Presence Of Oxalic Acid Research Articles

Chemically reduced graphene oxide-P25-Au nanocomposite materials and their photoelectrocatalytic and photocatalytic applications.

Visible light active photocatalysts consisting of gold nanoparticle (Au NP) decorated chemically reduced graphene oxide-P25 nanocomposite materials (CRGO-P25-Au NCMs) were prepared through a one-pot chemical reduction method. The nanocomposite materials were characterized using diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and electrochemical impedance spectroscopy (EIS) analyses. The performances of CRGO-P25-Au NCM modified ITO electrodes were evaluated towards the photoelectrochemical oxidation of methanol. The photoelectrode fabricated using CRGO-P25-Au NCM exhibited a higher photocurrent of 293 μA cm-2 compared to other control electrodes. The CRGO-P25-Au NCMs were also used for the photocatalytic reduction of highly toxic chromium(vi) ions to chromium(iii) ions in the presence of oxalic acid as a sacrificial electron donor. The results showed that around 75% of the Cr(vi) ions were photocatalytically reduced to Cr(iii) ions by the CRGO-P25-Au NCM within the light irradiation time of 1 h. In both applications, the enhanced catalytic activity of the CRGO-P25-Au NCM was attributed to the improved visible light absorption and the reduced charge recombination exerted by the interaction of CRGO and Au NPs with P25 and their synergistic effects.

A green protocol for one-pot three-component synthesis of 1-(benzothiazolylamino) methyl-2-naphthol catalyzed by oxalic acid

One-pot, efficient three-component condensation of aromatic aldehydes, 2-naphthol and 2-aminobenzothiazole in the presence of oxalic acid as an organocatalyst and effective catalyst for the synthesis of 1-(benzothiazolylamino) methyl-2-naphthol derivatives under thermal and solvent-free conditions is described. The present approach of this methodology offers several advantages such as high yields, clean reaction profiles, operational simplicity, being environmentally benign, lack of need for column chromatography and simple work-up procedure.

Synthesis, antimicrobial evaluation, and docking studies of some novel benzofuran based analogues of chalcone and 1,4-benzodiazepine

A series of novel {5-[4-hydroxy-3-(4-phenyl-2,3-dihydro-1H-benzo[b][1,4]diazepin-2-yl)benzyl]- benzofuran-2-yl}(phenyl)methanones (5a–5g) were prepared by the condensation of (E)-3-{5-[(2- benzoylbenzofuran-5-yl)methyl]-2-hydroxyphenyl}-1-phenylprop-2-en-1-one (chalcone) (4a) with various substituted o-phenylene diamines in the presence of oxalic acid as catalyst. The structures of all compounds were characterized by FTIR, 1H NMR, 13C NMR, and MS. The representative examples were screened in vitro for antimicrobial activity. Among all compounds 4g and 5g showed potent antibacterial activity, 4b and 5g showed good antifungal activity. The data was further compared with structure based investigations using docking studies with the crystal structure of adenosine-5'-(β,γ-imido)triphosphate (2ONJ) from Staphylococcus aureus for antibacterial activity and trypsin (1FY5) protein from Fusarium oxysporum for the antifungal activity. The score values estimated by genetic algorithm were found to have a good correlation with the experimental inhibitory potencies.

Iron removal in production of purified quartz by hydrometallurgical process

Iron, the predominant impurity in quartz ores, can be substantially removed via aqueous chemical processes using organic and inorganic acids. Quartz was highly purified by leaching with sulfuric acid (H2SO4) in the presence of reducing agents (oxalic acid, citric acid, and glucose). The effects of the parameters in the leaching tests were evaluated with the full factorial design method and the analysis of variance (ANOVA) method. Higher amounts of ferric oxide (Fe2O3) were removed in the presence of reducing agents during H2SO4 leaching. Under optimum conditions (20% pulp density, 0.5M H2SO4, 10g/L of oxalic acid, 90°C, and 120min), 98.9% of Fe2O3 was removed, resulting in a final quartz product with 1ppm of Fe2O3 in the presence of oxalic acid in H2SO4 leaching. Although oxalic acid showed particularly significant effects, citric acid and glucose also produced quartz products with low Fe2O3 content (1.8 and 3.1ppm of Fe2O3, respectively). The models obtained from the data of H2SO4 leaching with the addition of oxalic acid, citric acid, and glucose, based on the ANOVA results, were suitable for estimating the leaching yield. The process was simulated within the scope of economic modeling studies. These studies showed the economic feasibility of quartz purification by hydrometallurgical processes in obtaining quartz products with high market value and high quality.

