Varying Dye Concentration Research Articles

Optimization Photodegradation of Methylene Blue Dye using Bentonite/PDA/Fe3O4@CuO Composite by Response Surface Methodology

This study aims to synthesize bentonite/PDA/Fe3O4@CuO composites as a catalyst for the photodegradation of Methylene blue dye. Composite characterization involves X-ray Diffractometry (XRD), Scanning Electron Microscopy (SEM) with X-ray Energy Dispersion Spectrometry (EDS), UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis DRS), and Vibrating Sample Magnetometer (VSM). Response Surface Methodology (RSM) employs Central Composite Design (CCD) to optimize photodegradation by varying dye concentration, irradiation time, and catalyst dose. The bentonite/PDA/Fe3O4@CuO composites exhibit a saturation magnetization value of 54.82 emu/g and a band gap of 2.1 eV. The optimization revealed that concentration and dose significantly impact the photodegradation efficiency. A quadratic model is suitable for modeling the photodegradation of Methylene blue dye using bentonite/PDA/Fe3O4@CuO composites, as determined by analysis of variance (ANOVA). The optimal conditions for achieving maximum photodegradation efficiency were identified as a dye concentration of 10 mg/L, an exposure time of 90 min, and a catalyst dose of 1.67 g/L. Under these parameters, the photodegradation process exhibited a remarkable efficiency of 100%. The Bentonite/PDA/Fe3O4@CuO composites exhibited strong stability, efficiency, and recyclability. After six photodegradation cycles, there was a 5.18% decrease in photodegradation efficiency. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Development of a Sensitive Colorimetric Indicator for Detecting Beef Spoilage in Smart Packaging.

This study aimed to fabricate and characterize a novel colorimetric indicator designed to detect ammonia (NH3) and monitor meat freshness. The sensing platform was constructed using electrospun nanofibers made from polylactic acid (PLA), which were then impregnated with anthocyanins as a natural pH-sensitive dye, extracted from red cabbage. This research involved investigating the relationship between the various concentrations of anthocyanins and the colorimetric platform's efficiency when exposed to ammonia vapor. Scanning electron microscope (SEM) results were used to examine the morphology and structure of the nanofiber mats before and after the dip-coating process. The study also delved into the selectivity of the indicator when exposed to various volatile organic compounds (VOCs) and their stability under extreme humidity levels. Furthermore, the platform's sensitivity was evaluated as it encountered ammonia (NH3) in concentrations ranging from 1 to 100 ppm, with varying dye concentrations. The developed indicator demonstrated an exceptional detection limit of 1 ppm of MH3 within just 30 min, making it highly sensitive to subtle changes in gas concentration. The indicator proved effective in assessing meat freshness by detecting spoilage levels in beef over time. It reliably identified spoilage after 10 h and 7 days, corresponding to bacterial growth thresholds (107 CFU/mL), both at room temperature and in refrigerated environments, respectively. With its simple visual detection mechanism, the platform offered a straightforward and user-friendly solution for consumers and industry professionals alike to monitor packaged beef freshness, enhancing food safety and quality assurance.

Characterization of Near Infrared-Dye Colored Fabrics Using Hyperspectral Imaging.

Near-infrared (NIR) dyes have a unique ability to interact favorably with light in the NIR region, which is particularly interesting where stealth and camouflage are paramount, such as in military uniforms. Characterization of cotton fabric dyed with NIR-absorbing dyes using visible-NIR (Vis-NIR) and short-wave infrared (SWIR) hyperspectral imaging was done. The aim of the study was to discern spectral changes caused by variations in dye concentration and dyeing temperature as these parameters directly influence color- and crocking-fastness of fabrics impacting the camouflage effect. The fabric was dyed at three concentrations (2.5, 5, and 10%) and two dyeing temperatures (55 °C and 85 °C) and principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were performed on the spectra to discriminate the fabrics based on dye concentrations. The PCA models successfully segregated the fabrics based on the dye concentration and dyeing temperature, while PLS-DA models demonstrated classification accuracies between 75 and 100% in the Vis-NIR range. Spectra in the SWIR region could not be used to detect the differences in the concentrations of the NIR dyes. This finding is promising, as it aligns with the objective of creating NIR-dyed camouflage fabrics that remain indistinguishable under varying dye concentrations. These results open possibilities for further exploration in enhancing the stealth capabilities of textiles in military applications.

