Oxygen Groups Research Articles

Testing carbon structures for metal-free catalytic/photocatalytic ozonation to remove disinfection by-product formation potential

Different graphitic carbon structures were prepared and tested for catalytic and photocatalytic ozonation of the precursors of chlorination disinfection by-products to remove their disinfection formation potential (DBPFP). Commercial graphite was submitted to ball milling and two chemical treatments with ammonium nitrate or potassium oxalate to increase its surface area. Additionally, ozonation in gas phase and liquid phase were used to generate surface oxygen groups in these materials and in commercial graphene. All the carbon samples were tested and compared with commercial graphene oxide in the removal of humic acid solutions. The highest catalytic activity during the catalytic/photocatalytic ozonation of humic acid was observed for commercial graphene, ozonated graphene and for graphene oxide; however, this did not result in high DBPFP removal and the instability of the materials was demonstrated. With a moderate catalytic activity but better stability, ball-milled graphite ozonated in liquid phase, was selected for photocatalytic ozonation of real surface water leading to a high DBPFP removal at the conditions tested (88 % 5-HAAs (haloacetic acids), 70 % 4-THMs (trihalomethanes), 70 % AOX (adsorbable organic halides); conditions: semi-batch experiments; 0.5 L volume; 5 mg L−1 O3; Qg = 10 L h−1; DOC0 = 5 mg L−1; pH = 7.8; 180 min under simulated solar radiation with average irradiance 580 W m−2).

Oxygen concentration from days 1 to 3 after insemination affects the embryo culture quality, cumulative live birth rate, and perinatal outcomes.

We aimed to compare embryo development, cumulative live birth rate (CLBR), and perinatal outcomes of embryos cultured in 20% and 5% oxygenfrom days 1 to 3 after insemination. This retrospective study included patients who received in vitro fertilization (IVF) treatment between January 2015 and November 2019. Embryos of each patient were cultured at 20% or 5% oxygen from days 1-3 after insemination. The primary outcome was CLBR. Propensity score matching (PSM) was used to balance patients' baseline data in both oxygen groups. In total, 31,566 patients were enrolled. After PSM, the rate of high-quality day 3 embryos was significantly lower in the 20% than in the 5% oxygen group (0.49 ± 0.33 vs 0.51 ± 0.33; adjusted β = -0.03; 95% confidence interval [CI], -0.03 to -0.02). The CLBR was significantly lower in the 20% than in the 5% oxygen group (58.6% vs. 62.4%; adjusted odds ratio = 0.85; 95% CI, 0.81-0.90). The birthweight and Z score of singletons were significantly higher in the 20% than in the 5% oxygen group (birthweight: 3.30 ± 0.50 vs. 3.28 ± 0.48; adjusted β = 0.022; 95% CI, 0.004-0.040; Z score: 0.26 ± 1.04 vs. 0.22 ± 1.01; adjusted β = 0.037; 95% CI, 0.001-0.074). Culturing embryos at atmospheric oxygen concentrations from days 1 to 3 compromises embryo quality, reduces CLBR, and affects birthweight. The 5% oxygen concentration ismore suitable for embryo culture in IVF laboratories to achieve successful outcomes.

Molecular insights into H3O+/Fe2+ sieving on functionalized graphene surface: The role of the ionic microstructures caused by different oxygen groups

