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Graphene oxide (GO) is a sp2 hybridized carbon atom arranged in a honeycomb lattice. Graphene is a new allotrope of carbon compound which could prime new openings in research fields. GO was successfully synthesized via Phyllanthus Emblica (PE) leaf. Structures, morphologies and photo catalytic activities of the as synthesized nanomaterial were determined by using X-Ray diffraction (XRD), UV-Visible spectroscopy, Field emission scanning electron microscopy (FE-SEM), Energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), High resolution transmission electron microscopy (HRTEM) analysis. The photo catalytic activities of the as-synthesized GO were estimated for the degradation of malachite green (MG) and methyl violet (MV) in aqueous solution under replicated solar light. The photo catalytic degradation of GO was 94% for brilliant green and 99% for methyl violet in 120 min. [ABSTRACT FROM AUTHOR]

Graphene is a radiant star in the field of nanomaterials. It has gained prominent interest since of its very good mechanical, thermal, optical and electronic possessions. The basic chemical reaction elaborate in the Hummer's method was the oxidation of graphite, during which harmful toxic gases used to emit. Nowadays green chemistry is blossoming in the field of nanomaterial. In present work, we fabricate graphene oxide (GO) through different agricultural wastes i.e., Rice bran (RB), Sugarcane bagasse (SB), Orange peel (OP), and mixture of all these three wastes i.e., tricomposite agro waste (TAW) were mixed with ferrocene which gave electron transfer reaction to synthesized GO and compared it. At last, we concluded that particle size obtained for OPGO (23.99 nm) > graphite (17.17 nm) > SBGO (15.5 nm) > RBGO (2.235 nm) > TAWGO (1.77 nm). These green strategies are biocompatible and cost effective too. Basic information of GO crystal was obtained by X-ray diffraction (XRD) for determination of crystal structure, scanning electron microscopy (SEM) for morphological study, high resolution transmission electron spectroscopy (HRTEM) used for determine particle size, fourier transform infrared (FTIR) spectroscopy for functional group detection, thermogravametric analysis (TGA)/differential thermal analysis (DTA) for determine thermal stability of GO. [ABSTRACT FROM AUTHOR]

A novel, simple, sensitive and selective kinetic spectrophotometric method has been developed for the determination of Hg(II) in environmental samples. The method is based on the catalytic effect of Hg(II) on the potassium bromate-leucocrystal violet (LCV) reaction system in the acidic medium. Decolourization of LCV was used to monitor the reaction spectrophotometrically at 595 nm. The indicator reaction obeys Beer's law in the range of 0.005–0.05 μg mL − 1 . The effects of various parameters such as pH, time, temperature and the concentration of the reagents have been optimized for the indicator reaction. Sandell's sensitivity and molar absorptivity for the system were found to be 0.00006875 μg cm − 2 and 3.95 × 10 6 L mol − 1 cm − 1 , respectively. The detection limit and the limit of quantification were calculated to be 0.0021 μg mL − 1 and 0.014 μg mL − 1 , respectively. The proposed method involving KBrO 3 for the oxidation of LCV has successfully been applied for the determination of Hg(II) in vegetables, water, soil and fungicides samples. [ABSTRACT FROM AUTHOR]

The present paper reports the preparation of Cd 0.5 Pb 0.5 S thin films via a simple and inexpensive chemical bath deposition technique. Various preparation conditions were optimized for the deposition of good quality Cd 0.5 Pb 0.5 S thin films. The structural, morphological and optical properties of these films are discussed. The structural studies confirmed the polycrystalline nature of material with cubic structure. Using scanning electron microscopy, the surface morphology of the films was studied. The optical band gap of the film gets modified during annealing. The chemical composition of these thin films was studied by energy dispersive spectroscopy. The optical band gap energy for as-deposited and annealed Cd 0.5 Pb 0.5 S thin films were calculated and found in the range of 2.6 to 2.05 eV. [ABSTRACT FROM AUTHOR]