Amino-Functionalized Layered Crystalline Zirconium Phosphonates: Synthesis, Crystal Structure, and Spectroscopic Characterization.

Two new layered zirconium phosphonates functionalized with amino groups were synthesized starting from aminomethylphosphonic acid in the presence of different mineralizers, and their structures were solved from powder X-ray diffraction data. Their topologies are unprecedented in zirconium phosphonate chemistry: the first, of formula ZrH[F3(O3PCH2NH2)], prepared in the presence of hydrofluoric acid, features uncommon ZrO2F4 units and a remarkable thermal stability; the second, of formula Zr2H2[(C2O4)3(O3PCH2NH2)2]·2H2O, prepared in the presence of oxalic acid, is based on ZrO7 units with oxalate anions coordinated to the metal atom, which were never observed before in any zirconium phosphonate. In addition, the structure of another compound based on (2-aminoethyl)phosphonic acid is reported, which was the object of a previously published study. This compound has layered α-type structure with -NH3(+) groups located in the interlayer space. All of the reported compounds were further characterized by means of vibrational spectroscopy, which provided important information on fine structural details that cannot be deduced from the powder X-ray diffraction data.

Novel Approach to Surface Plasmon Resonance: A Third Dimension in Data Interpretation Through Surface Roughness Changes.

In a Surface Plasmon Resonance (SPR) experiment two key parameters are classically recorded: the time and the angle of SPR reflectivity. This paper brings into focus a third key parameter: SPR reflectivity. The SPR reflectivity is proved to be related to surface roughness changes. Practical investigations on (i) gold anodizing and (ii) polypyrrole film growth in presence of oxalic acid is detailed under potentiostatic conditions. These experimental results reveal the potential of using the SPR technique to investigate real-time changes both on the gold surface, but also in the gold film itself. This extends the versatility of the technique in particular as sensitive in-situ diagnostic tool.

A Facile Self-Assembly Synthesis of Whiskey ZnFe<sub>2</sub>O<sub>4</sub> as Superior Anode Materials for Lithium-Ion Batteries

A superior self-assemble whiskery ZnFe2O4 has been synthesized by a facile coprecipitation method in the presence of oxalic acid. After performed as anode for lithium ion battery, the ZnFe2O4 exhibits excellent electrochemical performance with an initial discharge capacity of 1364.6 mAh g-1, maintained an effective discharge capacity of 1086.9 mAh g-1 after 50 cycles and wonderful rate capacity (687.4 mAh g-1 at 3.0C). The excellent electrochemical performance was related to the novel whiskery structure, which is made of small spherical nanoparticles and hundreds of voids.

Photodegradation of Orange II using waste paper sludge-derived heterogeneous catalyst in the presence of oxalate under ultraviolet light emitting diode irradiation

A waste paper sludge-derived heterogeneous catalyst (WPS-Fe-350) was synthesized via a facile method and successfully applied for the degradation of Orange II in the presence of oxalic acid under the illumination of ultraviolet light emitting diode (UV-LED) Powder X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electronic microscopy and N2 sorption isotherm analysis indicated the formation of α-Fe2O3 in the mesoporous nanocomposite. The degradation test showed that WPS-Fe-350 exhibited rapid Orange II (OII) degradation and mineralization in the presence of oxalic acid under the illumination of UV-LED. The effects of pH, oxalic acid concentration and dosage of the catalyst on the degradation of OII were evaluated, respectively. Under the optimal conditions (1g/L catalyst dosage, 2mmol/L oxalic acid and pH3.0), the degradation percentage for a solution containing 30mg/L OII reached 83.4% under illumination by UV-LED for 80min. Moreover, five cyclic tests for OII degradation suggested that WPS-Fe-350 exhibited excellent stability of catalytic activity. Hence, this study provides an alternative environmentally friendly way to reuse waste paper sludge and an effective and economically viable method for degradation of azo dyes and other refractory organic pollutants in water.

