H2O2 Oxidation Research Articles

Utilizing H2O2 for the selective flotation separation of chalcopyrite and galena with their surface pre-adsorbed with Isopropyl Ethyl Thiocarbamate

Chalcopyrite and galena often coexisted in ore deposits, and they are usually processed by bulk flotation and then separated to obtain valuable mixed concentrateds. In this paper, we propose a flotation reagent strategy, that uses Isopropyl Ethyl Thiocarbamate (IPETC) and hydrogen peroxide (H2O2) to achieve different floatability on chalcopyrite and galena, it is evident that chalcopyrite and galena with IPETC adsorbed on the surface can be separated by H2O2. The flotation results show that H2O2 has a great inhibition effect on galena and exhibits a weak inhibition effect on chalcopyrite. Mixture of chalcopyrite and galena with IPETC adsorbed on the surface was successfully separated by flotation with 15 mg·L-1 H2O2 at pH 7. The inhibition mechanism of H2O2 was analyzed by contact angle measurements, single-channel scanning Inductively Coupled Plasma emission spectroscopy (single-channel ICP) analysis, Fourier Transform Infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The characterization analysis indicates that the rate of H2O2 oxidation of galena is faster, resulting in more hydrophilic oxidation products such as oxides and hydroxides on the surface of galena, while the surface of chalcopyrite is less affected by H2O2. Also, compared with chalcopyrite, the adsorbed IPETC on the galena surface can be easily blanketed by oxidation products, so realizes the effective separation of chalcopyrite and galena.

A novel strategy for realizing highly sensitive nonenzymatic detection of H2O2 based on regulating crystallinity of CoO nanosheets

This study reports a novel strategy to construct a highly sensitive electrochemical sensing method based on crystallinity regulation. Two kinds of CoO nanosheets with different crystallinity were prepared by adjusting annealing temperature. The results show that decreasing crystallinity of CoO nanosheets not only increases electrochemical surface area but also accelerates electron transport rate. This is beneficial to improve the electrocatalytic activity of CoO nanosheets for electrochemical oxidation of H2O2, and therefore makes the sensor detect H2O2 in a linear range of 0.2 µM to 11 mM, a sensitivity of 909.9 µA·mM−1·cm−2 and a low detection limit of 0.2 µM. This study provides a new perspective to regulate the electrocatalytic activity of nanomaterials for constructing highly sensitive electrochemical sensor.

Determination of H2O2 and its antioxidant activity by BCM@Au NPs ratiometric SERS sensor

As a reactive oxygen species (ROS), excessive production of H2O2 contributes to the development of several diseases such as, inflammation, cancer, and respiratory diseases. Supplementation with endogenous or exogenous antioxidants can scavenge ROS and reduce the oxidation of cellular molecules, thus alleviating the generation of diseases. Therefore, the determination of H2O2 content and its antioxidant activity is of great importance in disease diagnosis and treatment. In this paper, a ratiometric SERS sensor with a flexible cellulose membrane was designed for quantitative detection of H2O2 and assessment of antioxidant activity. First, gold seeds were reduced on bacterial cellulose membrane (BCM) and Au NPs were smoothly deposited on the bacterial cellulose membrane (BCM) using halides to reduce the reduction potential in the growth solution to form a flexible BCM@Au NPs SERS substrate. Afterwards, the oxidation of H2O2 was used to convert 3-mercaptophenylboronic acid (3-MPBA) to the corresponding phenol form 3-hydroxyphenylethanol (3-HTP). The change of substance resulted in a good linear relationship between the intensity ratio corresponding to the two Raman shifts of 881 cm−1 and 995 cm−1 and the H2O2 concentration with a detection limit of 0.0186 μM. This opens up a new method for the detection of H2O2 with high sensitivity and accuracy. In addition, this SERS platform was successfully used for the determination of antioxidant activity. It is promising to be applied to disease diagnosis and efficacy evaluation.