In this study, we utilize a series of molecular dynamics simulations to explore the effects of microstructures of H3O+ and Fe2+ ions on their transport and sieving behavior on a functionalized graphene surface. The functionalization of the surface is modified by varying the epoxy group (i.e., xepoxy = epoxy/(epoxy + hydroxyl)) from 0 to 60 %. Results demonstrate that significantly high ion density, relative to the bulk, occurs within the range from the solid surface to the first valley of Fe2+, which is defined as the transport region (0 to 6.7–10.3 Å). For xepoxy values in 0–20 and 40–60 %, the high number of hydrogen bonds (H-bonds) between interfacial groups (namely, hydroxyl and epoxy groups) and H3O+ results in a high H3O+ density in the interfacial contact layer, subsequently leading to a high Fe2+ density in the subcontact layer. Conversely, xepoxy value of 30 % results in a relatively high H3O+ density and the lowest Fe2+ density in the subcontact layer. A detailed examination of the hydration microstructure reveals that the larger effective hydration radius induces the higher diffusion coefficient of H3O+ and Fe2+, which occurs because the larger effective hydration radius, which corresponding to weaker hydration ability, allows the easier exchange of hydrated water in the second hydration shell with non-hydrated water, thereby increasing the ion diffusion coefficient. High H3O+ permeability is shown to arise from the combined effect of interfacial H-bond structures and the large effective hydration radius. Additionally, the H-bond structure and ionic hydration microstructure drive high selectivity due to the induced high-density and effective hydration ratios, respectively. Notably, a xepoxy value of 30 % offers relatively high H3O+permeability and the highest H3O+/Fe2+ selectivity, making it the optimal choice for separating H3O+ from Fe2+.

Oxygen Therapy in Patients With Intermediate-Risk Acute Pulmonary Embolism: A Randomized Trial

The effect of supplemental oxygen therapy in patients with intermediate-risk pulmonary embolism (PE) who do not have hypoxemia at baseline is uncertain. Does supplemental oxygen improve echocardiographic parameters in nonhypoxemic patients with intermediate-risk PE? This pilot trial randomly assigned nonhypoxemic patients with stable PE and echocardiographic right ventricle (RV) enlargement to receive anticoagulation plus supplemental oxygen for the first 48h vsanticoagulation alone. The primary outcome was normal echocardiographic RV size 48h after randomization. Secondary efficacy outcomes were the numerical change in the RV to left ventricle (LV) diameter ratio measured 48h and 7days after randomization with respect to the baseline ratio measured at inclusion. The study was stopped prematurely because of the COVID-19 pandemic after recruiting 70 patients (mean ± SD age, 67.3 ± 16.1 years; 36 female [51.4%]) with primary outcome data. Forty-eight h after randomization, normalization of the RV size occurred in 14 of the 33 patients (42.4%) assigned to oxygen and in eight of the 37 patients (21.6%) assigned to ambient air (P= .08). In the oxygen group, the mean RV to LV ratio was reduced from 1.28 ± 0.28 at baseline to 1.01 ± 0.16 at 48h (P< .001); in the ambient air group, mean RV to LV ratios were 1.21 ± 0.18 at baseline and 1.08 ± 0.19 at 48h (P< .01). At 90days, one major bleeding event and one death (both in the ambient air group) had occurred. In analyses limited by a small number of enrollees, compared with ambient air, supplemental oxygen did not significantly increase the proportion of patients with nonhypoxemic intermediate-risk PE whose RV to LV ratio normalized after 48h of treatment. This pilot trial showed improvement in some ancillary efficacy outcomes and provides support for a definitive clinical outcomes trial. ClinicalTrials.gov; No.: NCT04003116; URL: www. gov.

Green production of tunable multicolor nanoparticles with diamond structure from long-flame coal by a one-step mild oxidation

The complex compositions and structural features of low-rank coal obstruct its wide use in materials applications directly. Graphene nanocarbon hydrosol with uniform particle size and containing nanodiamond structures were prepared from long-flame coal by a simple H2O2 oxidation, achieving the highest extraction rate of 30.86%, and the depolymerization degree was 80.21% when the temperature was 80 °C. The average diameter of the carbon nanoparticles was 1.86 ± 0.62 nm with 2–3 graphite flake layers, and these graphite flake layers were derived from the stable crystalline domains in the raw coal. Carbon nanoparticles exhibited good excitation wavelength-dependent and concentration-dependent fluorescence, which can be tunable from blue to green fluorescence by adjusting the concentration (0.19–1.5 g/L) and excitation wavelength (340–460 nm), the reason may be due to the combined effect of the relative intensity changes of various types of oxygenous groups, low-lying effects resulting from n(OH)→π*(CO) interactions between the hydroxyl groups and carbonyl groups, and the aggregation of particle. The post-reaction residue has a similar structural composition to that of humic acid and could be used for developing functional materials and agricultural restoration. Therefore, preparing carbon nanoparticles and humic acid by mild oxidation of hydrogen peroxide for the high-value utilization of long-flame coal has good application prospects.

