Showing papers on "Oxalic acid published in 2016"
TL;DR: In this paper, the authors reported the production of highly thermal stable and functional cellulose nanocrystals (CNC) and nanofibrils (CNF) by hydrolysis using concentrated organic acids.
387 citations
TL;DR: In this article, a review of molecular distributions of water-soluble dicarboxylic acids and related compounds in atmospheric aerosols with a focus on their geographical variability, size distribution, sources and formation pathways is presented.
255 citations
TL;DR: In this paper, an effective decomposition of antibiotic sulfadiazine (SD) in a Fe0-catalyzed sonochemical Fenton like system (Sono-FL) was demonstrated.
Abstract: Effective decomposition of antibiotic sulfadiazine (SD) in a Fe0-catalyzed sonochemical Fenton like system (Sono-FL) was demonstrated. By using the response surface methodology (RSM), an optimized experimental condition of pH 7.00, 0.94 mM Fe0, 1.90 mM persulfate (PS) and 20 W ultrasound (US) power was concluded, which could reach the predicted SD degradation efficiency of 90%. Afterwards, effects of wastewater matrix (five inorganic anions and two chelating agents) on the SD degradation were investigated in the system, respectively. It was found that the SD degradation could be inhibited by SO42−, NO3−, HCO3−/CO32− and H2PO4− to different extents. Cl− would lead to an enhancement with a low dosage (5 mM), but an inhibition with a high dosage (100 mM). Unexpectedly, chlorinated organic intermediates were also found as SD decomposed. Appropriate dosages of oxalic acid (OxA) or EDTA could benefit the SD degradation in the Sono-FL system, while excessive chelating agents would play as competitive pollutants. It was summarized that inorganic anions would mainly react with SO4 − and/or OH to form sub-radicals of less oxidative potential. OxA and EDTA would not only participate in complexing dissolution of Fe0 but also provide additional oxidants such as H2O2 and [FeIVO]2+, through the electron transfer reactions caused by the iron-ligands species.
222 citations
TL;DR: The demonstrated acidic DES method exhibits certain advantages over previously reported CNC productions, namely, milder processing conditions and easily obtainable and relatively inexpensive biodegradable solvents with low toxicity.
182 citations
TL;DR: The results demonstrate the extreme promise of REMs for water treatment applications and approach the kinetic limit.
Abstract: This research focused on the synthesis, characterization, and performance testing of a novel Magneli phase (TinO2n–1), n = 4 to 6, reactive electrochemical membrane (REM) for water treatment. The REMs were synthesized from tubular asymmetric TiO2 ultrafiltration membranes, and optimal reactivity was achieved for REMs composed of high purity Ti4O7. Probe molecules were used to assess outer-sphere charge transfer (Fe(CN)64–) and organic compound oxidation through both direct oxidation (oxalic acid) and formation of OH• (coumarin, terephthalic acid). High membrane fluxes (3208 L m–2 h–1 bar–1 (LMH bar–1)) were achieved and resulted in a convection-enhanced rate constant for Fe(CN)64– oxidation of 1.4 × 10–4 m s–1, which is the highest reported in an electrochemical flow-through reactor and approached the kinetic limit. The optimal removal rate for oxalic acid was 401.5 ± 18.1 mmol h–1 m–2 at 793 LMH, with approximately 84% current efficiency. Experiments indicate OH• were produced only on the Ti4O7 REM and n...
154 citations
TL;DR: The reductive-complexing dissolution mechanism is proposed here, which converts the dissolved Co(III)- to Co(II)-L (L=IDA or MA) thereby selective recovery of Co as Co( II)-oxalate is possible.
142 citations
TL;DR: NJDL-12 has higher ability in acid production and has stronger adaptability to acidic environment than NJDL-03, and the citric acid production increases significantly for NJ DL-12 at acidic environment, whereas formic and oxalic acids decrease sharply for both two fungi.
