Atm Oxygen Research Articles

Effect of ultraviolet radiation c treatment on preservation of Naematelia aurantialba in modified atmosphere packaging

Naematelia aurantialba, known for its health benefits but perishable due to high water content, has a limited market life. This study explored extending its shelf life using ultraviolet C radiation within modified atmosphere packaging. Ultraviolet C, typically used for sterilizing produce, has untapped potential for preserving Naematelia aurantialba. Samples underwent ultraviolet C with various intensities, then were stored at 2 ± 1 °C in packaging bags with 4081 mL/m2·d·atm oxygen transmission rate, with quality checks every seven days until day 42. Samples treated with 0.19 kJ/m² ultraviolet C radiation within the MAP system significantly slowed color and texture changes in N. aurantialba, maintaining cell integrity. This treatment also reduced the loss of aroma substances and significantly increased the total phenolic and flavonoid content in the N. aurantialba. Simultaneously, these samples demonstrated tester preference, highlighting the treatment's effectiveness in enhancing freshness and marketability.

Effectiveness of Repetitive Hyperbaric Oxygen Therapy for Chronic Limb-Threatening Ischemia.

Lower extremity artery disease is strongly associated with morbidity and is typically addressed through revascularization interventions. We assessed the clinical outcomes of patients with chronic limb-threatening ischemia (CLTI) without revascularization who did and did not undergo repetitive hyperbaric oxygen therapy (HBOT). Between April 2002 and March 2017, the records of 58 patients with CLTI (Rutherford classification 4 in 19% and 5 in 81%) were evaluated retrospectively. HBOT was performed at 2.8 atm of oxygen (HBOT group). The control group included those who could not continue HBOT and historical controls. Patients in poor general health or with an indication for revascularization therapy were excluded. We examined major adverse events (MAEs) and limb salvage rates. Independent predictors and risk stratification were analyzed using a multivariate regression analysis. The mean age was 71±13 years. Of all patients, 67% had diabetes and 43% were undergoing hemodialysis. The mean follow-up period was 4.3±0.8 years. The overall survival rate was 84.5% and 81.0% at 1 and 3 years, respectively. The Cox regression analysis indicated that high body mass index (odds ratio [OR]: 0.86; 95% confidence interval [CI]: 0.76-0.97; p=0.01), well-nourished (OR: 1.21; 95% CI: 1.01-1.45), and HBOT (OR: 0.05; 95% CI: 0.01-0.26; p<0.001) independently predicted absence of MAEs. For major limb amputation, the ankle-brachial index (OR: 0.2; 95% CI: 0.05-0.86; p=0.03) and HBOT (OR: 0.04; 95% CI: 0.004-0.32; p=0.003) were independent predictors. Repetitive, stand-alone HBOT was associated with MAE-free survival and limb salvage in patients with CLTI.

Characterization of YBa2Cu4O8 superconductor prepared by using YBa2Cu3O7-x and CuO via solid state reaction technique with heating under ordinary oxygen pressure

The aim and objective of this study is to investigate the material synthesis and superconducting properties of YBa2Cu4O8 (Y-124) synthesized from YBa2Cu3O7-x (Y-123) and CuO powders. A commercial Y-123 and CuO powders were used to synthesize polycrystalline Y-124 employing the conventional solid state reaction method with heating at 1 atm oxygen pressure. Sodium nitrate was used as catalytic enhancer during the chemical reaction. The samples were subjected to twice sintering at 815 °C for 24 h with intermittent grinding. Analysis of the x-ray diffraction (XRD) data showed that Y-124 phase is dominance (81.1 wt%) in the samples with the presence of Y-123, and CuO as secondary phases. The thermogravimetric curve shows a small oxygen loss at ∼ 400 °C and rapid oxygen loss above ∼ 850 °C. Scanning electron microscope (SEM) images revealed that the samples had irregular grain shapes ranging in size from a few micrometers to fractions of a micrometer. The four-point-probe method was used to measure superconducting transition temperature (Tc). The samples exhibited a dual superconducting transition with the onset Tc of around 77 K and 87 K, respectively. This is consistent with the co-existence of superconducting phase Y-124 and Y-123. This two-level Tc characteristic of the sample gave potential application in multiples industries, including electronics, transportation, and data storage and processing. This study demonstrates how efficient and optimal conditions can be used to produce the Y-124 phase.

