Cavitation Reactor Research Articles

Novel Approach of Producing Oil in Water Emulsion Using Hydrodynamic Cavitation Reactor

The present work reports the use of venturi-based hydrodynamic cavitation reactor for the preparation of stable submicron emulsions. Different types of cavitating devices such as circular venturi and slit venturi have been used in this study. Effect of different operating parameters such as inlet pressure and number of passes of the emulsion through the cavitating zone on the droplet size and the stability of emulsion has been investigated. Emulsion of coconut oil in water has been chosen as the model system. Two types of emulsifying agents, namely, Tween 80 and Span 80, were used for the preparation of the emulsions, and the effect of emulsifying agent volume fraction on the emulsion droplet size has been illustrated. Zetasizer has been used to measure the droplet size and distribution of internal phase of emulsion. It has been established that the inlet pressure affects the droplet size of emulsion favorably due to the enhanced cavitational intensity with increasing inlet pressures. Among the two types ...

Decontamination of unsymmetrical dimethylhydrazine waste water by hydrodynamic cavitation-induced advanced Fenton process

A pilot scale hydrodynamic cavitation (HC) reactor, using iron metal blades, as the heterogeneous catalyst, with no external source of H2O2 was developed for catalytic decontamination of unsymmetrical dimethylhydrazine (UDMH) waste water. In situ generation of Fenton reagents suggested an induced advanced Fenton process (IAFP) to explain the enhancing effect of the used catalyst in the HC process. The effects of the applied catalyst, pH of the initial solution (1.0–9.7), initial UDMH concentration (2–15mg/l), inlet pressure (5.5–7.8bar), and downstream pressure (2–6bar), have been investigated. The results showed that the highest cavitation yield can be obtained at pH 3 and initial UDMH concentration of 10mg/l. Also, an increase in the inlet pressure would lead to an increase in the extent of UDMH degradation. In addition, the optimum value of 3bar was determined for the downstream pressure that resulted to 98.6% degradation of UDMH after 120min of processing time. Neither n-nitrosodimethylamine (NDMA) nor any other toxic byproduct (/end-product) was observed in the investigated samples. Formic acid and acetic acid, as well as nitromethane, were identified as oxidation by-products. The present work has conclusively established that hydrodynamic cavitation in combination with Fenton’s chemistry can be effectively used for the degradation of UDMH.

Intensified synthesis of biodiesel using hydrodynamic cavitation reactors based on the interesterification of waste cooking oil

In the present work, hydrodynamic cavitation reactor has been used for the intensification of synthesis of biodiesel from waste cooking oil (WCO) based on the interesterification reaction. Experiments have been performed using different cavitating devices such as orifice plate, circular and slit venturi and under varying operating parameters viz. inlet pressure (2–5bar), molar ratio of oil to methyl acetate (over the range of 1:10–1:14) and catalyst loading over the range of 0.5–1.25% by weight of oil. Maximum yield (90%) of biodiesel from WCO was obtained at oil to methyl acetate ratio of 1:12 and catalyst loading of 1.0% using slit venturi at the inlet pressure of 3bar. Also, higher cavitational yield (biodiesel produced per unit energy consumed) was obtained for the hydrodynamic cavitation based approach as compared to the ultrasound based approach and conventional method. The observed intensification is attributed to the microscale turbulence generated due to the cavitational effects that help in intensifying the transfer processes. Overall, the potential of WCO to produce good quality methyl esters in energy efficient manner using hydrodynamic cavitation reactor has been demonstrated based on the cavitational yield calculations and properties of synthesized biodiesel.

Study of Porous Plate Hydrodynamic Cavitation Device for P-Nitrophenol

Design a set of practical and effective hydraulic cavitation experiment device, hydraulic cavitation reactor, using porous plate for nitro phenol solution to simulate wastewater, respectively in different cavitation number initial pH value, initial concentration of the waste water, waste water, the cycle time, use different types of porous surface processing and analysis, through the experimental research, it is concluded that these factors and the relationship of nitro phenol degradation rate.