Crystallization-driven tuneable lasing of perylene doped into the nematic liquid crystal

Versatile devices with tunable capabilities for controlling lasing wavelength and intensity are in high demand. Liquid crystals (LCs) exhibit immense potential for such applications, offering fine-tuning possibilities through external factors. On the other hand, laser technology is currently a research hotspot in optoelectronics, and also in practical applications. The recent market introduction of laser television marks a significant stride toward making such advanced technology accessible in every household. In synergy with laser pumping, the LCs unquestionably can be rediscovered. This study presents a comprehensive investigation into the crystallization phenomenon within a host-guest device, compact in size, free from moving parts, and integrating the liquid crystalline (LC) matrix doped with 3,4,9,10-tetra-(3-alcoxy-carbonyl)-perylene (THCP) dye. The focus lies in examining the influence of varying dye concentrations on multicolor fluorescence, lasing behavior, and device morphology. The systematic analysis of Random Lasing (RL) energy thresholds and the impact of DC voltage on light intensity modulation is demonstrated. Morphological changes were monitored in real-time using optical microscopy techniques, including crossed polarizer, and fluorescence imaging under 450 nm excitation. Utilizing advanced Transmission Electron Microscopy (TEM) techniques, we explore exceptional insights into our set of devices, providing novel information about the THCP crystallization process for the first time in the literature. To gain a comprehensive understanding of the crystal forming and molecular geometry we examined additionally the THCP dye, using X-ray diffraction and Raman spectroscopy. Furthermore, we showcase that varying the pumping energy enables multicolor tuning in the fabricated systems, presenting an attractive feature in the context of laser display technologies.

Simultaneous film temperature and film thickness measurements for jet impingement applications using two-color laser-induced fluorescence

The study investigates a jet impingement cooling process of a cylindrical geometry relevant for electric and electronic applications. The applied two-color detection technique enables a simultaneous determination of film temperature and film thickness. For this purpose, the heat transfer oil Marlotherm LH was doped with the temperature-sensitive fluorescence tracer nile red. The temperature determination was realized by suitable band pass filters. Preliminary spectral investigations were carried out in terms of varying dye concentration, temperature and film thickness. At high dye concentrations (up to 37.5 mg/L), reabsorption effects lead to a spectral shift toward higher wavelengths with increasing film thickness. Low dye concentrations (0.29 mg/L, 0.59 mg/L) show no film thickness dependent spectral shift. A film temperature investigation at low dye concentration showed no bias of the intensity ratio due to film thickness, i.e., no additional spectral shift toward lower wavelengths was observed. The investigations on the jet impingement setup revealed an increasing film temperature and decreasing film thickness with increasing solid temperature. The average film temperature increases with increasing solid temperature from 298 (solid temperature 298 K) to 308 K (solid temperature 398 K). At higher solid temperatures, the film temperature increases with distance to the stagnation zone. The average film thickness decreases with increasing solid temperature from 0.24 to 0.17 mm. At high solid temperatures, the film temperature increased with radial distance to the stagnation zone. This behavior is caused by the increasing temperature gradient with increasing solid temperature and decreasing viscosity with increasing film temperature.

Fabrication of Tuneable Tissue-Mimicking Phantom for Optical Methods.