Quality retention and delay postharvest senescence of figs (Ficus carica L.) using 1-methylcyclopropene and modified atmosphere packaging during cold storage

The perishable and short shelf-life characteristics of figs result in nutrient loss and fruit waste. The application of 1-methylcyclopropene (1-MCP) and modified atmosphere packaging (MAP) is effective strategy for fruit preservation. In this study, 1-MCP and MAP were employed to inhibit figs decay and postharvest senescence during storage. Three treatments were evaluated, including the COM (untreated in commercial packaging), MAP (sealed in 4081 mL/m2·d·atm oxygen permeability bags), and treatment with 1-MCP and MAP (treated with 1.5 μL/L 1-MCP and sealed in 4081 mL/m2·d·atm oxygen permeability bags). Each treatment consisted of three replicates with 72 figs per replicate. Results indicated that treatment with 1-MCP and MAP inhibited fig decay, softening, and weight loss significantly, and changes in O2 and CO2 partial pressures. 1-MCP and MAP also effectively retained the higher contents of total phenol, total flavonoid, ascorbic acid and glutathione in figs, and increased activities of ascorbate peroxidase, peroxidase, superoxide dismutase and catalase. The production of superoxide anion (O2−·), and hydrogen peroxide (H2O2) in figs was prevented, and color were retained in 1-MCP and MAP treatment. Moreover, the analysis of volatile components indicated that 1-MCP and MAP improved the flavor of figs during storage and reduced the loss of aroma compounds in figs. Therefore, treatment with 1-MCP and MAP significantly extended storage life of figs.

Recyclable Cu/g-C3N4 nanometric semiconductor catalyzed N-formylation of amines via photocatalytic aerobic oxidative C[sbnd]C bond cleavage of aldehydes under visible-light irradiation

Due to its difficulty and complexity, the cleavage and subsequent functionalization of the C(sp3)-C(sp3) single bond has received less attention than the CC bond formation reactions that have been extensively studied. Herein, by utilizing Cu/g-C3N4 nanometric semiconductor as a recyclable photocatalyst, an aerobic oxidative CC bond cleavage of aldehydes was developed with the promotion of amines under visible light irradiation. Based on the reaction, phenylacetaldehyde was selected as a highly efficient formylation reagent for amines. Under blue light irradiation, good to excellent yields of formamides were achieved for various amines in 1 atm oxygen atmosphere at room temperature. This methodology offers a practical, neutral and gentle alternative to the preparation of formamides.

Evaluation of La2-x(Ca/Sr)xNi1-yFeyO4+δ (x = 0.5, 0.6; y = 0.4, 0.5) as cathodes for proton-conducting SOFC based on lanthanum tungstate

La2NiO4+δ, La1.4Ca0.6Ni0.6Fe0.4O4+δ (LCNF0604), La1.4Sr0.6Ni0.6Fe0.4O4+δ (LSNF0604), La1.4Sr0.6Ni0.5Fe0.5O4+δ (LSNF0605) and La1.5Sr0.5Ni0.6Fe0.4O4+δ (LSNF0504) were synthesized by the citrate-nitrate technique with the following four annealing steps at 950 °C in air (La2NiO4+δ, LCNF0604, LSNF0604) or in atmosphere with the reduced (10−5 atm) oxygen partial pressure (LSNF0605, LSNF0504). Phase purity of the samples is confirmed by the X-ray powder diffraction (XRPD). Electrochemical impedance spectroscopy studies of the symmetrical cells based on the proton-conducting La28−zW4+zO54+1.5z (z = 0.85, LWO85) electrolyte reveal that the polarization resistance (Rp) decreases in the row LCNF0604>La2NiO4+δ>LSNF0504>LSNF0604>LSNF0605 in the temperature interval of 600–800 °C in wet air. The process at low frequencies related to the surface exchange, provides the most significant contribution to the polarization resistance of the studied cells. Higher polarization resistance for the La2NiO4+δ/LWO85 cell can be associated with blocking of protons/protonic species. The minimal Rp value of 1 Ω cm2 at 800 °C in wet air is demonstrated by the LSNF0605/LWO85 symmetrical cell. The maximal power density for the anode-supported LSNF0605/LWO85/Ni-LWO85 single fuel cell is equal to 55 mW cm−2 at 750 °C. The performance of the fuel cell is limited by the formation of La2O3 at the LWO85/Ni-LWO85 interface due to chemical interaction between NiO and LWO85. To improve the performance of the studied fuel cell the development of new proton-conducting buffer layer stable to LWO85 is required.