Promising equipment for greenhouse wastewater treatment

The article presents the experimental results of greenhouse wastewater treatment by means of cavitation. It is noted that the use of ultrasonic cleaning has drawbacks. It is found that the use of hydrodynamic cavitation for wastewater treatment is a promising direction. It is noted that in effluents with residues of phenolic compounds, treatment is improved when using oxidizing agents such as hydrogen peroxide. A design of cavitation reactor for wastewater treatment using an ultrasonic radiation was proposed. The reactor was tested in an industrial environment and showed good treatment results. It was found that at simultaneous action of hydrodynamic cavitation and UV, the germicidal effect occurs. Due to this, pathogenic organisms are destructed. The article illustrates the experimental setup and cavitation reactor.

O uso da cavitação hidrodinâmica aplicado ao tratamento de água

A cavitação hidrodinâmica se apresenta como um processo oxidativo avançado (POA), permitindo integrar-se aos processos de tratamento de água para consumo humano. Esta pesquisa teve como objetivo investigar os efeitos de diferentes reatores de cavitação hidrodinâmica para tratar água contaminada com esgoto doméstico, avaliando a contaminação microbiológica e os parâmetros físico-químicos. Foram construídos três modelos de reatores com diferentes rotores (R1, R2 e R3). Os resultados obtidos nos reatores R1, R2 e R3 mostraram redução nas concentrações dos parâmetros químicos em todas as amostras, particularmente nitritos, nitratos, bicarbonatos e dureza total, ao passo que a contaminação microbiológica teve inativação completa dos microrganismos estudados (coliformes totais e Escherichia coli).

Modeling the shear rate and pressure drop in a hydrodynamic cavitation reactor with experimental validation based on KI decomposition studies

A mathematical model describing the shear rate and pressure variation in a complex flow field created in a hydrodynamic cavitation reactor (stator and rotor assembly) has been depicted in the present study. The design of the reactor is such that the rotor is provided with surface indentations and cavitational events are expected to occur on the surface of the rotor as well as within the indentations. The flow characteristics of the fluid have been investigated on the basis of high accuracy compact difference schemes and Navier–Stokes method. The evolution of streamlining structures during rotation, pressure field and shear rate of a Newtonian fluid flow have been numerically established. The simulation results suggest that the characteristics of shear rate and pressure area are quite different based on the magnitude of the rotation velocity of the rotor. It was observed that area of the high shear zone at the indentation leading edge shrinks with an increase in the rotational speed of the rotor, although the magnitude of the shear rate increases linearly. It is therefore concluded that higher rotational speeds of the rotor, tends to stabilize the flow, which in turn results into less cavitational activity compared to that observed around 2200–2500RPM. Experiments were carried out with initial concentration of KI as 2000ppm. Maximum of 50ppm of iodine liberation was observed at 2200RPM. Experimental as well as simulation results indicate that the maximum cavitational activity can be seen when rotation speed is around 2200–2500RPM.

Degradation of imidacloprid using combined advanced oxidation processes based on hydrodynamic cavitation

The harmful effects of wastewaters containing pesticides or insecticides on human and aquatic life impart the need of effectively treating the wastewater streams containing these contaminants. In the present work, hydrodynamic cavitation reactors have been applied for the degradation of imidacloprid with process intensification studies based on different additives and combination with other similar processes. Effect of different operating parameters viz. concentration (20–60ppm), pressure (1–8bar), temperature (34°C, 39°C and 42°C) and initial pH (2.5–8.3) has been investigated initially using orifice plate as cavitating device. It has been observed that 23.85% degradation of imidacloprid is obtained at optimized set of operating parameters. The efficacy of different process intensifying approaches based on the use of hydrogen peroxide (20–80ppm), Fenton’s reagent (H2O2:FeSO4 ratio as 1:1, 1:2, 2:1, 2:2, 4:1 and 4:2), advanced Fenton process (H2O2:Iron Powder ratio as 1:1, 2:1 and 4:1) and combination of Na2S2O8 and FeSO4 (FeSO4:Na2S2O8 ratio as 1:1, 1:2, 1:3 and 1:4) on the extent of degradation has been investigated. It was observed that near complete degradation of imidacloprid was achieved in all the cases at optimized values of process intensifying parameters. The time required for complete degradation of imidacloprid for approach based on hydrogen peroxide was 120min where as for the Fenton and advance Fenton process, the required time was only 60min. To check the effectiveness of hydrodynamic cavitation with different cavitating devices, few experiments were also performed with the help of slit venturi as a cavitating device at already optimized values of parameters. The present work has conclusively established that combined processes based on hydrodynamic cavitation can be effectively used for complete degradation of imidacloprid.