A sensitive spectrophotometric method for determination of dicofol in subparts per million levels is described, which is based on Fujiwara reaction. Dicofol on alkaline hydrolysis gives chloroform, which reacts with pyridine to produce red color. The color is discharged by addition of glacial acetic acid. The glutaconic aldehyde formed reacts with 4-aminoacetanilide to gave an orange-red dye which is extractable in 3-methyl-1-butanol. The extracted dye shows absorption maximum at 525 nm. Beer's law is obeyed in the range of 0.025–0.25 μg mL−1. Important analytical parameters such as time, temperature, reagent concentration, acidity etc. have been optimized for complete color reaction. Sandell's sensitivity and molar absorptivity for the system were found to be 0.000343 μg cm−2and 1.077 × 106L mol−1cm−1, respectively. The proposed method is satisfactorily applied to microlevel determination of dicofol in various environmental samples. [ABSTRACT FROM PUBLISHER]

A simple and highly selective surfactant assisted kinetic spectrophotometric method for the determination of thallium has been developed. The method is based on the quantitative oxidation of Tl(I) to Tl(III) using bromine water where the resulting Tl(III) liberated iodine from potassium iodide in acidic medium. The liberated iodine was subsequently reacted with I − ion to form tri-iodide ions (I 3 − ). The tri-iodide ions formed were further reacted with cetylpyridinium cation (CP + ) which produced a violet ion associate species having a λ max of 512 nm at which reaction was monitored. The reaction variables such as time, temperature, reagent concentration and acidity were optimized for the indicator reaction to achieve maximum sensitivity. The linear regression calibration concentration range of 0.007–0.1 μg mL − 1 Tl(I) was established as the Beer's law was obeyed in this range. Sandell's sensitivity and molar absorptivity of the ion associate species in terms of thallium were determined to be 0.000133 μg cm − 2 and 1.99 × 10 6 L mol − 1 cm − 1 respectively. The limit of detection was determined as 0.0029 μg mL − 1 . The developed method has successfully been applied for the determination of thallium in different environmental samples with satisfactory results. [ABSTRACT FROM AUTHOR]

A novel and sensitive kinetic spectrophotometric method for the determination of malathion has been developed. The method is based on the oxidation of malathion with slight excess of N-bromosuccinimide (NBS) at 30°C where unconsumed NBS was monitored with safranine dye spectrophotometerically at λmax 530nm using fixed time procedure after 10min of the reaction. The oxidized product was characterized as malaoxon by Fourier transformation infrared (FTIR) spectroscopy. Beer's law was obeyed in the concentration range of 0.025–0.25μgmL−1. Important analytical parameters such as time, temperature, reagents concentration, and acidity have been optimized for the reaction. Sandell's sensitivity and molar absorptivity for the reaction system were found to be 0.0003μgcm−2 and 9.6×105 Lmol−1 cm−1 respectively. The proposed method was successfully applied for the determination of malathion in different samples with satisfactory results. The results were compared with those obtained by GC–MS methods. [ABSTRACT FROM AUTHOR]

This work investigates the degradation of the azo dye solochrome dark blue (SDB) by measurement of the photocatalytic, sonocatalytic and sonophotocatalytic activities, under low ultrasonic frequency (40 kHz) and UV-C (254 nm) light, using Mn-doped ZnS semiconductor quantum dots (Mn2+:ZnS Qds) as catalysts, prepared by a simple chemical precipitation procedure. In order to study the different morphological and optical crystal properties, various characterization techniques were used, such as high resolution transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction, N2 adsorption-desorption at −196 °C and ultraviolet-visible spectroscopy. The average particle size of the semiconductor Qds was in the range of 3–4 nm. The optimal parameters affecting dye degradation, such as the catalyst loading, solution pH, time of irradiation, initial concentration of dye, dopant concentration, ultrasonic power and frequency effect were evaluated. The synthesized catalytic material exhibited a high activity for sonophotocatalytic degradation of SDB (89%), larger than that observed for sonocatalysis (69.7%) or photocatalysis (55.2%) alone, which was due to the improved electron-holes separation, formation of more reactive radicals and enhancement of the active surface area. Qds showed good stability and reusability after five repeated cycles. Finally, the degradation products were identified by liquid chromatography-mass spectrometry (LC-MS). [ABSTRACT FROM AUTHOR]

