Wastewater pollution and Treatment studies

Water is a vital resource for human well-being. However, with the increase in the population and industrial development, its quality has been affected. Therefore, there is a growing concern about a specific class of pollutants: the so-called emerging contaminants.

Increasing global demand for clean water and sustainable energy has necessitated the development of innovative and integrated technologies that address environmental and energy challenges concurrently. Among various approaches, AOPs (Advanced Oxidation Processes) have emerged as powerful techniques for the degradation of persistent organic pollutants in wastewater. These processes rely on the in situ generation of highly reactive species, particularly hydroxyl radicals (OH), which can non-selectively oxidize a wide range of contaminants.

Fenton reactions, ozonation, and electrochemical oxidation. The integration of different AOP mechanisms often leads to higher reaction rates, lower energy consumption, and improved mineralization of complex wastewater matrices.  Emerging organic contaminant attachments in water molecules have increased as a result of the industrialization of medications. Some sectors are using substantial resolution technologies to remove toxins from water because of increasing concerns. As a result, the creation of low-cost, efficient techniques for breaking down and producing energy from waste is beneficial for the quickly growing organic ingredient market.

Magnetic characteristics have sparked widespread interest and are critical due to their diversity and multidimensional nature. Among many magnetic characteristics, various magnetic materials, ferrites have captivated the interest of researchers owing to their exceptional combination of favourable properties, including moderate saturation magnetization, low magnetic losses, single-phase purity, and high adsorption capacity for pollutants, antibacterial properties, exceptional chemical stability, large surface to volume ratio, high coercivity, affordable cost, high electrical resistivity, and remarkable initial per adsorptive materials has been increasingly recognized for its noteworthy potential in a wide range of technology applications, such as data storage, drug-delivery, microwave absorption and reflection, and photocatalysis, among many other applications is a wonder in establishing new approaches.

Photocatalysis is a green, emerging technique for which further research is anticipated with various nanomaterials, driven by its ongoing advancements. This approach has a vast range of degradation or removal of pollutants for conserving mineralization.

 Figure 1: Photocatalytic process 

Currently, there are numerous methods for producing free radicals, such as composite activation, alkali activation, heat activation, UV activation, microwave activation, and ultrasonic activation. Aerogels and other 2D and 3D materials have previously demonstrated potential as persulfate activation options in the degradation of organic contaminants. This is because of their potential to accelerate the degradation of textile wastewater. Radicals can be activated by carbon-based compounds, and the method is more effective. More firmly bonded pollutants are broken down with the aid of PMS activation. e-/h+ pairs become active or are formed when light strikes them. This falls under the category of photocatalytic activity. The primary issue with either employing or not using a catalyst is that there aren't enough radicals to proceed through the oxidation and reduction processes. A catalyst that degrades pollutants can be made with a variety of methods. These include co-precipitation, auto-thermal stages, SCSs methods, sol-gel, microwave solution combustion synthesis, hydrothermal, green synthesis, Sölve Thermal, etc. 

In Figure 1, the basic ideas of solar-irradiated semiconductor photocatalysis are demonstrated. Photons from solar irradiation excite electrons in the valence band, moving them to the conduction band and leaving holes (h+) in the valence band when semiconductor compounds in wastewater or contaminants are present. Between these, the Band Gap is created. Reduction reactions can involve electrons in the conduction band. They can, for instance, convert carbon dioxide into useful compounds like methanol or methane or reduce protons to hydrogen gas. Redox processes are the term used to describe these reactions. The valence band's holes are capable of taking part in oxidation processes. They can aid in the breakdown of organic contaminants into carbon dioxide and water, or they can oxidise to water to produce oxygen and protons. Despite involving hole oxidation, these reactions are also categorised as redox processes. These chemical processes depend on the separation of charges. Applications for this method include reducing greenhouse gas emissions, producing hydrogen through water splitting, and cleaning up the environment by decomposing organic pollutants.