Presence Of Oxalic Acid Research Articles

Fluorspar to fluorochemicals upon low-temperature activation in water.

The dangerous chemical hydrogen fluoride sits at the apex of the fluorochemical industry, but the substantial hazards linked to its production under harsh conditions (above 300 degrees Celsius) and transport are typically contracted to specialists. All fluorochemicals for applications, including refrigeration, electric transportation, agrochemicals and pharmaceuticals, are prepared from fluorspar (CaF2) through a procedure that generates highly dangerous hydrogen fluoride1-5. Here we report a mild method to obtain fluorochemicals directly from fluorspar, bypassing the necessity to manufacture hydrogen fluoride. Acid-grade fluorspar (more than 97 per cent CaF2) is treated with the fluorophilic Lewis acid boric acid (B(OH)3) or silicon dioxide (SiO2), in the presence of oxalic acid, a Brønsted acid that is highly effective for Ca2+ sequestration. This scalable process carried out in water at low temperature (below 50 degrees Celsius) enables access to widely used fluorochemicals, including tetrafluoroboric acid, alkali metal fluorides, tetraalkylammonium fluorides and fluoro(hetero)arenes. The replacement of oxalic acid with sulfuric acid gave comparable results for B(OH)3, but was not as effective when the fluorophilic Lewis acid was SiO2. A similar process also works with the lower-purity metspar. The production of fluorochemicals directly from fluorspar offers the possibility of decentralized manufacturing-an attractive model for the fluorochemical industry. With the renewed interest in innovative methods to synthesize oxalic acid via carbon dioxide capture and biomass6,7, and the challenges posed by our dependence on fossil fuels for sulfur and therefore sulfuric acid supply8,9, our technology may represent a departure towards a sustainable fluorochemical industry.

Development of a natural iron-based mineral/biochar composite for efficient simultaneous removal of Cr(VI) and methylene blue in the presence of oxalic acid

The complexity of industrial wastewater, heavy metals and organic pollutants often co-exist, making it difficult for conventional water processing to effectively purify water. Herein, natural siderite and bagasse were facilely developed as an iron-based mineral/biochar composite (Fe@BC=1:2) via one-step co-pyrolysis. This process achieved the simultaneous removal of hexavalent chromium (Cr(VI)) and methylene blue (MB) in the presence of oxalic acid (OA). Biochar perfectly implemented the reduction and effective dispersion of iron ore. The formation of iron species optimized the Zeta potential and electrochemical performance of biochar, which facilitated the adsorption and electron transfer process for oxalate and Cr(VI). The Fe@BC=1:2/OA system demonstrated excellent performance under various conditions, and the pseudo-second-order kinetic model indicated that chemisorption was the dominant mechanism for the Cr(VI) and MB removal. The Cr(VI) reduction was synergistically driven by the electron transfer of OA over the conjugated structure of biochar and the iron species redox processes. This was accompanied by the generation and intensification of biochar-induced persistent free radicals (PFRs), which consequently triggered the oxidative degradation of the adsorbed MB. This work provides a broader perspective on preparing cost-effective iron-based biochar from natural minerals and biomass for the simultaneous removal of heavy metals and organic pollutants.

Ferroelectric Order in the Chiral Coordination Polymers [Ln2(L*)2(ox)2(H2O)2] with Ln=Gd3+ or Dy3+, L*=((S, S)‐1,3‐bis(1‐Carboxylethyl)imidazolium and Ox=Oxalate.

AbstractWe evidence the ferroelectricity of two isostructural magnetic coordination networks obtained from a chiral imidazolium dicarboxylate salt ((S, S)‐1,3‐bis(1‐carboxylethyl)imidazolium or [HL*]) and Gd3+ or Dy3+ ions in presence of oxalic acid (H2ox). The two compounds exhibit a chiral structure P1 and ferroelectric properties. The crystallographic study shows that the Dy based‐compound is isostructural to the Gd analog. The non‐centrosymmetry of the two samples was further checked by means of nonlinear optical spectroscopy. The room temperature ferroelectric character of the compounds has been investigated through by an original method, derived from that used for thin films, made possible by preparing the sample as thin slices of resin containing inclusions of the coordination compounds.

