UV-vis Absorption Spectroscopy Analysis Research Articles

Treatment of Automotive Paint Wastewater: Photocatalytic degradation of methylene blue using semi-conductive ZrO2

Addressing water pollution, particularly in the automotive industry's painting processes, is vital due to its significant environmental impact, and the use of photocatalysis, an environmentally friendly and energy-efficient advanced oxidation method, holds promise for removing non-biodegradable organic dyes from wastewater. In this study, the use of semiconductor ZrO2 nanoparticles in the photocatalytic degradation of pollutants in wastewater under UV light was investigated. Zeta potential, Brunauer–Emmett–Teller (BET) surface area and UV-Vis absorption spectroscopy analyses were performed on the ZrO2 nanoparticle synthesized under optimized experimental conditions. ZrO2 nanoparticles synthesized under the optimized experimental conditions exhibited a high specific surface area (51.793 m2/g). ZrO2 nanoparticles had strong absorption in the visible light region, and the energy band gap was estimated to be approximately 3.062 eV. The photocatalytic activity was evaluated by the degradation of methylene blue under UV light (366 nm). The effects of parameters such as the amount of catalyst, concentration and pH of the dye solution, the wavelength of the UV light source used (366 and 254 nm) and the type of test environment on the removal efficiency of methylene blue were investigated. ZrO2 nanoparticles showed a high degradation efficiency of 91% in a strong alkaline environment, which may be the result of the facilitated formation of –OH radicals due to the increased concentration of hydroxyl ions.

Effects of the ionizing irradiation of γ-rays, X-rays, and UV-rays on the optical properties of Ag-contained/Ag-free photo-thermo-refractive glass

To simulate the effects of ionizing irradiation on photo-thermo-refractive (PTR) glass in a cosmic environment, the optical properties changes under ionizing irradiation (γ-, X- and UV-ray) were investigated on PTR-glass with and without Ag doped (named as PTR-S and PTR-F, respectively) samples. Thermoluminescence (TL), transmission electron microscopy (TEM) measurements, UV-VIS absorption spectroscopy analysis, Gaussian peak fitting, and continuous wave electron paramagnetic resonance (CW-EPR) were used to determine the species of the irradiation-induced color centers. The radiation resistance properties of the Ag-species on the PTR-S glass were evaluated by comparing the defect center concentrations in the irradiated PTR-S and PTR-F glasses. The results showed that absorption in PTR-F and PTR-S glass increased significantly with increasing γ-irradiation dose, which was related to HC1, HC2, E′, L, ETC defect centers and Ag-species, and the formation of HC1, HC2, E’, and L-centers was reduced by the doping of Ag into the PTR-S glass matrix. Compared with the γ-irradiation, X-irradiation showed a similar effect. In comparison, UV-irradiation induced fewer defect centers and smaller Ag (NPs). This discrepancy could be caused by variations in photon energies.

Correlation between degree of crystallinity and bluing of Zn1–xCoxAl2O4 (0≤x≤1) nanopowders prepared by soft chemistry route

In this article, we report a facile precursor pyrolysis by sol-gel method to prepare spinel-type Cobalt-substituted zinc aluminate nanoparticles (Zn1–xCoxAl2O4, 0 ≤ x ≤ 1). The relationship between the degree of crystallinity and the optical properties under the effect of the calcination temperature was investigated. The synthesised powders were characterized by means of X-ray diffraction (XRD), Thermogravimetry and Differential thermal analysis (TG–DTA), field emission scanning electron microscopy (FE-SEM), Brunauer–Emmett–Teller analysis (BET), UV–Vis absorption spectroscopy analysis and colorimetric analysis (CIELab). A single-phase Zn1–xCoxAl2O4 (0 ≤ x ≤ 1) spinel was formed at an annealing temperature of 700 °C. Structural refinement via the Rietveld method shows that an annealing temperature in excess of 700 °C leads to a decrease in the amorphous phase rate. At 800 °C, the enrichment in 50% of cobalt leads to blue powders with a degree of crystallinity of approximately 92% and a quasi-spherical morphology of nanometric size less than 100 nm.