Abstract: Phosphate solubilizing fungi (PSF) have huge potentials in enhancing release of phosphorus from fertilizer. Two PSF (NJDL-03 and NJDL-12) were isolated and identified as Penicillium oxalicum and Aspergillus niger respectively in this study. The quantification and identification of organic acids were performed by HPLC. Total concentrations of organic acids secreted by NJDL-03 and NJDL-12 are ~4000 and ~10,000 mg/L with pH values of 3.6 and 2.4 respectively after five-days culture. Oxalic acid dominates acidity in the medium due to its high concentration and high acidity constant. The two fungi were also cultured for five days with the initial pH values of the medium varied from 6.5 to 1.5. The biomass reached the maximum when the initial pH values are 4.5 for NJDL-03 and 2.5 for NJDL-12. The organic acids for NJDL-12 reach the maximum at the initial pH = 5.5. However, the acids by NJDL-03 continue to decrease and proliferation of the fungus terminates at pH = 2.5. The citric acid production increases significantly for NJDL-12 at acidic environment, whereas formic and oxalic acids decrease sharply for both two fungi. This study shows that NJDL-12 has higher ability in acid production and has stronger adaptability to acidic environment than NJDL-03.
135 citations
TL;DR: In this article, the first report on metallic species transfer from aqueous solutions into hydrophobic deep eutectic and low-transition-temperature mixtures was presented.
114 citations
TL;DR: The optimal soil washing option for arsenic and cadmium was identified as phosphoric-oxalic acid-Na2EDTA sequence (POE) based on the high removal efficiency and the minimal harmful effects of the mobility and bioavailability of the remaining heavy metals.
110 citations
TL;DR: In this article, the best experimental conditions for leaching cobalt ions in a sulphuric acid-hydrogen peroxide system are studied, and the best leaching operation condition is an H2SO4 concentration of 3.0 mol L−1, liquid-solid ratio of 7 : 1 and hydrogen peroxide dosage of 1.6 mL g−1 for 2.5 h at 70 °C.
Abstract: Herein, the method of hydrometallurgy is adopted to recycle the precious metal cobalt in spent lithium ion batteries (LIBs). The best experimental conditions for leaching cobalt ions in sulphuric acid–hydrogen peroxide system are studied. The best leaching operation condition is an H2SO4 concentration of 3.0 mol L−1, liquid–solid ratio of 7 : 1 and hydrogen peroxide dosage of 1.6 mL g−1 for 2.5 h at 70 °C. Using the extraction characteristics of D2EHPA (di-(2-ethylhexyl) phosphoric acid) and PC-88A (2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester) for a specific ion in different pH value leaching solutions, the best experimental conditions are D2EHPA and PC-88A saponification rates of 20% and 30%, respectively, sulfonated kerosene volume of 70%, oil–water (O/A) ratio of 1 : 1, and extraction time of 10 min. Two extractions are applied, the first extraction occurs at pH 2.70 and the second extraction is done at pH 2.60 using D2EHPA to remove copper and manganese ions. After the extraction operation, PC-88A is used to further extract the leaching solution and maintain the pH at 4.25, so that cobalt and nickel ions are effectively separated, then cobalt ions are separated by oxalic acid and cobalt oxalate is obtained. The purity of cobalt is as high as 99.50%.
108 citations
TL;DR: The results illustrate the critical thresholds of organic acid concentration necessary to mobilize sorbed and precipitated P, bringing new insight on how the exudation of organic acids regulate chemical-microbial soil phosphorus transformations.
Abstract: We have used an integrated approach to study the mobility of inorganic phosphorus (P) from soil solid phase as well as the microbial biomass P and respiration at increasing doses of citric and oxalic acid in two different soils with contrasting agronomic P status. Citric or oxalic acids significantly increased soil solution P concentrations for doses over 2 mmol kg–1. However, low organic acid doses (<2 mmol kg–1) were associated with a steep increase in microbial biomass P, which was not seen for higher doses. In both soils, treatment with the tribasic citric acid led to a greater increase in soil solution P than the dibasic oxalic acid, likely due to the rapid degrading of oxalic acids in soils. After equilibration of soils with citric or oxalic acids, the adsorbed-to-solution distribution coefficient (Kd) and desorption rate constants (k–1) decreased whereas an increase in the response time of solution P equilibration (Tc) was observed. The extent of this effect was shown to be both soil and organic ac...
