Intensified degradation of tartrazine dye present in effluent using ultrasound combined with ultraviolet irradiation and oxidants.

Effluent containing tartrazine can affect the environment and human health significantly prompting the current study into degradation using a sonochemical reactor operated individually and combined with advanced oxidation processes. The optimum conditions for ultrasound treatment were established as dye concentration of 10 ppm, pH of 3, temperature as 35 °C, and power as 90 W. The combination approach of H2O2/UV, H2O2/US, and H2O2/UV/US resulted in higher degradation of 25.44%, 57.4%, and 74.36% respectively. Use of ZnO/UV/US approach increased the degradation significantly to 85.31% whereas maximum degradation as 93.11% was obtained for the US/UV/Fenton combination. COD reduction was found maximum as 83.78% for the US/UV/Fenton combination. The kinetic analysis showed that tartrazine dye degradation follows pseudo first-order kinetics for all the studied processes. Combination of Fenton with UV and US was elucidated as the best approach for degradation of tartrazine.

Degradation of Procion brilliant yellow H-E6G using ultrasonic and hydrodynamic cavitation combined with oxidants with demonstration at pilot scale.

The current study focuses on the degradation of Procion brilliant yellow H-E6G, an azo dye, using ultrasonic and hydrodynamic cavitation (HC), evaluating the impact of various parameters on the extent of degradation. The use of only ultrasound showed less oxidation capacity as indicated by only 19.1% degradation at an optimized power of 140 W, pH of 2.5, temperature of 40°C, and initial dye concentration of 15 ppm. The effectiveness of hybrid approaches involving US + H2 O2 , US + Fenton, and US + H2 O2 + potassium persulfate (KPS) was subsequently evaluated under optimized conditions. A notable enhancement in decolorization extent was observed for combined operations, including US + H2 O2 , US + Fenton, and US + H2 O2 + KPS (dual oxidant scheme) with the actual decolorization extents as 80.6%, 85%, and 92.2% respectively. An optimized scheme of US + H2 O2 + KPS was also utilized to decolorize the dye at a pilot scale using a US flow cell and also an HC reactor that yielded 91.8% and 88% reductions in initial concentration. The dye decolorization was elucidated to follow first-order kinetics for all the individual and combination approaches. The obtained values of the rate constants were also utilized for the evaluation of the synergistic index. A toxicity analysis was also performed on the dye, both before and following treatment, utilizing two bacterial strains. A comparative analysis of various treatment approaches has been presented focusing on factors such as cavitational yield, operational expenses, and energy requirements. The study elucidated that the combination of US + H2 O2 + KPS effectively removes Procion brilliant yellow H-E6G giving 92.2% as the maximum degradation at an operating cost of 0.1862 $/L. PRACTITIONER POINTS: First depiction of cavitative degradation of Procion brilliant yellow H-E6G Optimizing the equipment operating parameters and chemical oxidants Demonstration of optimized treatment scheme at pilot scale Evaluation of various approaches based on synergy and costs of treatment US + H2 O2  + KPS is the best approach for dye degradation.

Improved synthesis of metformin hydrochloride-sodium alginate (MH-NaALG) microspheres using ultrasonic spray drying.

Metformin Hydrochloride (MH), an orally administered antidiabetic drug from the biguanide family, encounters issues of wide particle size distribution, inefficient dissolution rates and short half-life leading to excess dosage which can result in lactic acidosis. Novel approaches that yield smaller particle size and uniform distribution at higher yields are significant to tackle problems associated with solubility and optimum dosage levels of the administered drugs. In the current research related to microsphere synthesis, a controlled process based on pressure and ultrasonic nozzles for the atomization of liquid, was applied with an objective of optimizing particle size of microspheres of MH in sodium alginate, a biopolymer excipient matrix. The study carried out in spray dryer elucidated parameter optimization using one variable at a time approach by varying important parameters as inlet temperature of air (120°C-150 °C), rate of flow of feed (1.5 mL/min-3 mL/min), aspirator rate (800 rpm-1400 rpm) and polymer content in feed solution (1 g-8 g) using ultrasonic and pressure nozzles for comparison with the target output parameter as particle size and yield. While the particle size at optimum conditions were <10 µm for both types of atomization, ultrasound assisted spray drying exhibited narrower distribution compared to the pressure atomization. Particle characterization performed using SEM, optical microscopy, FTIR, XRD and DSC revealed slight deformation with no chemical interaction and slight decrease in crystalline nature of pure drug. Overall, an improved process based on the use of ultrasound with optimized parameters has been demonstrated for synthesis of MH containing microspheres.

