Oxidative Pretreatment Research Articles

Effect of peroxydisulfate activated by B-doped NiFe2Ox for degrading contaminants and mitigating nanofiltration membrane fouling in the landfill leachate treatment

Catalytic oxidation pretreatment is a significant focus in the field of membrane fouling control; however, traditional catalytic materials are plagued by limitations in catalytic sites and challenges in recovery. In this study, a novel catalyst, B-doped NiFe2Ox, was prepared with magnetic recovery capabilities and abundant oxygen vacancies to address landfill leachate treatment and mitigate membrane fouling. The results demonstrated the efficient activation of persulfate (PS) by the catalytic sites on B-NiFe2Ox, which significantly degraded the complex organic pollutants like conjugated double bonds and aromatic compounds in landfill leachate. A large amount of humic acid and soluble microbial products in the landfill leachate were efficiently degraded upon contact with sulfate and hydroxyl radicals produced by B-NiFe2Ox/PS, thereby resulting in achieving a chemical oxygen demand removal efficiency of up to 72% and more than a twofold enhancement in filtration flux. Moreover, the characteristics of the fouled layer reveal that the B-NiFe2Ox/PS system facilitated the formation of a porous cake layer, maximizing the retention of functional groups on the NF270 membrane surface. Notably, a minor presence of B-NiFe2Ox is uniformly distributed within the cake layer, indicating the in-situ occurrence of weak catalytic oxidation reactions. This study provides an effective and innovative approach utilizing catalytic oxidation for membrane fouling control.

High-efficient synthesis of straw-derived carbon quantum dots for facilitating methanogenic performance in high-load co-digestion of food waste and excess sludge

Anaerobic digestion (AD), as a crucial technology for organic waste resource recovery, faces the challenge of low efficiency in converting high-load organic substance into biogas. In this study, high-load AD system with food waste and excess sludge as co-substrates was constructed. The effect and mechanism of carbon quantum dots (CQD) derived from straw in promoting the performance of AD systems have been studied. The oxidation pretreatment of straw with H2O2 and acetic acid increased the yield of hydrothermal synthesis CQD to approximately 40%. The effect of different CQD on CH4 yield performance was further explored. The cumulative CH4 yield performance of the fermenter was improved after adding CQD. The CQD synthesized from pretreated straw and the nitrogen-doped CQD synthesized using Chlorella as the nitrogen source showed competitive promotion performance, increasing cumulative CH4 yield by 17.71% and 8.87%, respectively. These CQD can effectively accelerate the degradation of dissolved organic matter and thus improve the CH4 yield performance, with the most significant effect of CQD synthesized from pretreated straw. Electrochemical analysis and the correlation analysis between microorganisms and performance parameters showed that these CQD established an electron conductive network to enhance the electron transfer of the system. This well conductive conditions enriched hydrogenotrophic methanogenic (Methanosarcina), electroactive bacteria (Clostridium_sensu_stricto_1), and hydrolytic-acidifying bacteria (norank_f__Bacteroidetes_vadinHA17). This study significantly enhanced the yield of straw-derived CQD through green methods, and deeply revealed the potential promoting mechanisms of biomass-derived CQD by investigating the correlation between system performance and microorganisms in high-load AD systems

On‐Purpose Production of Light Olefins Through Oxidative Dehydrogenation: An Overview of Recent Developments

AbstractProducts made from light olefins play an important role in our daily lives. Traditional light olefins production based on steam cracking and fluid catalytic cracking suffer from high energy consumption and CO2 emissions. Thereby, the continually increasing demand for light olefins needs to be met through more environmentally sustainable procedures. On‐purpose production routes are preferred choice among petrochemicals manufacturers, being energy efficient and having lower carbon footprint. Among them, oxidative dehydrogenation (ODH) of light paraffins is a thermodynamically favourable exothermic process as compared to non‐oxidative routes. They can be operated at lower temperatures and have propensity of low coke deposition on catalyst, thereby resisting rapid catalyst deactivation. Herein, we have analysed various catalytic systems utilised in the oxidative dehydrogenation process. We have reviewed role of support, chemical composition of catalyst, presence of dopant, oxidation state of active metal, controlled surface modification by oxidative and reductive pretreatments, and reaction factors for each system. The performance of various catalytic systems for ODH of ethane, propane and butane in the presence of O2, CO2, N2O and special oxidants have been reviewed. A short critical overview on emerging on‐purpose routes for the production of renewable 1,3 butadiene has also been discussed.

