Band 23, Heft 9

QDs (Quantum Dots) have been discovered as a revolutionary wastewater treatment solution due to their unique nanoscale properties and the quantum confinement effect. The present review serves to look into the different techniques of synthesis critically, the use of functionalization, and the whole idea of performance evaluation with QDs to give a holistic view of their potential use in environmental applications. By way of studying the plus and minuses of both techniques of the top-down and bottom-up synthesis methods, the dissertation indicates the significance of optimizing factors to improve the performance of colloidal QDs for the final targeted outcomes. Paying a lot of attention to the functionalization techniques is important as it contributes to the QDs’ reactivity and stability. This conclusion points out the existence of QDs in this solution, emphasizing their potential, but also their mentioned challenges of the higher synthesis cost, and security concerns requiring further research.

This study aims to enhance the performance and sustainability of Li-ion and Na-ion batteries by developing a hybrid PDO-CCTNN technique focused on optimizing energy density and efficiency for advanced energy storage applications across diverse sectors. The proposed method integrates Prairie Dog Optimization (PDO) to fine-tune operational parameters and Closed-Form Continuous-Time Neural Networks (CCTNN) to model battery dynamics, ensuring effective energy management, prolonged lifespan, and improved charging/discharging performance in MATLAB simulations. Simulation results demonstrate that the PDO-CCTNN method achieves a high energy density of 210 kWh/g and an efficiency of 94.1 %, outperforming conventional methods such as BOA, ICBO, GA, PSO, and BHMCO across multiple evaluation metrics. The PDO-CCTNN technique significantly boosts battery performance and sustainability, making it a promising solution for next-generation Li-ion and Na-ion batteries in energy storage systems, with high accuracy, optimized operation, and better adaptability for real-world energy applications.

Continuous-flow synthesis of nitro- o -xylene has been widely reported. However, critical scientific challenges remain unresolved, including product selectivity optimization, process economic viability, and operational safety. Herein, continuous-flow o -xylene nitration with mixed acid in a capillary microreactor is presented. A kinetic model of the pseudo-homogeneous nitration reaction was developed, and the mass transfer process was characterised by the first Damköhler number and Hatta number. Notably, the capillary microreactor exhibited limited mass transfer efficiency, restricting conversion enhancement. To address this, a heart-shaped channel plate was integrated into the micro-reaction system. Under the M-ratio of HNO 3 to o -xylene was 3, residence time was 35 s, temperature was 303 K, the conversion rate of 100 % was achieved. The developed micro-reactor system significantly improved both the selectivity and conversion of o -xylene nitration, demonstrating substantial potential for industrial application.

As the demand for sustainable energy and environmental protection grows, alternative biofuels like biodiesel derived from Jatropha Curcas show great potential. By utilizing advanced transesterification techniques with a potassium hydroxide (KOH) catalyst and methanol mixture, we can produce biodiesel and blend it with diesel fuel in varying proportions (1–5 %). These blends demonstrate favourable physical and thermal properties that meet ASTM standards, with kinematic viscosity ranging from 2.1 to 2.5 × 10 −6  m 2 /s. An experimental evaluation of biodiesel/diesel blends in compression ignition (CI) engines with direct injection, tested under various load conditions (10–70 %), produces compelling results. Among the tested blends, the 5 % biodiesel mixture shows superior performance, exhibiting optimal in-cylinder pressure (32 bar), brake specific fuel consumption (BSFC) of 0.32 ± 0.02 kg/kWh, brake power (BP) of 5.2 ± 0.17 kW, and brake thermal efficiency (BTE) of 34 %. Additionally, this blend results in lower emissions of carbon monoxide (CO) at 0.40 %, hydrocarbons (HC) at 23 ± 1 ppm, carbon dioxide (CO 2 ) at 5.8 ± 0.18 %, and nitrogen oxides (NO x ) at 275 ± 6 ppm when compared to pure fossil diesel. These findings indicate that the recommended biodiesel blend is a viable option for use in CI engines, providing a sustainable and environmentally friendly energy solution for future applications.

Industrial sectors use high volumes of water and produce huge quantities of wastewater that are full of many types of pollutants, such as phosphates, total dissolved solids (TDS), and those that involve biological oxygen demand (BOD). In this study, the integrated sonolysis and pulsed electrochemical oxidation (S-PEO) process for treating industrial wastewater was examined, with a focus on maximizing pollutant removal and reducing energy usage. Optimal conditions for maximal treatment efficiency were determined by methodically varying key operational parameters, including initial pH, electrolysis time, and current. The results showed that, when the S-PEO process was run at optimal circumstances (pH of 7, electrolysis period of 40 min, and current of 0.5 Amp), it was produced remarkable removal efficiencies. With a low power consumption of 0.19 kWh/m 3 , the removal efficiencies for phosphates, TDS, and BOD were about 98.70 %, 97.44 %, and 95.49 %, respectively. To assess and optimize the process parameters, a methodical approach utilizing response surface methodology (RSM) and central composite design (CCD) was utilized. At a 95 % confidence level, statistical validation using analysis of variance (ANOVA) showed that the independent variables and their interactions had a meaningful impact. Additionally, the study used a quadratic regression model to estimate power consumption and pollutant removal efficiencies with accuracy. The model’s dependability is confirmed by the high value 0.91 of the correlation coefficient. These results emphasize the S-PEO process’s potential as an efficient and environmentally friendly method of treating industrial wastewater.

