The extraction of bioactive components from natural sources has gained significant attention in recent years due to increasing demand for natural and functional constituents in various industries, including pharmaceuticals, food, and cosmetics. This review paper aims to provide a comprehensive overview of the studies on extracting bioactive components from natural sources using different advanced extraction techniques. It highlights the need for efficient extraction methods to preserve these components' integrity and bioactivity. Various extraction techniques as supercritical-fluid extraction, microwave-assisted extraction, ultrasound-assisted extraction, subcritical solvent extraction, and solid-phase microextraction are explored in detail, highlighting their principles, advantages, and limitations. The review further examines the impact of different factors on the extraction process, including solvent selection, extraction time, temperature, ultrasonication-amplitude, etc. Additionally, emerging techniques, such as green extraction methods and nanotechnology-based approaches, are discussed, emphasizing their potential to enhance the extraction efficiency and sustainability of the process. Furthermore, the review presents case studies and experimental results from recent research articles, providing insights into applying different extraction techniques for specific bioactive components, such as phenolics, flavonoids, alkaloids, and essential oils. It discusses the extraction yield, bioactivity, and potential utilization of the extracted components in various industries. Overall, this review paper is valuable for researchers, scientists, and industry professionals interested in extracting bioactive components from natural sources. It consolidates the current knowledge on different advanced extraction techniques, their optimization parameters, and their potential applications, facilitating further advancements in the field and the development of innovative extraction methods for bioactive component extraction from natural sources.

Hydrodynamic cavitation (HC) has been explored by many researchers over the years after the first publication on hydrolysis of fatty oils using HC was published by Pandit and Joshi [Pandit AB, Joshi JB. Hydrolysis of fatty oils: effect of cavitation. Chem Eng Sci 1993; 48: 3440–3442]. Before this publication, most of the studies related to cavitation in hydraulic system were concentrated to avoid the generation of cavities/cavitating conditions. The fundamental concept was to harness the energy released by cavities in a positive way for various chemical and mechanical processes. In HC, cavitation is generated by a combination of flow constriction and pressure-velocity conditions, which are monitored in such a way that cavitating conditions will be reached in a flowing system and thus generate hot spots. It allows the entire process to operate at otherwise ambient conditions of temperature and pressure while generating the cavitating conditions locally. In this review paper, we have explained in detail various cavitating devices and the effect of geometrical and operating parameters that affect the cavitation conditions. The optimization of different cavitating devices is discussed, and some strategies have been suggested for designing these devices for different applications. Also, various applications of HC such as wastewater treatment, preparation of nanoemulsions, biodiesel synthesis, water disinfection, and nanoparticle synthesis were discussed in detail.

In recent years, water pollution has become a major problem for the environment and human health due to the industrial effluents discharged into the water bodies. Day by day, new molecules such as pesticides, dyes, and pharmaceutical drugs are being detected in the water bodies, which are bio-refractory to microorganisms. In the last two decades, scientists have tried different advanced oxidation processes (AOPs) such as Fenton, photocatalytic, hydrodynamic, acoustic cavitation processes, etc. to mineralize such complex molecules. Among these processes, hydrodynamic cavitation (HC) has emerged as a new energy-efficient technology for the treatment of various bio-refractory pollutants present in aqueous effluent. In this review, various geometrical and operating parameters of HC process have been discussed emphasizing the effect and importance of these parameters in the designing of HC reactor. The advantages of combining HC with other oxidants and AOPs such as H₂O₂, ozone, Fenton process, and photocatalytic process have been discussed with some recommendation for large-scale operation. It has been observed that the geometry of the HC device and other operating parameters such as operating pressure and cavitation number are the key design parameters that ultimately decide the efficacy and potentiality of HC in degrading bio-refractory pollutants on an industrial scale.