Preparation and performance of catalyst for organic peroxide wastewater treatment

To improve the oxidation pretreatment efficiency of wastewater from organic peroxides, a catalyst (CeO2-C catalyst) was developed using the calcination method with ceramic particles as the support. The crystalline structure and elemental composition of the CeO2-C catalyst were characterized by Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS), and X-ray diffraction (XRD). This study explored the effects of CeO2 mass ratio, calcination temperature, and calcination time on the performance of the catalyst. The optimal preparation conditions were established through orthogonal experiments. Additionally, the synergistic effect of the catalyst on the ozone oxidation treatment of peroxide wastewater was investigated. The results indicated that the optimal preparation parameters were a CeO2 mass ratio of 4 %, a calcination temperature of 500 °C, and a duration of 5 h, respectively. After five cycles of reuse, the catalytic activity slightly decreased but remained relatively stable. With an ozone flow rate of 6 L/min, the CeO2-C/ozone catalytic oxidation process achieved a Chemical Oxygen Demand (COD) removal rate of 28.11 % in wastewater, and the B/C (the ratio of BOD concentration to COD concentration) of wastewater improved from 0.093 to 0.152. The calcination method proved effective for preparing the CeO2-C catalyst, which demonstrated significant catalytic performance and held promising application prospects in the oxidation pretreatment of organic peroxide wastewater.

Chemical oxidation of arsenopyrite by strong oxidizing agents: For oxidative pretreatment of refractory arsenopyritic gold ores

Chemical oxidation of arsenopyrite by strong oxidizing agents: For oxidative pretreatment of refractory arsenopyritic gold ores

A dual-mechanism pretreatment idea for improving the derived Raman spectrum for (micro)plastic analysis

ABSTRACT Raman spectroscopy is an effective tool for microplastic analysis, but its performance can be limited by weak signals and surface interference. This study aims to enhance derived Raman spectra through chemical surface treatments. Fresh and biofouled plastic debris samples, including polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), were treated overnight with various chemical solutions: 30% H2O2, 5% NaOCl, 5% HCl, and a sequential treatment of 5% HCl followed by 5% NaOCl (HCl:NaOCl). Stereo microscope examinations revealed that single-solution treatments removed some stains but left others behind, while complete stain removal was achieved with the HCl:NaOCl treatment. The control samples exhibited a high fluorescence issue, but oxidation pretreatment effectively reduced this, with 5% NaOCl outperforming 30% H2O2. Despite eliminating fluorescence, residual stains still obscured peak signals. In contrast, the sequential HCl:NaOCl treatment removed almost visible stain, resulting in very clean surfaces, minimal background signals, and significantly higher S/N ratios for peak signals. This study demonstrates that dual-mechanism pretreatments – combining acid dissolution and oxidation – are far more effective than single treatments, benefiting applications that require clean plastic samples for subsequent operations.

Adequately converting poplar sawdust’s carbohydrates to furfural and glucose by employing acid oxidation pretreatment and solid acid catalysis

The utilization of lignocellulosic biorefinery residue has always been a major obstacle hindering its industrialization. In this work, the acetic acid assisted hydrogen peroxide pretreatment (AHP) and enzymatic hydrolysis was employed to facilitate the efficient bioconversion of poplar sawdust (PS), while simultaneously utilizing the solid acid catalyst (SA) synthesized from enzymatically hydrolyzed PS (EPS) for furfural production from prehydrolysate. It demonstrated that enzymatic hydrolysis of PS achieved a glucose yield of 61.3 %, which can be attributed to the effective removal of xylan and lignin through AHP pretreatment. The structural characterization revealed that SA-EPS exhibited a higher pore density, more acidic sites, and an increased presence of acidic groups compared with SA prepared from PS. Ultimately, the utilization of SA-EPS significantly augmented furfural yield and selectivity to 54.3 % and 64.1 %, respectively. By successfully synthesizing SA using lignin-rich EPS, the value-added benefits and increased efficiency have been achieved in biorefinery processes.