Comparative study of different ultrasound based hybrid oxidation approaches for treatment of real effluent from coke oven plant.

The present study investigates the treatment of real coke plant effluent utilising several ultrasound-based hybrid oxidation approaches including Ultrasound (US) alone, US + catalyst, US + H2O2, US + Fenton, US + Ozone, and US + Peroxone, with main objective as maximizing the reduction of chemical oxygen demand (COD). Ultrasonic horn at power of 130 W, frequency as 20 kHz and duty cycle as 70% was applied. Study with varying catalyst (TiO2) dose from 0.5 g/L - 2 g/L revealed 1 g/L as the optimum dose resulting in 65.15% reduction in COD. A 40 ml/L dose of H2O2 was shown to be optimal, giving an 81.96% reduction in COD, based on the study of varied doses of H2O2 from 20 ml/L to 60 ml/L. US + Fenton reagent combination at optimum Fe2+/H2O2 (w/v) ratio of 1:1 resulted in a COD reduction of 85.29% whereas reduction of COD as 81.75% was obtained at the optimum flow rate of ozone as 1 LPM for US + Ozone approach. US + Peroxone demonstrated the best efficiency (90.48%) for COD reduction. To find the toxicity effects, the treated (US + peroxone) and non-treated samples were tested for the growth of bacterial cultures. It was observed that the toxicity of the treated sample increased only marginally after treatment. High-resolution liquid chromatography mass spectrometry (HR-LCMS) analysis was also performed to establish intermediate compounds. Overall, the coupling of ultrasound with oxidation processes produced better results with US + Peroxone established as best treatment approach for coke plant effluent.

Degradation of Procion Brilliant Purple H-3R using ultrasound coupled with advanced oxidation processes.

The complexity of wastewater matrix poses a challenge for conventional processes especially due to the presence of refractory compounds such as dyes. The present work focuses on utilizing ultrasound-induced cavitation in conjunction with different oxidants such as hydrogen peroxide, Fenton's reagent and potassium persulfate to treat Procion Brilliant Purple H-3R dye containing wastewater. The impact of various operating parameters as pH, frequency, and power on degradation levels has been studied with the aim of optimizing degradation. The optimal conditions for the degradation of Procion Brilliant Purple H-3R were determined as pH of 12, frequency of 22 kHz, and power of 250 W, resulting in a maximum degradation of 70.25%. Combination of a cavitation reactor with hydrogen peroxide, Fenton reagent, and KPS was then applied at optimized conditions, which confirmed a notable enhancement in degradation compared to the only ultrasound based process. Specifically, the degradation extent was 95.99% for combination with H2O2 at 0.5 g/L loading, 99.79% for combination with Fenton at H2O2/Fe2+ ratio of 50:1, and 99.05% for combination with KPS at loading of 0.75 g/L. The kinetic rate constant for the combined approach of US + Fenton was also maximum at 7.47 × 10-1 L mg-1 min-1. Toxicity analysis was conducted on two bacterial strains, Escherichia coli and Staphylococcus aureus, using the wastewater in native form and after treatment. The various processes were evaluated in terms of the cavitational yield and overall treatment cost and it was determined that US + Fenton process is the most efficient treatment method for fully degrading Procion Brilliant Purple H-3R, particularly at larger scales of operation and cost efficiently as demonstrated in the work.

Mapping of 20 L capacity ultrasonic reactor using cavitation activity meter and dye degradation.

Mapping of a novel 20 L capacity ultrasonic (US) reactor having a total of 44 transducers was done by measuring the local cavitation intensity using a cavitation activity meter at different horizontal planes and subsequent validation based on dye degradation. A fixed frequency of 33 kHz and temperature of 30 °C was used during the mapping performed at two different power levels of 250 W and 400 W. In addition, the mapping of specific plane 2 was also performed with transducers operating on walls 1 and 3, while switching the transducers on walls 2 and 4 off and vice versa so as to establish the role of using multiple transducers. Degradation of RO4 dye was also measured at the plane 2 at various powers as 250 W, 400 W, and 1000 W. The degradation of the RO4 dye directly correlated to the cavitation intensity measured at the various location inside the US reactor. The average cavitation intensity was 265.38, 317.25, 185, and 300.5 Cavins for power dissipations of 250 W, 400 W, 250 W (wall 1 and 3 transducers in operation), and 400 W (wall 2 and 4 transducers in operation), respectively. Correspondingly, the average degradation was 10.35 %, 13.03 %, 5.52 %, and 8.9 % for same sequence of operational power and transducers. The investigation amply illustrated dependency of the cavitational activity on the location, power dissipation, and operating mode elucidating important design related information useful for scale up of sonochemical reactors.