TL;DR: In this paper, a polymerizable sol-gel approach was used to demonstrate the photoreduction of Cr(VI) in aqueous medium, and a magnetically recoverable support for Fe3O4 was chosen as the magnetically recoveryable support, onto which, 10, 20, 30, 30 and 50% of TiO2 have been dispersed following the polyamide solgel approach.
Abstract: TiO2 synthesized by polymerizable sol–gel approach is used to demonstrate the photoreduction of Cr(VI) in aqueous medium. Fe3O4 is chosen as the magnetically recoverable support, onto which, 10, 20, 30 and 50% of TiO2 have been dispersed following the polymerizable sol–gel approach. The synthesized materials are characterized using XRD, SEM, XPS, Raman spectroscopy, diffuse reflectance spectroscopy and BET surface area measurement. Different hole-scavengers (oxalic acid, ammonium oxalate and ethanol) and an electron scavenger (potassium periodate) have been studied to compare the efficiency of Cr(VI) photoreduction in nitrogen as well as air atmosphere. With 5 mM oxalic acid as the hole-scavenger, the TiO2/Fe3O4 materials have demonstrated superior activity to the nonsupported bulk TiO2 toward Cr(VI) photoreduction in aerobic atmosphere. Particularly, 30% TiO2/Fe3O4 has shown the highest Cr(VI) photoreduction rate among the lot. The 30% TiO2/Fe3O4 catalyst has also demonstrated good recoverability as well...
TL;DR: In this article, solvent extraction and precipitation stripping were used to produce rare earth elements (REEs), and the results showed that about 95, 90, 87% and 80% of neodymium, lanthanum, cerium, and yttrium, respectively, can be extracted in optimum conditions of extraction.
TL;DR: In this article, the authors evaluated the performance of DCF in Fe-MCM-41/O3 process and found that DCF had a high level of detoxification after 30min treatment.
TL;DR: In this paper, a magnetically separable nanocomposite photocatalyst reduced graphene oxide (RGO)/ZnFe2O4/Ag3PO4, prepared by the solvothermal and in situ precipitation method, was first investigated as the photocat catalyst for 2,4-dichlorophenol degradation under visible light irradiation.
Abstract: Novel magnetically separable nanocomposite photocatalyst reduced graphene oxide (RGO)/ZnFe2O4/Ag3PO4, prepared by the solvothermal and in situ precipitation method, was first investigated as the photocatalyst for 2,4-dichlorophenol (2,4-DCP) degradation under visible light irradiation. The catalysts with different mass ratios were systematically characterized with FT-IR, XPS, XRD, SEM, FESEM, UV–vis, and PL. The nanocomposite RGO/ZnFe2O4/Ag3PO4 showed enhanced photocatalytic activity and stability compared with pure Ag3PO4 under the same conditions. During the photocatalysis process, intermediates of 4-chlorophenol (4-CP) and some other low molecular weight acids, including maleic acid, glyoxylic acid, glycolic acid, oxalic acid, acetic acid, and formic acid were detected through GC/MS. According to these analyses and the capture experiments of reactive species, the photocatalytic mechanism of RGO/ZnFe2O4/Ag3PO4 was discussed on the basis of the heterojunction energy-band theory and Z-scheme theory, and a...