Tissue mimicking optical phantoms are commonly used to calibrate or validate the performance of near-infrared spectroscopy or tomography. Human tissue is not only irregular in shape, but also exhibits dynamic behaviour, which can cause changes in optical properties. However, existing phantoms lack complex structures and/or continuously varying optical properties. The project aimed to design, fabricate and characterise a novel phantom system for testing near-infrared imaging devices. We designed a dynamic tissue-mimicking phantom platform which features arbitrary internal shapes and variable optical properties. The solid part of phantom was made of silicone material with absorbing and scattering properties similar to the brain. We printed a semi-ellipsoidal sphere (a major axis=20 mmand a minor axis=the third axis=12 mm) using a water-soluble material polyvinyl alcohol (PVA). The shape was placed at the depth of 5 mm in the silicone bulk. The desired internal hollow structure was formed after curing and submerging the phantom in water. The liquid part contained dyes and Intralipid. The optical properties within the internal shape were adjusted by injecting the liquid solutions of varying dye concentrations with a syringe pump at a constant rate. The phantom was measured by a frequency domain near-infrared spectroscopy (FD NIRS) and imaged by a time domain near-infrared optical tomography (TD NIROT). A dynamic phantom system with a complex internal structure and varying optical properties was created. Changes in light intensity were detected by the FD NIRS. The internal structure of this phantom was accurately recovered by NIROT image reconstruction. We successfully developed a novel phantom system with an internal complex shape and continuously adjustable optical properties. This phantom was accurately imaged using NIROT, and the changing light intensity was detected by NIRS. It is a valuable tool for validating optical technologies.

Removal of Brilliant Green Cationic Dye Using Bioadsorbent Material from Oyster Shells

This study explored the potential of coral rock, specifically coquina derived from oyster shells, as a bioadsorbent for the removal of dyes from wastewater generated by the textile industry. The investigation included an examination of particle size fractions (300 µm and less than 300 µm) and thermal treatment; the investigation involved drying at 120 °C and calcination at temperatures ranging from 200 °C to 800 °C. The material was subjected to a comprehensive analysis through various characterization techniques. Laboratory-scale experiments were conducted to evaluate the removal capacity and adsorption kinetics of the bioadsorbent utilizing brilliant green dye. The experiments involved varying dye concentrations (25, 50, and 75 mg L−1), pH levels (2 to 12), and different doses of biosorbent material (0.2 to 0.6 g L−1), with constant agitation. Various kinetic models were applied to fit the experimental data, with the pseudo-second-order model demonstrating the best fit. The findings reveal that coquina rock, characterized by a temperature of 120 °C and a particle size of greater than 300 µm, exhibits remarkable effectiveness. It achieved a removal efficiency of 90% within 15 to 20 min at pH 7.8. This study concludes that coquina rock not only stands out as demonstrating remarkable efficacy in dye removal but also underscores a sustainable approach, leveraging readily available and environmentally friendly materials for wastewater treatment.

Amorphous iron oxyhydroxides nano precursors used for Reactive Yellow 84 removal from aqueous solutions

In this research, we investigated the potential use of amorphous iron oxyhydroxides, ferrihydrite (FHY), for the removal of persistent pollutants from aqueous solutions. Ethylenediaminetetraacetic acid (EDTA) and ethylenediamine-N, N′-disuccinic acid (EDDS) were used as complexing agents during synthesis aiming to enhance the FHY properties. Synthesized materials were characterized by X-ray diffraction, SEM and TEM Microscopy, N2 sorption/desorption, and FT-IR Spectroscopy for their mineralogy, crystallinity, morphology and size, surface properties, and the organic content in their structure. The addition of chelating agents led to differences in nanoparticles morphology, amorphic degree, and surface properties. Reactive Yellow 84 dye was chosen as a representative refractory pollutant and laboratory-scale adsorption studies were conducted at varying dye concentrations. Ca. 100 % RY 84 dye removal efficiency was achieved within one hour at dye concentrations of 5–10 mg/L for an adsorbent dosage of 1 mg/L FHY. Adsorption kinetics and isothermal studies were considered, the uptake capacity was calculated for each nanomaterial and empiric mechanistic information was derived. The results showed that ferrihydrite exhibits the best performance, with a maximum uptake capacity of 40.73 mg Reactive Yellow 84 dye per gram adsorbent followed by FHY_EDTA and FHY_EDDS (up to 35.86 mg/g). Coupling the adsorption with photodegradation processes led to a significant increase in removal efficiencies of persistent RY 84 from polluted aqueous solution, in good timing, suggesting a feasible alternative at sites where dye concentration in effluents is elevated.