Coproduction of hydrogen peroxide and formic acid as potential hydrogen-carrier through photocatalytic reformation of sacrificial chemical

This study explores the challenges to photo-reforming sacrificial chemicals into beneficial by-products while improving photocatalytic activity in H2O2 production by addressing several issues. The resorcinol-formaldehyde/graphitic carbon nitride composite (RF0.2GCN) with nanosheet-like RF morphology achieved a higher degree of surface-to-surface contact through -C-NH-CH2- and -NH-CH-OH than the nanosphere (RF0.8GCN). The RF0.2GCN produced H2O2 at 325.2 µg g−1 s−1 in the presence of oxalic acid (OA) at pH 2.1 with apparent quantum yield (AQY) of 12.7 %. The conduction band position potential was +0.54 VNHE, which is thermodynamically unfavorable for H+/H2 (E°: 0.00 VNHE) and O2/·O2- (E°: −0.046 VNHE) reaction and also inhibits the decomposition of H2O2 (H2O2/·OH, E°: +0.39 VNHE). Furthermore, the decomposition of OA formed formic acid (FA) at 82 % selectivity and concurrent CO2·- formation could promote electron density in the conduction band via its electron-donating ability·H2O2 was purified by isolating FA using anion exchange resin, and FA was recovered by desorption from the resin using HCl (pH 3).

Oxalic acid-enhanced sulfamethoxazole degradation by V2O3/percarbonate process: Insights into the reactive oxygen species generation and conversion

Sewage disposal technology in advanced oxidation processes (AOPs) should be enriched for providing more options for practical application. Herein, degradative and mechanistic investigation of heterogeneous V2O3-activated sodium percarbonate (SPC) process was implemented in the presence of oxalic acid (OA). The experimental results indicated a strong dependency of sulfamethoxazole (SMX) degradation on SPC dosage and a wide adaptability to the ambient pH in V2O3/SPC/OA system. Efficient removal of SMX in water reached 93.4 % within 10 min at the initial presence of 0.1 g/L V2O3 and 2 mM SPC. Mechanistic experiments revealed that •OH played an indispensable role in SMX degradation, which partially dominated the degradation process and partially was the main precursor of CO3•- and O2•-. Moreover, except for the single electron transfer from low-valence state of vanadium (V) species to SPC, the intramolecular electron transfer process from –OOH ligand of V complex to hydrogen peroxide (H2O2) also participated in the generation of •OH. Additionally, the introduction of OA could provide a complex, transient acidic and reductive condition for facilitating the SMX removal process. On the other hand, the addition of OA restricted the conversion of •OH to CO3•- and O2•-. Zeolite was employed to absorb the V species in the aqueous solution after the reaction and the residual vanadium concentrations were <2 mg/L. The existence of HPO42-, CO32– and humic acid exerted severe inhibition on the decontamination of SMX, and F- and NO3– exerted slight suppression, whereas the existence of Cl- and SO42- did not show conspicuous impairment. This work filled the gap of decontamination performance of SMX in vanadium based heterogenous SPC system and deepened the understanding of the application of reductant.

Using the inherent elements in yeast biomass to produce Ni2P/N-doped biocarbon composites for efficient hexavalent chromium reduction.

The heterogeneous catalytic reduction of Cr(VI) to Cr(III) is an effective strategy for aqueous Cr(VI) contamination abatement, which requires the development of highly efficient, low-cost, and recyclable catalysts. Herein, Ni2P/N-doped biocarbon composites (Ni2P/N-BC) were fabricated through an anoxic pyrolysis process using NaCl and KCl as activators. A precursor of yeast biomass provided the essential C, N, and P elements for Ni2P/N-BC formation. When adopted for Cr(VI) reduction in the presence of oxalic acid as a reductant, the fabricated Ni2P/N-BC performed superior catalytic activity with a 100% Cr(VI) reduction efficiency within 10 min (Ni2P/N-BC-5 = 0.2 g L-1, oxalic acid = 0.4 g L-1, Cr(VI) = 20 mg L-1). Typical affecting parameters, e.g., catalyst dosage, oxalic acid loading, reaction temperature, initial solution pH, and water matrix, were investigated. Ni2P/N-BC exhibited good applicability in a broad pH range from 3.0 to 9.0 and in actual aquatic systems. Cr(VI) reduction efficiency remained 92.7% after five recycle runs. Such promising catalytic activity may originate from the well-crystallized Ni2P, N-doped biocarbon framework and high specific surface area of the materials. Preliminary reaction mechanism analysis indicated that the favorable charge state of Ni2P, fast hydrogen transfer, affinity of oxalic acid to Cr(VI), and inherent electron transfer in the biocarbon matrix contributed to effective Cr(VI) reduction. This work not only provides a facile and low-cost strategy to construct Ni2P/N-doped biocarbon nanosheet composite using environmentally benign biomass but also brings new insights for the remediation of Cr(VI) contamination.

