Search

Neurotransmitters are essential chemical messengers required for proper brain function, and any changes in their concentrations can lead to neuronal diseases. Therefore, sensitive and selective detection is crucial. This study presents a fast and simple colorimetric method for dopamine detection using three reagent solutions: AgNP and MPA, Ag/Au nanocomposite, and mercaptophenylacetic acid. TEM images showed a narrow distribution of Ag and Au nanoparticles with average sizes of 20 nm and 13 nm, respectively, with gold nanoparticles bound to the edges of silver nanoparticles. A paper-based biosensor was created using manual wax printing for the colorimetric detection of dopamine. Visual detection onsite showed color changes with both the silver nanoparticles and mercaptophenylacetic acid mixture and the silver–gold nanoparticle composite. Electrochemical detection using a glassy carbon electrode modified with 8 mM mercaptophenylacetic acid demonstrated high selectivity and sensitivity towards dopamine, with a peak in the range of 0.7–0.9 V. Interferences were minimized, ensuring high sensitivity and selective detection of dopamine. [ABSTRACT FROM AUTHOR]

Neodymium and samarium based nanocomposites with efficient photocatalytic activity were synthesized and their structural and morphology were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy techniques. The SEM results of synthesized nanocomposites depict the flaked morphology of graphitic carbon nitride with interlinked stacked structure of metallic framework. UV-visible spectral studies revealed that the absorption edge has been shifted to longer wavelength in samarium and neodymium based samples which results in the decreased band gap of g-C3N4 being used as main precursor. The photocatalytic activity of the synthesized catalysts was assessed by studying the degradation of Rhodamine B and Congo red dyes under visible light. The obtained results depict that Fe2O3/g-C3N4/CNTs/Sm2O3 nanocomposite is more efficient with 86.1% degradation efficiency and 80.2% for Rhodamine B and Congo red as compared to Fe2O3/g-C3N4/CNTs/Nd2O3. Present studies revealed that superoxide ions and holes play significant role in the degradation of dye effluents. Further, the possible mechanism of the photocatalytic degradation of pollutants using samarium based nanocomposites is also proposed. [ABSTRACT FROM AUTHOR]

Azo dyes are extensively used in textile industry but their discharge with industrial effluents pollutes water resources which harms flora and fauna in the environment. Nanomaterials and composites have competent photo-catalytic efficiencies to reduce organic pollutants and inactivate micro-organisms. However, these photocatalysts suffer from structural leaching and instability, which makes their applications limited. The aim of present study is to overcome these limitations and to degrade methyl orange (MO) azo dye by providing organic-inorganic hetero-junction active sites under UV-visible light irradiation. Tween-80 templates were used to prepare porous methyacryl organo silicates (PMOS) by co-condensation of sodium silicate and 3-methacryloxypropyl trimethoxysilane. The fabrication of porous methyacryl organo silicate materials (Ag@PMOS) was carried out by reducing the silver moieties on and in the surfaces of PMOS. The resulting Ag@PMOS scaffolds were studied by Fourier transform infrared spectroscopy, which showed conformational vibrations of organic and silver moieties in fingerprint region. UV/visible spectroscopy was used to monitor photocatalytic efficiencies while thermogravimetric analysis displayed heat resistance competency of synthesized materials. Transmission electron microscopy demonstrated spherical particle shape of PMOS and well-ordered hexagonal patterns in Ag@PMOS, which were also enlightened by X-ray powder diffraction method. While, photoluminescence (PL) study examined the excessive formation of hydroxyl free radicals by Ag@PMOS during photocatalysis of MO. The synthesized material exhibited well-ordered crystalline networks of Ag@PMOS with good surface area, which made it effective for degradation of MO. The results showed 26% and 56% absorption reduction under visible and UV-conditions, respectively. Moreover, the reduction efficiency was increased remarkably after using hydrogen peroxide and found to be 53% and 85% under visible and UV-irradiation, respectively. The promising recycled results showed 24%, 21%, 17% (without using H2O2) and 54%, 51%, 48% (using H2O2) absorption decline under visible light irradiation. Moreover, 53%, 50%, 49% (without using H2O2) and 83%, 80%, 78% (using H2O2) absorption reductions were examined under UV-light irradiation without and with H2O2. Which pointed toward high reduction capabilities and better stability of Ag@PMOS. The synthesis of highly porous PMOS, efficient photo-degradation of MO under UV-light by fabricated Ag@PMOS and reproducibility of the degradation results made the present work more innovative for degradation of MO for water decontamination. [ABSTRACT FROM AUTHOR]

The design of sustainable and efficient materials for efficient energy storage and degradation of environmental pollutants (specifically organic dyes) is a matter of major interest these days. For this purpose, cerium- and ytterbium-based GO/g-C3N4/Fe2O3 composites have been synthesized to explore their properties, especially in charge storage devices such as supercapacitors, and also as photocatalysts for the degradation of carcinogenic dyes from the environment. Physicochemical studies have been carried out using XRD, FTIR, SEM, and BET techniques. Electrochemical techniques (cyclic voltammetry, galvanic charge discharge, and electrochemical impedance spectroscopy) have been employed to measure super-capacitance and EDLC properties. Results show that the gravimetric capacitance calculated from GCD results is 219 Fg−1 for ytterbium- and 169 Fg−1 for cerium-based nanocomposites at the current density of 1 A/g and scan rate of 2 mV/sec. The specific capacitance calculated for the ytterbium-based nanocomposite is 189 Fg−1 as compared to 125 Fg−1 for the cerium-based material. EIS results pointed to an enhanced resistance offered by cerium-based nanocomposites as compared to that of ytterbium, which can be assumed with the difference in particle size, as confirmed from structural studies including XRD. From obtained results, ytterbium oxide-based GO/g-C3N4/Fe2O3 is proven to be a better electro-catalyst as compared to cerium-based nanocomposites. Photocatalytic results are also in agreement with electrochemical results, as the degradation efficiency of ytterbium oxide-based GO/g-C3N4/Fe2O3 (67.11 and 83.50% for rhodamine B and methylene blue dyes) surpasses values observed for cerium-based GO/g-C3N4/Fe2O3 (63.08 and 70.61%). [ABSTRACT FROM AUTHOR]

Commercially available QPPO/PVA based anion exchange membrane (AEM) BIII was to inquire the percentage discharge of anionic dye Eosin-B (EB) at terrain temperature from wastewater. The impact of EB initial concentration, membrane dosage, ionic strength, contact time and temperature on EB percentage removal was contemplated. The EB percentage removal was increased from 22 to 99.56% and 38.15–99.56% with contact time and membrane dosage respectively while decreased from 99.56 to 29%, 99.56 to 54.61% and 99.56 to 92.22% with enhancing initial concentration of EB, ionic strength and temperature respectively. Nonlinear isotherm models were utilized to demonstrate EB adsorption onto AEM BIII. Attained results exhibited that nonliner Freundlich isotherm model best fitted to EB adsorption onto AEM BIII. For EB adsorption onto AEM BIII, adsorption kinetics were inquired in detail by using several kinetic models but EB adsorption nicely fitted to pseudo-second-order kinetics. Similarly thermodynamic analysis was performed and results pointed to an exothermic adsorption of EB onto AEM BIII. The membrane could be reused for four concecutive cycles with loosing its efficiency. [Display omitted] • QPPO/PVA based commercial anion exchange membrane. • exothermic adsorption of EB onto AEM BIII. • A novel membrane against absorption of EB. • Nonlinear isotherm models were utilized to demonstrate EB adsorption. [ABSTRACT FROM AUTHOR]