Enhanced photocatalytic performance of CuFeO2-ZnO heterostructures for methylene blue degradation under sunlight

One of the strategies to overcome the drawbacks of fast charge recombination of a photocatalyst is to develop semiconductor heterostructures. Herein, we report a two-step precipitation-hydrothermal process to create CuFeO₂-ZnO heterostructures with different weight percentages of CuFeO₂ (0.5, 1, 5, and 10%). Though X-ray diffraction detected the presence of CuFeO₂ on ZnO above 5%, Raman spectroscopy could reveal the presence of CuFeO₂ phase as low as 0.5 wt%. For all of the compositions, the bandgap of ZnO did not vary (3.15 eV) on forming heterostructures with CuFeO₂. The oxidation of methylene blue under sunlight was used to determine the photocatalytic performance of the heterostructures. In comparison to pure ZnO and CuFeO₂, CuFeO₂-ZnO heterostructures exhibited a better photocatalytic efficiency. Overall, 5 wt% CuFeO₂ on ZnO showed 100% degradation with a rate constant of 0.272?±?0.002 min^?1, which is 16 times faster than ZnO. Time-resolved photoluminescence analysis indicated a higher lifespan of charge carriers in the 5wt% CuFeO₂-ZnO heterostructure (32.3 ns) than that of CuFeO₂ (0.85 ns) and ZnO (27.6 ns). The Mott–Schottky flat band potentials of ZnO and CuFeO₂ was determined to be -0.82 and 1.17 eV, respectively, revealing the presence of Type I heterostructures. The heterostructures also showed outstanding recyclability, with a degradation rate of 97% even after four cycles. The current study shows the significance of forming p-type CuFeO₂ and n-type ZnO heterostructures for enhanced photocatalysis.

     

Experimental investigation of dryout phenomena under oscillatory flow conditions

In water-cooled nuclear reactors, the maximum power which can be extracted from the core is limited by critical heat flux (CHF). CHF in the high-quality region is known as dryout. In advanced nuclear reactors, the coolant flow occurs solely by virtue of natural circulation; however, instabilities may occur during off-normal operations. This may lead to premature dryout due to lower coolant flow rates seen by the heater during such oscillations. This paper describes the experimental investigation on the effect of flow oscillations on the CHF with the time period of 120 s, which is observed typically in the large-scale natural circulation system. Based on observations made with respect to temperature transient, the continuous dryout is preceded by the transient dryout for higher flow oscillations. But as flow fluctuation decreases, the transient dryout phenomenon is found to disappear. The applicability of the look-up table to predict CHF under oscillatory flow conditions using suitable correction factors (CFs) for premature dryout has been evaluated. CFs for the CHF under oscillations suggested by previous authors have been compared. The maximum possible degradation in CHF value suggested by previous authors has been found to agree with the present experimental data. Percentage fluctuation in heat transfer coefficient (HTC) at fully developed annular flow conditions has been evaluated, and it is found that fluctuation in HTC is in phase with the fluctuation in flow.     

In-vitro digestibility,textural and quality characteristics of ditalini pasta fortified with green banana flour and its type -IV modified starch

Resistant starch in unripe banana offers a possibility to alter the glycemic properties in convenience foods, such as pasta. In this study, pasta formulations were tried by replacing 30% semolina with varying proportions of green banana flour (GBF) and banana-modified starch (MS). The effect of substitution on physicochemical and functional properties, including in-vitro starch digestibility, antioxidant property and consumer acceptability, was evaluated. Among the composite flours, MS recorded higher swelling power and water holding capacity. The replacement of semolina with GBF resulted in higher resistant starch, 4–5 times enhanced indigestible fraction, phenols, flavonoids and antioxidant activity in pasta. Pronounced increment was also observed in potassium, calcium and magnesium content in blended pasta. Optimal cooking time was reduced with the addition of GBF, whereas it was enhanced with MS. GBF and MS in the blends, decreased the hydrolysis rate (up to 24%) and glycemic index (up to 17%) of pasta. However, the addition of MS beyond 10% negatively influenced springiness and chewiness. Microstructural studies explained the positive structural changes with the addition of GBF and MS. Sensory attributes disclosed that the addition of 25% GBF and 5% MS is a desirable proportion for pasta with a functional characteristics.     

A novel elephant herd optimization model with a deep extreme Learning machine for solar radiation prediction using weather forecasts

The Journal of Supercomputing - In recent times, the exploitation of solar resources has remained a major issue due to increasing energy utilization globally. For effective solar resource...     