A green and efficient four-component sequential protocol for the synthesis of novel 16-(aryl)benzo[a]indeno[2′,1′:5,6]pyrano[2,3-c]phenazin-15(16H)-one derivatives using oxalic acid as a reusable and cost-effective organic catalyst

A sequential one-pot four-component reaction for the efficient synthesis of novel 16-(aryl)benzo[a]indeno[2′,1′:5,6]pyrano[2,3-c]phenazin-15(16H)-one derivatives has been developed. The synthesis was achieved by reacting 2-hydroxynaphthalene-1,4-dione, benzene-1,2-diamine, aromatic aldehydes, and 1,3-indandione in the presence of oxalic acid as a reusable and homogenous organocatalyst in EtOH/H2O (1:1) under reflux. The present approach of this methodology offers several advantages such as high yields, clean reaction profiles, operational simplicity, simple work-up procedures, and green aspects by avoiding toxic catalysts and solvents.

Structures of organic additives modified magnetite nanoparticles

Magnetite (Fe3O4) nanoparticles and magnetite-based inorganic–organic hybrids are attracting increasing attention in biomedicine, as thermoseeds for hyperthermia and contrast media in magnetic resonance imaging. Controlling the size of Fe3O4 thermoseeds is important, as particle size affects their heat generation under alternative magnetic fields. Fe3O4 is easily synthesized via aqueous processes. We previously demonstrated that adding organic polymers during synthesis affected the size and crystallinity of the resulting Fe3O4. However, the relationship of the chemical structure of the low-molecular-weight organic additive of its effect on the product has not been elucidated. In this study, organic compounds containing varying functional groups and surface charges were added to the precursor solution of Fe3O4. Crystalline Fe3O4 formed in the presence of neutral acetone, cationic ethylenediamine, and anionic acetic acid. These nanoparticles had slightly smaller particle sizes than those prepared in the absence of additives. The presence of oxalic acid and tris(hydroxymethyl)aminomethane inhibited Fe3O4 nucleation, instead yielding lepidocrosite- or akaganeite-type FeOOH. These differences were attributed to the ability to form complexes between iron ions and the organic additives. The saturation magnetizations of the products were consistent with Fe3O4. This indicated that the crystal phase of the iron oxide products differed, even when prepared in the presence of organic additives of the same functional group. It is concluded that state of ion-organic molecule complex in the solutions is a key factor governing nanostructure of the resultant iron oxide.

Dissolution of Manganese from Polymetallic Material Using Sulfuric-Oxalic Acid Medium

Sedimentary rocks have been found to host several Mn minerals in addition to some economic metal values. Besides recoverable Al occurring as gibbsite mineral, the latter include Cu, Zn, Co, Ni, U as well as rare earth elements. In this work, the ore material was subjected to sulfuric acid leaching in the presence of oxalic acid as a reductant to maximize the extraction of Mn. The optimum leaching conditions to achieve almost complete leaching efficiency of Mn with Fe dissolution not exceeding 13% involved 0.5 M sulfuric acid and 0.25 M oxalic acid in a solid/liquid ratio of 1/15 at 85°C for 105 min using an ore size of -150 μm. The leaching behavior of the associated interesting metal values (Al, Cu and Zn) has also been investigated.

ChemInform Abstract: One‐Pot Conversion of Carbohydrates into Pyrrole‐2‐carbaldehydes as Sustainable Platform Chemicals.

AbstractCarbohydrates such as glucose (I) are converted into title compounds (III) by the reaction with primary amines (II) in the presence of oxalic acid.