Role of H2O2 in the fluctuating patterns of COD (chemical oxygen demand) during the treatment of palm oil mill effluent (POME) using pilot scale triple frequency ultrasound cavitation reactor

Palm oil mill effluent (POME) is a highly contaminating wastewater due to its high chemical oxygen demand (COD) and biochemical oxygen demand (BOD). Conventional treatment methods require longer residence time (10–15days) and higher operating cost. Owing to this, finding a suitable and efficient method for the treatment of POME is crucial. In this investigation, ultrasound cavitation technology has been used as an alternative technique to treat POME. Cavitation is the phenomenon of formation, growth and collapse of bubbles in a liquid. The end process of collapse leads to intense conditions of temperature and pressure and shock waves which assist various physical and chemical transformations. Two different ultrasound systems i.e. ultrasonic bath (37kHz) and a hexagonal triple frequency ultrasonic reactor (28, 40 and 70kHz) of 15L have been used. The results showed a fluctuating COD pattern (in between 45,000 and 60,000mg/L) while using ultrasound bath alone, whereas a non-fluctuating COD pattern with a final COD of 27,000mg/L was achieved when hydrogen peroxide was introduced. Similarly for the triple frequency ultrasound reactor, coupling all the three frequencies resulted into a final COD of 41,300mg/L compared to any other individual or combination of two frequencies. With the possibility of larger and continuous ultrasonic cavitational reactors, it is believed that this could be a promising and a fruitful green process engineering technique for the treatment of POME.

Устройства для уменьшения трения при волочении и сонохимической очистки проволоки от смазки

Article is devoted to reduce friction during drawing wire at the expense of ultrasonic axial vibration the portage, sonochemical cleaning it from technological lubricant type residues in aqueous solutions of detergents by acoustic cavitation generated by energy dissipation of elastic vibrations in the washing solution, as well as the design of ultrasonic devices for the implementation of these technology. At the expense of axial ultrasonic oscillations for the reducing friction on the surface of the wire is formed additional hardening. Cleaning - it removal from the surface of the wire technological lubricant and under-lubricant layer before polishing, coppering and applying corrosion-resistant coatings in the manufacture of welding wire or before applying insulation in the production of electrical wires. It can be performed as a separate process, which implemented on the rewinding machine. A device may be used as a part of drawing machine, or together with the rewinding machine. The paper presents the principles of calculation of the integrating waveguide transformers - essential elements for controlling devices with ultrasonic oscillations and their industrial use. They allows to integrate the power of several of ultrasonic transducers, does not obstacles to the rectilinear trajectory of drawing wire. Is shown the original design of small cavitation reactors which located inside transformers and are providing sufficiently sonochemical effects on cleaning solutions.

Enhancing the Degradation of Rhodamine B by Hydrodynamic Cavitation with CCl<sub>4</sub> Augmentation

The degradation of Rhodamine B, a common pollutant existing in industrial wastewater, has been explored using a hydrodynamic cavitation reactor combined with CCl4treatment. The effects of CCl4concentration, operating pH values, inlet pressure, initial temperatures and initial RhB concentration were investigated. The result shows that the removal of RhB increases from 70.78% to 80.38% with increasing CCl4concentrations during hydrodynamic cavitation. Degradation of RhB with CCl4treatment increased as the operating pH value and its initial concentration decreased, a 7-fold increase (from 0.22×102min1to 1.68×102min1) in the kinetic rate constants were found at pH values ranging from 4.0 to 2.0. In addition, RhB degradation with CCl4treatment increased as the inlet pressure and temperature increased. From the present work, we conclude that the RhB degradation reaction follows a pseudo-first-order kinetics, and the mechanisms of CCl4enhancement are subsequently discussed.