Preparation of Breadfruit Leaf Biochar for the Application of Congo Red Dye Removal from Aqueous Solution and Optimization of Factors by RSM-BBD

In this work, biochar produced from breadfruit leaves was utilized to remove the toxic Congo red dye. XRD, FTIR, and FESEM-EDX were implemented to characterize the biochar. Response surface methodology (RSM) and the Box-Behnken design (BBD) techniques were used to evaluate Congo red’s optimum adsorption efficiency. The adsorption of Congo red was studied by varying dye concentrations (5–50 mg/L), times (30–240 min), pH (6–9), and dosages (0.5–2 g/100 mL). X-ray diffractometer results show that the structure of biochar is amorphous. The biochar exhibited unbounded OH, aliphatic CH group, and C=O stretch, as shown by the band peaks at 3340 cm−1, 2924 cm−1, and 1625 cm−1 intensities. RSM-BBD design results showed maximum removal efficiency of 99.96% for Congo red at pH 6.37, dye concentration 45 mg/L, time 105 min, and dosage 1.92 g, respectively. The adsorption of Congo red by biochar was successfully modeled using the Langmuir model and pseudo-second-order model. The biochar produced from breadfruit leaves exhibited a high adsorption capacity of 17.81 mg/g for Congo red adsorption. It suggests that the adsorption is both homogenous monolayer and physicochemical.

One-bath one-dye class dyeing of polyester/cotton blend fabric with disperse dye after esterification of cotton fabric

Most often, reactive and disperse dyes are utilized separately in two- bath two-step dyeing method to dye polyester-cotton blend fabric. The cost of this conventional dyeing method is very expensive; energy and chemical usage is also quite higher in addition to this, the dyeing cycle is complex as compared to one-bath two-step dyeing methods or single-bath single-step dyeing methods. The single-bath single-step dyeing procedure with a single type of dye class was studied in this research. Following surface treatment of cotton through esterification procedures, polyester-cotton blend fabric dyed in single-bath single-step dyeing processes with disperse dye was examined. The association between time and the percentage of esterification was investigated at room temperature. Varying dye concentrations and dyeing temperatures were utilized to dye surface-treated p/c blend fabric in an HTHP dyeing machine. The color strength of dyed material and their fastness properties and the Surface chemistry by using FTIR were evaluated. The influence of dye concentration and temperature on color strength was investigated. With a 15% esterifying agent concentration and a reaction period of 2.5 h, the optimum value for surface modification was obtained, yielding a percent esterification of 34.95. The optimal value was attained with a dye concentration above 1% at a temperature of 120 °C, according to the dyeing experiment results. The findings of this study revealed that when compared to conventional two-bath dyed fabric, one-step one-bath dyed modified polyester/cotton blend with Disperse dye fabric has good wash fastness, and color strength, and is environmentally friendly.

Piezo-photocatalytic activity of Bi2VO5.5 for methylene blue dye degradation

This study comprises the combined effect of piezocatalytic and photocatalytic activity to obtain improved piezo-photocatalytic dye degradation efficiency in visible light. Single-phase Bi2VO5.5 powder was prepared through solid-state synthesis at 750 °C in 8 h. Time-dependent photocurrent responses were conducted to understand the phenomenon of charge carrier transport in visible light. Bi2VO5.5 powder sample demonstrated high photocatalytic efficiency and good reusability possessing a bandgap value of 2.13 eV. Bi2VO5.5 powder sample attained ∼70% and ∼58% degradation efficiency during photocatalysis and piezocatalysis respectively. The piezo-photocatalytic methylene blue dye attained ∼82% degradation efficiency in 240 min duration of visible light illumination. The scavenger test depicted holes (h+) as the principal active species in the piezo-photocatalytic dye degradation. There incurred no severe loss in photocatalytic efficiency even after 4 cycles which proclaims the reusability of the Bi2VO5.5 powder sample. A study on the kinetic rate constant with varying dye concentrations was conducted. With varied dye concentration of 5, 10, 15 mg/L, the kinetic rate constant obtained was 0.00528, 0.0030, and 0.00125 min−1, respectively. Germination index was found through a phytotoxicity test using vigna radiata seeds. Here visible light along with mechanical energy has been used to achieve higher MB dye degradation efficiency through piezo-photocatalysis.