Facet-Dependent Competitive Adsorption Mechanisms of Chromate and Oxalic Acid on γ-FeO(OH) Nanocrystals.

Facet-dependent toxic metal adsorption of iron oxides widely occurred in natural environments. It is known that organic acids can alter the adsorption behaviors of trace elements by cooperative or competitive effects. However, the coadsorption mechanisms of the specific facets are still not fully understood. In the current investigation, Cr(VI) adsorption onto the lepidocrocite (γ-FeO(OH))-exposed facets in the presence of oxalic acid (OA) was studied using macroexperiments, in situ attenuated total reflectance Fourier transform infrared spectroscopy, X-ray adsorption fine structure, and density functional theory calculations. Rod-like lepidocrocite (R-LEP) with a high ratio of {001}/{010} facet showed excellent Cr(VI) adsorption capacity than that of plate-like lepidocrocite (P-LEP, the dominant facet is {010}) in the absence/presence of OA. Interestingly, OA reacted with R-LEP would be easier to diminish Cr(VI) adsorption than with P-LEP. The competitive adsorption occurred on the {001} facet due to the formation of inner-sphere OA configurations (monodentate mononuclear and bidentate mononuclear structures) and a bidentate binuclear Cr(VI) complex. However, OA coordinated with {010} facets via the outer-sphere complexes, while Cr(VI) could form a protonated monodentate binuclear configuration. These observations suggest that the competitive adsorption processes between OA and Cr(VI) exhibit facet dependence. Furthermore, lepidocrocite-exposed facets determine the interfacial interactions and geochemical behaviors of Cr(VI) in polluted environments.

Oxalic acid enhanced removal of heavy metal and pesticide by peroxymonosulphate activation with a green biochar iron composite: Reactivity and mechanism

Nowadays, clean-up of heavy metals and pesticides from environment has received great attention. A green biochar iron composite (PC-ZVI) was successfully synthesized using pomelo peel residues and FeCl3 solution. Peroxymonosulfate (PMS) was introduced into the PC-ZVI system for Cr(VI) and atrazine (AE) removal, and results showed that PMS greatly promoted Cr(VI) and AE removal. The presence of oxalic acid (OA) could maintain a relatively high dissolved Fe2+ species for Cr(VI) reduction and AE oxidation in the PC-ZVI/PMS process. The contribution order of reactive oxygen species followed as HO• > SO4•- greater than1O2 > O2•− in both Cr(VI) and AE removal by PC-ZVI/PMS/OA process. A total of six intermediates products of AE degradation were detected, and AE molecular was effectively degraded into CO2, H2O, inorganic N and Cl through hydroxylation, substitution and de-alkylation processes. The underlying mechanism of Cr(VI) and AE removal by PC-ZVI/PMS/OA process was also proposed. Most Cr(VI) species were transformed into Cr2O3 and Cr(OH)3 through reduction and precipitation processes. PC-ZVI has a relatively high recyclability toward both Cr(VI) and AE removal from solutions. The potential toxicity of PC-ZVI solution was small at three PC-ZVI dosages levels, and the corresponding toxicity of AE reaction solution by PC-ZVI/PMS/OA process decreased as reaction time increased. The order of both Cr(VI) and AE removal in different water systems was tap water > river water > lake water > wastewater, and this PC-ZVI/PMS/OA process exhibited the better adaptability in application for several actual water environments.