Acoustic cavitation for the process intensification of biological oxidation of CETP effluent containing mainly pharmaceutical compounds: Understanding into effect of parameters and toxicity analysis.

The current work investigates the efficacy of acoustic cavitation (AC) based pretreatment as a process intensification method for improving the conventional biological oxidation (BO) treatment of the effluent from common effluent treatment plant (CETP) mainly containing pharmaceutical compounds. The effluent acclimatized with cow dung-based sludge was utilized for the aerobic oxidation with an optimum condition of 1:3 ratio of sludge to effluent and 6 h as duration. COD reduction of 19.58% was achieved with the conventional biological oxidation, which was demonstrated to be improved by incorporating acoustic cavitation-based pretreatment approaches under optimized conditions of 125 W and 70% duty cycle for only AC as well as oxidant loadings as 1000 mg/L for H2O2, 250 mg/L Fe(II) with 1000 mg/L H2O2 for Fenton, 1000 mg/L for KPS and 0.5 L/min for the O3 during the combination approaches. The improved COD reduction after the use of pretreatment approaches followed by the BO of 6 h duration was 29.26%, 72.42%, 85.47%, 45.68% and 69.26% for the AC, AC + H2O2, AC + Fenton, AC + KPS and AC + O3 based approaches respectively. The toxicity assay of the effluent before and after every pretreatment approach using bacterial strains ofStaphylococcus aureusandPseudomonas aeruginosaensured the biodegradability of the treated effluent as no toxic intermediates could be seen. Overall, the present work elucidated the effectiveness of acoustic cavitation-based pretreatment approaches for the improvement of conventional BO of CETP effluent.

A novel method for the remediation of wastewater containing acid red 131 dye using acoustic cavitation combined with sulphur-doped TiO2 and oxidants.

The present study investigated the degradation of Acid Red 131 (AR131) dye using a combination of ultrasound-induced cavitation, ultraviolet (UV) irradiation, chemical oxidants, and photocatalyst, focusing on the effect of operating parameters. It was established that acidic pH, higher input power, and lower initial concentration resulted in higher degradation. Sulphur-doped titanium dioxide (S-TiO2) synthesized using a novel ultrasound-assisted method showed an optimum dosage of 300 ppm for the AR131 degradation with sulphur to titanium ratio of 2:1. In the combination approach, the optimum dosage of hydrogen peroxide (H2O2) and potassium persulfate (KPS) was established as 100 ppm and 400 ppm respectively. The maximum degradation of 90.3% was obtained using a combined approach of US + KPS + UV/S-TiO2 whereas, a maximum synergetic coefficient of 1.57 was obtained for the approach of US + UV/S-TiO2 with degradation of 86.96%. It was also elucidated that for combination approaches of US + H2O2, US + H2O2 + KPS, and US + H2O2 + KPS + UV/S-TiO2, the synergetic coefficients were lower than one due to undesirable side reactions and radical scavenging. Scale-up studies performed at 15 times of the laboratory scale volume, elucidated that the maximum degradation was obtained as 58.01% for the approach of US + KPS + UV/S-TiO2. Therefore, the approach of US + KPS + UV/S-TiO2 was elucidated as the most efficient in degrading the AR131 dye at both small and large scale of operation. In terms of synergy, the approach of US + UV/S-TiO2 was more efficient. Overall, an optimized combination approach was successfully demonstrated for the effective degradation of AR131 dye with synergism and better results at a large scale.

Sonochemical synthesis of Ce-TiO2 nanocatalyst and subsequent application for treatment of real textile industry effluent.