Single- and multi-component adsorption of cadmium and zinc using activated carbon derived from bagasse--an agricultural waste

The use of low-cost activated carbon derived from bagasse, an agricultural waste material, has been investigated as a replacement for the current expensive methods of removing heavy metals from wastewater. With a view to find a suitable application of the material, activated carbon has been derived, characterized and utilized for the removal of cadmium and zinc. The uptake of cadmium was found to be slightly greater than that of zinc and the sorption capacity increases with increase in temperature. The adsorption studies were carried out both in single- and multi-component systems. Adsorption data on derived carbon follows both the Freundlich and Langmuir models. The data are better fitted by the Freundlich isotherm as compared to Langmuir in both the single- and multi-component systems. Isotherms have been used to obtain the thermodynamic parameters. The kinetics of adsorption depends on the adsorbate concentration and the physical and chemical characteristics of the adsorbent. Studies were conducted to delineate the effect of temperature, initial adsorbate concentration, particle size of the adsorbent and solid-to-liquid ratio. On the basis of these studies, various parameters such as mass transfer coefficient, effective diffusion coefficient, activation energy and entropy of activation were evaluated to establish the mechanisms. It was concluded that the adsorption occurs through a film diffusion mechanism at low as well as at higher concentrations.     

Renewable energy scenario in Telangana

ABSTRACT

This article presents an analysis of the current situation of renewable energy in Telangana, India, and predicts the future of renewable energy resources in the state. In India, maximum power is generated using conventional energy sources such as coal and mineral oil. They highly pollute the atmosphere. If new power plants are to be set up, then the import of highly volatile fossil fuels is inevitable. Though nuclear energy is a good alternative to reduce fossil fuel consumption, it is equally hazardous to human life. Hence, the energy world should think of judicious use of renewable energy resources such as solar, wind, ocean, biomass, and geothermal energy. The R&D activities carried out in India in the past three decades have shown good progress in finding a feasible solution to the problem of searching new renewable energy resources. Telangana is the state committed to use the renewable resources in a better way to fulfil its electrical energy needs. This article also analyses the current energy needs of the state and forecasts energy consumption and production in the future with the aim of finding whether the state can continue on the path of development and augment its renewable energy resources.     

Effect of exhaust gas recirculation on a nanoparticle-doped biodiesel- and diesel-blends-fuelled diesel engine

ABSTRACT

This work investigates the effect of adding Cerium oxide nanoparticles at different proportions (30, 60 and 90?ppm) to Calophyllum inophyllum methyl ester and diesel blends (20% CI methyl ester and 80% diesel) in a four-stroke single-cylinder diesel engine. Addition of nanoparticles is a strategy to reduce emission and to improve the performance of the biodiesel. Modified fuels are introduced into the engine by admitting exhaust gas recirculation (EGR) at a rate of 10% and 20% so as to reduce nitrogen oxide (NO_X) emissions from biodiesel and diesel blends. Results revealed a significant reduction in emissions (CO, NO_X, HC and Smoke) at a 10% EGR rate. However, brake thermal efficiency is reduced with an increase in brake-specific fuel consumption at higher EGR rates. Hence, it is observed that 10% EGR rate is an effective method to control the emission of biodiesel and diesel blends without compromising much on engine efficiency.     

Performance analysis of evacuated tubes coupled solar still with double basin solar still and solid fins

ABSTRACT

Experimental set up of double basin solar still with evacuated tubes has been fabricated by locally available materials and then carry out research work by use of solid fins. Here 2.5?cm constant depth of water maintained and 3?cm depth mild steel fins are used. Experimental results have been obtained during month of March and April 2018 during clear sky days. Month of March 2018 is chosen for experiments on double basin solar still with evacuated tubes only and April 2018 is chosen for experiments on double basin solar still with evacuated tubes and fins. After series of experiments, it has been found that, the fins increase 25% distillate output compared with alone double basin solar still with evacuated tubes. It also increases distillate output during sunshine hours as well as off-sunshine hours.     

Genotype diversity of Escherichia coli isolates in natural waters determined by PFGE and ERIC-PCR

Most library-dependent bacterial source tracking studies using Escherichia coli (E. coli) have focused on strain diversity of isolates obtained from known human and animal faecal sources for library development. In contrast, this study evaluated the genotype variation of E. coli isolated from natural surface water using pulsed field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus sequence polymerase chain reaction (ERIC-PCR) to better understand these naturally occurring populations. A total of 650 water samples were collected over a nine month period from eleven sampling stations from Lake Waco and Belton Lake in Central Texas. Of the 650 water samples collected, 412 were positive for E. coli, yielding a total of 631 E. coli isolates (1-12 isolates collected per sample). PFGE and ERIC-PCR patterns were successfully generated for 555 isolates and were compared using the curve-based Pearson's product-moment correlation coefficient. The 555 E. coli isolates represented 461 PFGE genotypes, with 84% (386/461) of the genotypes being represented by individual isolates. The remaining 75 genotypes were represented by 2-5 isolates each. Using ERIC-PCR, the 555 E. coli isolates represented 175 genotypes, with 63% (109/175) of the genotypes being represented by individual isolates. In contrast to the PFGE results, two ERIC-PCR genotypes represented 37% of the E. coli isolates, (83 and 124 isolates, respectively), and were found throughout the watersheds both spatially and temporally. Based on the PFGE genotype diversity of water isolates, there is little evidence that a small number of environmentally-adapted E. coli represent dominant populations in the studied waterbodies. However, with the lower discriminatory power technique ERIC-PCR, an opposing conclusion might have been drawn. These results emphasize the importance of considering the resolving power of the source tracking technique being used when assessing strain diversity and geographical stability.