Effect of oxidation treatment on the selective separation of molybdenite from chalcocite using flotation

Molybdenite is associated with primary and secondary copper sulfide minerals. Few studies have focused on the selective flotation of molybdenite to separate it from secondary copper sulfide minerals, such as chalcocite. This study evaluated the use of oxidation treatment to separate molybdenite from chalcocite. The effects of oxidation treatment with hydrogen peroxide (H2O2) on the flotation behaviors of molybdenite and chalcocite in the presence of collectors (i.e., potassium amyl xanthate and diesel oil) were evaluated, and the impacts of H2O2 concentration, oxidation treatment duration, and pH level were assessed. Chalcocite flotation tests showed that the H2O2 treatment significantly reduced the recovery of chalcocite due to the formation of copper hydroxide and sulfate species on the chalcocite surface, which altered its surface hydrophobicity. On the other hand, the low surface oxidation of molybdenite led to high flotation recovery after the oxidation treatment. Oxidation treatment with a 10 mM H2O2 solution at a pH of 9 for 20 min resulted in a separation efficiency of 87%, with 98% molybdenite recovery and 11% chalcocite recovery. The results show that H2O2 oxidation treatment enables the selective flotation of molybdenite to separate it from chalcocite.

Dynamic characteristics and functional analysis provide new insights into the role of GauERF105 for resistance against Verticillium dahliae in cotton

BackgroundThe cotton industry suffers significant yield losses annually due to Verticillium wilt, which is considered the most destructive disease affecting the crop. However, the precise mechanisms behind this disease in cotton remain largely unexplored.MethodsOur approach involved utilizing transcriptome data from G. australe which was exposed to Verticillium dahliae infection. From this data, we identified ethylene-responsive factors and further investigated their potential role in resistance through functional validations via Virus-induced gene silencing (VIGS) in cotton and overexpression in Arabidopsis.ResultsA total of 23 ethylene response factors (ERFs) were identified and their expression was analyzed at different time intervals (24 h, 48 h, and 72 h post-inoculation). Among them, GauERF105 was selected based on qRT-PCR expression analysis for further investigation. To demonstrate the significance of GauERF105, VIGS was utilized, revealing that suppressing GauERF105 leads to more severe infections in cotton plants compared to the wild-type. Additionally, the silenced plants exhibited reduced lignin deposition in the stems compared to the WT plants, indicating that the silencing of GauERF105 also impacts lignin content. The overexpression of GauERF105 in Arabidopsis confirmed its pivotal role in conferring resistance against Verticillium dahliae infection. Our results suggest that WT possesses higher levels of the oxidative stress markers MDA and H2O2 as compared to the overexpressed lines. In contrast, the activities of the antioxidant enzymes SOD and POD were higher in the overexpressed lines compared to the WT. Furthermore, DAB and trypan staining of the overexpressed lines suggested a greater impact of the disease in the wild-type compared to the transgenic lines.ConclusionsOur findings provide confirmation that GauERF105 is a crucial candidate in the defense mechanism of cotton against Verticillium dahliae invasion, and plays a pivotal role in this process. These results have the potential to facilitate the development of germplasm resistance in cotton.

Designing integrated Janus membrane based on a double-cross-linked polyphenol hydrophilic layer for complex emulsion separation

Efficient separation materials with multifunctional and switchable properties are urgently needed to treat submicron-scale oily droplets. Herein, tannic acid (TA) and polyethylenimine (PEI) were blended with poly(vinylidene fluoride) (PVDF) and used to coat a polydimethylsiloxane (PDMS)-modified non-woven fabric immersed in a CuSO4/H2O2 coagulation bath. TA and PEI form a phenolamine hydrophilic network that migrates to the surface and firmly binds to the PVDF substrate. CuSO4 catalyses the H2O2 oxidation, promoting the self-polymerisation of phenol hydroxyl group for forming a carboxyl group. Furthermore, the remaining Cu2+ ions complex with TA to form a metal–phenol cross-linked network. A double-cross-linked hydrophilic layer with polyphenols as connection points was formed on the PVDF surface. The hydrophilic contact angle of the membrane reached 0°. A rough structure with PDMS micro-/nanoparticles was constructed on the PVDF underside via surface nanocasting and the hydrophobic contact angle of the membranes reached 165°. In experiments, each side of the obtained Janus membranes demonstrated surface superhydrophilic and superlipophilic properties and a high flux and excellent separation efficiency for various oil–water emulsions. The integrated Janus membranes are suitable for unidirectional liquid collection, oil–water emulsion separation, cationic pigment adsorption and dealing with complex dye–emulsion pollutants. The integrated structure formed by the hydrophilic layer and the membrane enhances the fouling resistance of the membrane and the removal rate of pollutants reached >99 %. This research presents a simple approach to prepare Janus membranes with asymmetric wettability.