Effect of annealing temperature on phase transitions and photo-Fenton catalytic activity of CoFe2O4 nanopowder

In this work, the hydrothermal technique was used to synthesize cobalt ferrite (CFO) magnetic nanoparticles. Then, the as-prepared CFO sample was annealed at four different temperatures (600, 700, 800, and 900 °C) to study the effect of the annealing temperature on the crystallite growth, magnetic properties, phase transitions, and photo-Fenton catalytic activity of CFO powder samples. The properties of CoFe2O4 were characterized by X-ray powder diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, Brunauer–Emmet–Teller analysis, vibrating sample magnetometry, and catalytic tests. The results showed that the annealing temperature significantly affected the phase structure, crystallite size, morphology, specific surface area, magnetic properties, and catalytic activity of CFO powder samples. The calcined CFO sample had higher catalytic activity than the as-prepared CFO. At the annealing temperature of 600 °C (CFO-600), the catalytic efficiency and rate constant of this material for the degradation of methylene blue under ultraviolet A irradiation for 60 min reached 95% and 3.16 h−1, respectively, in the presence of oxalic acid as a potential oxidizing agent. We also found that a higher number of Fe3+ ions occupying octahedral sites on the CFO surface resulted in a higher activity of the CFO photo-Fenton catalyst. In particular, the CFO-600 powder with excellent magnetic properties exhibited a good recycling catalytic performance. The present material holds promise as a potential practical candidate for treating pollution caused by organic dyes and limiting secondary contaminants released during the photocatalyst process.

Oxalic-activated minerals enhance the stabilization of polypropylene and polyamide microplastics in soil: Crucial roles of mineral dissolution coupled surface oxygen-functional groups

Low-molecular-weight organic acids (LMWOAs) prevalent in soil environments may influence the transport, fate, and orientation of microplastics (MPs) by mediating mineral interfaces. Nevertheless, few studies have reported their impact on the environmental behavior of MPs in soil. Here, the functional regulation of oxalic at mineral interfaces and its stabilizing mechanism for MPs were investigated. The results showed that oxalic drove MPs stability onto minerals and new adsorption pathways, which are dependent on the bifunctionality of minerals induced by oxalic acid. Besides, our findings reveal that in the absence of oxalic acid, the stability of hydrophilic and hydrophobic MPs on kaolinite (KL) mainly displays hydrophobic dispersion, whereas electrostatic interaction is dominant on ferric sesquioxide (FS). Moreover, the amide functional groups ([NHCO]) of PA-MPs may have positive feedback on the stability of MPs. In the presence of oxalic acid (2–100 mM), the MPs stability efficiency and property onto minerals were integrally increased in batch studies. Our results demonstrate the oxalic acid-activated interfacial interaction of minerals via dissolution coupled O-functional groups. Oxalic-induced functionality at mineral interfaces further activates electrostatic interaction, cation bridge effect, hydrogen forces, ligand exchange and hydrophobicity. These findings provide new insights into the regulating mechanisms of oxalic-activated mineral interfacial properties for environmental behavior of emerging pollutants.

Predicting the catalytic performance of Nb-doped nickel oxide catalysts for the oxidative dehydrogenation of ethane by knowing their electrochemical properties

In the present article, a relationship between the catalytic performance in the oxidative dehydrogenation of ethane (ODHE) for Nb-doped NiO catalysts and their electrochemical properties has been proposed. To do so, highly stable and selective Nb-doped NiO catalysts for the ODHE to ethylene have been synthesized by optimizing synthesis parameters such as the amount of oxalic acid in the synthesis gel and the calcination temperature. These catalysts have been characterized by means of XRD, HRTEM, Raman and UV–vis diffuse reflectance spectroscopies, TPR and XPS. Moreover, Electrochemical Impedance Spectroscopy (EIS), capacitance measurements (Mott-Schottky analysis) and cyclic voltammetries studies were also carried out. Electrochemical characterization indicates changes in the type of semiconductivity: p-type for samples calcined at 350 °C and the sample prepared in the absence of oxalic acid and calcined at 500 °C, to n-type for samples prepared in the presence of oxalic acid in the synthesis gel and calcined at 500 °C. According to the obtained results, the most selective catalysts present a low Nb-incorporation on the NiO lattice with a large amount of tiny Nb2O5 nanoparticles covering NiO crystallites. This work presents, for the first time, a complete electrochemical characterization of Nb-doped NiO catalysts showing a correlation between electrochemical properties and catalytic performance.

