Advanced oxidation processes (AOPs) have been developed to decompose toxic pollutants to protect the aquatic environment. AOP has been considered an alternative treatment method for wastewater ...treatment. Bromine is present in natural waters posing toxic effects on human health and hence, its removal from drinking water sources is necessary. Of the many techniques advanced oxidation is covered in this review. This review systematically examines literature published from 1997 to April 2024, sourced from Scopus, PubMed, Science Direct, and Web of Science databases, focusing on the efficacy of AOPs for pollutant removal from aqueous solutions containing bromide ions to investigate the impact of bromide ions on AOPs. Data and information extracted from each article eligible for inclusion in the review include the type of AOP, type of pollutants, and removal efficiency of AOP under the presence and absence of bromide ion. Of the 1784 documents screened, 90 studies met inclusion criteria, providing insights into various AOPs, including UV/chlorine, UV/PS, UV/H2O2, UV/catalyst, and visible light/catalyst processes. The observed impact of bromide ion presence on the efficacy of AOP processes, alongside the AOP method under scrutiny, is contingent upon various factors such as the nature of the target pollutant, catalyst type, and bromide ion concentration. These considerations are crucial in selecting the best method for removing specific pollutants under defined conditions. Challenges were encountered during result analysis included variations in experimental setups, disparities in pollutant types and concentrations, and inconsistencies in reporting AOP performance metrics. Addressing these parameters in research reports will enhance the coherence and utility of subsequent systematic reviews.
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•AOPs reveal the various mechanisms for radical production.•Brˉ ions affect the removal efficiency of pollutants by AOPs.•Brˉ effect is related to AOPs type, Brˉ concentration and nature of pollutants.•Promoting effect of Brˉ is due to formation of Br2.●ˉ, Br●, Br2●ˉ, and ●ClBrˉ radicals.
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•Synergetic degradation of atenolol by HC-PS as zero-waste discharge process was investigated.•The contribution of SO4− radical was higher than that of OH radical.•The presence of ...SO42− ions has the highest promoting effect on the performance of HC-PS process.
This research investigates atenolol (ATL) removal from the aqueous solution by a combination of hydrodynamic cavitation (HC) and sodium persulfate (HC-PS) as zero-waste discharge process. The effect of pH, reaction time, PS dose, initial ATL concentration, coexisting anions and natural organic matters (NOMs) has been studied. The highest ATL removal by HC and HC-PS processes was obtained at pH 3 and 6, respectively. The presence of coexisting anions viz., Cl−, NO3−, I−, SO42−, and PO43− promoted the degradation of ATL, while the efficiency of ATL degradation was inhibited by the presence HCO3− and CO32− anions and NOMs. The highest synergetic and strongest inhibition effect of ATL degradation by the HC-PS process was observed in the presence of SO42− ions (synergetic index value, 4.61) and CO32− ions (synergetic index value, 0.44). Radical trapping experiments showed that the relative contributions of hydroxyl and sulfate radical to degrade ATL were 41.7% and 58.3%, respectively. In case of HC-PS process, degradation initiated with the protonation of ATL in the presence of free active radicals was followed by the ether bond cleavage, oxidation of primary and secondary amine moieties, and finally mineralization. The HC-PS process is proved to be a potential treatment method to destroy pharmaceutical pollutants from water and wastewater sources.
