanoparticles in solving environmental problems caused by wastewater in the environment. Efficient treatment of these wastewaters and channeling them to various areas, such as agriculture, means solving current problems.
Therefore, the use of wastewater after treatment is a major issue that worries the whole world. Nanotechnological methods have recently become very relevant.