Enhancing morphological, electro-optical and dielectric properties of polymer-dispersed liquid crystal by doping of disperse Orange 25 dye in LC E7

ABSTRACT In this work, we have investigated morphological, electro-optical and dielectric properties of disperse orange 25 dye-doped polymer-dispersed liquid crystal (DPDLC) films. The DPDLC film composed of monomer Norland optical adhesive (NOA 65), nematic liquid crystal (E7), and disperse orange 25 dye was prepared through the polymerisation-induced phase separation (PIPS) method. The polarising optical microscope (POM) has been utilised to observe the effect of dye concentration and voltage on liquid crystal (LC) droplet morphology. The electro-optical properties of such DPDLC films were studied at a fixed frequency of 200 Hz and different voltage and temperature conditions (0–100 V, 25–50°C). The change in absorbance value with varying dye concentration and the electric field was monitored through a UV-Vis spectrophotometer. Dielectric relaxation characteristics of DPDLC films were examined using a precision impedance analyser in the frequency range 20 Hz–20 MHz and temperature range 25–60°C. Debye and Cole-Cole fitting techniques were used to describe the dielectric properties of DPDLC films.

Synthesis and catalytic evaluation of silver@nickel oxide and alginate biopolymer nanocomposite hydrogel beads

In this study, silver–nickel oxide/calcium alginate (Ag@NiO/Alg) hydrogel beads were synthesized by incorporating the nanomaterial into the polymer solution followed by their extrusion from a syringe to coagulating solution for crosslinking. The Ag@NiO/Alg beads formed through this procedure were characterized by different instrumental techniques. The catalytic efficiency of Ag@NiO/Alg was evaluated for the reduction of rhodamine B (RhB) and methyl orange (MO), in the presence of sodium borohydride. After applying various kinetic order equations to the experimental data, the reactions were found to follow pseudo-first order kinetics using the Ag@NiO/Alg catalyst. The apparent rate constant (kapp) was determined as 0.33358 min−1 and 0.20882 min−1 for the catalytic reduction of RhB and MO, respectively. Furthermore, reduction reactions were studied at varying dye concentration and catalyst dosages. The recovered catalyst was reused up to five cycles without significant drop in the activity.

Fluorescence Spectroscopy for Studying Evaporating Droplets Using the Dye Eosin-Y.

Laser-induced fluorescence (LIF) spectroscopy using dyes is frequently applied for characterization of liquids and two-phase flows. The technique is utilized e.g., for mixing studies, thermometry, or droplet sizing. One major application of the LIF technique combined with Mie-scattering is the planar measurement of droplet sizes in spray systems. However, its uncertainty is determined, among others, by varying dye concentration and temperature changes occurring during mixing and droplet evaporation. Systematic experimental investigations are necessary to determine the influence of dye enrichment effects on the LIF-signal of single droplets. For these investigations, the fluorescence dye Eosin-Y is dissolved in water and ethanol, which are typical solvents and working fluids in bio-medical applications and power engineering. A photo-physical characterization of the mixtures under various conditions was conducted using a spectrometric LIF setup and a micro cell. For ethanol, a small temperature dependency of the Eosin-Y LIF signal is observed up to 373 K. Photo-dissociation of Eosin-Y is negligible for solution in ethanol while it is distinct in water. The LIF signals of the single droplets are studied with an acoustic levitator. Effects of droplet evaporation, droplet deformation and varying dye concentration on the LIF-signal are studied. The single droplet measurements revealed a complex change of the fluorescence signal with reduced droplet size. This is due to droplet deformations leading to variations in the internal illumination field as well as dye enrichment during evaporation.