Characterization of bamboo shoot cellulose nanofibers modified by TEMPO oxidation and ball milling method and its application in W/O emulsion

It has rarely been reported that the modification of bamboo shoot nanofibers by oxidation combined with physical and applied in food emulsions. In this study, the combination of 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation and the ball milling technique was employed to prepare bamboo shoot cellulose nanofibers (TOCNF) for W/O emulsions. A comparative study of the properties and structures of CNF prepared only by ball milling and TOCNF prepared by oxidation-ball milling was carried out, and a preliminary structural and rheological study of their application to emulsions was carried out. The results showed that TOCNF had higher water holding, swelling, and oil holding properties, cholesterol and glucose adsorption capacity than CNF. The combination of oxidative pretreatment and ball milling resulted in a dense entangled network structure, uniform particle size distribution, and high zeta potential value of TOCNF. The higher crystallinity of the TOCNF (68%) resulted in improved thermal stability. In addition, compared with the CNF-stabilized emulsion, with TOCNF dispersion as the internal aqueous phase, the emulsion droplets had a more uniform particle size distribution (6.61 ± 3.59 μm), higher gel strength, and thixotropic resilience of up to 71.24%. Thus, TEMPO oxidation combined with the ball milling method can be an effective means to improve nanofibers and provide a theoretical basis for expanding the application of bamboo shoot cellulose resources in the food colloid field.

A Study on the Surface Oxidation Pretreatment and Nickel Plating Mechanism of Carbon Fiber.

This study explores the effects of various temperatures on the surface modification of carbon fibers, as well as the effect of differing voltages and currents on the morphology, deposition rate, and thickness of the Ni plating layers. Post-treatment characterization of the samples was conducted utilizing scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) methods, thus facilitating a discussion on the mechanism of Ni plating. The findings demonstrate that at a temperature of 500 °C, the carbon fiber surface exhibits the highest concentration of functional groups, including hydroxyl (-OH), carboxyl (-COOH), and carbonyl (-C=O), resulting in the most efficacious modification. Specifically, exceeding 500 °C leads to significant carbon fiber mass loss, compromising the reinforcement effect. Under a stable voltage of 7.5 V, the Ni-plated layer on the carbon fibers appear smooth, fine, uniform, and complete. Conversely, at a voltage of 15 V, the instantaneous high voltage induces the continuous growth of Ni2+ ions along a singular deposition point, forming a spherical Ni-plated layer. In addition, a current of 0.6 A yields a comparatively uniform and dense carbon fiber coating. Nickel-plated layers on a carbon fiber surface with different morphologies have certain innovative significance for the structural design of composite reinforcements.

Effect of substituted cobalt–chromium–iron oxides’ dissolution kinetics in oxidizing formulation on decontamination process

Removing radioactive corrosion products from Cr-containing iron oxides require a multi-step and multi-cycle decontamination process. The present article brings out the effect of divalent metal ion substitution on the release rate of chromium in the oxidative pre-treatment step. The non-stoichiometric cobalt chromium ferrites were synthesized, characterized and effect of Zn2+/Ni2+ substitution on the dissolution behavior was probed. The dissolution rates decreased with increasing the degree of inclusion and showed minima at ~ 0.4–0.6 atom% which is explained on the basis of lattice structure. It is concluded that the dissolution kinetics of native nickel–chromium ferrites in reactors increases with metal ion inclusion.