High-efficient degradation of ibuprofen as typical PPCP through a novel electrochemical approach of traditional peroxone method

An electrogenerated peroxone process was innovatively structured to effectively degrade the antiphlogistic ibuprofen (IBU) representing typical refractory pharmaceutical. The process involved electrogenerated O3 from H2O oxidation using a Ti mesh/SnO2-F anode in membrane electrode assembly (MEA) and electrogenerated H2O2 from O2 reduction using a carbon-polytetrafluoroethylene (C/PTFE) cathode. The synergetic system of H2O2 and O3 formed in situ could generate hydroxyl radical (OH) to achieve IBU degradation and total organic carbon (TOC) removal. The effects of current density, aqueous initial pH, and coexisting anions on IBU removal efficiencies were investigated and then optimized as 30 mA/cm2 and neutral condition. As a result, IBU decomposition and TOC mineralization could be finished after 10 min and 120 min electrolysis, respectively. The stability of the synergetic system combining MEA with C/PTFE-O2 was also evaluated and confirmed through multiple cycles of electrogenerated peroxone based on TOC removal efficiency. In addition, IBU degradation pathways were proposed according to the identification of intermediates (e.g. hydroxylated IBU, phenolics, and carboxylic acids) by HPLC-MS/MS. These results manifested that this synergetic system is a promising technology to remove aqueous recalcitrant pharmaceuticals.

Degradation of real lindane wastes using advanced oxidation technologies based on electrogenerated hydrogen peroxide

In this work, hydrogen peroxide (H2O2) is produced using an optimized electrochemical cell equipped with a gas diffusion electrode (GDE) as cathode, reaching efficiencies as high as 20.1%, when operating in a single compartment configuration, which increases up to the range 50–60, when a proton exchange membrane is used to separate the anodic and cathodic compartments, pointing out the great significance of the anodic oxidation of H2O2 and the scavenging effects of the oxidants produced on the anode surface. As compared to previous materials tested, the GDE implemented in this cell underwent a more sustainable manufacturing procedure and exhibited an outstanding performance. The H2O2 produced electrochemically is dosed to the real leachate of an industrial dump, strongly polluted with derivatives of lindane. This waste is associated to the operation of a large facility in the seventies and contains different isomers of hexachlorocyclohexane and other chlorinated hydrocarbons, produced during the ageing of the dump. Effects of the addition of iron (II) sulfate salts and irradiation of UVC were also evaluated. All electrochemically-assisted technologies evaluated (named as chemical (EACO), Fenton (EAFO), photolysis (EAPO) and photo-Fenton (EAPFO) oxidations) were able to successfully remove the pollutants, although with important differences in the efficiencies reached. Results demonstrate that EACO, that is, oxidation by molecular H2O2 is the most effective treatment for the treatment of this type of wastes, pointing out that activation of H2O2 to hydroxyl radicals, either by electrochemically assisted Fenton or photolysis is not positive for this waste. As well, among the different pollutants contained in the raw waste, removal of hexachlorocyclohexane (HCHs) and non-chlorinated volatile organic compounds (VOCs) stands out (both groups being the primary species contained in the wastes). These results are very important not only because of the outstanding productions of H2O2 reached with the novel approach of electrochemical cell used, but also because of the implications of the mechanistic understanding of the attack of H2O2 species in the design of a full-scale application to remediate this real important problem.

