Ultrasound assisted synthesis of performic acid in a continuous flow microstructured reactor

Fast, Efficient, Catalyst-Free Epoxidation of Butyl Rubber Using Oxone/Acetone for Improved Filler Dispersion

Incorporation of a polar filler such as silica into a nonpolar rubber matrix is challenging and energy consuming due to their large difference in polarity. Epoxidation of carbon-carbon double bonds in unsaturated rubber, especially for rubber with low unsaturation such as butyl rubber, is an effective method to introduce polar functional groups to the rubber macromolecules for better filler dispersion. Although different epoxidation reagents including hydrogen peroxide (H2O2), peracid, and meta-chloroperoxybenzoic acid (mCPBA) have been previously reported, these reagents have different drawbacks. In this article, a metal-free epoxidation reagent, dimethyl dioxirane (DMDO), generated from acetone and Oxone is explored for efficient epoxidation of rubber with low unsaturation. The effects of the addition manner of the reactant Oxone and buffer sodium bicarbonate (NaHCO3) and reaction temperature on the epoxide formation are studied. Compared to peracid, a faster and more efficient epoxidation without the generation of a ring-opened product is achieved when DMDO is used as the epoxidation reagent. Furthermore, it is found that the epoxidation using DMDO is not sensitive to the water concentration in the rubber solution up to 20 wt %. The addition of quaternary ammonium salt as a phase transfer catalyst not only improves the conversion but also further increases the water tolerance to 25 wt %. The reaction conditions for preparation of epoxidized butyl rubber with different percentages of epoxide group are optimized by Design of Experiments (DoE). At the end, improved dispersion of silica in the matrix of epoxidized butyl rubber is achieved, as revealed by the rubber process analyzer (RPA) and atomic force microscopy (AFM).

A review on existing and emerging approaches for textile wastewater treatments: challenges and future perspectives

This comprehensive review explores the complex environment of textile wastewater treatment technologies, highlighting both well-established and emerging techniques. Textile wastewater poses a significant environmental challenge, containing diverse contaminants and chemicals. The review presents a detailed examination of conventional treatments such as coagulation, flocculation, and biological processes, highlighting their effectiveness and limitations. In textile industry, various textile operations such as sizing, de-sizing, dyeing, bleaching, and mercerization consume large quantities of water generating effluent high in color, chemical oxygen demand, and solids. The dyes, mordants, and variety of other chemicals used in textile processing lead to effluent variable in characteristics. Furthermore, it explores innovative and emerging techniques, including advanced oxidation processes, membrane filtration, and nanotechnology-based solutions. Future perspectives in textile wastewater treatment are discussed in-depth, emphasizing the importance of interdisciplinary research, technological advancements, and the integration of circular economy principles. Numerous dyes used in the textile industry have been shown to have mutagenic, cytotoxic, and ecotoxic potential in studies. Therefore, it is necessary to assess the methods used to remediate textile waste water. Major topics including the chemical composition of textile waste water, the chemistry of the dye molecules, the selection of a treatment technique, the benefits and drawbacks of the various treatment options, and the cost of operation are also addressed. Overall, this review offers a valuable resource for researchers and industry professionals working in the textile industry, pointing towards a more sustainable and environmentally responsible future.

Process intensification in continuous flow organic synthesis with enabling and hybrid technologies

Industrial organic synthesis is time and energy consuming, and generates substantial waste. Traditional conductive heating and mixing in batch reactors is no longer competitive with continuous-flow synthetic methods and enabling technologies that can strongly promote reaction kinetics. These advances lead to faster and simplified downstream processes with easier workup, purification and process scale-up. In the current Industry 4.0 revolution, new advances that are based on cyber-physical systems and artificial intelligence will be able to optimize and invigorate synthetic processes by connecting cascade reactors with continuous in-line monitoring and even predict solutions in case of unforeseen events. Alternative energy sources, such as dielectric and ohmic heating, ultrasound, hydrodynamic cavitation, reactive extruders and plasma have revolutionized standard procedures. So-called hybrid or hyphenated techniques, where the combination of two different energy sources often generates synergistic effects, are also worthy of mention. Herein, we report our consolidated experience of all of these alternative techniques.