Impact thermal and calcium oxide pretreatment on the anaerobic digestion of food waste: performance and carbon emissions

Impact thermal and calcium oxide pretreatment on the anaerobic digestion of food waste: performance and carbon emissions

Enhanced hydrolysis of waste activated sludge and recovery of volatile fatty acids: Performance and mechanistic analysis of synergistic treatment with sodium citrate and calcium oxide

Anaerobic fermentation has emerged as a promising method of transforming waste activated sludge into high-value products (e.g., volatile fatty acids (VFAs)). This work developed sodium citrate (SC)-calcium oxide (CaO) pretreatment to accelerate the production of VFAs by enhancing sludge solubilization and disintegration of extracellular polymeric substances. The results showed that co-pretreatment with 0.25 g/g TSS of SC and 0.05 g/g TSS of CaO effectively boosted VFAs accumulation (5823.3 mg COD/L), which was 12.2 times higher than the Control group. SC-CaO pretreatment enhanced hydrolysis and acidogenesis by providing ample organic substrates, thereby promoting the growth of hydrolytic and acidogenic bacteria. Additionally, the fermentation broth resulting from co-pretreatment exhibited lower phosphorus concentration and higher biodegradability. Economic analysis confirmed that the combined pretreatment is cost-effective. This work provides a viable strategy for enhancing high-value product recovery from sludge.

Sustainable mortar reinforced with recycled glass fiber derived from pyrolysis of wind turbine blade waste

Pyrolysis technology has recently made significant progress in recycling millions of tons of wind turbine waste (WTB). Short fibers represent its main product (∼70 wt%), which needs further studies to explore its future applications. In this context, this work aims to the valorization of the recycled glass fiber (rGF) derived from pyrolysis of WTB (at 550 °C) in the production of rGF-reinforced mortar composite (rGF/M) for sustainable building applications. The research began by subjecting the derived rGF to sieving (rGFs), washing (rGFw), and oxidation (rGFo) pretreatments for purification and removing any impurities, organic residues, and char particles. Afterward, the chemical degradation of the treated rGF in a strong alkaline cement solution with pH = 14 was studied for up to 90 days. In parallel, the mortar composite samples were fabricated at 1 wt% of the treated rGF batches (rGFr, rGFw, and rGFo) to study the effect of different pretreatments on their microstructure, dispersion, compressive strength, flexural strength, and water absorption capabilities behavior after different curing periods (28 and 90 days). The results showed that rGFo (7.84%) showed a lower degradation rate versus rGFw (16.41%) and rGFr (30.76%). Meanwhile, the highest curing period (90 days) contributed to improving the properties of the mortar composites in general, especially in the case of using rGFo which led to improved compressive strength (15%) and reduced absorption coefficient (38%) and cumulative water content (32%) with a uniform distribution of short fibers in the matrices and a slight increase in flexural strength compared to control mortar sample (8.6 MPa). While rGFs provides better flexural strength (9.3 MPa) with a 12% improvement. Based on these results it can be concluded that rGFo has high potential in sustainable building materials with high competition with virgin glass fiber.

Upgrading the quality of biomass by advanced oxidative torrefaction pretreatment: Rebuilding the oxidative torrefaction mechanism based on hemicellulose, cellulose, and lignin

The oxidative torrefaction pretreatment (OTP) is a promising approach to upgrade the quality of biomass. This work investigated the oxidative torrefaction mechanism based on the OTP experiment of biomass pseudo component (cellulose, hemicellulose, and lignin) at varying OTP temperatures and oxygen concentrations. Results showed that more mass of biomass was transferred into the torrefied gaseous and liquid products with OTP temperature and oxygen concentration increasing, remaining less mass in torrefied solid product. The element distribution in biomass pseudo component was optimized after OTP, presenting as the removal of oxygen element and the enrichment of carbon element. The variation of these two elements in hemicellulose after OTP was much higher than that of cellulose and lignin due to the more intensive thermal decomposition reaction in hemicellulose. The chemical compounds in torrefied liquid products from biomass pseudo component were highly differentiated with each other, the anhydrosugars (e.g., levoglucosenone (LGO) and levoglucosan (LG)) and furans (e.g., furfural (FF)) from OTP of cellulose, the furans (e.g., furfural (FF)) and acids (e.g., acetic acid (AA)) from OTP of hemicellulose, the phenols from OTP of lignin. The concentrations of the released gas components during OTP of biomass pseudo component were ranked as CO2 > CO > H2 ≈ CH4. The thermal degradation mechanism of biomass OTP was revealed.