Hierarchical wood cells impose well-textured carbon nanotubes with cobalt single atoms: Bioinspired construction and application in zinc–air battery

The construction of oxygen reduction reaction (ORR) electrocatalysts with well-textured structure and desirable activity remains great challenge for the complicated procedures and poor interface. Herein, inspired by sea anemones, the highly ordered Co–based carbon nanotubes electrocatalysts were elaborately assembled on wood fibers via stoichiometry. The porous cell-wall and abundant oxygen groups in lignocellulosic scaffold impose such preferable structure, in which the Co–based carbon nanotubes with Co single atoms and Co nanoparticles were tuned to possess higher catalytic activity and capture more oxygen species. As expected, the as-prepared electrocatalyst displays outstanding ORR performance with a half-wave potential of 0.9 V. The assembled Zn–air battery using this cathode catalyst shows a high-power density of 196 mW cm−2, superior to the commercial Pt/C catalysts. This work could inspire developing other biomimetic architectures for high-performance energy storage and conversion systems.

Revealing the Adsorption Mechanisms of Methanol on Lithium-Doped Porous Carbon through Experimental and Theoretical Calculations.

Previous reports have shown that it is difficult to improve the methanol adsorption performance of nitrogen and oxygen groups due to their low polarity. Here, we first prepared porous carbon with a high specific surface area and large pore volume using benzimidazole as a carbon precursor and KOH as an activating agent. Then, we improved the surface polarity of the porous carbon by doping with Lithium (Li) to enhance the methanol adsorption performance. The results showed that the methanol adsorption capacity of Li-doped porous carbon reached 35.4 mmol g-1, which increased by 57% compared to undoped porous carbon. Molecular simulation results showed that Li doping not only improved the methanol adsorption performance at low pressure, but also at relatively high pressure. This is mainly because Li-modified porous carbon has higher surface polarity than nitrogen and oxygen-modified surfaces, which can generate stronger electrostatic interactions. Furthermore, through density functional theory (DFT) calculations, we determined the adsorption energy, adsorption distance, and charge transfer between Li atom and methanol. Our results demonstrate that Li doping enhances the adsorption energy, reduces the adsorption distance, and increases the charge transfer in porous carbon. The mechanism of methanol adsorption by Li groups was revealed through experimental and theoretical calculations, providing a theoretical basis for the design and preparation of methanol adsorbents.

Co-adsorption and selective-adsorption of heavy metals and dyes from aqueous solution by bio-based humus/chitosan hydrogels

An eco-friendly adsorbent was prepared by reverse suspension crosslinking method to remove multiple pollutants from aqueous solution. Both raw materials, derived from humus (HS) and chitosan (CS), are biodegradable and low-cost natural biopolymers. After combining HS with CS, the adsorption capacity was significantly improved due to compensation effects between the two components. HS/CS exhibited the features of amphoteric adsorption through pH adjustment, enabling it to adsorb not only anionic pollutants (Methyl Orange (MO) and Cr(VI)), but also cationic ones (Methylene Blue (MB) and Pb(II)). The adsorption capacities were approximately 242 mg/g, 69 mg/g, 188 mg/g and 57 mg/g for MO, Cr(VI), MB and Pb(II), respectively. HS/CS showed a slight preference for MO in MO/Cr(VI) co-adsorption system, whereas strong selectivity for MB over Pb(II) in MB/Pb(II) system under acidic condition (pH<3.0). This selective behavior would allow for potential applications in separating MB/Pb(II) effluents and selectively recycling Pb(II) in acidic environment. The isothermal and kinetic adsorption behaviors followed Langmuir model and pseudo-second-order model, respectively. The density functional theory (DFT) confirmed that the interaction between metal ions and adsorbents was primarily attributed to chelation and electrostatic adsorption, owing to nitric and oxygenic functional groups. Whereas, the adsorption mechanisms for dyes were involved in electrostatic attraction, H-bond and π–π bond, due to available hydrogen, oxygen, nitrogen atoms and aromatic groups on the surface of adsorbent and adsorbates. The adsorbent could be efficiently regenerated and retained over 90% of its adsorption capacity after five cycles, which has a potential for practical applications in water treatment.