Bioremoval of methylene blue from aqueous solutions by Syringa vulgaris L. hull biomass

The adsorption capacity of Syringa vulgaris L. (the common lilac) hull was investigated in this study for methylene blue dye removal. Biosorption assays were performed with varying dye concentration, contact time, pH, biosorbent dosage and temperature. Besides, the equilibrium, thermodynamics and kinetics of the process were designated for the evaluation of the biosorption process. According to the results, removal of the dye reached up to 97.5% for the optimized reaction conditions (adsorbent dose: 2.5 g; stirring speed: 150 rpm; initial dye conc. 5 mg/L; temperature: 333 K; agitation time: 30 min and pH: 6). Kinetic study recommended the pseudo-second order kinetic model with regression coefficient (R2 > 0.999) as being able to better define kinetic data than pseudo-first order and Elovich kinetic models. The biosorption isotherm data were analyzed using Freundlich, Langmuir, Dubinin–Radushkevich and Temkin isotherms for the proposed biosorption process. The endothermic and spontaneous nature of the proposed process was revealed by the thermodynamic studies. Finally, it is concluded that S. vulgaris L. hull biomass can be employed as an economically reasonable, eco-friendly, and sustainable biosorbent in the treatment of industrial effluents containing methylene blue-like dyes.

Catalytic potential of cobalt oxide and agar nanocomposite hydrogel for the chemical reduction of organic pollutants

In this study, cobalt oxide nanoparticles (Co3O4 NPs) were synthesized by precipitation method from cobalt sulphate solution with basic pH, followed by calcination. The ex-situ synthesized Co3O4 NPs were mixed with hot agar (AG) aqueous solution. The preparation of AG- Co3O4 nanocomposite hydrogel was carried out by self-association method promoted by thermal denaturation. The quenching of hot suspension from 80 °C to room temperature resulted in the formation of AG-Co3O4 nanocomposite hydrogel. The as-synthesized AG-Co3O4 was characterized by FTIR, XRD and SEM techniques. In order to test the catalytic activity, AG-Co3O4 was used as a heterogeneous catalyst for the reduction of methylene blue (MB), congo red (CR) and 4-nitrophenol (4-NP). The excellent performance of the AG-Co3O4 was shown by the reaction rate constant (kapp) values of 0.3623, 0.2114 and 0.2893 for MB, 4-NP and CR, respectively. All these results were obtained with R2 above 94 and utilization of an AG-Co3O4 catalyst. Furthermore, the catalytic reduction was studied with varying dye concentration and catalyst dose. This study showed that AG-Co3O4 catalyst has high potential for remediation of environmental pollutants in wastewaters.

Simulation of a Novel Configuration for Luminescent Solar Concentrator Photovoltaic Devices Using Bifacial Silicon Solar Cells

In this study, a novel configuration for luminescent solar concentrator photovoltaic (LSC PV) devices is presented, with vertically placed bifacial PV solar cells made of mono-crystalline silicon (mono c-Si). This LSC PV device comprises multiple rectangular cuboid lightguides, made of poly (methyl methacrylate) (PMMA), containing Lumogen dyes, in particular, either Lumogen red 305 or orange 240. The bifacial solar cells are located in between these lightguide cubes and can, therefore, receive irradiance at both of their surfaces. The main aim of this study is to theoretically determine the power conversion efficiency (PCE) of five differently configured LSC PV devices. For this purpose, Monte Carlo ray tracing simulations were executed to analyze the irradiance at receiving PV cell surfaces, as well as the optical performance of these LSC PV devices. Five different LSC PV devices, with different geometries and varying dye concentrations, were modeled. To maximize the device efficiency, the bifacial cells were also attached to the back side of the lightguides. The ray tracing simulations resulted in a maximum efficiency of 16.9% under standard test conditions (STC) for a 15 × 15 cm2 LSC PV device, consisting of nine rectangular cuboid 5 × 5 × 1 cm3 PMMA lightguides with 5 ppm orange 240 dye, with 12 vertically positioned 5 × 1 cm2 bifacial cells in between the lightguides and nine 5 × 5 cm2 PV cells attached to the back of the device. If the cells are not applied to the back of this LSC PV device configuration, the maximum PCE will be 2.9% (under STC), where the LSC PV device consists of 25 cubical 1 × 1 × 1 cm3 PMMA lightguides with 110 ppm red 305 dye and 40 vertically oriented bifacial PV cells of 1 × 1 cm2 in between the lightguides. These results show the vast future potential for LSC PV technologies, with a higher performance and efficiency than the common threshold PCE for LSC PV devices of 10%.