Greening microwave-assisted digestion method using hydrogen peroxide for determination of elemental impurities by ICP-OES in antihypertensive active pharmaceutical ingredients

Microwave-assisted wet digestion (MAWD) using only H2O2 was proposed for oxidizing active pharmaceutical ingredients (APIs) for hypertension treatment and subsequent determination by inductively coupled plasma optical emission spectrometry (ICP-OES). Diltiazem hydrochloride (DIL) presented the most refractory characteristic for oxidation using MAWD-H2O2. This proposed MAWD-H2O2 method was validated for specificity, accuracy, and precision according to United States Pharmacopeia (USP) Chapter 233 guidelines. Regarding specificity, the most sensitive emission lines were utilized to analyze all elemental impurities in the digests, and no significant spectral interferences were observed. Sample masses of 500 mg for all APIs and a digestion temperature of 250 °C provided digests with residual carbon (RC) below 2400 mg L−1 of C. Additionally, the residual acidity of the MAWD-H2O2 digests was lower than the acidity presented by the HNO3 digests. The highest and lowest residual carbon content (RCC) for digests were observed for DIL and captopril (CAP), respectively, using MAWD-H2O2. When comparing the RCC for MAWD-H2O2 and MAWD-HNO3 digests for APIs containing aromatic rings, it was evident that H2O2 offered equivalent conditions for digesting these compounds. Accuracy tests showed recovery values of 91–110% for all elemental impurities, as recommended by USP chapter 233. Validation experiments for precision presented relative standard deviation (RSD) values below 6.4% and 10% under repeatability and intermediate precision conditions, respectively. The limits of quantification (LOQs) provided by MAWD-H2O2 are at most half of those recommended by of USP and International Council for Harmonisation of Technical Requirements (ICH). In conclusion, MAWD-H2O2 can be considered an alternative method for API digestion, aligning with green analytical chemistry principles, as it does not employ toxic reagents, minimizes waste, and the main products of H2O2 oxidation are water and oxygen. Considering the analytical Eco-Scale, the MAWD-H2O2 method scored 81, classifying it as an excellent green analysis.

Bamboo polysaccharides elicit hypocrellin A biosynthesis of a bambusicolous fungus Shiraia sp. S9.

Hypocrellin A (HA), a fungal perylenequinone from bambusicolous Shiraia species, is a newly developed photosensitizer for photodynamic therapy in cancer and other infectious diseases. The lower yield of HA is an important bottleneck for its biomedical application. This study is the first report of the enhancement of HA production in mycelium culture of Shiraia sp. S9 by the polysaccharides from its host bamboo which serve as a strong elicitor. A purified bamboo polysaccharide (BPSE) with an average molecular weight of 34.2kDa was found to be the most effective elicitor to enhance fungal HA production and characterized as a polysaccharide fraction mainly composed of arabinose and galactose (53.7: 36.9). When BPSE was added to the culture at 10mg/L on day 3, the highest HA production of 422.8mg/L was achieved on day 8, which was about 4.0-fold of the control. BPSE changed the gene expressions mainly responsible for central carbon metabolism and the cellular oxidative stress. The induced generation of H2O2 and nitric oxide was found to be involved in both the permeabilization of cell membrane and HA biosynthesis, leading to enhancements in both intra- and extracellular HA production. Our results indicated the roles of plant polysaccharides in host-fungal interactions and provided a new elicitation technique to improve fungal perylenequinone production in mycelium cultures.

Tandem photocatalytic production of H2O2 and propylene oxide on 5-Bromoisatin modified carbon nitride

Propylene oxide (PO) is an important raw material and synthetic intermediate for organic chemical synthesis. The direct in-situ synthesis of hydrogen peroxide (H2O2) using molecular oxygen to produce PO is considered as one of the most promising methods. Herein, we propose a photocatalytic multiphase system for the production of PO with oxygen. The ligand 5-bromoindoline-2,3-dione doped graphitic carbon nitride (CN/Bd) was employed as a photocatalyst for the in-situ production of H2O2, in tandem with epoxidation catalyst titanium silicalite-1 (TS-1) to achieve the epoxidation of propylene. This system achieved H2-free and efficient production of PO at room temperature with a high yield of 1.33 mmol·g−1·h−1, the selectivity of PO over 99% and H2O2 utilization efficiency over 95%. The combination of in-situ H2O2 generation and selective oxidation reaction realizes the efficient utilization of H2O2 and provides guidance for safer industrial production of PO.