TL;DR: In this article, the performance of 1,1,trichloroethane (1,1-TCA) degradation involving redox reactions in zeolite-supported nanozerovalent iron composite (Z-nZVI)-catalyzed sodium percarbonate (SPC) system in aqueous solution with five different chelating agents (CAs) including oxalic acid (OA), citric acid monohydrate (CAM), glutamic acid (GA), ethylenediaminetetraacetic acid (EDTA), and Lasc
Abstract: This study primarily focused on the performance of 1,1,1-trichloroethane (1,1,1-TCA) and trichloroethylene (TCE) degradation involving redox reactions in zeolite-supported nanozerovalent iron composite (Z-nZVI)-catalyzed sodium percarbonate (SPC) system in aqueous solution with five different chelating agents (CAs) including oxalic acid (OA), citric acid monohydrate (CAM), glutamic acid (GA), ethylenediaminetetraacetic acid (EDTA), and L-ascorbic acid (ASC). The experimental results showed that the addition of OA achieved almost 100 % degradation of 1,1,1-TCA and TCE. The addition of CAM and GA also significantly increased the contaminant degradation, while excessive addition of them inhibited the degradation. In contrast, EDTA and ASC showed negative impacts on 1,1,1-TCA and TCE degradation, which might be due to the strong reactivity with iron and OH● scavenging characteristics. The efficiency with CA addition on 1,1,1-TCA and TCE degradation decreased in the order of OA > CAM > GA > no CAs > EDTA > ASC. The extensive investigations using probe compound tests and scavenger tests revealed that both contaminants degraded primarily by OH● and O2
–● in chelated Z-nZVI-catalyzed SPC system. The significant improvement in 1,1,1-TCA and TCE degradation efficiency was accredited due to the (i) increase in concentration of Fe2+ and (ii) continuous generation of OH● radicals and maintenance of its quantity, ensuring more stability in the aqueous solution. Finally, the complete mineralization of 1,1,1-TCA and TCE in the OA-chelated, Z-nZVI-catalyzed SPC system was confirmed without any chlorinated intermediate by-products detected, demonstrating a great potential of this technique in the application of groundwater remediation.
TL;DR: In this article, the performance of novel N-doped carbon materials prepared by an easy ball milling method was evaluated in two distinct advanced oxidation processes (AOPs): catalytic wet air oxidation (CWAO) and catalytic ozonation (COZ), using oxalic acid as model pollutant.
Abstract: The performance of novel N-doped carbon materials prepared by an easy ball milling method was evaluated in two distinct advanced oxidation processes (AOPs): catalytic wet air oxidation (CWAO) and catalytic ozonation (COZ), using oxalic acid as model pollutant. The ball milling method allows the incorporation of large amounts of N-groups onto the surface of carbon nanotubes, namely pyridine-like N atoms (N-6), pyrrole-like N atoms (N-5) and quaternary nitrogen (N-Q), resulting in highly active catalysts for the oxidation of oxalic acid by both AOPs. The material prepared by ball milling with melamine without solvent is the most promising sample, combining an easy preparation with high amount of N-functionalities. Under the operation conditions used, oxalic acid was completely mineralized in 5 min by CWAO and in 4 h by COZ. The novel metal-free catalyst developed by this easy ball milling method demonstrated to be effective, confirming that this solvent-free methodology is quite adequate for the preparation of N-doped carbon materials with enhanced properties for the mineralization of organic pollutants by the studied processes.
TL;DR: In this article, the effect of chemical citric acid and other leaching reagents including inorganic acid, organic acid, and other organic acid on nickel extraction from low-grade Indonesian saprolitic ores was evaluated.
TL;DR: In this paper, the hygroscopic properties of oxalic acid/levoglucosan mixed particles are investigated with the hygscopicity tandem differential mobility analyzer (HTDMA).