Norfloxacin (NOFX), a broadly used fluoroquinolone antibiotic, has been a subject of great concern in the past few years due to its undesirable effect on human beings and aquatic ecosystems. In this study, novel Mn doped ZnS (Mn:ZnS) quantum dots (QDs) were prepared through a facile chemical precipitation method and used as photocatalysts for NOFX degradation. Prior to photodegradation experiments, morphological and optical parameters of the QDs were examined through transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray analysis, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, fluorescence spectroscopy, Brunauer–Emmett–Teller analysis, and differential thermal and thermogravimetric analyses. Mn:ZnS QDs exhibited excellent properties of photodegradation, not only under UV irradiation but also in sunlight, which induced NOFX to photodegrade. The utmost photodegradation efficiency was obtained under optimal conditions (25 mL of NOFX, 15 mg/L, pH 10, 60 min UV irradiation, 60 mgs QDs), adopting first order kinetics. In addition, hydroxyl radicals produced by the conduction band electrons were found to be the primary reason dominating the transformation of NOFX in basic conditions, while holes, oxygen atoms, as well as the doped metal (Mn) enhanced the degradation. The QDs showed excellent reusability and stability in four repeated cycles. Finally, four different pathways were predicted, derived from the identified intermediates, with piperazinyl ring transformation being the primary one. It is expected that the synthesized Mn:ZnS QDs could be utilized as efficient photocatalytic materials for energy conversion and ecological remediation. [ABSTRACT FROM AUTHOR]

A nano-sensor based on N-doped carbon dots (NCDs)@ZnO (NCZ) composite was fabricated and efficacy for detecting glucose from human blood and urine samples in a straightforward manner was examined. The composite was prepared following a green hydrothermal method under ambient condition using a novel plant material, Dregea volubilis fruit and structural and optical properties were evaluated using standard techniques. The composite exhibited excellent characteristics including good photostability, biocompatibility, low toxicity, and strong fluorescence, with a decent quantum yield of up to 59%. The NCZ composite has been very sensitive and could selectively detect glucose in urine and blood samples. Selective glucose quenching was efficacious at different concentrations of glucose (1–6 mM) and in the pH range of 7–8, limit of detection was 0.25 mM. The potential uses of carbon-based materials have grown, thanks to the excellent sensing/detection capabilities of the NCZ composite as well as the capacity to prevent nanoparticle aggregation, opening up new possibilities for the development of environmentally benign nano-sensors. [ABSTRACT FROM AUTHOR]

The study of nanocomposites formed by doping of graphene oxide with a metal and polymer is presented in this paper. The graphene oxide contains oxygenated functional groups, like epoxy, hydroxyl and carboxyl, as shown by Fourier transform infrared spectroscopy (FTIR) studies. The existence of these functional groups on the surface of graphene oxide disperses the polymer chain and leads to a good interaction with the metal. The characterization of the prepared nanocomposite was done by X-ray diffraction, energy dispersive X-ray analysis, FTIR, Raman spectroscopy, scanning electron microscopy and high resolution transmission electron microscopy. The results showed that the obtained nanocomposite comprises nano-shaped thin stacked flakes with a well-defined multilayered edge structure. It was also seen that the metal particles were uniformly dispersed on the graphene surface with an average particle size of 1–25 nm. The synthesized nanocomposites can be used for adsorption and degradation of dyes. [ABSTRACT FROM AUTHOR]

Review: 168 refs. [ABSTRACT FROM AUTHOR]