Functional Nanozymes Consisting of Co2+‐ZIF‐67 Metal‐Organic Framework Nanoparticles and Co2+‐ZIF‐67/Polyaniline Conjugates

AbstractCo2+‐ZIF‐67 metal‐organic framework nanoparticles (NMOFs), act as nanozymes catalyzing diverse processes, including peroxidase, oxidase, and catalase activities. Peroxidase activities are reflected by the nanozyme‐catalyzed H2O2 oxidation of dopamine to aminochrome, the H2O2 oxidation of NADH to NAD+, the H2O2‐catalyzed generation of chemiluminescence through oxidation of luminol, and the H2O2‐mediated oxidation of aniline to polyaniline. Oxidase activities of the nanozyme are demonstrated by the Co2+‐ZIF‐67 NMOFs catalyzed aerobic oxidation of dopamine to aminochrome and of NADH to NAD+, and catalase activities of the nanozyme are reflected by the catalytic decomposition of H2O2. Moreover, the Co2+‐ZIF‐67 catalyzed oxidation of aniline to polyaniline (PAN) by H2O2 is accompanied by the coating of NMOFs with PAN to yield a Co2+‐ZIF‐67/PAN hybrid material. Coating the particles in the presence of guest substrates leads to molecular imprinted PAN matrices revealing enhanced ZIF‐67 catalyzed transformations as compared to non‐imprinted PAN matrices. This is demonstrated by imprinting of 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid), ABTS2−, in the PAN coating and the 3.3‐fold enhanced catalyzed oxidation of ABTS2− by H2O2, as compared to the non‐imprinted PAN hybrid composite. Moreover, imprinting of L‐/D‐DOPA in the PAN coating of Co2+‐ZIF‐67 NMOFs leads to chiro‐selective H2O2‐guided oxidation of L‐/D‐DOPA to dopachrome by the NMOFs/PAN composite.

ZnO-Bi2O3 Heterostructured Composite for the Photocatalytic Degradation of Orange 16 Reactive Dye: Synergistic Effect of UV Irradiation and Hydrogen Peroxide

The development of semiconductor photocatalysts has recently witnessed notable momentum in the photocatalytic degradation of organic pollutants. ZnO is one of the most widely used photocatalysts; however, its activity is limited by the inefficient absorption of visible light and the fast electron–hole recombination. The incorporation of another metal or semiconductor with ZnO boosts its performance. In this present study, a heterostructured ZnO-Bi2O3 composite was synthesized via a simple co-precipitation method and was investigated for the UV-driven photocatalytic degradation of the Reactive Orange 16 (RO16), a model textile dye. The successful fabrication of ZnO-Bi2O3 microstructures with crystalline nature was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX). The discoloration of the dye solution was quantified using UV–Vis spectroscopy to determine the photocatalytic efficiency. The photocatalytic activity results demonstrated that the photodegradation at ZnO-Bi2O3 heterojunction was more efficient and 300 and 33% faster than individual Bi2O3 and ZnO catalysts, respectively, an effect that is indicative of a synergistic effect. In the presence of ZnO-Bi2O3 particles, the UV light-driven activity for RO16 degradation was twice as high as in its absence. The influence of adding the oxidant H2O2 on the UV-induced photocatalytic degradation was investigated and the results revealed a two-time increase in the photocatalytic activity of ZnO-Bi2O3 compared to UV irradiation alone, which could be ascribed to a summative degradative effect between UV and H2O2. Hence, this approach holds the potential for environmentally friendly wastewater treatment.

Extremely high selective Si1−xGex-film wet etchant generating highly dissolved oxygen via peracetic acid oxidant for lateral gate-all-around FETs with a logic node of less than 3-nm