Treatment of real textile industry effluent using photocatalysis, sonocatalysis, sonophotocatalysis and H2O2 assisted sonophotocatalysis have been studied based on the use of Ce-TiO2 nanocatalyst synthesized using sonochemical co-precipitation method. Characterization studies of the obtained catalyst revealed crystallite size as 1.44 nm with particles having spherical morphology. A shift of the absorption edge to the visible light range was also observed in UV-Vis diffuse reflectance spectra (UV-DRS) analysis. The effects of different operational parameters viz catalyst dose (0.5 g/L-2 g/L), temperature (30 °C-55 °C) and pH (3-12) on the COD reduction were studied. The reduction in the COD was higher at lower pH and the optimum temperature established was 45 °C. It was also elucidated that the required catalyst dose was lesser in combined sonophotocatalysis when compared with individual photocatalysis and sonocatalysis. Combination of processes and addition of oxidants increased the COD reduction with the sonophotocatalytic oxidation combined with H2O2 treatment showing the best results for COD reduction (84.75%). The highest reduction in COD for photocatalysis was only 45.09% and for sonocatalysis, it was marginally higher at 58.62%. The highest reduction in COD achieved by sonophotocatalysis was 64.41%. Toxicity tests coupled with Liquid Chromatography Mass Spectrometry (LC-MS) analysis revealed that there were no additional toxic intermediates added to the system during the treatment. Kinetic study allowed establishing that generalized kinetic model fits the experimental results well. Overall, the combined advanced oxidation processes showed better results than the individual processes with higher COD reduction and lower requirement of the catalyst.

Improvements in azithromycin recrystallization using ultrasound for size reduction.

The primary motive of the current work is to achieve smaller mean particle size with narrow size distribution that can enhance the bioavailability of azithromycin (ARZ), an essential requirement due to its poor water solubility. Recrystallization of ARZ was evaluated using cooling as well as antisolvent crystallization approaches in the presence of ultrasonic irradiation with detailed study into effect of different parameters such as ultrasonic power, time and temperature. Ultrasound assisted antisolvent crystallization at low temperatures (<10℃) yielded best size reduction up to 80% with narrower distribution and also gave better yield of the product, that too within 5 min of sonication. With scale up considerations, recirculation mode of operation was also evaluated which offered promising results for the size reduction. Images captured using optical microscope and SEM revealed a nearly uniform rod/plate-shaped geometry. Increase in amorphous nature of ARZ was confirmed based on XRD analysis. FTIR analysis showed no significant changes in the functional groups when compared to the original sample. Overall, the work demonstrated an improved reprocessing approach based on the use of ultrasound with insights into effect of operating parameters and effect of ultrasound on various characteristics.

Intensification of alkaline delignification of sugarcane bagasse using ultrasound assisted approach.

Ultrasound-assisted approach has been investigated for delignification so as to develop green and sustainable technology. Combination of NaOH with ultrasound has been applied with detailed study into effect of various parameters such as time (operating range of 15-90 min), alkali concentration (0.25 M-2.5 M), solvent loading (1:15-1:30 w/v), temperature (50-90 ˚C), power (40-140 W) and duty cycle (40-70 %) at fixed frequency of 20 kHz. The optimized operating conditions established for the ultrasonic horn were 1 M as the NaOH concentration, 1 h as treatment time, 70˚C as the operating temperature, 1:20 as the biomass loading ratio, 100 W as the ultrasonic power and 70% duty cycle yielding 67.30% as the delignification extent. Comparative study performed using conventional and ultrasonic bath assisted alkaline treatment revealed lower delignification as 48.09% and 61.55% respectively. The biomass samples were characterized by SEM, XRD, FTIR and BET techniques to establish the role of ultrasound during the treatment. The morphological changes based on the ultrasound treatment demonstrated by SEM were favorable for enhanced delignification and also the crystallinity index was more in the case of ultrasound treated material than that obtained by conventional method. Specific surface area and pore size determinations based on BET analysis also confirmed beneficial role of ultrasound. The overall results clearly demonstrated the intensification obtained due to the use of ultrasonic reactors.

Application of hybrid oxidative processes based on cavitation for the treatment of commercial dye industry effluents.