Heterogeneous photodegradation of paracetamol using Goethite/H 2 O 2 and Goethite/oxalic acid systems under artificial and natural light

Abstract Heterogeneous photodegradation of paracetamol (PC) in the α-FeOOH (Goethite) used as a catalyst was studied in aqueous suspension up on irradiation at 365 nm and by solar light. The mechanism involves PC-Goethite system operate electron–hole pairs. The rate of photocatalytic degradation of PC is slow and follows pseudo-first order kinetics. The addition of H 2 O 2 in the previous solution leads to OH radicals formation via the Fenton system. Goethite in the presence of oxalic acid can form Goethite–oxalate complex on the surface. So under irradiation the photo-reduction of Goethite–oxalate complexes yields Fe(II) and oxalate radicals (C 2 O 4 ) − , which induces the formation of active species ( OOH\O 2 − ) leading to the Fenton reaction. The effect of catalyst loading, initial concentration of PC, hydrogen peroxide (H 2 O 2 ) and oxalic acid concentrations were determined. The optimal initial concentration of hydrogen peroxide and oxalic acid for the PC degradation with Goethite under the experimental conditions was found to be 5 × 10 −3 and 5 × 10 −4 mol L −1 respectively. The photodegradation of PC in the mixtures PC–Goethite, PC–Goethite–H 2 O 2 and PC–Goethite–oxalic acid under solar light was significantly accelerated in comparison with artificial irradiation at 365 nm.

Studies on the Kinetics of Oxidation of 4-Oxo-4-phenylbutanoic Acid by Benzimidazolium Fluorochromate in the Presence of Oxalic Acid in Acetic Acid-Water Medium

Kinetics of oxidation of 4-oxo-4-phenyl butanoic acid (4-oxo acid) by benzimidazolium fluorochromate (BIFC) in acetic acid-water medium with perchloric acid in the presence of oxalic acid (OA) has been studied. The reaction is first order each in (BIFC), (4-oxo acid) and (H + ). The reaction has been found to be catalyzed by H + ions. The reaction rate increased remarkably with the increase in the proportion of acetic acid in the solvent medium. Various thermodynamic parameters have been determined at different acetic acid-water composition. A suitable mechanism has been proposed.

Hydrogen production using solar grade wasted silicon

In recent years, establishing a reliable and effective technology to recycle or recover valuable material from the spent modules or development discharges has gained worldwide recognition and popularity as an environmentally friendly way of disposing the industrial production wastes. Crystalline silicon wafer plays an important role in the photovoltaic industry, which gets wasted more than 40% in the slicing process. The challenge associated with the complete removal of silicon carbide particles from the cutting waste conquers the key point in recycling of crystalline silicon. In this article, solar grade wasted silicon was reused to produce hydrogen via chemical reaction between Si and H2O using alkali as catalyst or photocatalytic water splitting using purified Si as photocatalysts. The structure, compositional and optical properties of the wasted silicon were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible (UV-vis) spectroscopy. The morphology of wasted silicon powder was measured by scanning electron microscopic(SEM), high resolution transmission electron microscopic (HRTEM). Electronic structure of wasted silicon powder was characterized by photoluminescence spectroscopy(PL). Although subjecting to a series of chemical treatments, there is still few silicon carbide existed in the refined powder. The amount of H2 production detected (2.055 mmol) in the catalytic reaction greatly exceeds the hydrogen yield in the chemical reaction between silicon and sodium hydrate (0.2 mmol), indicating the feasibility of chemical reaction between wasted photovoltaic silicon and H2O catalyzed by alkali. The refined silicon powder displayed photocatalytic activity for hydrogen production in the presence of oxalic acid as sacrifice reagent. The study proposes methods for the utilization of industrial discharge from crystalline silicon solar cells, yielding valuable hydrogen evolution with the advantages of low energy consumption, low pollution, and easy operation.

TiO 2 –SiO 2 –PDMS nanocomposites with self-cleaning properties for stone protection and consolidation