Preparation of magnetic nanoparticles as photo‒Fenton catalysts by a hydrothermal‒assisted thermal treatment method

The magnetic CoFe2O4 nanoparticles, prepared by hydrothermal method combining with the heat treatment at 600oC, were used to act as a photo‒Fenton catalyst in the methylene blue (MB) degradation reaction. The composition, structure, and surface morphology of the prepared materials were studied by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX) spectroscopy. The optical properties of CoFe2O4 before and after calcination, analyzed by UV-Vis diffuse reflectance (DRS) spectroscopy, demonstrated that after heating at 600oC, the structure and crystallinity of CoFe2O4 were increased. The calcination process also caused the CoFe2O4 sintering to grow to a larger size, thereby reducing the surface area of the CoFe2O4 after calcination compared to the original ones. This value was determined through nitrogen the adsorption‒desorption isotherms curve. The magnetism of CoFe2O4 before and after calcination was studied by vibrating sample magnetometer (VSM). After sintering at 600oC, the saturation magnetization (Ms) and residual magnetism (Mr) of CoFe2O4 were higher than those of the original. The Fenton photocatalytic performance was evaluated by MB degradation reaction under UVA radiation in the presence of oxalic acid as an active free radical generating agent. In the methylene blue degradation reaction at room temperature, the prepared CoFe2O4 catalyst showed the maximum degradation efficiency of 97% for MB and the reaction yields were almost unchanged after three consecutive reactions. This method promised in making ferrite materials for water treatment based on some advantages such as simple process, low cost, and environmentally friendly solvent usage.

Biosynthesis of NiFe2O4 nanoparticles using Murayya koenigii for photocatalytic dye degradation and antibacterial application

Biosynthesis of nickel ferrite (NiFe2O4) nanoparticles (NPs) using an aqueous extract of Murraya koenigii (M. koenigii) leaves is a novel, environmentally benign and cost effective method. NiFe2O4 NPs were characterized by different spectroscopic and microscopic techniques, including Ultraviolet–Visible (UV–Vis) spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, Thermogravimetric Analysis (TGA), Transmission Electron Microscopy (TEM), High-Resolution Scanning Electron Microscopy (HRSEM), Energy-dispersive X-ray spectrometry (EDX) and Vibrating-Sample Magnetometer (VSM). The observed results revealed that prepared NiFe2O4 NPs are highly pure, crystalline, partially spherical with an average size of 2–6 nm and attribute magnetic properties. The magnetization of the obtained biosynthesized nanoparticles is noticed ∼5.2 emu/g at 10 K Oe. The NiFe2O4 NPs exhibited a heterogeneous photo Fenton's catalytic feature in the presence of oxalic acid at ambient conditions. The effects of pH, dosage of NiFe2O4 catalyst and doses of oxalic acid on the degradation efficiency of 10 mg/L MB dye were assessed. The optimal degradation efficiency of ⁓ 98.5% was achieved within 70 min, and the observed results elucidated that the photocatalytic reactions follow first-order chemical kinetics. Thermodynamic parameters such as activation energy (Ea), enthalpy of activation (ΔH‡), entropy of activation (ΔS‡), and free energy of activation (ΔG‡) were evaluated, applying Arrhenius and activated complex theory ascertained the endothermic, less random and nonspontaneous features of photocatalytic process. NiFe2O4 NPs were also tested against different bacteria and found to have antibacterial properties. Hence, magnetic NiFe2O4 NPs can be exploited for its multifunctional applications, and specifically for the remediation of dye-contaminated wastewater.

Electrodeposition of Cu-Reinforced Polyaniline Coating for Protection of AH36 Steel in Natural Seawater

The marine environment is highly corrosive for mild and low alloy steels. This study aimed to enhance the corrosion resistance of the AH36 steel in a saline medium by coating it with a copper particles reinforced polyaniline (PANI) layer. PANI and Cu particles were grown on the steel surface by electrodepositing methods. Firstly, PANI was electropolymerized in the presence of oxalic acid, followed by the electrodeposition of Cu particles at different deposition times. The coating showed a well-distribution of Cu particles in the polymer matrix and excellent adhesion. Furthermore, the Cu particles and PANI-coated steels exhibited corrosion resistance significantly in the saline medium compared to the bare substrate and pristine PANI-coated samples. The improved corrosion protection of a Cu@PANI coating on the AH36 steel could contribute to forming a physical barrier by filling Cu particles on the PANI pores.