Reduction of inhibitory effect of lignin via degradation and improvement of anaerobic digestion performance of maize straw by oxidative pretreatment with Fe2+-activated persulfate

The stable aromatic structure of lignin is one of the factors that limit the utilization of maize straw. In this study, pretreatment with Fe2+/persulfate (PS) was used to remove lignin while reducing the contents of lignin derivatives produced in the pretreatment. In comparison with the original straw, the lignin and hemicellulose contents of the pretreated straw were reduced to 54.58 % and 72.91 %, respectively. In the Fourier transform infrared spectrum, the characteristic peaks of both syringyl and guaiacyl units were significantly weaker after pretreatment with Fe2+/PS, which indicated that the pretreatment destroyed the structure of lignin. The pretreatment products were examined by gas chromatography–mass spectrometry, and the results indicated that the present pretreatment method reduced the contents of soluble inhibitors produced from lignin. After pretreatment, only levulinic acid, 4-hydroxybenzaldehyde, vanillin, 4-hydroxybenzoic acid, xylose, coumaric acid, and 4-coumaric acid were produce, whereas more than 20 soluble inhibitors are known to be produced from lignin. In anaerobic fermentation experiments, in comparison with the control group, the pretreated group exhibited higher gas production (an increase of 18.09 %) and a significantly higher methane content. This indicates that pretreatment with Fe2+/PS can improve the efficiency of the resource utilization of maize straw by degrading lignin.

Study on high-efficiency sulfide removement using sulfate radical-based AOPs and its oxidation mechanism of refractory gold ore

Pyrite enclosure poses a significant challenge in refractory gold ore processing, inhibiting gold leaching. This study explores Sulfate Radical-based Advanced Oxidation Processes (SR-AOPs) as an effective alternative for pretreating such ores. The oxidation pretreatments were performed under heat and ultrasound activation methods, including heat and ultrasound, and the influences of pretreatment time, pH, ultrasound power, pretreatment temperature, and precursor (PDS) concentration were investigated. Both ultrasonic and heat activation effectively mitigate the negative impact of pyrite enclosure on gold leaching. Specifically, the gold leaching rate improved from 21.9 % to 46.1 % and 74.9 % with heat and ultrasound activation, respectively The and generated by PDS dominate the pyrite oxidation according to EPR and quenching tests. Meanwhile, the SR-AOPs treatment also promotes the interactions between pyrite enclosure and leaching agent, reducing the negative influences of pyrite. Kinetic studies indicated that the oxidation processes are different under heat and ultrasound activation. Heat activation is governed by an interfacial chemical reaction, with an activation energy of 25.57 kJ/mol. In contrast, ultrasound-induced cavitation and microjets remove the oxidation layer, disrupt the pyrite crystal structure, and expose encapsulated gold. These effects accelerate pyrite oxidation, shifting the kinetic control step from interfacial chemical reaction to internal diffusion, with a reduced activation energy of 35.06 kJ/mol.

Advancing Thermophilic Anaerobic Digestion of Corn Whole Stillage: Lignocellulose Decomposition and Microbial Community Characterization

Converting corn grains into bioethanol is an expanding practice for sustainable fuel production, but this is accompanied by the production of large quantities of by-products such as whole stillage. In the present study, the influence of advanced wet oxidation and steam explosion (AWOEx) pretreatment on biogas production and lignocellulose decomposition of corn whole stillage (CWS) was evaluated using semi-continuous thermophilic reactors. The digestion of the CWS was shown to be feasible with an organic loading rate (OLR) of 1.12 ± 0.03 kg VS/m3 day and a hydraulic retention time (HRT) of 30 days, achieving a methane yield of 0.75 ± 0.05 L CH4/g VSfed for untreated stillage and 0.86 ± 0.04 L CH4/g VSfed for pretreated stillage, corresponding with an increase in methane yield of about 15%. However, the reactors showed unstable performance with the highest investigated OLRs and shortest HRTs. Under optimal conditions, the conversion efficiencies of COD, cellulose, hemicellulose, and lignin were 88, 95, 97, and 59% for pretreated CWS, and 86, 94, 95, and 51% for untreated CWS, respectively. Microbial community analysis showed that Proteiniphilum, MBA03, and Acetomicrobium were the dominant genera in the digestate and were likely responsible for the conversion of proteins and volatile fatty acids in CWS.