Performance enhancement of polymer electrolyte membrane fuel cell by PtCo3 nanoporous film as high mass-specific power density catalyst using laser deposition and processing

This study demonstrates the performance of polymer electrolyte membrane fuel cell (PEMFC) can be significantly enhanced with laser deposited and processed PtCo3 nanoporous film as the catalyst layer. The PtCo3 nanoporous film is fabricated by first depositing a thin film of stacked PtCo3 nanoparticles on gas diffusion layer using pulsed laser deposition and then subjecting the film to scanning continuous-wave laser processing. The heating by the scanning laser beam increases electrochemical surface area substantially, which could be ascribed to formation of Pt skin on each nanoparticle via Pt surface segregation. Furthermore, the durability of the catalyst under accelerated degradation test is greatly enhanced, which may be attributed to inhibition of Co leaching by the Pt skin and strengthening of the contacts between nanoparticles caused by concomitant sintering effect. Application of such catalyst to the cathode of a PEMFC exhibits a 2.4-fold increase in current density with respect to that without laser processing, raising the cathode mass-specific power density to 8.79 kW g−1 with 1 atm oxygen and 12.0 kW g−1 with 1.5 atm oxygen.

Modified atmosphere packaging combined with CO2 and 1-methylcyclopropene prolong the storability and maintain antioxidant properties of cherry tomato

Cherry tomato is a perishable fruit vegetable that requires packaging for a relatively long distribution period. In this study, we combined the effects of changing the normal composition of air in the package and short-term pre-storage treatment of fruits with 1-methylcyclopropene (1-MCP) and high CO2 to maintain quality and extend the distribution period of ‘Unicorn’ cherry tomato. The treatments were modified atmosphere packaging (MAP), active modified atmosphere packaging (AMAP), high CO2 + MAP, and 1-MCP + MAP. All the treatments were sealed with 40,000 cc/m2 day atm oxygen transmission rate (OTR) film and stored at 20 and 10 °C up to 11 and 15 days, respectively. Based on the observed results of physicochemical and antioxidant parameters, the order of importance to prolong storability and maintain antioxidant properties of cherry tomatoes could be MAP + CO2 > MAP + 1-MCP > AMAP > MAP. The current study provides important practical information on the packaging systems of cherry tomatoes to extend the distribution period and maintain antioxidant properties for the satisfaction of either the domestic or the neighboring overseas consumers.

Copper‐Catalyzed Remote C5‐Selective Chlorination of 8‐Amidoquinolines Using Sulfonyl Chlorides as Cl Source

AbstractSulfonyl chloride has been rarely used as Cl source in transition metal‐catalyzed C−H functionalizations. We report the unprecedented copper‐catalyzed remote C5‐chlorination of substituted 8‐amidoquinolines with sulfonyl chloride under 1 atm oxygen. 10 sulfonyl chlorides and 15 substituted 8‐amidoquinolines were tested, generating moderate to high yields. The catalytic system showed high regio‐selectivity, as well as good functional group tolerance.

Defect formation peculiarities and redox properties of novel oxygen carrier material LaCu0.5Ti0.5O3±δ at elevated temperatures

The disordered perovskite-like phase LaCu0.5Ti0.5O3±δ (LCTO) with Pnma space group is synthesized by solid-state reaction route. Coulometric and thermogravimetric measurements in 300–1223 K temperature and 10−16 – 0.21 atm oxygen partial pressure ranges reveal narrow equilibrium oxygen content interval for the studied compound. Moreover, LCTO is shown to possess both over- and non-stoichiometry depending on external conditions. The complete reduction of LaCu0.5Ti0.5O3±δ results in a formation of La2O3, La2Ti2O7–x oxides and metallic copper. Defect chemistry modeling and DFT calculations evidence oxygen vacancies formed in LaCu0.5Ti0.5O3±δ at reduction can be considered mobile species. A decomposition mechanism for studied cuprate is proposed based on experimental results.

Efficient Aerobic Oxidation of Ethyl Lactate to Ethyl Pyruvate over V2O5/g-C3N4 Catalysts.

Graphitic carbon nitride (g-C3N4)-supported V2O5 catalysts were prepared by the impregnation pyrolysis method, and their physicochemical properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS), UV–vis, TGA, N2 adsorption, and H2-TPR. These catalysts exhibit extremely high activity and selectivity in the aerobic oxidation of ethyl lactate to ethyl pyruvate. The excellent catalytic performance derives from the high surface-chemisorbed oxygen species. Low calcination temperature and interaction with g-C3N4 are conducive to increasing the surface-chemisorbed oxygen species of V2O5. The optimal catalyst 13V2O5/g-C3N4 gives 96.2% conversion of ethyl lactate with 85.6% selectivity toward ethyl pyruvate in 4 h at 130 °C and 1 atm oxygen, which is significantly superior to those of previously reported V-containing catalysts. This catalyst is also stable and reusable, and the ethyl pyruvate yield is reduced by less than 10% after four runs without any regeneration treatment.