Construction of Supported MnOx/MgAl Hydrotalcite Catalysts and Their Highly Efficient Catalytic Performance for Low-Temperature Formaldehyde Removal

A series of supported MnOx/MgAl-layered double hydroxide (LDH) catalysts were prepared by hydrothermal co-precipitation to investigate their catalytic performances for low-temperature formaldehyde oxidation reactions. Activity tests show that the 10Mn/Mg3Al1-LDH catalyst exhibits higher efficiency for low-temperature formaldehyde oxidation with a high CO2 yield. It also shows remarkable long-term operational stability as well as good adaptability to different velocities and humidities. Various characterizations were carried out to establish the possible structure–activity correlations. The results show that there were a large number of hydroxyl groups in the 10Mn/MgAl-LDH catalysts, and the hydroxyl groups were positively correlated with Mg2+ content. The outstanding catalytic performance of 10Mn/Mg3Al1-LDH can be attributed to abundant surface hydroxyl groups, surface adsorbed oxygen and higher Mn4+/Mn3+ ratios. Through in situ Fourier-transform infrared spectroscopy (in situ FTIR), it was revealed that formaldehyde was gradually converted into CO2 and water with dioxymethylene (DOM), formate and carbonate as the major intermediates under the action of both active oxygen and active hydroxyl groups. The active oxygen and active hydroxyl groups consumed in the process are continuously replenished by the effective reaction between the oxygen molecules in the air and the active site of the catalyst. The low-temperature asynchronous conversion of formaldehyde results in the accumulation of some intermediates on the catalyst surface covering the active center, which induces catalyst deactivation.

Effect of Surface Treatments with Low-Pressure Plasma on the Adhesion of Zirconia.

The purpose of this study was to investigate the effect of low-pressure plasma on the contact angle, shear bond strength (SBS), and the failure mode of zirconia ceramic. Zirconia specimens were divided into three groups according to the surface treatment methods as follows: sandblasting with aluminum oxide (ZR-C), sandblasting with aluminum oxide and oxygen plasma (ZR-CP), and argon plasma (ZR-P). The contact angle, SBS, and surface characteristics were tested after thermocycling. Data analysis was made using the Kruskal-Wallis test and one-way analysis of variance. Plasma treatment significantly reduced the contact angle (p < 0.001) with the lowest value for the Zr-P group. An increase in oxygen and a decrease in carbon was observed on the zirconia surface in both plasma groups. For the SBS, there were significant differences among the groups (p < 0.018), the Zr-CP group showing the highest bond strength. Mixed failures were the most frequent. Plasma treatment was effective in increasing the wettability, increasing the oxygen/carbon ratio without changing zirconia surface morphology. The sandblasting plus plasma with oxygen group exhibited the highest bond strength.

Phosphate-driven H2O2 decomposition on DNA-bound bio-inspired activated carbon-based sensing platform for biological and food samples.