Electric modulus approach to the analysis of electric relaxation and magnetodielectric effect in reduced graphene oxide–poly(vinyl alcohol) nanocomposite

The polymers poly(vinyl alcohol) (PVA) is used as matrices to synthesize a nanocomposite with reduced graphene oxide (rGO). The structural and optical properties of the rGO and the nanocomposites (rGO–PVA) are studied by XRD, FTIR analysis, FESEM studies, Raman spectroscopy and UV–VIS absorption spectroscopy analysis. Interaction of PVA polymer chains with rGO is confirmed from FTIR study. The bandgap of the PVA and rGO–PVA nanocomposites has been studied from UV–VIS absorption spectrum. The refractive index and optical dielectric constants of PVA, GO, rGO and rGO–PVA nanocomposites have been discussed from optical spectrum analysis. The visual structures of the GO, rGO and rGO–PVA nanocomposites are observed from FESEM study. The electric modulus M*(ɷ) formalism used in the analysis enabled us to distinguish and separate the relaxation processes, dominated by marked conductivity in the e*(ɷ) representation. In the ceramics studies, the relaxation times are thermally activated and the dipole process has a clearly non-Debye behaviour. The relaxation process is described with the use of the activation energy of approximately EA = 0.12 eV and the characteristic relaxation time, τ0 = 2.07 × 10–7 s. The dielectric property of the nanocomposite (rGO–PVA) is studied in zero magnetic field and in magnetic field (H) up to 1.2 T. From these data, magnetodielectric effects are obtained as the variation of real (e′) and imaginary (e″) parts of complex dielectric constant with H at some frequencies. In our study at 100 kHz for the increase of H from zero to 1 T e′ decreases by 2.5% in rGO–PVA. This fact is indicative of the interaction between rGO filler particles and PVA polymer chains.

Synthesis and characterization of reduced graphene oxide–V2O5 nanocomposite for enhanced photocatalytic activity under different types of irradiation

Photocatalytic degradation of methylene blue with use of reduced graphene oxide (rGO)-V2O5 nanocomposites under mercury-lamp, visible-light, and UV-light irradiation is investigated. Graphene oxide (GO) synthesized by a modified Hummer's method was reduced to rGO by chemical reduction with hydrazine hydrate. In addition, V2O5 nanorods and rGO-V2O5 nanocomposite were synthesized by a hydrothermal method. The samples prepared were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, UV–vis diffuse reflectance spectra, photoluminescence, and UV–vis absorption analysis. XRD analysis of rGO-V2O5 nanocomposite indicated characteristic peaks of GO and V2O5 nanorods. Different nanostructure morphologies of the samples were revealed by FE-SEM. Raman spectroscopy showed the coexistence of rGO characteristic peaks and different vibrational modes of V2O5. The band gap of V2O5 nanorods (2.26 eV) reduced after graphene decoration to 1.60 eV for rGO-V2O5 nanocomposite. Moreover, unlike V2O5 nanorods, strong photoluminescence quenching in the visible range of the spectrum for rGO-V2O5 nanocomposite was observed. Detailed UV–vis absorption spectroscopy analysis revealed gradual degradation of methylene blue with increasing time under illumination with different irradiation sources. The maximum degradation efficiency for decolorizing methylene blue solution by rGO-V2O5 nanocomposites is about 85% after 255 min of illumination with a mercury lamp.

One-Step Synthesis of CdSe Quantum Dots by Using Hydrazine Hydrate Reduction of Selenium Dioxide

Hydrazine hydrate was used as a novel reducing agent for the synthesis of water soluble and stable cadmium selenide (CdSe) quantum dots (QDs). The as-prepared CdSe quantum dots were investigated by X-ray powder diffraction, high-resolution transmission electron microscopy, photoluminescence, and UV-vis absorption spectroscopy analyses. The results show that the as-prepared CdSe QDs possess a cubic crystal structure and an average size of 2 nm. The effects of the pH of the original solution, thioglycollic acid (TGA)/Cd2+ molar ratio (nTGA/nCd2+), and the Cd/Se molar ratio on the luminescence properties of CdSe QDs were also systematically analysed.