Ultrasonic enhanced emulsification process in 3D printed microfluidic device to encapsulate active pharmaceutical ingredients

A new method to prepare polymer encapsulated repaglinide nanoparticles through ultrasonic enhanced microchannel emulsification technique was explored. Using the concept of 3D printing, three different shaped micromixers (T-type, Y-type, and F-type) followed by a serpentine microchannel was fabricated using SS-316. Parametric study was performed on all three fabricated micromixers. The best results were obtained for the Y-microchannel in a microfluidic system alone, which showed a minimum particle size of 513.6 nm with 75.4% encapsulation efficiency (EE). In the selected microchannel, to further reduce the drug particle size and to increase% EE, convective mixing between immiscible fluids was enhanced by implementing ultrasound. Compared to the microfluidic system, particle size and EE were significantly improved in the ultrasonic microfluidic system. The experimental results revealed that the minimum particle size of 75.4 ± 1.3 nm with 82.9 ± 0.2% EE was achieved using an ultrasonic enhanced microfluidic system. The zeta potential of + 29.5 mV was obtained for emulsion prepared using the ultrasonic microfluidic system, whereas + 22 mV was prepared using a microfluidic system. Moreover, a backscattering measurement was performed to predict the stability of prepared emulsions. Integrating the ultrasound with a microfluidic system has proven beneficial for drug encapsulation.

Understanding flow chemistry for the production of active pharmaceutical ingredients

Multi-step organic syntheses of various drugs, active pharmaceutical ingredients, and other pharmaceutically and agriculturally important compounds have already been reported using flow synthesis. Compared to batch, hazardous and reactive reagents can be handled safely in flow. This review discusses the pros and cons of flow chemistry in today’s scenario and recent developments in flow devices. The review majorly emphasizes on the recent developments in the flow synthesis of pharmaceutically important products in last five years including flibanserin, imatinib, buclizine, cinnarizine, cyclizine, meclizine, ribociclib, celecoxib, SC-560 and mavacoxib, efavirenz, fluconazole, melitracen HCl, rasagiline, tamsulosin, valsartan, and hydroxychloroquine. Critical steps and new development in the flow synthesis of selected compounds are also discussed.

Sono-oxidative desulfurization of fuels using heterogeneous and homogeneous catalysts: A comprehensive review

Recently, environmental pollution has increased significantly due to petroleum-based fuels widely used in vehicles. This environmental pollution is mainly due to the acidic SO₂ gas generated by the combustion of fuels and emitted into the atmosphere. SO₂ gas causes not only acid rain but also corrosion of metal parts of engines in vehicles. In addition, it functions as a catalyst poison in catalytic converters in exhaust system. Due to these damages, strict regulations have been introduced to reduce the amount of sulfur in fuels. As of 2005, the permissible amount of sulfur in diesel fuels in Europe and America has been limited to 10 and 15 ppm by weight, respectively. Due to the decreasing oil reserves in the world, high viscosity petroleums containing high sulfur and heavier fractions (i.e., low-quality oils) are increasing, thus making desulfurization difficult and leading to high costly process. Since time and economic loss are very important today, these two terms have to be reduced to a minimum. Recently, ultrasound wave in ODS shown as an alternative to HDS is utilized to further increase desulfurization in shorter times. Ultrasound wave locally creates high temperatures and high pressures (hot-spot theory) in liquid, causing the desulfurization reaction to accelerate further. In this review, the advantages and difficulties of oxidative desulfurization, the economics of ultrasound-assisted oxidative desulfurization are summarized and recommendations for improving the process are presented.

Recovery of lactose from aqueous solution by application of ultrasound through millichannel

Instead of direct disposal of whey, extraction of valuable products from it may reduce the environmental pollution. In the present study, the effect of ultrasound irradiation through millichannel on recovery of lactose was investigated. The ultrasonic baths of varying amplitude (20–40%) and frequency (25–35 kHz), two different configurations of millichannel i.e., coil and serpentine, were used to know their individual and combined effect on the lactose yield. Box-Behnken design was employed to examine the interactive effect of different operating conditions. The recovery of lactose was enhanced approximately by 5–53% and induction time was reduced by 1.79–1.85 times in comparison to the conventional process. The size of the lactose crystals was reduced from 139.5 to 42.486 μm at 40% amplitude and 49.879 μm at 35 kHz frequency. Optimized condition showed 63% yield of lactose at 3.6 supersaturation, 35 kHz frequency, and 45 min of sonication time.

Continuous flow chemistry: where are we now? Recent applications, challenges and limitations

A general outlook of the changing face of chemical synthesis is provided in this article through recent applications of continuous flow processing in both industry and academia. The benefits, major challenges and limitations associated with the use of this mode of processing are also given due attention as an attempt to put into perspective the current position of continuous flow processing, either as an alternative or potential combinatory technology for batch processing.