The present work demonstrates the significant role of ultrasound (US) in intensifying the efficacy of the combination with Fenton reagent and/or ozone for the treatment of real dye industry industrial effluent procured from the local industry. Initial part of the work focused on analysing the literature based on combination approaches of US with different oxidants applied for the treatment of real and simulated effluents focusing on the dyes. The work also provides guidelines for the selection of optimal operating parameters for maximizing the intensification of the degradation. The second part of the work presents an experimental study into combined approaches of ultrasound with ozone (O3) and Fenton's reagent for treatment of real effluent. Under optimized conditions (100 W, 20 kHz and duty cycle of 70%), maximum COD reductions of 94.79% and 51% were observed using a combined approach of US + Fenton oxidation followed by lime treatment for the treatment of effluent-I and effluent-II respectively at H2O2 loading of 17.5 g/L, H2O2/Fe2+ ratio of 3, pH of 4, CaO dose of 1 g/L and an overall treatment time of 70 min. US + Fenton + O3 followed by lime was also applied for treatment under ozone loading of 1 g/h for the treatment of effluent-I and it was found that maximum COD reduction of 95.12% was obtained within 30 min of treatment time, indicating use of ozone did not result in significant value addition in terms of COD reduction but resulted in faster treatment. HC (inlet pressure: 4 bar) + Fenton + Lime scheme was successfully replicated on a pilot-scale resulting in maximum COD reduction of 57.65% within 70 min of treatment time. Overall, it has been concluded that the hybrid oxidative processes as US + Fenton followed by lime treatment is established as the best approach ensuring effective COD reduction at the same time obtaining final colourless/reusable effluent.

Improved direct synthesis of TiO2 catalyst using sonication and its application for the desulfurization of thiophene.

TiO2 catalyst was synthesized in the presence of ultrasound (ultrasonic horn at 20 kHz frequency and 70% duty cycle) at different power (80 W to 120 W) and durations as well as surfactant concentration with an objective of establishing best conditions for achieving lowest particle size of the photocatalyst. Detailed characterization in terms of crystal phase, crystallinity, functional groups and morphology of the photocatalyst has been performed using SEM, XRD and FTIR analysis. It was demonstrated that sonication significantly reduced the particle size with high degree of sphericity and homogeneity as compared to conventionally synthesized TiO2 with similar crystallinity in both cases. The catalytic performance was subsequently evaluated for the deep desulfurization of thiophene. Different desulfurization approaches including individual US (ultrasonic horn at 20 kHz frequency, 110 W power and 70% duty cycle) and UV irradiations, US/UV, US/UV/H2O2, US/UV/TiO2 and US/UV/H2O2/TiO2 were applied to evaluate the catalytic activity. The best approach was demonstrated as US/UV/H2O2/TiO2 and also activity of catalyst synthesized using ultrasound was much better compared to conventionally synthesized catalyst. The studies related to different model solvents demonstrated lowest reactivity for toluene whereas n-hexane and n-octane resulted in complete desulfurization in 60 min and 50 min treatment respectively. The desulfurization followed pseudo first order reaction kinetics irrespective of the solvent used. Overall the work clearly demonstrated the efficacy of ultrasound in improving the catalyst synthesis as well as desulfurization of thiophene.

Improved modification of clinoptilolite with silver using ultrasonic radiation.

The modification of natural clinoptilolite with silver ions using ultrasound has been investigated in the current work. The modification process was performed using clinoptilolite of different fractions (0-3.0 mm) over the temperature range of 25-55 °C, ultrasonic power range of 8.0-12.5 W and AgNO3 concentration range of 0.01-0.1 M. The zeolite modification was performed in the presence of sonication and mechanical stirring in separate runs for comparison. Fundamental analysis demonstrated that the use of ultrasound ensures desorption of air from clinoptilolite particles and accelerates the diffusion of Ag+ ions and subsequent ion exchange. Increasing the particle size of clinoptilolite led to a natural decrease in its sorption capacity. A slight increase in the sorption capacity with an increase in the equivalent particle diameter from 0.081 to 0.35 mm was seen due to changes in the structure of clinoptilolite particles during mechanical grinding. The calculated temperature coefficient of the sorption process of Ag+ ions as <1.47 means that the modification takes place with dominant control in the intradiffusion region. Increasing the power of ultrasonic irradiation did not provide a monotonous change in the sorption capacity of clinoptilolite. Increasing the concentration of argentum nitrate solution provided an increase in the content of silver ions in clinoptilolite. In general, the advantage of using ultrasonic vibrations to modify the natural clinoptilolite of different fractions with Ag+ ions was demonstrated in terms of achieving higher sorption capacity, also elucidating the effect of different operating conditions.

Intensified synthesis of palm olein designer lipids using sonication.