Combining multiple advanced oxidation processes (AOPs) is essential for the efficient treatment of dye wastewater. In this study, the degradation efficiencies of various oxidation methods, including ...hydrodynamic cavitation (HC), dielectric barrier discharge (DBD) plasma oxidation, ultraviolet C (UVC), and their combination HC + DBD + UVC, were investigated for Methyl Orange (MO). The photolysis of ozone (O3) and the degradation mechanism associated with HC + DBD + UVC were analyzed to elucidate the pathway of MO degradation. The results demonstrated that the combination of HC + DBD + UVC exhibited a significantly enhanced degradation efficiency compared to other process combinations, achieving a removal efficiency exceeding 91% within a 5-min timeframe. Optimal parameters for achieving a 99.5% degradation rate of 10 mg/L MO were determined as follows: pH 4, inlet pressure of 1.5 MPa, utilization of eight UV lamps with a power input of 46.11 W. During the degradation process, hydroxyl radicals (·OH) and ozone (O3) played crucial roles, while the incorporation of UV lamps effectively mitigated ozone (O3) emissions and enhanced the oxidation of ozone (O3). In conjunction with the analysis of degradation products using liquid chromatography-mass spectrometry, it is highly probable that the MO degradation pathway involves reductive cleavage of the azo bond through ·OH attack. Compared to other experimental methods in literature, HC + DBD + UVC exhibits significant advantages such as enhanced efficiency and absence of additives. This innovative approach offers a rapid and practical on-site solution for efficient MO dye wastewater treatment.
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•A unique hybrid advanced oxidation process, HC + DBD + UVC.•Optimizations of various parameters for degradation of MO dye in the hybrid system.•Analysis revealed that photolysis reduces ozone emissions.•HC + DBD + UVC combination treatment demonstrated high efficiency and zero secondary pollution.
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•Application of hydrodynamic and acoustic cavitation to oxidation of organic pollutants.•Design of cavitation devices for effluent treatment.•Comparison of efficiency of oxidation of ...organic pollutants in the cavitation processes.
Hydrodynamic and acoustic cavitation combined with advanced oxidation processes (AOPs), including, among others, the Fenton process, is a promising alternative to the technologies of wastewater treatment technologies in use today. The present review discusses processes based on cavitation combined with AOPs and evaluates their effectiveness in oxidation of organic contaminants. Complete degradation of, among others, p-nitrotoluene, p-aminophenol, 1,4-dioxane, alachlor, chloroform, trichloroethylene, sodium pentachlorophenate and carbon tetrachloride was achieved by using hydrodynamic cavitation or acoustic cavitation alone. Cavitation is also an effective method of disinfection of water. Complete oxidation of hardly degradable organic contaminants, including pharmaceuticals, organic dyes, insecticides, phenol and its derivatives was observed when using hybrid processes: hydrodynamic or acoustic cavitation combined with the Fenton process, ozonation, hydrogen peroxide, UV irradiation, catalysts and persulfates. The review also discusses the cavitational reactors used in the wastewater treatment and the effect of process parameters (including pH, temperature, concentration and kind of contaminants) on the effectiveness of oxidation. The oxidation effectiveness for individual treatment methods is compared and their advantages and limitations discussed. The analysis of economics of the treatment processes performed to evaluate the possibility of scaling up reveals that the only economical processes should be based on hydrodynamic cavitation (mainly due to low cost of reactors and low consumption of electrical energy compared with ultrasonic reactors).
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•Effects of CGU structure on ARHCR performance are studied by CFD.•ARHCRs with rotor–stator interactions are far superior to non-interaction ones.•Hemisphere-shaped CGUs show the best ...performance among other common structures.•Effects of diameter, distance, height, and inclination angle are revealed.•This work offers a viable way to design high-performance ARHCRs.
The advanced rotational hydrodynamic cavitation reactors (ARHCRs) that appeared recently have shown obvious advantages compared with conventional devices in various process intensifications. In ARHCRs, the cavitation generation unit (CGU) located on the rotor and stator basically determines their performance. For the first time, the present study investigated the effect of the CGU structure on the performance of a representative ARHCR by utilizing computational fluid dynamics. The amount of generated cavitation and required torque of the axis for various shapes, diameters, interaction distances, heights, and inclination angles of the CGU were analyzed. The results indicate that the interaction-type ARHCR (cavitation is generated by stator-rotor interaction) was far superior to the non-interaction type one. In addition, the hemisphere-shaped CGU demonstrates the best performance compared with that with cone-cylinder, cone, and cylinder shapes. Moreover, by evaluating the effects of various geometrical factors, the hemisphere-shaped CGU with a diameter of 12 mm, an interaction distance of 1 mm, a height of 1 mm, and an inclination angle of 10° achieved the highest performance. The reasons leading to different performance were elaborated in accordance with the flow and pressure field distributions, as well as the generated cavitation patterns. The findings of this work can strongly support the fundamental understanding, design, and application of ARHCRs for process intensifications.