Enhanced photocatalytic reduction of cadmium on calcium ferrite-based nanocomposites by simulated solar radiation

Calcium ferrite-based TiO2 nanomaterials were successfully fabricated via a solid state dispersion method. The prepared products were characterized by XRD, SEM, and UV-Vis absorption spectroscopy analyses and showed strong photo absorption in the UV and visible spectral region. The composite catalyst with 15% TiO2 showed the highest photocatalytic activity and the degradation level of solution containing 10 mg/L cadmium ions was 99.02% after photocatalytic reduction for 180 min under Xe lamp irradiation. The doping of TiO2 into calcium ferrite promoted the efficient separation of photogenerated electrons and holes, and hence fulfilled the effective photocatalytic reduction of Cd2+ under simulated solar light irradiation.

Enhanced visible photocatalytic activity of nitrogen doped single-crystal-like TiO2 by synergistic treatment with urea and mixed nitrates

Abstract

Insights into the Properties of Deep Eutectic Solvent Based on Reline for Ga-Controllable CIGS Solar Cell in One-Step Electrodeposition

A deep eutectic solvent (DES) called Reline has attracted great interests in photovoltaic application. Many efforts have been made to get high efficiency solar cells by electrodeposition in such a low-cost and green electrolyte. In this work, the micro-structure and electrochemical properties of Reline are investigated. The metal complex system of Reline and metal salts is deduced by FTIR and UV-Vis absorption spectroscopy analyses. The theoretical diffusion coefficients of Cu, In and Ga at 65°C are calculated by Cyclic voltammetry analysis to perform a controllable Ga/(In+Ga) ratio over a large range (0 ∼ 0.53) by different pulse potentiostatic methods. Based on these achievements and optimizations, the best CIGS solar cell device with a promising efficiency of 10.1% is achieved.

Facile solvothermal synthesis of MnFe2O4 hollow nanospheres and their photocatalytic degradation of benzene investigated by in situ FTIR

MnFe2O4 hollow nanospheres were successfully fabricated via a facile one-pot solvothermal method. The prepared products were characterized by XRD, SEM, TEM, FTIR and UV–Vis absorption spectroscopy analyses. Benzene can be effectively degradated on the MnFe2O4 nanospheres when irradiated with visible light. By using the in situ FTIR technique, ethyl acetate, carboxylic acid, aldehyde and acetylene could be regarded as the intermediate products, and CO2 was produced as the final mineralization product during the reaction process. Hydroxyl radicals were confirmed as active species in the photocatalytic reaction by the photoluminescence technique.

Junction properties and conduction mechanism of new terbium complexes with triethylene glycol ligand for potential application in organic electronic device

Terbium-picrate triethylene glycol (EO3-Tb-Pic) complex was prepared in thin film and single layer device structure of ITO/EO3-Tb-Pic/Al, using spin coating technique. The UV-Vis absorption spectroscopy analysis was performed to evaluate the electronic molecular transition of the complex. The optical band gap, Eg estimated from the Tauc model revealed that EO3-Tb-Pic thin film exhibited a direct transition with Eg of 2.70 eV. The electronic parameters of the ITO/EO3-Tb-Pic/Al device such as the ideality factor n, barrier height Φb, saturation current Io, and series resistance Rs, were extracted from the conventional lnI-V, Cheung's functions and Norde's method. It was found that the evaluated parameters calculated from Norde's and Cheung's methods were consistent with those calculated from the conventional I-V method. In the double logarithmic I-V plot, three distinct regions based on the slope were identified, and the conduction mechanisms were discussed and explained. The mobility, μ value was estimated from SCLC region as 2.58×10−7 cm2/(V·s). This newly obtained lanthanide complex may be potentially utilized in electronic devices.