Multispecies Diffusion of Yttrium, Rare Earth Elements and Hafnium in Garnet

AbstractWe report experimental data for Y, La, Lu and Hf diffusion in garnet, in which diffusant concentrations and silica activity have been systematically varied. Experiments were conducted at 950 and 1050 °C, at 1 atm pressure and oxygen fugacity corresponding to the quartz–fayalite–magnetite buffer. At Y and REE concentrations below several hundred ppm we observe both slow and fast diffusion mechanisms, which operate simultaneously and correspond to relatively high and low concentrations, respectively. Diffusivity of Y and REE is independent of silica activity over the studied range. General formulae for REE diffusion in garnet, incorporating data from this and previous studies, are logDREE(f)(m2 s−1)=−10·24(±0·21)−221057(±4284)2·303RT(K) for the ‘fast’ REE diffusion mechanism at 1 atm pressure, and logDREE(s)(m2 s−1)=−9·28(±0·65)−265200(±38540)+10800(±2600)×P(GPa)2·303RT(K) for the ‘slow’ REE diffusion mechanism. These slow and fast diffusion mechanisms are in agreement with previous, apparently conflicting, datasets for REE diffusion in garnet. Comparison with high-pressure experiments suggests that at high pressures (&amp;gt;∼1 GPa minimum) the fast diffusion mechanism no longer operates to a significant degree. When Y and/or REE surface concentrations are greater than several hundred ppm, complex concentration profiles develop. These profiles are consistent with a multi-site diffusion–reaction model, whereby Y and REE cations diffuse through, and exchange between, different crystallographic sites. Diffusion profiles of Hf do not exhibit any of the complexities observed for Y and REE profiles, and can be modeled using a standard (i.e. single mechanism) solution to the diffusion equation. Hafnium diffusion in garnet shows a negative dependence on silica activity, and is described by logDHf(m2 s−1)=−8·85(±0·38)−299344(±15136)+12500(±900)×P(GPa)2·303RT(K)−0·52(±0·09)×log⁡10aSiO2. In many natural garnets, diffusion of both Lu and Hf would be sufficiently slow that the Lu–Hf system can be reliably used to date garnet growth. In cases in which significant Lu diffusion does occur, preferential retention of 176Hf/177Hf relative to 176Lu/177Hf will skew isochron relationships such that their apparent ages may not correspond to anything meaningful (e.g. garnet growth, peak temperature or the closure temperature of Lu or Hf). Late-stage reheating events are capable of causing larger degrees of preferential retention of 176Hf/177Hf relative to 176Lu/177Hf and partial to full resetting of the Sm–Nd system within garnet, thus increasing the separation between garnet Lu–Hf and Sm–Nd isochron dates, owing to the fact that these systems are more significantly disturbed through diffusion as more radiogenic 176Hf and 143Nd have accumulated.

Effect of modified atmosphere packaging on quality and shelf life of baby leaf lettuce

Freshly harvested baby leaf lettuce (Lactuca sativa L. cv. Red Romaine) leaves were packaged with 1,300, 20,000, 40,000, or 100,000 cm3/m2/day/atm oxygen transmission rate (OTR) packaging films as ...

Distribution of Ni, Co, Precious, and Platinum Group Metals in Copper Making Process

The distribution coefficients of Ni, Co, Ag, Au, Pt, and Pd between molten copper and silica-saturated iron silicate slags ( {text{L}}_{text{Me}}^{{{text{Cu}}/{text{s}}}} ) were measured experimentally. The distribution behaviors were studied under typical conditions of copper converting and fire refining, i.e., from 1250 °C to 1350 °C, and from 10−8 to 10−4 atm oxygen partial pressure. The coefficients were determined as the ratios of the trace element weight concentrations measured in situ, directly from the equilibrated metal and slag phases. For the quantitative elemental analysis of the phases, state-of-the-art analytic techniques, including electron probe microanalysis and laser ablation-inductively coupled plasma-mass spectrometry, were employed. The distribution coefficients {text{L}}_{text{Me}}^{{{text{Cu}}/{text{s}}}} determined can be arranged in the following order: Pt > Au > Pd >> Ag > (Cu) > Ni > Co > (Fe).