Vanadium selective separation enhancement from iron in black shale using oxalic acid due to FeS2 (1 0 0) surface passivation: A theoretical and experimental study

Iron impurity tends to precipitate and reduces vanadium product purity during vanadium extraction from black shale. Oxalic acid is an eco-friendly leachant which can enhance vanadium selective separation from iron impurity. In this paper, the separation mechanism was systematically investigated. The mineral phases transformations and thermodynamics analysis indicate that the FeS2 in black shale can react with H2C2O4, HC2O4-, C2O42- and O2, as a result, the pyrite surface was coated by ferrous oxalate passivation layer, which can depress pyrite dissolution reaction. Meanwhile, the density functional theory (DFT) calculations show that the H2C2O4, HC2O4- and C2O42- can reconstruct FeS2 (100) surface by adsorption, and the adsorption energy can be as low as −3.73 eV for C2O42- adsorption configuration. The electrons in Fe atoms were transferred to O atoms and the stable Fe-O bands together with closed seven/eight-membered rings structures were formed as passivation layer, which can weaken and reduce Fe atoms reactive activation for the FeS2 during oxalic acid leaching. This study reveals vanadium separation from iron due to pyrite passivation in presence of oxalic acid at an atomic level.

Mineralization of diazinon by low-cost CuO-Kaolin nanocomposite under visible light based RSM methodology: Kinetics, cost analysis, reaction pathway and bioassay

A convenient and low-cost co-precipitation method was utilized for stabilization of CuO nanoparticles on Kaolin. The prepared CuO-Kaolin was characterized by XRD, FT-IR, SEM, EDX and pHPZC techniques. In this empirical study, response surface methodology (RSM) based central composite design (CCD) was applied for optimization of operational factors in the photocatalytic removal of Diazinon (DZ). Under optimum conditions, i.e. initial pH=7, initial DZ concentration=30 mg L-1, photocatalyst amount=0.4g L-1 and in the presence of oxalic acid, folic acid and sodium carbonate=5 mg L-1, about 87.23 % DZ removal was achieved by CuO-Kaolin after 180 min of reaction. The ANOVA results of the polynomial model prove that the model is quite meaningful (F-value> 0.001 and P-value< 0.0001). Further, estimated electrical energy per order consumption (EEO) for visible light (VIS)/CuO-Kaolin system was calculated as 213.66 kWh m−3 with operational cost (OC) utilization of 52.053 USD kg−1 that was revealed this process is highly feasible and economic comparing with other photocatalytic processes (VIS/CuO, VIS/Kaolin and VIS). Ten cycle experiments confirmed that the CuO-Kaolin propounded a satisfied stability and recycling potency. By applying the OFAT technique, 96.05 % of DZ degradation and 79.19 % of DZ mineralization could be achieved after 180 min. The five main compounds produced during the VIS/CuO-Kaolin embracing 2-isopropyl-6-methyl-4-pyrimidinol (IMP), diethyl phosphonate, diazoxon, hydroxydiazinon, and diazinon methyl ketone are formed in the path of DZ degradation. The results of toxicity in the photocatalytic removal of DZ by D. magna showed LC50 and TU 48 h equal to 18.79 and 5.32 vol percent.

The influence of complexing agents on the cobalt-based catalysts properties and activities

In this study, CoAl2O4 samples were synthesized using sol–gel method in the presence of citric acid (CoAlCA), malic acid (CoAlMA), oxalic acid (CoAlOA) and urea (CoAlU) as complexing agents. The presence of cubic spinel structure for both CoAl2O4 and Co3O4 phases was confirmed by XRD. FTIR analysis emphasized that the composition of Co3+ ions decreased in order: CoAlOA (50.3 %) > CoAlU (41.8 %) > CoAlMA (40.7 %) > CoAlCA (24.3 %), which denotes that the presence of oxalic acid as complexation agent favors cobalt oxidation from Co2+ to Co3+ and, consequently, the expansion of Co3O4 phase. In the presence of citric acid, as a complexing agent, tetrahedral Co2+ ions prevailed and CoAl2O4 is the dominant phase.The catalytic performances of CoAl2O4 spinel oxides have been evaluated in lactonization of 1,4-butanediol, coupled with acetophenone hydrogenation and in the Claisen-Schmidt condensation reaction of benzaldehyde with acetophenone and the results provided a good relationship between Co3+/Co2+ ratio, the reactants conversion and the products yield.