Degradation of diclofenac sodium using combined processes based on hydrodynamic cavitation and heterogeneous photocatalysis

Diclofenac sodium, a widely detected pharmaceutical drug in wastewater samples, has been selected as a model pollutant for degradation using novel combined approach of hydrodynamic cavitation and heterogeneous photocatalysis. A slit venturi has been used as cavitating device in the hydrodynamic cavitation reactor. The effect of various operating parameters such as inlet fluid pressure (2–4bar) and initial pH of the solution (4–7.5) on the extent of degradation have been studied. The maximum extent of degradation of diclofenac sodium was obtained at inlet fluid pressure of 3bar and initial pH as 4 using hydrodynamic cavitation alone. The loadings of TiO2 and H2O2 have been optimised to maximise the extent of degradation of diclofenac sodium. Kinetic study revealed that the degradation of diclofenac sodium fitted first order kinetics over the selected range of operating protocols. It has been observed that combination of hydrodynamic cavitation with UV, UV/TiO2 and UV/TiO2/H2O2 results in enhanced extents of degradation as compared to the individual schemes. The maximum extent of degradation as 95% with 76% reduction in TOC has been observed using hydrodynamic cavitation in conjunction with UV/TiO2/H2O2 under the optimised operating conditions. The diclofenac sodium degradation byproducts have been identified using LC/MS analysis.

Sonochemical and hydrodynamic cavitation reactors for laccase/hydrogen peroxide cotton bleaching

The main goal of this work is to develop a novel and environmental-friendly technology for cotton bleaching with reduced processing costs. This work exploits a combined laccase–hydrogen peroxide process assisted by ultrasound. For this purpose, specific reactors were studied, namely ultrasonic power generator type K8 (850kHz) and ultrasonic bath equipment Ultrasonic cleaner USC600TH (45kHz). The optimal operating conditions for bleaching were chosen considering the highest levels of hydroxyl radical production and the lowest energy input. The capacity to produce hydroxyl radicals by hydrodynamic cavitation was also assessed in two homogenizers, EmulsiFlex®-C3 and APV-2000. Laccase nanoemulsions were produced by high pressure homogenization using BSA (bovine serum albumin) as emulsifier. The bleaching efficiency of these formulations was tested and the results showed higher whiteness values when compared to free laccase. The combination of laccase–hydrogen peroxide process with ultrasound energy produced higher whiteness levels than those obtained by conventional methods. The amount of hydrogen peroxide was reduced 50% as well as the energy consumption in terms of temperature (reduction of 40°C) and operating time (reduction of 90min).

Generation and Optimization of Palm Oil-Based Oil-in-Water (O/W) Submicron-Emulsions and Encapsulation of Curcumin Using a Liquid Whistle Hydrodynamic Cavitation Reactor (LWHCR)

The production of palm oil-based submicron emulsions in the presence of Tween 80 has been studied in a liquid whistle hydrodynamic cavitation reactor (LWHCR). Preliminary investigations have been carried out using two orifice plates with the hole diameters of 0.0010 and 0.0016 cm with an aim of investigating the efficiency of LWHCR in the oxidation of aqueous solution of potassium iodide (KI). Based on the preliminary studies, the orifice plate with the smallest hole diameter was chosen for the generation of submicron emulsions. The effect of operating parameters of LWHCR such as the distance between the orifice plate and blade (0.5, 0.6, and 0.8 cm) and the inlet operating pressures (400, 600, and 800 psi) has been successfully investigated and optimized. It has been observed that the minimum droplet size of 476 nm with a PDI of 0.5 was achieved using an orifice plate–blade distance of 0.6 cm and at an inlet operating pressure of 800 psi. Furthermore, the influence of the addition of a co-surfactant, Spa...