The present study deals with intensified synthesis of designer lipids with application of ultrasound based on biocatalyzed reaction between long chain triglyceride and medium chain fatty acid. The effects of various reaction conditions like molar ratio of reactant, reaction temperature, and enzyme loading along with the effect of ultrasound parameters such as duty cycle and irradiation time on the rate of formation of designer lipids has been investigated. The ultrasound assisted process was also compared with the traditional process so as to clearly bring out the intensification effects. During the study, it was clearly demonstrated that the optimum reaction conditions for maximum yield of designer lipids as 92% was molar ratio of medium chain fatty acid to long chain triglyceride as 4:1, reaction temperature of 40 °C, enzyme loading of 3%, duty cycle of 70%, 240 W as power dissipation and 360 min as reaction time. The recyclability study of enzyme showed its effectiveness up to 10 cycles. The synthesized designer lipid showed higher oxidative stability for 35 days and also showed Newtonian behaviour with eye appealing colour. The current study demonstrates development of an eco-friendly technique for intensified synthesis of designer lipids having numerous nutraceutical benefits.

Degradation of nitrogen-containing hazardous compounds using advanced oxidation processes: A review on aliphatic and aromatic amines, dyes, and pesticides.

Nitrogen-containing amino and azo compounds are widely used in textile, agricultural and chemical industries. Most of these compounds have been demonstrated to be resistant to conventional degradation processes. Advanced oxidation processes can be effective to mineralize nitrogen-containing compounds and improve the efficacy of overall treatment schemes. Due to a global concern for the occurrence of toxic and hazardous amino-compounds and their harmful degradation products in water, it is important to develop technologies that focus on all the aspects of their degradation. Our focus is to present a state-of-the-art review on the degradation of several amine- and azo-based compounds using advanced oxidation processes. The categories reviewed are aromatic amines, aliphatic amines, N-containing dyes and N-containing pesticides. Data has been compiled for degradation efficiencies of each process, reaction mechanisms focusing on specific attack of oxidants on N atoms, the effect of process parameters like pH, initial concentration, time of treatment, etc. and identification of intermediates. Several AOPs have been compared to provide a systematic overview of available literature that will drive essential aspects of future research on amine-based compounds. Ozone is observed to be highly reactive to most amines, dyes and pesticides, followed by Fenton processes. Degradation of amines is highly sensitive to pH and mechanisms differ at different pH values. Cavitation is a promising alternative pre-treatment method for cost reduction. Hybrid methods under optimized conditions are demonstrated to give synergistic effects and must be tailored for specific effluents in question. In conclusion, even though nitrogen-containing compounds are recalcitrant in nature, the use of advanced oxidation processes at carefully established optimum conditions can yield highly efficient degradation of the compounds.

Comparison of acoustic and hydrodynamic cavitation based hybrid AOPs for COD reduction of commercial effluent from CETP.

The present work investigates the treatment of commercial effluent obtained from Common Effluent Treatment Plants (CETP) using acoustic cavitation (AC) and hydrodynamic cavitation (HC) based hybrid AOPs. Comparison of different hybrid AOPs viz. H2O2, Fe2+/H2O2, Fe2+/H2O2/Air, Fe2+/H2O2/S2O82- and Fe2+/H2O2/S2O82-/Air in combination with both AC and HC has been performed in terms of extent of chemical oxygen demand (COD) reduction and kinetic rate constants. The best results of COD reduction as 95.2% and 97.28% were obtained for AC/Fe2+/H2O2/Air and HC/Fe2+/H2O2/Air systems respectively at Fe2+/H2O2 ratio of 0.1 and pH of 2 within 60 min of treatment under conditions of ultrasonic power dissipation as 150 W, inlet pressure for HC as 4 bar (as applicable depending on process) and temperature of 30 ± 2 °C. Slightly lower efficacy was established for the combination approach involving AC or HC coupled with Fe2+-activated S2O82- and H2O2 yielding COD reduction of 82.9% and 86.93% for the AC/Fe2+/H2O2/S2O82-/Air and HC/Fe2+/H2O2/S2O82-/Air systems respectively at Fe2+/H2O2/S2O82- ratio of 1:40:17.5. Cost estimation on the basis of cavitational yield performed on the AC and HC based treatment systems revealed economical nature of HC based treatment. Kinetic studies were also performed by fitting the experimental data with pseudo first order kinetic model (PFOKM), generalized kinetic model (GKM) and Behnajady-Modirshahla-Ghanbery kinetic model (BMGKM). It was demonstrated that GKM provided best fitting for all the experiments whereas BMGKM was most suitable for Fenton based reactions. It was clearly established that complex CETP effluent can be effectively treated using the combined approaches based on HC with potential for larger scale operation.