Abstract: . Water-soluble organic compounds (WSOCs) are important components of organics in the atmospheric fine particulate matter. Although WSOCs play an important role in the hygroscopicity of aerosols, knowledge on the water uptake behavior of internally mixed WSOC aerosols remains limited. Here, the hygroscopic properties of single components such as levoglucosan, oxalic acid, malonic acid, succinic acid, phthalic acid, and multicomponent WSOC aerosols mainly involving oxalic acid are investigated with the hygroscopicity tandem differential mobility analyzer (HTDMA). The coexisting hygroscopic species including levoglucosan, malonic acid, and phthalic acid have a strong influence on the hygroscopic growth and phase behavior of oxalic acid, even suppressing its crystallization completely during the drying process. The phase behaviors of oxalic acid/levoglucosan mixed particles are confirmed by infrared spectra. The discrepancies between measured growth factors and predictions from Extended Aerosol Inorganics Model (E-AIM) with the Universal Quasi-Chemical Functional Group Activity Coefficient (UNIFAC) method and Zdanovskii–Stokes–Robinson (ZSR) approach increase at medium and high relative humidity (RH) assuming oxalic acid in a crystalline solid state. For the internal mixture of oxalic acid with levoglucosan or succinic acid, there is enhanced water uptake at high RH compared to the model predictions based on reasonable oxalic acid phase assumption. Organic mixture has more complex effects on the hygroscopicity of ammonium sulfate than single species. Although hygroscopic species such as levoglucosan account for a small fraction in the multicomponent aerosols, they may still strongly influence the hygroscopic behavior of ammonium sulfate by changing the phase state of oxalic acid which plays the role of "intermediate" species. Considering the abundance of oxalic acid in the atmospheric aerosols, its mixtures with hygroscopic species may significantly promote water uptake under high RH conditions and thus affect the cloud condensation nuclei (CCN) activity, optical properties, and chemical reactivity of atmospheric particles.
TL;DR: In this article, the photodegradation pathways of phenol, as well as the efficiency of photocatalysis by commercial TiO2 is investigated, and the results indicated that phenol was removed completely after 24h of UV-C irradiation.
Abstract: Investigating the photodegradation pathways of phenol, as well as the efficiency of photocatalysis by commercial TiO2 is the main task in this present work. Commercial TiO2 particles with the following characteristics: 96 % anatase, 4 % rutile, and 400 nm particles size were used as catalyst source. The photocatalytic process was carried out by mixing 100 ppm of phenol solution and 0.9 g/L of TiO2 particles with magnetic stirrer under UV-C light with 210 nm wavelength. UV–Vis spectrophotometer and COD measurement were used to evaluate the efficiency of photocatalysis. On the other hand, the formed intermediate products during phenol photodegradation were identified by LC–MS, UV–Vis spectrophotometer, and photoluminescence techniques. The results indicated that phenol was removed completely after 24 h of UV-C irradiation. The absorbance peak of phenol slightly decreased during the first 16 h. However, the peak dramatically reduced and disappeared at 24 h of irradiation. This degradation mechanism also occurred similarly to the COD value. There were two phases in photocatalysis of phenol. In phase-I, phenol was decomposed to hydroxylated compounds such as catechol, benzoquinone, and complexes with two benzene rings. In the mineralization phase, hydroxylated compounds were mineralized strongly by hydroxyl radicals, hydrogen radicals, and UV energy to form short-chain organic compounds such as formic acid, glycerol, and oxalic acid. Finally, hydrocarbon chains were broken easily and removed in the forms of carbon dioxide and water.
TL;DR: In this paper, the structural and spectral properties of carboxylate complexes were compared using 1,2-addition of either formic or oxalic acid to (PNHP)Mn(CO)2 (PNP = the deprotonated, amide form of the ligand N{CH2CH2(PiPr2)}2).
TL;DR: In this paper, three different morphological Na3V2(PO4)3 (irregular shaped, the porous sponge-like and plate like) were successfully prepared through controlling the amount of oxalic acid by a simple two-step reduction method.
TL;DR: This study elucidates the mechanisms of lead immobilization by FAp and A. niger, and sheds its perspective in lead remediation, especially for high Pb concentration solution.
TL;DR: A series of CuO/ZnO/Al2O3 catalysts were prepared via a direct combustion of Cu nitrate, Zn and Al acetate with citric acid, oxalic acid or urea as fuel.
TL;DR: An eco-friendly and hydrometallurgical process for the recovery of cobalt and lithium from spent lithium-ion batteries has been proposed, which includes pretreatment, citric acid leaching, selective chemical precipitation and circulatory leaching.
TL;DR: In this paper, a solar driven photocatalytic system, Fe(III)/UV, in the presence of organic sacrificial agents was evaluated using a lab-scale tubular photoreactor with compound parabolic collectors under simulated solar radiation.