Abstract This study deals with the design of two hydrophobic hybrid SiO 2 –TiO 2 materials and their application in the field of monument conservation. The nanocomposite consolidants were based on the modification of tetraethoxysilane (TEOS) with the incorporation of both TiO 2 nanoparticles and hydroxyl-terminated polydimethylsiloxane (PDMS). The TiO 2 nanoparticles have been prepared from the hydrolysis of titanium tetraisopropoxide (TTIP) in the presence of oxalic acid as a catalyst. The physico-chemical properties of the designed hydrophobic nanocrystalline SiO 2 –TiO 2 –PDMS composites have been extensively studied before their application as consolidants on a limestone. Overall, the effectiveness of the nanocomposites was evaluated by the comparative characterization of untreated and treated stone specimens. The results of both capillary water absorption and contact angle measurements point out that the TiO 2 –SiO 2 –PDMS nanocomposites functioned as hydrophobic coatings. Furthermore, the results obtained from microdrilling resistance and Fourier Transform Infrared spectroscopy (FTIR) revealed a penetration depth of the nanocomposites within the stone of c. 15 mm. The innovation of these syntheses pertains to the application of hydrophobic semi-transparent and transparent nanocomposites with self-cleaning and strengthening properties, without altering the colour of the stone surface and the water vapour permeability.

Photocatalytic degradation of diazinon by illuminated WO3 nanopowder

In this study, photocatalytic degradation of diazinon as a model phosphorothioate insecticide by tungsten oxide nanopowder under UV irradiation was investigated. Effect of operational parameters including WO3 dosage, pH, initial diazinon concentration, and organic compounds (humic acid, oxalic acid, phenol, ethylenediaminetetraacetic acid (EDTA)) on the photocatalytic degradation of diazinon was studied. Degradation efficiency of diazinon by WO3/UV process was more effective than WO3-alone and UV-alone. As the nanocatalyst dosage increased, the photocatalytic degradation of the diazinon decreased. Removal efficiency was decreased by increasing pH and initial diazinon concentration. The reaction rate constant (kobs) was decreased from 0.1233 to 0.0001/min, and the value of electrical energy per order (EEo) was increased from 38.93 to 48,000 (kWh/m3) with increasing initial diazinon concentration from 5 to 50 mg/L, respectively. The photocatalytic degradation of diazinon was increased in the presence of oxalic acid and EDTA, while different trend was observed in the presence of phenol and humic acid. Proper photocatalytic activity was observed even after five successive cycles. Finally, UV/WO3 is identified as a promising technique for the removal of diazinon with high efficiency in a short reaction time.

Facile synthesis of polyaniline nanotubes and their enhanced stimuli-response under electric fields

Polyaniline (PANI) nanotubes were fabricated successfully using a micelle soft-template method in the presence of oxalic acid as a dopant and applied as the dispersed phase of an electrorheological (ER) fluid.

Iron oxalate capped iron–copper nanomaterial for oxidative transformation of aldehydes

An efficient, sustainable and green procedure for the synthesis of selective orthorhombic iron(oxalate) capped Fe–Cu bimetallic oxide nanomaterial [Fe(ox)Fe–CuOx] was developed using a sodium borohydride reduction of iron(ii) salt in the presence of oxalic acid at room temperature followed by addition of copper sulfate in water.

Synthesis and chelation properties of a new polymeric ligand derived from 1-amino-2-naphthol-4-sulfonic Acid.

A novel chelating resin for preconcentration of heavy metals from various seawater samples has been developed by condensing 1-amino-2-hydroxy-7-[(4-hydroxyphenyl)diazenyl] naphthalene-4-sulfonic acid (AHDNS) with formaldehyde (1:2 mole ratio) in the presence of oxalic acid as the catalyst. The resin thus obtained was used as a solid sorbent for the separation of divalent metal ions present at trace levels in seawater. The functionalized phenol (AHDNS) was characterized by spectral studies. The polymeric resin AHDNS-formaldehyde (AHDNS-F) obtained by condensing the functionalized phenol and formaldehyde was characterized by IR and NMR spectral studies. The chelating property of the AHDNS-F resin towards divalent metal ions was studied as a function of pH and in the presence of electrolyte. The metal uptake properties of the resin were determined by using an atomic absorption spectrophotometer. This procedure was validated for recovery of divalent metal ions from seawater samples. The recoveries of cadmium, cobalt, copper, manganese, lead, and zinc were above 92% under the optimum preconcentration conditions. The LOD was <0.73 μg/L and the RSDs were <2%. Thus, the AHDNS-F resin can be widely used as a solid sorbent for the preconcentration of trace metals at ppm levels in seawater samples.