We report the synthesis of graphene oxide/nickel oxide/β-cyclodextrin (GO/NiO/β-CD) nanocomposite and the efficiency of the nanocomposite in decolourising two different dyes, methylene blue (MB) and methyl violet (MV). GO was prepared by modified Hummer's method while hydrothermal method was used for the preparation of GO/NiO/β-CD. The as-synthesised nanocomposites were characterised by X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and high resolution transmission electron microscopy (HR-TEM). Photocatalytic degradation was carried out under solar light by monitoring the concentration of MB and MV dyes. Degradation reaction followed Langmuir-Hinshelwood pseudo first-order kinetic model. The apparent reaction rate constant (k) for MB increased as compared to MV under solar light irradiation. The MB showed better photocatalytic degradation efficiency by GO/NiO/β-CD composites. GO/NiO/β-CD nanocomposite has been very favourable for photocatalytic application. [ABSTRACT FROM AUTHOR]

Among carbon-based nanomaterials, carbon dots (CDs) have received a surge of interest in recent years due to their attractive features such as tunable photoluminescence, cost effectiveness, nontoxic renewable resources, quick and direct reactions, chemical and superior water solubility, good cell-membrane permeability, and simple operation. CDs and their composites have a large potential for sensing contaminants present in physical systems such as water resources as well as biological systems. Tuning the properties of CDs is a very important subject. This review discusses in detail heteroatom doping (N-doped CDs, N-CDs) and the formation of metal-based CD nanocomposites using a combination of matrices, such as metals and metal oxides. The properties of N-CDs and metal-based CDs nanocomposites, their syntheses, and applications in both chemical sensing and biosensing are reviewed. [ABSTRACT FROM AUTHOR]

The effect of cationic micelles of cetyltrimethylammonium bromide (CTAB) and anionic micelles of sodium dodecyl sulphate (SDS) on the kinetics of oxidation of cyclopentanone by N-bromophthalimide (NBP) was studied iodometrically at 308 K. In addition to the kinetic experiments, conductivity measurements have also been done to obtain critical micelle concentration and other thermodynamic properties. The kinetic observations indicate fractional order and first order dependence with respect to [cyclopentanone] and [NBP] respectively. Cationic surfactant (CTAB) strongly catalyses the oxidation of Cyclopentanone in aqueous acetic acid medium. Typical kobs and [CTAB] profile were observed i.e. with the progressive increase in [CTAB], the reaction rate increased and at higher concentration of CTAB, constancy in kobs was observed. Anionic surfactant (sodium dodecylsulphate, SDS), mercuric acetate and phthalimide did not influence the reaction rate. The presence of inorganic salts (KCl, KBr) exhibits a severe hike in the reaction rate. The various activation parameters in the presence of CTAB have been also evaluated. A suitable mechanism consistent with the experimental findings has been proposed. [ABSTRACT FROM AUTHOR]

Abstract: The Pd(II) homogeneous catalysis of periodates oxidation of crotonic acid (CA) in perchloric acid has been studied. The linear dependence of the reaction rate at lower [IO4 −] and [Pd(II)] tends towards zero order at their higher concentrations. The reaction exhibited zero order in [CA]. Negligible effect of change in [H+], ionic strength of medium and varying [Cl−] on rate of reaction is observed. [Pd]2+ and [IO4 −] are assumed as the most reactive species of Pd(II) chloride and periodate, respectively. Acetaldehyde and glyoxylic acid have been identified as the main oxidation products of the reaction. Various activation parameters have also been calculated and recorded. On the basis of experimental findings, a suitable mechanism consistent with the observed kinetics was proposed. A comparative study was also made between the kinetic results of the present investigation and those of Pd(II) catalysed oxidation CA by chloramines-T in acidic medium. [Copyright &y& Elsevier]