Abstract: Toxic hexavalent chromium reduction to less toxic trivalent chromium was evaluated using a solar driven photocatalytic system, Fe(III)/UV, in the presence of organic sacrificial agents. The photocatalytic reduction experiments were conducted in a lab-scale tubular photoreactor with compound parabolic collectors under simulated solar radiation. The effect of parameters such as iron (1–12 mg L −1 ) and citric acid (0.058–3.840 mM) concentrations, pH value (3.0–8.0), temperature (15–40 °C), UVA irradiation source and initial Cr(VI) concentration (1, 10, 20, 40 mg L −1 ) on the process efficiency was analyzed, and also the addition of other organic ligands like oxalic acid, maleic acid and EDTA. The presence of citric acid proved to enhance the Cr(VI) reduction by Fe(III)/UV due to the formation of Fe(III)-Citrate complexes, providing a quicker pathway for ferric iron regeneration in the presence of UV–vis light. The organic ligands proved to act also as sacrificial agents of reactive oxygen species formed, avoiding the Cr(III) re-oxidation. The catalytic activity of the organic ligands in the Cr(VI) reduction by Fe(III)/UV followed this order: citric acid > oxalic acid > EDTA > maleic acid. The best Cr(VI) reduction (99% in 15 min) was achieved with citric acid in a Cr(VI):Citric acid molar ratio of 1:3 at pH 5 and 25 °C. Finally, the photocatalytic reduction of Cr(VI) present in a real effluent was achieved after 30 min, demonstrating the potential of the Fe(III)/UVA-vis/citric acid system for the treatment of Cr(VI) containing wastewaters.
TL;DR: Oxalic acid treatment benefited the control of CI and the maintenance of fruit quality in tomatoes stored for long periods (approximately 32days), apparently alleviated CI development and membrane damage.
TL;DR: In this paper, the degradation of oxalic acid and oxamic acid solutions in 0.10 mM Na 2 SO 4 at pH 3.0 has been studied by solar photolysis (SP), electro-Fenton (EF) and solar photoelectro-fenton (SPEF), with a stirred electrochemical cell containing a 3 cm 2 boron-doped diamond (BDD) anode and a 3cm 2 air-diffusion cathode.
TL;DR: Results suggest that A. niger F22 can be used as a microbial nematicide for the control of root-knot nematode disease.
Abstract: Restricted usage of chemical nematicides has led to development of environmentally safe alternatives. A culture filtrate of Aspergillus niger F22 was highly active against Meloidogyne incognita with marked mortality of second-stage juveniles (J2s) and inhibition of egg hatching. The nematicidal component was identified as oxalic acid by organic acid analysis and gas chromatography-mass spectroscopy (GC-MS). Exposure to 2 mmol/L oxalic acid resulted in 100% juvenile mortality at 1 day after treatment and suppressed egg hatching by 95.6% at 7 days after treatment. Oxalic acid showed similar nematicidal activity against M. hapla, but was not highly toxic to Bursaphelenchus xylophilus. The fungus was incubated on solid medium and dried culture was used for preparation of a wettable powder-type (WP) formulation as an active ingredient. Two WP formulations, F22-WP10 (ai 10%) and oxalic acid-WP8 (ai 8%), were prepared using F22 solid culture and oxalic acid. In a field naturally infested with M. incognita, application of a mixture of F22-WP10 + oxalic acid-WP8 at 1,000- and 500-fold dilutions significantly reduced gall formation on the roots of watermelon plants by 58.8 and 70.7%, respectively, compared to the non-treated control. The disease control efficacy of the mixture of F22-WP10 + oxalic acid-WP8 was significantly higher than that of a chemical nematicide, Sunchungtan (ai 30% fosthiazate). These results suggest that A. niger F22 can be used as a microbial nematicide for the control of root-knot nematode disease.
TL;DR: Under optimum conditions, 95% V was recovered in the presence of hydrogen peroxide in citric acid leaching, and the effects of leaching time, temperature, concentration of reagents and solid/liquid (S/L) ratio were investigated.