Ultraviolet‐protective thin film based on PVA–melanin/rod‐coated silver nanowires and its application as a transparent capacitor

ABSTRACTMelanin is a biopigment in many organisms with interesting intrinsic properties suitable for emerging and sustainable technologies. In this work, we report the fabrication of transparent ultraviolet (UV)‐protective thin films based on synthetic melanin in poly(vinyl alcohol) (PVA) matrixes. Melanin was synthesized through the auto‐oxidation of l‐3,4‐dihydroxyphenylalanine (l‐DOPA) under oxygen pressure, resulting in excellent solubility in water. A thin film with a composition of 3 wt % melanin (synthesized at 6 atm oxygen pressure) and silver nanowires (AgNWs) deposited on the surface has good transparency in visible light and 100% UV irradiation photoprotection. Encapsulated PVA–melanin/AgNW films dipped in water for 7 days retained 98% of their UV irradiation photoprotection. Moreover, using a transparent conductive oxide substrate, this UV‐protective system can be simultaneously used as a transparent capacitor. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47805.

Molecular Oxygen-Promoted General and Site-Specific Alkylation with Organoboronic Acid.

A general alkylating method using organoboronic acid under 1 atm of oxygen is developed. It allows a facile access to a wide range of functionalized molecules with privileged scaffolds in drugs and natural products such as oxindoles, quinolinones, chromones, naphthoquinones, coumarins, and quinolones. In contrast to previous alkylation approaches that generally requiring transition-metal catalysis and a stoichiometric chemical oxidant, the present strategy features metal-free, molecular oxygen as the terminal oxidant and site specificity.

Influence of Hot Water Immersion and MAP Pre-treatments on Sterilization and Asparagus Spear Qualities During Cold Storage

The purpose of this study was to determine how asparagus spear qualities are affected by hot water immersion (HWT) and modified atmosphere packaging (MAP) pre-treatments. Asparagus spears were treated either with different durations of HWT or packed with 10,000 cc/m2·day·atm oxygen transmission rate (OTR) film as the MAP treatment, and then stored at 4°C until the final storage day. Respiration and ethylene production rates in asparagus increased after HWT, with 8 and 16 min treatments having the most effect on these parameters. Fresh weight loss was less than 0.3% with all treatments. Gas composition (i.e., C2H4, CO2, and O2) within the packaging was not significant among all treatments during storage. The MAP and HWT treatments made no difference not only in fresh weight but also in gas composition. Microbial growth (i.e., total aerobic bacteria, yeast, mold, and E. coli) was lower with the 2 and 4 min treatments than with the other treatments. Electrolyte leakage was less in the control, 2 min, and 4 min treatments compared to the 8 and 16 min treatments. The hue angle and total chlorophyll values, which are associated with yellowing, remained constant at the 2 and 4 min treatments compared to the other treatments, which did not have maintained values. Asparagine content accumulated in the control, 2 and 4 min treatments, whereas the 8 and 16 min treatments showed a decrease in asparagine content. Stem firmness was similar to pre-storage measurements with the 4 min treatment. Stem length for all of the treatments was slightly increased before storage regardless of HWT duration. Asparagus off-odor and visual qualities were the best with 4 min treatment compared to the other treatments. Consequently, HWT for 2-4 min and MAP Pre-treatments were effective in maintaining the measured qualities among the treatment and control groups. In contrast, HWT for more than 8 min offset any beneficial heat-treatment effects for long-term storage; as indicated by tissue softening at the stem tip, which resulted in secondary damages that included microorganism infection and deterioration of visual quality in the vegetables.

The Effect of La on the Oxidation and Corrosion Resistance of $$\hbox {Cu}_{52}\hbox {Ni}_{30}\hbox {Fe}_{18}$$ Cu 52 Ni 30 Fe 18 Alloy Inert Anode for Aluminum Electrolysis