Biological treatment of red bronze dye through anaerobic process

Industries that are ever increasing are major contributors to environmental pollution due to inappropriate waste handling. Textile wastewater contains mutagenic and carcinogenic chemicals which are harmful to natural phenomenon of receiving water channels. Therefore, textile wastes should be treated before discharging in the environment. Treatment of red bronze dye was investigated in the upflow anaerobic bioreactor. Varying dye concentrations (40~325 mg/L) were treated by adjusting primary pH at neutral. The performance of reactor was judged by conventional process parameters like pH, turbidity, dissolved oxygen (DO), electroconductivity (EC), total dissolve solids (TDS), removal efficiency, and chemical oxygen demand (COD). The maximum removal efficiency occurred at 150 mg/L dye concentration with addition of 50 ml of biomass. The pH of the water remained basic, COD removal ranged between 60 and 91%, and the maximum removal was done at 91%. EC and TDS were also low indicating good dye removal efficiency of the reactor.

Nanoreactor based enhancement of photocatalysis with Co0.7Zn0.3Fe2O4@SrTiO3 core-shell nanocomposites

The activity of nanocatalysts on photocatalysis needs to be comprehensively understood based on different parameters affecting its performance. Also, magnetically recoverable nanocatalysts combining decent magnetization, effective adsorption and efficient photocatalysis is a necessity for future water purification schemes. In this context, the synthesis of core-shell nanostructures and understanding of nanostructure driven catalytic activity gains huge significance. Influence of pore hierarchy on the adsorption and photocatalytic efficiency is an emerging topic of investigation. Here, the Co0.7Zn0.3Fe2O4-SrTiO3 nanocomposites (CZFO@STO) were synthesized by hydrothermal route. TEM images confirmed core-shell morphology. CZFO@STO exhibited enhanced macroporosity as evaluated by BET analysis. The XPS studies indicated formation of a straddling type heterojunction extending the optical activity of STO to visible region. The CZFO@STO exhibited a high visible light photocatalytic activity rate constant of 5.08 × 10−1 min−1 on Congo Red. The origin of the enhanced activity attributed to nanostructuring as indicated by experiment varying dye concentration. The adsorption of Congo Red and Methylene Blue in single and binary system onto CZFO@STO was explained based on Langmuir isotherm and pseudo-second-order model. As a photocatalyst, the CZFO@STO are magnetically recoverable and exhibited good recycling properties even in binary impurity system. An understanding of the enhanced catalytic activity is developed based on the adsorption capacity of dyes, scheme of adsorption, hierarchy of pores and advantages offered by core-shell nanostructuring including enrichment by shell and formation of a nanoreactor. The study could catapult bigger role for core-shell nanocomposites in adsorption driven fields of applications like catalysis, gas capture, sensing and energy storage.

Lasing of optically pumped large droplets: instant and gradual blueshift

Results for the interaction of a 532 nm pulsed laser beam with individual pendant rhodamine 6G dye droplets of a large-size parameter, x≈7300, are reported. By varying dye concentration and pumping energy, typical fluorescence bands detected in such cases are obtained, along with a narrow, instantly, or gradually blueshifted band assigned to the lasing effect at the droplet surface. The maximum blueshift value of the lasing peak wavelength is associated with the maximum of the dye fluorescence gain curve when self-absorption effects are not present. Lasing peak position is not further influenced by pumping energy or droplet diameter decrease after lasing reaches the gain curve peak wavelength.