Hydrogen peroxide (H2O2) is one of the most important reactive oxygen species (ROS). Increased endogenous H2O2 levels indicate oxidative stress and could be a potential marker of many diseases, including Alzheimer's, cardiovascular diseases, and diabetes. However, consuming H2O2-incorporated food has adverse effects on humans and is a serious health concern. We used salmon testes DNA with bio-inspired activated carbon (AC) as an electrocatalyst for developing a novel H2O2 sensor. The phosphate backbone of DNA contains negatively charged oxygen groups that specifically attract protons from H2O2 reduction. We observed a linearity range of 0.01-250.0μM in the H2O2 reduction peak current with a detection limit of 2.5 and 45.7nM for chronoamperometric and differential pulse voltammetric studies. High biocompatibility of the sensor was achieved by the DNA, facilitating endogenous H2O2 detection. Moreover, this non-enzymatic sensor could also help in the rapid screening of H2O2-contaminated foods.

Ortho-C-H methoxylation of aryl halides enabled by a polarity-reversed N-O reagent.

Oxygen-substituted arenes widely exist in biologically important molecules and can serve as versatile handles to install other functional groups. However, direct and site-selective installation of oxygen groups to common aromatic compounds remains challenging, especially when additional arene functionalization is simultaneously required. Current arene C-H oxidation strategies generally require directing groups or precisely prefunctionalized substrates to control site-selectivity. While palladium/norbornene cooperative catalysis is promising for site-specific arene vicinal difunctionalization through simultaneous reactions with an electrophile and a nucleophile, the electrophile scope has been limited to species based on relatively 'soft' elements, such as carbon, nitrogen and sulfur. Here we report the development of an ortho oxygenation reaction with common aryl halides to rapidly deliver diverse aryl ethers. The coupling of the 'hard' oxygen electrophile is enabled by a stable, polarity-reversed, conformationally predistorted N-O reagent and facilitated by a C7-bromo-substituted norbornene mediator. Mechanistic studies reveal a unique SN2-type pathway between the N-O reagent as the oxygen electrophile and an electron-rich Pd(II) nucleophile.

Nitrogen-rich carbon composite fabricated from waste shrimp shells for highly efficient oxo-vanadate adsorption-coupled reduction

Protein, calcium carbonate, and chitin are abundant in shrimp shells. In this study, chemical treatment followed by hydrothermal carbonization was used to synthesize the nitrogen-rich hydrochar (HSHC) from shrimp shells. The untreated hydrochar exhibited a higher amount of calcium (25.37%) and less amount of nitrogen (2.68%) with alkaline pH (9.1). Interestingly chemical pre-treatment on shrimp shells boosted the nitrogen content to 6.81% and eliminated the calcium while controlling the pH to 6.4, which was beneficial for oxo-vanadate removal. The HSHC achieved vanadium(V) adsorption capacity of 21.20 mg/g at an optimal solution pH of 3.0, whereas the pristine hydrochar performed poorly (0.66 mg/g). The abundance of oxygen and nitrogen-based functional groups that developed through the chemical treatment resulted in improved adsorption coupled reduction performance of HSHC. This study proposed an inexpensive and environmentally friendly method for converting waste shrimp shells into value-added adsorbent.

Adding Non-Invasive Positive Pressure Ventilation to Supplemental Oxygen During Exercise Training in Severe Chronic Obstructive Pulmonary Disease: A Randomized Controlled Study.