The effect of La on the high-temperature oxidation and corrosion performance of ternary $$\hbox {Cu}_{52}\hbox {Ni}_{30}\hbox {Fe}_{18}$$ alloy inert anode for aluminum electrolysis in low-temperature KF–NaF– $$\hbox {AlF}_{3}$$ electrolyte was studied. The results indicate that the oxidation kinetics of ( $$\hbox {Cu}_{52}\hbox {Ni}_{30}\hbox {Fe}_{18})_{1{-}x}\hbox {La}_{x}$$ (x = 0, 0.5, 1, 2 wt%) alloys at $$850\,^{\circ }\hbox {C}$$ under 1 atm oxygen atmosphere follow the parabolic law. The oxidation scales are stratified state, which contains the Cu oxide as the external layer. While the internal layer of the oxidation products are the mixture of Fe oxide, Ni oxide and nickel ferrite. The Cu outward diffusion oxidation is the dominant factor for the $$\hbox {Cu}_{52}\hbox {Ni}_{30}\hbox {Fe}_{18}$$ alloy during high temperature oxidation. After adding La to the $$\hbox {Cu}_{52}\hbox {Ni}_{30}\hbox {Fe}_{18}$$ alloy, the oxidation mechanism has become the combined action with outward diffusion of Cu and internal diffusion of O to form the Ni/Fe oxide underneath the outmost CuO layer. The corrosion resistance of $$\hbox {Cu}_{52}\hbox {Ni}_{30}\hbox {Fe}_{18}$$ alloy anode during the aluminum electrolysis is further improved by adding 0.5 wt% La. Compared with $$\hbox {Cu}_{52}\hbox {Ni}_{30}\hbox {Fe}_{18 }$$ alloy, the corrosion rate of the $$\hbox {Cu}_{52}\hbox {Ni}_{30}\hbox {Fe}_{18 }$$ alloy with 0.5 wt% addition of La has reduced from 1.9 to 1.8 cm/a.

BaFeO3-Δ-Based Materials for Intermediate-Temperature Solid Oxide Fuel Cells and Beyond

Energy conversion and storage is a central problem to modern society, requiring the deployment of novel “green” technologies. Solid oxide fuel cells (SOFCs) are very promising because they can convert chemical energy directly to electricity with efficiencies as high as 60%. However, one of the bottlenecks of this technology is the limited activity of typical cathode materials. In this presentation, we will overview doped-BaFeO3-δ (BFO) as a potential high-activity SOFC cathode material. We first fabricate Ba0.95La0.05FeO3-δ (BLF) single crystal thin films by pulsed laser deposition (PLD) on yttria-stabilized zirconia (YSZ) substrates. The phase structure, surface morphology and roughness of the BLF thin films are characterized by X-ray diffraction and atomic force microscopy. X-ray photoelectron spectroscopy is used to analyze the elemental composition and chemical state of the deposited thin film [1-2]. Electrochemical impedance spectra measurements obtained from the symmetric cells with the configuration of BLF /SDC/YSZ/SDC/ BLF reveal that polarization resistance of BLF (001) thin films (100 nm) is as low as ~0.1 Ω cm2 at 700 °C and 0.21 atm oxygen pressure. The polarization resistances of BLF are lower than those of other perovskite electrodes. Furthermore, our computational results, including density functional theory and molecular dynamics simulations, show that the BLF has a low vacancy formation energy and fast oxygen transport [3-4]. The effect of various A- and B-site substitutions on the BFO’s activity from both an experimental [5, 6] and computational [7] perspective are then explored. Finally, opportunities to develop ferrites are discussed together with their use as low temperature electrocatalysts. Acknowledgements The authors gratefully acknowledge the Research Grants Council of Hong Kong for support through the project 16207615 and 16227016.

Effect of dissolved oxygen/nZVI/persulfate process on the elimination of 4-chlorophenol from aqueous solution: Modeling and optimization study

4-Chlorophenol (4-CP) is a hazardous and toxic chemical that enters into water bodies mainly through industrial effluents. The present study investigated the effect of under pressure dissolved oxygen on 4-CP degradation in the presence of nanoscale zero-valent iron (nZVI) and sodium persulfate. The impact of oxygen pressure, as a qualitative variable at three levels (1, 1.5 and 2 atm), along with five quantitative variables, including persulfate concentration (0-2mM), nZVI dosage (0-1 g/L), pH (3-11), reaction time (5-90min) and 4-CP concentration (50-500mg/L) on the 4-CP elimination from aqueous solutions, was examined using response surface methodology. There was a direct relationship between the dissolved oxygen under pressure and the 4-CP removal efficiency. Also, the gained R2 and adjusted R2 for three developed models of 1, 1.5 and 2 atm oxygen pressure were 0.971 and 0.9569, 0.9689 and 0.9538, and 0.9642 and 0.9468, respectively. The best removal process conditions for pH 4.2, 1.6mM persulfate, 64.79 min reaction time, 97.89mg/L initial 4-CP and 1 g/L nZVI dosage. The results indicated that dissolved oxygen under pressure-nZVI-persulfate could be considered a promising process for elimination of organic compounds from aqueous solutions.