A novel beads adsorbent, consisting of calcium alginate entrapped on magnetic nanoparticles functionalized with methionine (MFMNABs), was developed for effective elimination of arsenic from water. The material was characterized by FT-IR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopic), XRD (X-ray Diffraction) and TEM (Transmission Electron Microscopy). The arsenic removal capacity of the material was studied by altering variables such as pH of the solution, contact time, adsorbent dose and adsorbate concentration. The maximal removal of As(III) was 99.56% under optimal conditions with an equilibrium time of 110 min and pH 7.0–7.5. The adsorption followed a second order kinetics and data best fitted the Langmuir isotherm with a correlation coefficient of R2 = 0.9890 and adsorption capacity (qm) of 6.6533 mg/g. The thermodynamic study showed entropy change (∆S) and enthalpy change (∆H) to be 34.32 J mol−1 K and 5.25 kJ mol−1, respectively. This study proved that it was feasible to treat an As(III) solution with MFMNABs. The synthesized adsorbent was cost-effective, environmentally friendly and versatile, compared to other adsorbents. The adsorption study was carried by low cost spectrophotometric method using N- bromosuccinimide and rhodamine-B developed in our laboratory. [ABSTRACT FROM AUTHOR]

This work is particularly aimed at the preparation of ZnS and Cu doped ZnS (Cu:ZnS) QDs by facile and easy technique, chemical precipitation method for the degradation of water pollutants and a simple scheme was proposed to prepare the urea-sensing system. The morphological and optical properties of the synthesized QDs was studied using high resolution transmission and scanning electron microscopes, X-ray diffraction, energy dispersive X-ray analysis, fluorescence and ultraviolet–visible spectroscopy, differential thermal and thermogravimetric analyses, Brunauer–Emmett–Teller analysis. The photocatalytic performance was systematically assessed by the photodegradation of an important pharmaceutical water pollutant, Amoxicillin (AMX) and a dye Fast Sulphon Black F (SFBF) in aqueous medium under UV light irradiation. Also, a very sensitive system was prepared by depositing the dots over an indium-tin-oxide (ITO) glass substrate for the sensing of biologically active molecule urea as it is an important monitor of public health in water and soil productivity. The results illustrated excellent photocatalytic efficiency (86.46% for AMX and 99.41% for SFBF) with stability up to four cycles of degradation reaction. The optimal photocatalyst dosage for achieving maximum removal of AMX was found to be 70 mg at a pH of 9.5, with a treatment time of 40 min. Similarly, for SFBF, the optimal photocatalyst dosage was determined to be 60 mg at pH 9, with a treatment time of 60 min. Further, the electrochemical analysis was done by fabricating Urease enzyme (UR)/Cu:ZnS QDs/ITO bioelectrode and then the fabricated bioelectrode, was utilized to determine the different concentrations of urea by cyclic voltammetry. Thus, the obtained limit of detection and sensitivity of the fabricated biosensing device for urea detection was obtained to be 0.0092 μM and 12 μA μM−1cm−2, respectively; under the optimized experimental conditions. Hence, it is anticipated that Cu:ZnS QDs can also successfully be applied as a promising material for fabrication of novel bioelectrode for urea determination and the biosensing platform is desirable and viable. [Display omitted] • Preparation and characterization of ZnS and Cu doped ZnS (Cu:ZnS) QDs. • Photocatalytic degradation of water pollutants and biosensing of urea. • Photocatalytic efficiency was found to be excellent with high stability. • Bioelectrode fabrication using Urease enzyme and Cu:ZnS QDs for detecting urea. [ABSTRACT FROM AUTHOR]