Chronic obstructive pulmonary disease is currently the fourth leading cause of death in the world. Pulmonary rehabilitation is recommended for chronic obstructive pulmonary disease. This study aimed to evaluate the effects of non-invasive ventilation, supplemental oxygen, and exercise training and supplemental oxygen during exercise training during pulmonary rehabilitation practice in comparison with only exercise training on lung functions, blood gases, lactate levels, respiratory muscle pressures, dyspnea, walking distances, quality of life, and depression in patients with severe chronic obstructive pulmonary disease. The main outcome measure is exercise capacity (6-minute walk test), and the secondary end-point included quality of life. Thirty-five patients (mean ± SD age, 65.4 ± 6.5 years) with a mean bronchodilator forced expiratory volume in the first second of expiration of 39.4 ± 7%, undergoing an 8-week outpatient pulmonary rehabilitation, were randomized to either non-invasive ventilation, supplemental oxygen, and exercise training, supplemental oxygen during exercise training, or exercise training groups. The improvements in respiratory muscle strength were higher in non-invasive ventilation, supplemental oxygen, and exercise training patients than the moderate improvements in the exercise training group. Both non-invasive ventilation, supplemental oxygen, and exercise training and supplemental oxygen during exercise training groups showed significant increases in the 6-minute walk test and incremental shuttle walk test. However, the increase in walking distance was better in non-invasive ventilation, supplemental oxygen, and exercise training group (69.8 ± 53.2 m in 6-minute walk test and 66.6 ± 65.2 m in incremental shuttle walk test, P = .001 and P = .005, respectively) compared to supplemental oxygen during exercise training group (42.5+55.5 m in 6-minute walk test and 53.5+70.2 m in incremental shuttle walk test, P = .01 each, respectively). The total St. George's Respiratory Questionnaire score was similar in all study groups after the intervention. Symptoms of depression significantly improved only in non-invasive ventilation, supplemental oxygen, and exercise training group (-2.8+2.8, P = .006). Non-invasive positive-pressure ventilation (NIPPV) added to supplemental oxygen during exercise training was associated with better physiological adaptations than other modalities.

In situ recycling of Al foil and cathode materials from spent lithium-ion batteries through exogenous advanced oxidation

The efficient and sustainable recycling of spent lithium-ion batteries (LIBs), especially valuable metal enriched cathodes, is critical to achieve the goals of carbon peaking and carbon neutrality of new energy industry. However, current energy-intensive separation technologies to liberate cathode materials from current collector can hardly balance urgent requirements to sustainability and efficiency. Herein, an improved advanced oxidation technology based on ultrasonic assisted S2O82−-Fe2+-H+ system (USFH) was innovatively proposed to exfoliate the cathode materials from Al foil through the selective degradation of polyvinylidene difluoride binders (PVDF), with the emphasis on degradation mechanism. Experimental results illustrate that nearly all of coating materials were effectively separated from Al foil under the optimized conditions. Then, the density function theory (DFT) calculations and possible chemical reactions were conducted to reveal the detailed degradation mechanism for PVDF. It can be discovered that the functional groups in PVDF will be attacked by free radicals generated in USFH, leading to defluoridation with the formation of oxyorganics containing oxygen groups (e.g. C=O, O–H) and fracture of C–C skeleton to olefins, carboxylic acids, ketones and alkanes with shorter carbon chains, along with exfoliation of organic intermediates into solution. It may promise a green and efficient alternative by novel improved advanced oxidation technology with sound fundamental theory for in-situ recycling of spent LIBs.

Stability of the Photoluminescent Response on Hydroxyapatite/Multi-Walled Carbon Nanotube Composites

The application of hydroxyapatite (HAp)/multi-walled carbon nanotube composites in the medical area as coatings in prosthetics has been widely used because the carbon nanotubes reinforce the mechanical properties of hydroxyapatite. Despite that, their photoluminescent properties have not been studied, nor has the effect of different amounts of multi-walled carbon nanotubes on this property or what happened with their response with time. This work demonstrated that the photoluminescent response of HAp and HAp/multi-walled carbon nanotubes functionalized with oxygen groups (OMWCNT) composites was stabilized over time. The evaluated parameters were: three different amounts of OMWCNT (15, 25, and 35 mg) and two different thermal treatment temperatures (250 and 400 °C); all the samples were measured twice, after preparation and over a year after. The results indicated that over time the photoluminescent response is stabilized due to the passivation of surface defects, independently of the amount of OMWCNT used and the thermal treatment. In the end, the photoluminescent properties of these composites will extend their utilization in the medical area or open the door to new applications.