Ozone-enhanced photoionization ion mobility spectrometry coupled with time-resolved dynamic diluter for on-site monitoring of H2S in humid atmosphere

The online monitoring of hydrogen sulfide (H2S) presents a critical advancement for environmental protection and public health, yet existing methodologies struggle to achieve on-site, on-line and highly sensitive detection in atmospheric conditions. This study introduces a novel approach employing ozone-enhanced photoionization ion mobility spectrometry (IMS) in conjunction with a time-resolved dynamic diluter (TRDD) for the efficacious identification of H2S within environments of high humidity, such as sewers. This method ingeniously addresses the challenge of distinguishing H2S in the presence of water vapor through a dual strategy of ozone oxidization pretreatment and TRDD injection. The strategic placement of ozone within the drift region significantly amplifies the sensitivity of the IMS detection, showcasing the method's superior sensitivity, stability, and humidity interference resilience. Notably, this technique achieves a detection limit for H2S at an impressive 2.5 parts per billion (ppb), maintaining a consistent relative standard deviation (RSD) of 2.5 % over three consecutive days. Furthermore, the approach effectively mitigates the effects of moisture, maintaining an RSD of 3.0 % despite a relative humidity (RH) increase from 22 % to 95 %. Applied to the on-site measurement of H2S in sewer systems, the method demonstrated all the aforementioned performance characteristics, marking it a promising way of high humidity environment H2S monitoring.

Low-temperature thermocatalytic removal of formaldehyde in air using copper manganite spinels

The removal of formaldehyde (FA) is vital for indoor air quality management in light of its carcinogenic propensity and adverse environmental impact. A series of copper manganite spinel structures (e.g., CuMn2O4) are prepared using the sol-gel combustion method and treated with reduction or oxidation pretreatment at 300 °C condition. Accordingly, CuMn2O4–O (“O” suffix for oxidation pre-treatment in air) is identified as the best performer to achieve 100% conversion (XFA) of FA (50 ppm) at 90 °C; its performance, if assessed in terms of reaction kinetic rate (r) at XFA = 10%, is 5.02E-03 mmol g−1 h−1. The FA removal performance increases systematically with decreases in flow rate, FA concentration, and relative humidity (RH) or with increases in bed mass. The reaction pathways and intermediates of FA catalytic oxidation on CuMn2O4-A are studied with density functional theory simulations, temperature-programmed characterization experiments, and in-situ diffuse reflectance infrared Fourier transform spectroscopy. The synergistic combination of large quantities of adsorbed oxygen (OA) species and oxidized metal species (e.g., Cu2+) contribute to the enhanced catalytic performance of CuMn2O4–O to oxidize FA into CO2 with the reaction intermediates of H2CO2 (DOM), HCOO−, and CO. The present study is expected to provide valuable insights into the thermocatalytic oxidation of FA over spinel CuMn2O4 materials and their catalytic performances in relation to the key process variables.

Impact of TEMPO-Oxidation Pretreatment of Red Ginseng Residual on Nanofibrillation

Red ginseng extract is one of the most widely used herbal medicines to prevent and cure various diseases. Among the processed products derived from red ginseng, the water-insoluble part as red ginseng residual (RGR) becomes waste, even though it contains important ingredients. TEMPO-oxidation (TO) can be used as a pre-treatment with different degrees of oxidation (DO) (0 to 0.4) in red ginseng residual (RGR-TO) by introducing chemical oxidation and high-pressure homogenizer (HPH) as a nanofibrillation process. 1H NMR was used to determine the carbohydrate composition and calculate DO, size was examined using a nanoparticle analyzer, and the zeta potential was used to determine surface charge density. RGR-TO with different concentrations had different compositions; glucose and uronic acid were the main ingredients. All treated RGR-TO showed higher oxidant levels than the untreated counterpart (RGR-TO 0). As the oxidant levels increased, the zeta potential and uronic acid increased, but the size of the nanofibril from RGR-TO decreased. The results of this study showed that TEMPO-oxidation pretreatment was effective in producing RGR cellulose nanofibril (CNF) with a variety of properties by adjusting the level of oxidation pretreatment and the number of HPH passes.