For lateral gate-all-around (LGAA) field-effect transistors (FETs) having design rules of logic devices below 3-nm and 3D-DRAM below 10-nm, multi-stacked Si1−xGex/Si-films should be epitaxially grown on the Si surfaces, and a highly selective wet etching of Si1−xGex-film is essentially followed for forming nanoscale-thick (5–7 nm) Si channel multi-sheets. A high selective etchant has required a lateral Si1−xGex etch rate of >30 nm⋅min-1 and etch rate selectivity between Si1−xGex- and Si-films of >200:1 at patterned multi-stacked Si1−xGex/Si-films. The selective Si1−xGex-film etchant using an etching agent (HF), a selectivity enhancing agent (CH3COOH), and a strong oxidant peracetic acid (PAA; CH3COOOH) unlike a conventional oxidant (H2O2 or HNO3) presented an extremely high Si0.5Ge0.5-film etch rate (82 nm⋅min-1@5 wt% of PAA) and etch rate selectivity between the Si0.5Ge0.5- and Si-films (265:1). Thus, it performed sufficient lateral Si1−xGex-film etching in the 3 multi-stacked Si0.5Ge0.5/Si-films line pattern and satisfied the requirement for a selective etching of Si1−xGex-film for LGAA having a logic-node of less than 2.1-nm. The excellent Si1−xGex-film etch rate using PAA was driven by a lower decomposition energy, lower Gibbs free energy, and higher standard reduction potential compared to the oxidant H2O2. Therefore, the amount of diffused dissolved oxygen using 5 wt% PAA was ∼1.48 times higher than that of H2O2; hence, the chemical oxidation degree (GeOx, and SiOx-bonds on the Si0.5Ge0.5-film surface) for 5 wt% PAA was ∼1.1 times higher than that of H2O2. Furthermore, the etch rate of the Si0.5Ge0.5-film using 5 wt% PAA was ∼5.4 times higher than that of H2O2; thus, we provide a cost effective Si1−xGex-film etching process for LGAA.

Modulating the Schottky barrier heights of plasmonic metal/semiconductor heterojunctions by graphene substrates for boosting photocatalytic water oxidation

Construction of plasmonic metal/semiconductor heterojunctions represents a promising approach to extending the light absorption range and simultaneously maintaining the high redox potentials of photogenerated carriers. However, unsuitable Schottky barrier height (ΦB) blocks the metal-to-semiconductor injection of hot electrons and increases the probability of their recombination with hot holes. Herein, a verstile protocol is demonstrated to address this issue based on the introduction of a reduced graphene oxide (rGO) substrate. As a proof-of-concept design, a Au/TiO2/rGO stacked photocatalyst is fabricated with TiO2 sandwiched between rGO and Au. In this smart design, rGO with work function smaller than that of Au upshifts the Fermi level of Au/TiO2 and reduces the ΦB between Au and TiO2. As a result, the hot electron injection efficiency from plasmonic Au to the conduction band of TiO2 is greatly augmented, increasing the number of separated hot holes participating in H2O oxidation. Profitting from the enhanced utilization of hot carriers, the Au/TiO2/rGO delivers markedly improved photocatalytic activity in O2 evolution as compared with Au/TiO2. This work provides us guidance to build high-efficient plasmonic photocatalysts for renewable fuel production and highlights the importance in reinforcing the separation and transfer of hot charges.

Self-assembly regulation of montmorillonite nanosheet for Pb(II) removal from aqueous solution

L-cysteine (Lcys) induced the self-assembly of montmorillonite nanosheets (MMTNS), creating a three-dimensional structured adsorbent with high adsorption capacity for Pb(II). Lcys was grafted onto the edge of MMTNS by hydrogen-bonding and then formed disulfide bonds (–S–S–) under the oxidation of H2O2 to form MMTNS-Lcys adsorbent. This technique maintains the exposed adsorption sites of MMTNS and resolves the challenge of nanosheet separation from water. MMTNS-Lcys possessed a large specific surface area (73.95 m2 g−1) and pore volume (0.1124 cm3 g−1), exhibiting outstanding adsorption performance for Pb(II), The adsorption process is consistent with the Pseudo-first-order kinetic and Langmuir isotherm models, indicating the monolayer adsorption of Pb(II) on the homogeneous surface of the MMTNS-Lcys adsorbent, with a maximum adsorption capacity of 46.92 mg/g (C0 = 80 mg/L, M = 0.5 g/L, T = 25 °C, pH = 6). These findings offer valuable insights for the design and development of future adsorbent materials.