Acute and sub-chronic toxicological evaluation of Averrhoa carambola leaves in Sprague Dawley rats.

Averrhoa carambola is a species of tree native to tropical Southeast Asia. It possesses antioxidant and anti-hyperlipidemia effects and has traditionally been used to treat a variety of ailments. However, the presence of oxalic acid in its fruits might restrict its consumption by individuals suffering from kidney disease, and caramboxin can cause neurotoxicity. In this study, we evaluated the acute and sub-chronic toxicity of the methanolic extract of A. carambola leaves (MEAC) in male and female rats. In the acute study, female rats were given a single oral dose of 5000mg/kg of MEAC and closely examined for distinct indications of toxic effects during the first 4h, periodically for 48h, and daily thereafter for 14days. Rats of both sexes were employed in the sub-chronic investigation for the 28-day repeated dose oral toxicity study. Results of the acute study revealed the safety of MEAC up to a dose of 5000mg/kg where the rats did not show changes or signs of toxicity. In the sub-chronic toxicity study, MEAC (250, 500, and 1000mg/kg) administration did not affect the body weight, food, and water consumption, motor coordination, behavior, or mental alertness in the treated rats. In addition, no variations in hematological or biochemical markers were found in MEAC-treated rats. In conclusion, these findings pinpoint the safety of MEAC at doses up to 5000mg/kg. The leaves of A. carambola could be safely consumed by people with kidney disease to treat other ailments.

Caryota urens: value addition, nutritional and medicinal values

Caryota urens which is commonly known as Kithul, is a multipurpose and underutilized palm mainly distributed in Asia. Due to its numerous applications, it has been considered an important plant that ensures the livelihood of the village people in Sri Lanka. Thus, this article reviews the nutritional and medicinal values of kithul palm and its value-added products. Kithul sap is widely used in the production of kithul treacle and jaggery due to its high amount of sugar content. Kithul seed oil is high in palmitic and oleic acid and is a good source of biofuels. Kithul fruit has skin-irritating nature due to the presence of oxalic acid, and also it contains anti-nutritional substances such as phytate, tannin and saponin. Different parts of Kithul palm such as leaves, flowers, fruit, sap is rich in antioxidants, anti -inflammatory, antimicrobial, and anti-diabetic properties due to the existence of flavonoids, glycosides like phytochemicals. Low gelatinization temperature has identified Kithul flour as a good gelling agent, stabilizer and thickener. Owning to its low Glycemic Index, kithul flour has become beneficial for people suffering from diabetics. Thus, valueadded products like biscuits, noodles, bread, muffin, rotti, porridge, dessert, yoghurt are identified as potential products that must be commercialized with more investigations.

Metal-doped CdS/MoS2 heterojunctions for photocatalytic degradation of organic pollutant

The present work describes the synthesis of metal-doped CdS/MoS2 heterojunctions, prepared by a two-step microwave-assisted solvothermal approach. The samples were characterized by X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman analysis as well as diffuse reflectance spectroscopy (DRS). The photocatalytic activity was assessed against the decomposition of 4-nitrophenol, in the presence of oxalic acid as sacrificial agent. At macroscopic scale, the hybrids demonstrated a certain level of phase separation, implying an inhomogeneous distribution of cocatalyst nanoparticles within the main semiconductor matrix. XPS analysis revealed that the main molybdenum-based species found was MoS2, whereas MoO3 was formed also. DRS measurements showed an actual shift of the absorption edge of hybrids, when compared with the corresponding one of bare CdS nanoparticles. The different photocatalytic activities may be attributed to differences in the relative population of heterojunctions and to the variable ratio of the molybdenum-based species (disulfide/trioxide) within each hybrid. Comparison with analogous studies suggests that the chemical speciation of the third component is critical towards the development of photocatalytic systems carrying a large population of heterojunctions.