The present study aims to investigate the degradation of HPMC on a laboratory scale by acoustic and hydrodynamic cavitation. The effects of temperature and the addition of an external oxidizing agent ...on the effectiveness of HPMC degradation were systematically investigated by SEC/MALS-RI, FTIR and 1H NMR. The results of the experiments without cavitation show that an external oxidizing agent alone reduces the weight-average molar mass at 60 °C in 30 min for 45.1 % (from 335 to 184 kg mol−1). However, the weight-average molar mass of HPMC decreased significantly more in the cavitation treatment, for 98.8 % (from 335 to 4 kg mol−1) in 30 min at optimal operating conditions of hydrodynamic cavitation (i.e. addition of external oxidant and 60 °C) with a concomitant narrowing of the molar mass distribution, as shown by the dispersity value, which decreased from 2.24 to 1.31. Compared to acoustic cavitation, hydrodynamic cavitation also proved to be more energy efficient. The FTIR spectra of the cavitated HPMC samples without the addition of H2O2 show negligible oxidation of the hydroxyl groups and the glycosidic bonds, confirming that mechanical effects predominate in HPMC degradation in these cases. In contrast, when H2O2 was added, FTIR and 1H NMR show typical signals for cellulose oxidation products, especially when the experiments were performed at 60 °C, confirming that chemical as well as mechanical effects are responsible for the extensive HPMC degradation in these cases. Since treatment methods that lead to lower molar masses and narrower molar mass distributions of the polymers are lacking or require longer treatment times (e.g. 24 h), mechanochemical treatment methods such as cavitation have great potential, as they enable faster polymer degradation (in our case 30 min) through a combination of mechanical and/or chemical degradation mechanisms.
Disinfection, which aims to eliminate pathogenic microorganisms, is an essential step of water treatment. Hydrodynamic cavitation (HC) has emerged as a promising technology for large-scale ...disinfection without introducing new chemicals. HC, which can effectively induce sonochemistry by mechanical means, creates extraordinary conditions of pressures of ~1000 bar, local hotspots with ~5000 K, and high oxidation (hydroxyl radicals) in room environment. These conditions can produce highly destructive effects on microorganisms in water. In addition, the enhancements of chemical reactions and mass transfers by HC produce the synergism between HC and disinfectants or other physical treatment methods. HC is generated by hydrodynamic cavitation reactors (HCRs), therefore, their performance basically determines the effectiveness, economical efficiency, and applicability of HC disinfection. Therefore, developing high-performance HCRs and revealing the corresponding disinfection mechanisms are the most crucial issues today. In this review, we summarize the fundamental principles of HC and HCRs and recent development in HC disinfection. The energy release from cavitation phenomenon and corresponding mechanisms are elaborated. The performance (effectiveness, treatment ratio, and cost) of various HCRs, effects of treatment conditions on performance, and applicability of HC disinfection are evaluated and discussed. Finally, recommendations are provided for the future progress based on the analysis of previous studies.
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•The state-of-the-art understanding of HC disinfection is reviewed.•Effectiveness and cost of various HCRs are quantitatively assessed.•The effects of treatment conditions for various HCRs are discussed.•Disinfection by ARHCRs is found to be economically realistic even at the pilot scale.•Developing new ARHCRs and applying the hybrid method are the developing trends.