Density functional studies on the thermal decomposition of H2O2 and heterogeneous oxidation of benzene on the Cu surface

The related research of volatile organic compounds (VOCs) is of great significance to atmospheric governance. Benzene is extremely harmful to humans and the environment as a representative substance in VOCs. In recent years, H2O2, a highly effective oxidant, has seen usage in flue gas purification. However, the purification efficiency remains limited due to the low utilization rate of hydroxyl radicals (·OH), which are derived from H2O2 decomposition. This research primarily focuses on catalyst selection. Density functional theory (DFT) was employed to investigate the characteristics of H2O2 adsorption and decomposition on Cu-based catalysts, as well as the ineffective consumption reaction of·OH on the Cu surface. Concurrently, the interaction mechanism between benzene and·OH on Cu surface was investigated. The findings demonstrate that Cu-based catalysts can enhance the decomposition of H2O2 molecules, and that H2O2 can dissociate to·OH on the surface. Moreover, these catalysts exert a pronounced inhibitory effect on the ineffective consumption reaction between·OH, H2O2 molecules, and the HO2·. The degradation process of benzene under the influence of·OH was analyzed, and the critical step of the reaction, along with the specifics of the ring-opening reaction, were determined. These reactions mechanisms were elucidated, thereby providing theoretical support for the development of novel catalysts.

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.

Iron and Hydrogen Peroxidation-Induced Post-Treatment Improvement of Municipal Mesophilic Digestate in an Alkaline Environment and Its Impact on Biosolids Quality

Challenges associated with mesophilic digestate (MD) involve volume, odor, and pathogens, which effective post-digestion treatments can address. The efficiency of MD post-treatment can be enhanced by conditioning with ferric chloride (FeCl3), hydrogen peroxide (H2O2), and polymer. This study aimed to observe the effect of combined chemical conditioning on volume reduction, phosphorus (P) release, odor, and pathogen reduction potential for MD. MD was conditioned with polymer only, polymer and FeCl3 at pH adjusted to 8.0 with lime (Ca(OH)2), and a blend of polymer, FeCl3, and hydrogen peroxide (H2O2) at pH 8.0. The results show that adding all three chemicals improved post-treatment efficiency at 2.1 kg/t DS FeCl3, 2.1 kg/t DS polymer, and 600 mg/L H2O2 at pH 8.0, compared with polymer or dual conditioning. At the combined dose, cake solid content, centrate P removal, and odor reduction capability improved compared with raw MD by 20%, 99%, and 66%, respectively. Combined chemical treatment reduced fecal coliform by 98% but does not fulfil class A requirements and showed 50% regrowth potential. The synergic effect of polymer, FeCl3, H2O2, and alkaline pH breakdown EPS, reduced water holding capacity and formed compacted flocs for better water removal and settling. This combination also precipitated P through FeCl3 while H2O2 oxidation curbs odor, enhancing further P removal from centrate.

Salt-induced nanoporous gold electrodes: One-step scalable fabrication of high-performance flexible electrochemical sensors from gold nanoparticles

Here, a simple filtration method for the fabrication of salt-induced nanoporous gold electrodes (SINPGEs) from gold nanoparticles (AuNPs) is reported. This method employs sodium chloride (NaCl) to trigger the aggregation, room-temperature sintering and region-selective deposition of AuNPs on patterned polyvinylidene fluoride (PVDF) membranes during filtration, which enables the one-step scalable fabrication of flexible SINPGEs three-electrode arrays with high conductivity, good mechanical property, large surface area and extremely low cost. Moreover, compared with traditional gold disc electrodes, the nanoporous structure of SINPGEs was demonstrated to apparently improve the electrochemical responses of various electroactive species, e.g., dopamine (DA), uric acid (UA), ascorbic acid (AA) and hydrogen peroxide (H2O2), reflected by the apparent enlargement of redox currents. In addition, the passivation effect of chloride ions (Cl−) on the oxidation of H2O2 at SINPGEs can be greatly repressed by a simple electrochemical activation approach, producing a sensitive H2O2 sensor with a calibration range of 1.0–1000 μM in the presence of 0.1 M Cl−. The present work thus establishes a new approach to the scalable construction of gold electrode-based electrochemical sensors with high performance and low cost.