The current environmental scenario has compelled global economies to explore more sustainable and renewable energy resources. The focus of international policies is to enhance the use of alternative renewable energy sources while minimizing the carbon footprint. Vegetable oils and biodiesel can emerge as promising fuels of the future. However, using vegetable oils and biodiesel in engines can cause problematic issues like sticking rings, injector choking, and wear decay of the vital parts of engine during operation. This paper aims to study the prospects and scope of using Jatropha Curcas straight vegetable oil and diesel blends in the engine without making hardware modifications. Initially, Jatropha Curcas oil was pretreated to remove free fatty acid and wax content. Performance and emission tests were carried out on a single-cylinder, four-stroke, and constant-speed engine. A splash blend of 10 % Jatropha Curcas oil in diesel showed almost synonymous performance to that of pure diesel. A 512- hour endurance test was conducted on a bench engine test to evaluate the effect of Jatropha Curcas oil & diesel blend on wear and deposits, rating vital engine parts and fuel injection equipment. Trace metal analysis showed better results for diesel than Jatropha blend. The deposits and merit rating of vital engine parts conclude that after the removal of FFA and wax, a 10 % pretreated vegetable oil blend can be successfully used in stationary diesel engines.

Thermal energy storage utilizing phase change materials (PCMs) is important for conserving energy because of its high latent heat capacity and ability to maintain a steady temperature during the phase change. However, no single organic PCM provides all of the required qualities, such as ideal melting temperature and latent heat, to perform effectively under specified environmental circumstances. To address this, binary eutectic PCMs are prepared by mixing two or more organic PCMs and optimizing their thermophysical properties. Despite these advancements, their low thermal conductivity remains an issue, limiting overall performance. This study focuses on developing nano-enhanced eutectic phase change material consisting of 64 wt% myristic acid and 36 wt% stearic acid, further improved by incorporating Ag 2 O nanoparticles at concentrations of 0.3–3.0 wt%. Dispersion of nanoparticles within composite phase change material was testified by FTIR and XRD analyses. However, thermal conductivity of the eutectic PCM was significantly enhanced up to 105 % at an equivalent loading of 3.0 wt% nanoparticles. Thermal aging tests also showed thermochemical stability for both pure and composite PCMs in the case of 1,000 cycles. This paper concludes that nano-embedded eutectic PCM may be a potentially well-suited material for medium- and low-temperature applications.

This study investigates the design, operation, and thermal performance of a solar-assisted heat pump dryer (SAHPD), conceptualized as a low-temperature hybrid thermal reactor for efficient drying of agricultural biomass. Focused on post-harvest processing of cardamom, the system integrates a vapor compression heat pump with a flat-plate solar collector, aiming to enhance energy recovery and improve moisture removal efficiency under tropical climatic conditions. Experiments were conducted in Karnataka, India, using a 10 kg batch of fresh cardamom subjected to drying over an 8-h period. The system was tested in three configurations: solar drying (SD), heat pump drying (HPD), and the integrated SAHPD mode. Key environmental parameters, including ambient temperature, relative humidity, and solar radiation (with peaks up to 870 W/m 2 ), were recorded in real-time. Drying kinetics, energy efficiency, and total moisture loss were evaluated for each mode. The integrated SAHPD system demonstrated superior reactor performance, achieving approximately 80 % moisture removal (about 6 kg), while maintaining product quality and significantly reducing drying time. Compared to standalone modes, the SAHPD showed improved thermal utilization and operational stability under fluctuating weather conditions. The experimental results position the SAHPD as a promising thermal reactor configuration for sustainable, energy-efficient drying of moisture-laden biomass. This study contributes to the growing body of work on thermal reactor engineering for agricultural processes, supporting the development of environmentally responsible and process-intensified technologies in biomass conversion and post-harvest systems.

This study investigates micromixers with terminator-shaped chambers and various obstructions using Computational Fluid Dynamics (CFD). The two types of obstructions, curved and angle-shaped, were used to create chaotic advection. For Reynolds values between 0.1 and 30, the effects of obstruction shape and constriction channel width on mixing performance were investigated. Plots of the ethanol mass fraction on the x–y plane at mid-height and on the y–z planes at different distances from the confluence point were used to investigate the mixing field and its characteristics. With the constriction channel width of 75 μm, the Micromixer with Curved–Shaped Obstructions (M-CSO) achieves a mixing efficiency of around 98 % at Re = 0.1 and Re = 30. With a constriction channel width of 75 μm, the Micromixer with Angle-Shaped Obstructions (M-ASO) achieves a mixing efficiency of around 99 % at Re = 0.1 and Re = 30. The findings demonstrate that the M-ASO exhibits superior mixing efficiency.