Fruits contain a variety of beneficial components such as carotenoids, anthocyanins, vitamins, fiber, polyphenols, and flavonols, which play crucial roles in cellular regeneration, detoxification, ...and the treatment of numerous diseases. Consequently, nutritionists often recommend incorporating fruits into a healthy lifestyle, which can be done by consuming fresh fruit beverages. However, preserving this kind of product to extend its shelf life typically involves heat treatments, which can adversely affect their nutritional and sensory properties, leading to the degradation of functional compounds. As an alternative approach, recent years have seen the exploration of various green technologies in beverage processing. These technologies include electrical pulses, high pressure, ultrasound, ohmic heating, microwaves, and hydrodynamic cavitation. This review aimed to provide insights into the different emerging technologies for processing fruit-based beverages, with a particular focus on hydrodynamic cavitation. It explores the mechanism, configuration, evolution in fruit processing, and advantages of this innovative technology. By delving into these aspects, we can better understand how hydrodynamic cavitation impact on particle size, enzymes, and microbial inactivation, preserving the nutritional integrity of fruit-based beverages.
•Novel beverages involve innovative components, enhancing functionality, and promoting health benefits.•Hydrodynamic cavitation (HC) has emerged as an alternative method for fresh fruit beverage processing.•The mechanical effect of cavitation leads to an increase in the concentration of bioactive compounds.
The use of cavitation in advanced oxidation processes (AOPs) to treat acidic effluents and process water has become a promising trend in the area of environmental protection. The pH value of ...effluents – often acidified using an inorganic acid, is one of the key parameters of optimization process. However, in the majority of cases the effect of kind of inorganic acid on the effectiveness of degradation is not studied.
The present study describes the results of investigations on the use of hydrodynamic cavitation (HC) for the treatment of a model effluent containing 20 organic compounds, representing various groups of industrial pollutants. The effluent was acidified using three different mineral acids. It was demonstrated that the kind of acid used strongly affects the effectiveness of radical processes of oxidation of organic contaminants as well as formation of harmful secondary pollutants. One of important examples is a risk of formation of p-nitrotolune. Sulfuric acid was the only chemical used for acidification which caused effective treatment with lack of formation of monitored type of secondary pollutants. The best treatment effectiveness – during a 6-hour cavitation process - in most cases much above 80% along with 90% TOC removal was obtained in the case of sulfuric acid. Nitric acid provided lower effectiveness (above 60% for most of the compounds). The worst performance are reported for hydrochloric acid – below 50% of degradation for most of the compounds.
•Type of inorganic acid plays a dominant role in by-products formation.•Simple change in acidification reagent provide effective minimization of by-products.•Effective formation of sulfate radicals from sulfate ions by cavitation•Highly effective degradation of contaminants by cavitation aided by sulfate anions•Highest degradation efficiency obtained in presence of SO42− comparing to Cl− and NO3−
The effect of temperature on the intensity and the dynamics of cavitation is investigated. Experiments of cavitating flows are conducted at various cavitation numbers and temperatures, leading to ...different cavity intensities and dynamic behaviors. The thermodynamic effects significantly influence the cavitation extent at elevated temperatures (over 58 °C) in water. Three regimes of instability, i.e. the sheet cavitation, the periodic single-cloud cavitation, and the aperiodic multi-clouds cavitation are distinguished based on their temporal-spatial evolutions. Application of DMD and POD decompositions on the velocity fields and gray level snapshots to determine the coherent structures and the various mechanics causing different shedding behaviors are discussed. The coherent structures obtained in cloud cavitation consist of the re-entrant jet and counter-rotating vortex structures, which are more aggressive dynamic behavior and are absent in the sheet cavitation. To inhibit the effects of hydrodynamic cavitation, it is recommended that a temperature range (55 °C–60 °C) of water be avoided in practical applications. Since working under this temperature range has larger potentials of transforming the steady sheet cavitation to unsteady cloud cavitation with the larger cavitation extent and the vigorous vapor cloud shedding.
•Efficiency of machinery with cavitation can be improved by adjusting temperature.•HC phenomenon is highly affected by thermal delays, σ number and Re number. .•Cavitation intensity peaks and shedding regimes transition happens at 58 °C.•Data analysis predicts larger dynamical structures in cloud cavitation process.
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