Surface‐Modified Carbon Materials for CO2 Electroreduction

AbstractThe electrochemical reduction of CO2 to produce sustainable fuels and chemicals has attracted great attention in recent years. It is shown that surface‐modified carbons catalyze the CO2RR. This study reports a strategy to modify the surface of commercially available carbon materials by adding oxygen and nitrogen surface groups without modifying its graphitic structure. Clear differences in CO2RR activity, selectivity and the turnover frequency between the surface‐modified carbons were observed, and these differences were ascribed to the nature of the surface groups chemistry and the point of zero charge (PZC). The results show that nitrogen‐containing surface groups are highly selective towards the formation of CO from the electroreduction of CO2 in comparison with the oxygen‐containing surface groups, and the carbon without surface groups. This demonstrates that the selectivity of carbon for CO2RR can be rationally tuned by simply altering the surface chemistry via surface functionalization.

Temperature-Dependent Optical Properties of Oxidized Graphenes.

In this study, we investigate how changing important synthesis-related parameters can affect and control the optical characteristics of graphene oxide (GO) and reduced graphene oxide (rGO). These parameters include drying time and reduction time at two different temperatures. We obtain an understanding of their impact on optical transitions, optical bandgap, absorption coefficient, and absorbance spectrum width by analyzing these factors. Accordingly, GO has an optical bandgap of about 4 eV, which is decreased by the reduction process to 1.9 eV. Both GO and rGO display greater absorption in the visible spectrum, which improves photon capture and boosts efficiency in energy conversion applications. Additionally, our results show that GO and rGO have higher absorption coefficients than those previously reported for dispersions of exfoliated graphene. Defects in GO and rGO, as well as the presence of functional oxygen groups, are the main contributors to this increased absorption. Several measurements are carried out, including spectroscopic and morphological studies, to further support our findings.

Diclofenac-Impregnated Mesoporous Carbon-Based Electrode Material for the Analysis of the Arsenic Drug Roxarsone.

This paper describes a novel electrode material, diclofenac-impregnated mesoporous carbon modified with a cationic surfactant, cetyltrimethylammonium bromide (DF-CMK-3/CTAB), for ultratrace analysis of the arsenic drug roxarsone (ROX). DF-CMK-3 amorphous carbon is a material with a high specific surface area and well-defined, hexagonally ordered, thin mesopores. The functional groups attached to the carbonaceous surface, such as chromene and pyron-like oxygen groups, lactam, and aromatic carbon rings, have the basic character and they can donate electrons. Modification of DF-CMK-3 with a CTAB layer significantly increases the analytical signal due to electrostatic interactions between the cationic surfactant and the anion form of ROX in the acidic medium. The voltammetric procedure at the glassy carbon sensor modified with DF-CMK-3/CTAB exhibited excellent sensitivity (limit of detection of 9.6 × 10-11 M) with a wide range of linearity from 5.0 × 10-10 to 1.0 × 10-4 M. Analysis of real samples (treated municipal wastewater and river water) showed recoveries from 96 to 102% without applying the complicated sample pretreatment step. The sensor demonstrated excellent sensitivity in the analysis of the arsenic drug ROX in the presence of interferences in environmental water samples.

Surface modification of polyethylene using argon and argon/methane DBD atmospheric pressure plasma jet

This article investigates the surface modification of polyethylene (PE) using an atmospheric pressure plasma jet of the DBD type (APPJ) maintained with pure argon (Ar) and with a premixed gas containing 90% argon and 10% of CH4. First and for both plasma jets, the jet length and the optical emissions coming from the plasma species were studied in terms of flow rate and applied voltage. Comparing to Ar, it has been shown that when the premixed gas is used, the jet length gets smaller, the transition point from laminar to turbulent regime was shifted to a low flow rate, and the emission of CH, H2 and C2 appeared, while O and N2 emission coming from ambient air was quenching. The PE surface treatment in both laminar and turbulent regime has been evaluated using water contact angle (WCA) measurement and attenuated total reflection (ATR). The obtained results showed that the hydrophilicity of PE has been improved in both plasma jets due to oxygen group (C=O) incorporation, but Ar plasma jet was observed to induce surface degradation compared to Ar/CH4 plasma due to the higher excited species.