Optimization of a Multiple Impinging Jets Cavitation Reactor Using Zero‐Valent Iron Powder as Catalyst

AbstractThe effect of a combination of impinging jets and hydrodynamic cavitation technology was investigated by a multiple impinging jets cavitation reactor (MIJCR). Zero‐valent iron (ZVI) powder and rhodamine B were chosen as heterogeneous catalyst and model pollutant, respectively. ZVI addition resulted in more than five times higher decolorization efficiency compared to runs without ZVI. In situ generation of Fenton reagents suggested an advanced Fenton process to explain the enhancing effect of the applied catalyst. Impinging jets and aeration led to significant enhancement of the process, and optimum values of inter‐nozzle distance and initial catalyst concentration favored the decolorization of rhodamine B.

Hydrodynamic cavitation as a novel approach for delignification of wheat straw for paper manufacturing

The present work deals with application of hydrodynamic cavitation for intensification of delignification of wheat straw as an essential step in the paper manufacturing process. Wheat straw was first treated with potassium hydroxide (KOH) for 48h and subsequently alkali treated wheat straw was subjected to hydrodynamic cavitation. Hydrodynamic cavitation reactor used in the work is basically a stator and rotor assembly, where the rotor is provided with indentations and cavitational events are expected to occur on the surface of rotor as well as within the indentations. It has been observed that treatment of alkali treated wheat straw in hydrodynamic cavitation reactor for 10–15min increases the tensile index of the synthesized paper sheets to about 50–55%, which is sufficient for paper board manufacture. The final mechanical properties of the paper can be effectively managed by controlling the processing parameters as well as the cavitational parameters. It has also been established that hydrodynamic cavitation proves to be an effective method over other standard digestion techniques of delignification in terms of electrical energy requirements as well as the required time for processing. Overall, the work is first of its kind application of hydrodynamic cavitation for enhancing the effectiveness of delignification and presents novel results of significant interest to the paper and pulp industry opening an entirely new area of application of cavitational reactors.

Application of cavitation in uranium leaching

Cavitation is mostly considered as an operational problem and not desirable phenomena. The rapid creation and collapse of bubbles can destroy pump and erode other equipment. Recently, cavitation has been explored to enhance mass transfer and also to enhance or alter chemical reactions. Cavitation by definition is the formation, growth and rapid collapse of bubbles. Cavitation can be generated by different techniques. Hydrodynamic (hydraulic) and acoustic cavitations are the results of overcoming the tension existing in a liquid using fluid and sound energy, respectively. Optic, charge particle and steam bubble cavitations are the consequence of local deposition of energy using light, high energy elementary particles beam and steam bubble, respectively. For industrial application, hydrodynamic and acoustic cavitations are more important. Steam bubble cavitation is a recent invention and is a highly promising candidate for industrial applications in future. Improvement in recovery and enhancement in rate of recovery during leaching by ultrasound is documented in literature. Uranium leaching from carnotite ore with ultrasound was reported in 1968 by Russia and ultrasonic leaching of urania impregnated in graphite fuel was reported in 1961 by the USA. There is no other published literature available on uranium leaching with cavitation. However, lot more research has been carried out under sonochemistry for process intensification. Different types of cavitation reactor schemes are proposed by researchers for the process intensification. In this paper, we have reviewed uranium leaching with cavitation using different cavitation mechanisms. Effect of cavitation-aided leaching of uranium from MgF2 has been experimentally established. Uranium leaching of Narwapahar ore with acoustic and hydrodynamic cavitation also has been studied.