Modification of poly (butylene terephthalate) with core-shell nanoparticles containing UV-absorber

A type of core-shell polymer nanoparticles capable of UV-stabilizing and toughening, was synthesized via the two-step emulsion polymerization of butyl acrylate (BA), methyl methacrylate (MMA) and glycidyl methacrylate (GMA), in the presence of 2-hydroxy-4-(3-methacryloxy-2-hydroxyl-proroxy) benzophenone (BPMA) as UV-stabilizing agent. Fourier transformed infrared (FTIR) analysis indicated that BPMA was successfully incorporated into the nanoparticles. The microstructures and microphases were investigated by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) and the results showed that the particles with an average diameter about 80 nm exhibited a core-shell structure and had a low glass transition temperature around −42 °C and a high glass transition temperature around 107 °C. UV–Vis absorption spectroscopy analysis revealed that poly (BA-MMA-BPMA-GMA) nanoparticles maintained almost the same UV-absorbing ability as 2, 4-Dihydroxybenzophenone (UV-0). Moreover, poly (BA-MMA-BPMA-GMA) was well dispersed in the poly (butylene terephthalate) (PBT) matrix as studied by scanning electron microscope (SEM). The mechanical properties before and after UV-irradiation illustrated that both of the UV-stability and toughness of PBT were remarkably improved by the core-shell nanoparticles simultaneously. In addition, thermogravimetry analysis (TGA) showed that PBT/poly (BA-MMA-BPMA-GMA) had better thermal stability than PBT/poly (BA-MMA-GMA)/UV-0 system and the UV-degradation degree of PBT was greatly retarded by poly (BA-MMA-BPMA-GMA).

Synergistic antimicrobial effects of polyaniline combined with silver nanoparticles

AbstractSilver/polyaniline nanocomposites (Ag NPs/PANI) containing PANI nanofiber and Ag nanoparticles were synthesized by one‐step approach without using any extra reducing agent or surfactant and applied to new antimicrobial agents. Morphologies and crystallinity of the nanocomposites were characterized with SEM and XRD. The results showed that the average diameter of the PANI nanofibers is around 50–150 nm, and the average particle size of Ag NPs is around 100 nm. The crystallinity of PANI gets better with increasing silver nitride concentration. UV–vis absorption spectroscopy analysis indicated that the Ag NPs have some effect on the microstructure of PANI. The antimicrobial properties of Ag NPs/PANI against Gram‐negative Escherichia coli, Gram‐positive Staphylococcus aureus and fungous Yeast were evaluated using viable cell counts. The test results demonstrated that Ag NPs/PANI have enhanced antimicrobial efficacy compared to that of pure Ag NPs or pure PANI under the same test condition. The mechanism of the synergistic antimicrobial effect of Ag NPs with PANI was also proposed. In addition, thermal gravity analysis indicated that pure PANI and Ag NPs/PANI exhibit better thermal stability. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Controllable assembly of Ag/C/Ni magnetic nanocables and its low activation energy dehydrogenation catalysis

Double-shelled Ag/C/Ni nanocables have been synthesized through a deposition covering process of Ni nanoparticles (NPs) onto Ag/C pentagonal prism nanowires (NWs). The proposed synthesis mechanism is corroborated by scanning electron microscopy, transition electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV-vis absorption spectroscopy. The resulting Ag/C/Ni nanocables with an average diameter of ∼270 nm are made up of Ag NW core (∼200 nm diameter) with internal amorphous C layer (∼10 nm thickness) and outer Ni shell (∼25 nm thickness). The UV-vis absorption spectroscopy analysis indicates that the covering of the Ni shell on the Ag/C nanowire can dampen the surface plasmon resonance (SPR) of Ag wire core and lead to a red-shifted SPR absorption peak. In particular, compared with Ni NPs, the resultant double-shelled Ag/C/Ni magnetic nanocables exhibits higher catalytic activity for the dehydrogenation toward aqueous ammonia borane under ambient atmosphere, and its calculated activation energy is lower than those of many bimetallic catalysts.