• Current review highlights the optical properties and various sensing strategies of Mn-doped ZnS QDs as excellent probes for sensing applications. • Focuses on most recent promising developments, concepts and excellent applications of doped QDs for chemo- and bio-sensing. • Various approaches in sensing as well as benefits and/or shortcomings of surface modification of QDs has been considered for fabricating desirable QDs structures for specific applications. • Over 200 publications are overviewed and discussed, dealing with fluorescence, phosphorescence, chemiluminescence, electrochemiluminescence and biosensing. Quantum dots (QDs), due inter alia to their colourtunable symmetry, narrow emission, broad absorption, stability, and solution processibility have received an upsurge of interest in the last decade as potential materials for diverse applications. Doped QDs, in particular, have gained significant attention as a new class of luminescent materials since dopants influence the optical behaviour of QDs. Therefore, doped ZnS QDs possess conspicuous properties like longer dopant emission lifetime and lower toxicity. The dopant emission lifetimes of transition-metal ions are longer than the energy-gap and defect-related luminescence of the host as well as the biological background fluorescence to offer immense prospect for removal of background fluorescence for sensing applications. Probes based on phosphorescence or fluorescence enhancement of QDs is crucial for the development of the detection capability. This current review highlights the optical property and various sensing strategies of Mn-doped ZnS QDs that make them exceptional probes for applications in sensing. The review not only intends to present an all-encompassing study of the well-documented usages of QDs, but is also rather addressing the current promising improvements, concepts, and excellent applications in research of doped QDs for chemo- and biosensing. Over 200 publications are overviewed and considered here in the perspective of leading applications in sensing dealing with for instance, fluorescence, phosphorescence, chemiluminescence, electrochemiluminescence and biosensing features. [ABSTRACT FROM AUTHOR]

The electrical, optical and bending characteristics of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/Au/PEDOT:PSS deposited on polyethylene terephthalate (PET) substrate were studied as a function of inserted Au film thickness. The results were compared with those of indium-tin-oxide (ITO) and single layer PEDOT: PSS electrodes. It was found that insertion of Au film with optimized thickness between PEDOT:PSS layers improved the sheet resistance in comparison to single PEDOT:PSS film and ITO film. It was demonstrated that PEDOT: PSS(35 nm)/Au(15 nm)//PEDOT: PSS(35 nm) exhibits sheet resistance of 20.9 Ω/sq and maximum optical transmission of 82.6% in the visible region. Moreover, this multilayer electrode showed dramatically improved mechanical stability compared to ITO, when subjected to multiple bends. Its sheet resistance variation was 3.8% after applying 2000 bending cycles at radius of curvature 6 mm in comparison to 6.7% for single PEDOT: PSS film and 11.4% for ITO. [ABSTRACT FROM AUTHOR]

The kinetics of micellar catalyzed oxidation of galactose by N-bromophthalimide was studied in the presence of acidic medium at 308 K. The oxidation reaction exhibits first-order kinetics with respect to oxidant ( N-bromophthalimide), fractional order with respect to substrate (galactose) and positive fractional order with respect to HClO 4 on the rate of reaction. The rate of the reaction increased with decreasing the dielectric constant of the medium. With a progressive increase in the concentration of CTAB, the rate of reaction increased and after reaching peak kobs, decreased at higher concentrations of CTAB. There catalytic roles are best explained by Berezin’s model. The influence of salts on the reaction rate was also studied. The various activation parameters have been calculated. The rate constant and binding constant with the surfactant have also been evaluated. A suitable mechanism consistent with the experimental findings has been proposed. [ABSTRACT FROM AUTHOR]

In this contribution, ternary telluride ABTe 2 compounds are proposed as promising candidates for n- type semiconductor materials in photovoltaic and photochemical devices. We report the successful calculations of the most fundamental properties needed in the previous applications such as the effective mass, dielectric constant and the exciton binding energy. This latter one has been evaluated from the density functional theory (DFT) method in the first time for these materials. An easy dissociation for hole-electron pair is suggested due to the small value of exciton binding energy at room temperature (i.e., lower than the thermal energy, 25 meV) for most of the studied compounds. The band structure and density of states of ABTe 2 are calculated using the hybridHSE06 functional, PBE0 and in addition the pure GGA-PBE functionals. Additionally, to elucidate the optical properties of these compounds, the complex dielectric function and optical reflectivity were computed for a wide range of photon radiation. Therefore, ABTe 2 materials are expected to be promising candidates for visible light driven photovoltaic and photocatalytic devices. Crystal structure of ABTe 2 compounds (a : rhombohedral with R 3 ‾ m ; b : trigonal with P-3m1 ; c : hexagonal structure with P6 3 /mmc space group). Image 1 [ABSTRACT FROM AUTHOR]