Optimization of a heterogeneous catalytic hydrodynamic cavitation reactor performance in decolorization of Rhodamine B: Application of scrap iron sheets

A low pressure pilot scale hydrodynamic cavitation (HC) reactor with 30L volume, using fixed scrap iron sheets, as the heterogeneous catalyst, with no external source of H2O2 was devised to investigate the effects of operating parameters of the HC reactor performance. In situ generation of Fenton reagents suggested an induced advanced Fenton process (IAFP) to explain the enhancing effect of the used catalyst in the HC process. The reactor optimization was done based upon the extent of decolorization (ED) of aqueous solution of Rhodamine B (RhB). To have a perfect study on the pertinent parameters of the heterogeneous catalyzed HC reactor, the following cases as, the effects of scrap iron sheets, inlet pressure (2.4–5.8bar), the distance between orifice plates and catalyst sheets (submerged and inline located orifice plates), back-pressure (2–6bar), orifice plates type (4 various orifice plates), pH (2–10) and initial RhB concentration (2–14mgL−1) have been investigated. The results showed that the highest cavitational yield can be obtained at pH 3 and initial dye concentration of 10mgL−1. Also, an increase in the inlet pressure would lead to an increase in the ED. In addition, it was found that using the deeper holes (thicker orifice plates) would lead to lower ED, and holes with larger diameter would lead to the higher ED in the same cross-sectional area, but in the same holes’ diameters, higher cross-sectional area leads to the lower ED. The submerged operation mode showed a greater cavitational effects rather than the inline mode. Also, for the inline mode, the optimum value of 3bar was obtained for the back-pressure condition in the system. Moreover, according to the analysis of changes in the UV–Vis spectra of RhB, both degradation of RhB chromophore structure and N-deethylation were occurred during the catalyzed HC process.

Interaction mechanism of double bubbles in hydrodynamic cavitation

Bubble-bubble interaction is an important factor in cavitation bubble dynamics. In this paper, the dynamic behaviors of double cavitation bubbles driven by varying pressure field downstream of an orifice plate in hydrodynamic cavitation reactor are examined. The bubble-bubble interaction between two bubbles with different radii is considered. We have shown the different dynamic behaviors between double cavitation bubbles and a single bubble by solving two coupling nonlinear equations using the Runge-Kutta fourth order method with adaptive step size control. The simulation results indicate that, when considering the role of the neighbor smaller bubble, the oscillation of the bigger bubble gradually exhibits a lag in comparison with the single-bubble case, and the extent of the lag becomes much more obvious as time goes by. This phenomenon is more easily observed with the increase of the initial radius of the smaller bubble. In comparison with the single-bubble case, the oscillation of the bigger bubble is enhanced by the neighbor smaller bubble. Especially, the pressure pulse of the bigger bubble rises intensely when the sizes of two bubbles approach, and a series of peak values for different initial radii are acquired when the initial radius ratio of two bubbles is in the range of 0.9 similar to 1.0. Although the increase of the center distance between two bubbles can weaken the mutual interaction, it has no significant influence on the enhancement trend. On the one hand, the interaction between two bubbles with different radii can suppress the growth of the smaller bubble; on the other hand, it also can enhance the growth of the bigger one at the same time. The significant enhancement effect due to the interaction of multi-bubbles should be paid more attention because it can be used to reinforce the cavitation intensity for various potential applications in future.

Hydrodynamic cavitation as a novel approach for wastewater treatment in wood finishing industry

In the present work, hydrodynamic cavitation has been evaluated as a novel treatment scheme for wastewater generated from wood finishing industry. The earlier work on hydrodynamic cavitation has been mostly with synthetically prepared pollutants (typically less volatile compounds) and the current work is the first to report a treatment strategy for the real wastewater generated by wood finishing industry, which contains high concentration of volatile organic compounds. Hydrodynamic cavitation reactor is basically a stator and rotor assembly, where the rotor is provided with some indentations and cavitation events are expected on the surface of rotor as well as within the indentations. The effect of various operating parameters such as speed of rotor, loading of H2O2 and the residence time of wastewater in the cavitating device, on the extent of COD reduction of the wastewater have been investigated. It has been observed that the rate of degradation of wastewater is dependent on the speed of rotor, H2O2 concentration and the liquid phase residence time. Addition of H2O2 resulted in enhanced degradation till an optimum concentration which is dependent on the type of wastewater stream. It has been observed that the cavitational yield increases by 46% at optimum loading of H2O2.