Degradation of benzene present in wastewater using hydrodynamic cavitation in combination with air.

The degradation of benzene present in wastewater using hydrodynamic cavitation (HC) alone as well as in combination with air has been studied using nozzles as cavitating device of HC reactor. Initially, the energy efficiency of the HC reactor operated at different inlet pressures was determined using the calorimetric studies. Maximum energy efficiency of 53.4% was obtained at an inlet pressure of 3.9 bar. The treatment processes were compared under adiabatic as well as isothermal conditions and it was observed that under the adiabatic condition, the extent of degradation is higher as compared to isothermal condition. Studies related to the understanding the effect of inlet pressure (range of 1.8-3.9 bar) revealed that the maximum degradation as 98.9% was obtained at 2.4 bar pressure using the individual operation of HC under adiabatic conditions and in 70 min of treatment. The combination of HC with air was investigated at different air flow rates with best results for maximum degradation of benzene achieved at air flow rate of 60 mL/sec. A novel approach of using cavitation for a limited fraction of total treatment time was also demonstrated to be beneficial in terms of the extent of degradation as well as energy requirements and cost of operation. Based on the cavitational intensity, the resonant radius of aggregates of cavitation bubbles was also determined for distilled water as well as for aqueous solution of benzene. Overall, significant benefits of using HC combined with air have been demonstrated for degradation of benzene along with fundamental understanding into cavitation effects.

Application of structured triacylglycerols in food products for value addition.

The present study aims to evaluate the suitability of structured triacylglycerol (ST) consisting of medium chain triacylglycerol (MCT) as low calorie and instant energy source in combination with essential fatty acids for formulations in different food products to add value to existing products. The study investigates the effect of presence of ST on the physicochemical and sensory properties of various food products such as mayonnaise enriched with ST synthesized from medium chain fatty acid (MCFA) and rice bran oil, cookies enriched with ST synthesized from MCFA and oleic acid rich moringa oil, energy bar with ST synthesized from MCFA and omega 3 enriched fish oil, as well as yogurt drink with ST synthesized from MCFA and omega 6 enriched flaxseed oil. The obtained results established the suitability of incorporation of ST in food products and comparison with standard market products revealed the validity of the products to sustain the demand with value addition. The oxidative stability studies of all the products in the presence of natural antioxidants from moringa leaves and pomegranate peel using the peroxide value test and rancimat analysis demonstrated similar stability to the standard marketed product. Application of plant wastes and residues in the form of leaves or peels as the likely sources for isolating bioactive compounds demonstrates potential of the sustainable approach also giving benefit of increasing the stability of the product. The study also points towards possible replacement option for synthetic carcinogenic antioxidants with natural antioxidants obtained from moringa leaves and pomegranate peel. The present work clearly demonstrates the effective use of structured triacylglycerols synthesized using green methodologies for creating unique health enriched food products with all worthy and green components.

Evaluation of different cavitational reactors for size reduction of DADPS.

The present study deals with the size reduction based on the recrystallization (antisolvent approach using water) of 3,3'-Diamino Diphenyl Sulfone (DADPS) using different types of cavitational reactors as an alternative to the conventional process of mechanical size reduction, which is an energy intensive approach. Ultrasound was applied for fixed time specific to the reactors namely ultrasonic probes at different power dissipation levels and also ultrasonic bath. A High Speed Homogenizer was also used at varying speeds of rotation to establishing the efficacy for size reduction. The processed sample was analysed for particle size and morphology using particle size analyser and optical microscopy respectively. The final yield of recrystallization was also determined. The power density in W/L and power intensity in W/m2 calculated for each equipment has been used to establish efficacy for size reduction since all devices had dissimilar configurations. Based on the studies of varying power intensity of the different US equipment, it was established that larger the power intensity and power density, smaller was the resultant final particle size after treatment for same time. Among the various ultrasonic devices used, Sonics VCX750 probe yielded the best size reduction of 85.47% when operated at 40% amplitude for 60 min for a volume of 200 ml. A High Speed Homogenizer used at 7000 rpm gave 92.35% of size reduction in 15 min operation and also demonstrated the best energy efficiency. The work has elucidated the comparison of different cavitational devices for size reduction for the first time and presented the best reactors and conditions for the desired size reduction.