Alkaline H2O2 Research Articles

Effects of Ceria Abrasives on the Chemical Mechanical Polishing of Molybdenum Film with Alkaline H2O2 Slurries

Abstract The impact of ceria abrasives on the chemical mechanical polishing (CMP) of molybdenum (Mo) films was examined in alkaline slurries utilizing H2O2 as an oxidizer and ceria abrasives. The static etching rate (SER) decreased after the addition of ceria abrasives to the alkaline H2O2-based slurry, while the removal rate (RR) increased except for that of the slurry at pH 9. At pH 9, following the etching of the Mo film in an H2O2 solution with ceria, the surface became coated with MoO3 and Ce2Mo4O15 species. These species originated from the interaction between ceria, H2O2, and molybdic acid. The Ce2Mo4O15 particles envelop the MoO3 surface, thereby preventing the etching of loose MoO3 and hindering further oxidation of Mo to MoO3. This process effectively reduces the RR of Mo. Utilizing ceria slurries at appropriate pH values facilitates achieving a smooth surface with a reasonable RR.

Theoretical and experimental studies of NO removal in alkaline H2O2 system

NO in flue gas is one of the atmospheric pollutants, and it is necessary to study effective NO removal technology. It was identified that the alkaline H2O2 system achieved over 98 % NO removal efficiency with a gas–liquid contact time of 3 s in this paper. This paper investigates the mechanism of NO removal in alkaline H2O2 solution through both experimental and theoretical calculations. The results reveal the NO removal process can be divided into three phases by the NaOH/H2O2 molar ratio. (1) The ∙O2– dominated phase, where trace metal Fe catalyzes ∙O2– radical generation from H2O2 as Fe (OH)2+, reacting primarily with NO to form ONOO–. The energy barrier for this process is1.299 kcal/mol, with a reaction rate constant of 9.12 E + 11 s-1M−1. (2) The HO2– dominated phase, HO2– was generated through OH– and H2O2 neutralization, which converts NO to NO2 and regenerating OH–. The energy barrier for HO2– reacting with NO is 3.833 kcal/mol, and the reaction rate constant is 2.07E + 10 s-1M−1. (3) The O22– dominated phase, O22– was a further ionization of HO2– and converting NO to NO2– directly. The energy barrier for this process is 7.079 kcal/mol, and the reaction rate constant is 1.49 E + 08 s-1M−1.

Innovative method for rice straw valorization into nanocellulose, lignin and silica

Nanocellulose was extracted from rice straw biomass using alkaline pretreatment, H2O2 bleaching and acidic hydrolysis. A novel solution was come up with where the acidic liquid after hydrolysis was used for adjusting the pH of the black liquor from pretreatment to produce lignin- and silica-rich precipitates as functional byproducts. Following this method, crystalline nanocellulose with length < 300 nm and high crystallinity of >80 % can be attained. Silica-rich precipitate was refined using a low temperature thermal treatment process for increased silica purity while maintaining a high degree of amorphous (> 75 %). Economic assessment shows that only around $23 is needed to produce 920 g of crystalline nanocellulose, 1.2 kg of highly amorphous bio-silica and 330 g of soda lignin. Such results show that these novel production methods have high economic efficiencies and should be considered for scaling up or be studied for similar biomass materials.

Returnable MoS2@carbon nitride nanotube composite hollow spheres drive photo-self-Fenton-PMS system for synergistic catalytic and photocatalytic tetracycline degradation

In this work, we synthesized hollow sphere composites of MoS2@carbon nitride nanotube (MoS2@TCN-S) for in-situ formation of H2O2 under visible light. The photo-self-Fenton system was further coupled with peroxymonosulfate (P-SF-PMS) for promoted reactive oxygen species generation and tetracycline degradation, so that the P-SF-PMS(MoS2@TCN-S) system can remove 94.3 % TC within 120 min, and the removal efficiencies after 15 cycles decrease by less than 5 %. The P-SF-PMS(MoS2@TCN-S) system also shows excellent degradation performance for actual wastewater, with COD removal rates of domestic sewage and secondary sedimentation tank effluent reaching 64.6 % and 58.7 % within 120 min. Quenching experiment and ESR results reveal the synergy of PMS and P-SF system, which was the key to improving the degradability and pH (3–9) adaptability of the P-SF-PMS system. Under alkaline conditions, PMS and H2O2 generated on MoS2@TCN-S activate each other and form 1O2 and OH, which solves the problem of poor degradation of P-SF system under alkaline conditions. Under acidic and neutral conditions, O2– becomes the main ROS, the activation of PMS by O2– and the synergistic effect of PMS and H2O2 make the P-SF-PMS system get rid of the dependence on H+. In addition, direct Z-scheme heterojunction enables MoS2@TCN-S to exhibit faster electron transfer ability, faster H2O2 generation ability, stronger adsorption capacity for PMS, and lower activation barrier for *HSO5, which also enhances the synergistic effect between PMS and P-SF system. In this study, a new type of multi-functional water purification material is proposed, and the synergism of PMS and P-SF system is revealed.

Well-defined Ni3N nanoparticles armored in hollow carbon nanotube shell for high-efficiency bifunctional hydrogen electrocatalysis

Alkaline H2-O2 fuel cells and water electrolysis are crucial for hydrogen energy recycling. However, the sluggish kinetics of the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) in an alkaline medium pose significant obstacles. Thus, it is imperative but challenging to develop highly efficient and stable non-precious metal electrocatalysts for alkaline HOR and HER. Here, we present the intriguing synthesis of well-defined Ni3N nanoparticles armored within an N-doped hollow carbon nanotube shell (Ni3N@NC) via the conversion of a hydrogen-bonded organic framework (HOF) to metal-organic framework (MOF), followed by high-temperature pyrolysis. As-developed Ni3N@NC demonstrates exceptional bifunctionality in alkaline HOR/HER electrocatalysis, with a high HOR limiting current density of 2.67 mA cm−2 comparable to the benchmark 20 wt% Pt/C, while achieving a lead in overpotential of 145 mV and stronger CO-tolerance. Additionally, it achieves a low overpotential of 21 mV to attain a HER current density of 10 mA cm−2 with long-term stability up to 340 h, both exceeding those of Pt/C. Structural analyses and electrochemical studies reveal that the remarkable bifunctional hydrogen electrocatalytic performance of Ni3N@NC can be ascribed to the synergistic coupling among the well-dispersed small-sized Ni3N nanoparticles, chain-mail structure, and optimized electronic structure enabled by strong metal-support interaction. Furthermore, theoretical calculations indicate that the high-efficiency HOR/HER observed in Ni3N@NC is attributed to the strong OH− affinity, moderate H adsorption, and enhanced water formation/dissociation ability of the Ni3N active sites. This work underscores the significance of rational structural design in enhancing performance and inspires further development of advanced nanostructures for efficient hydrogen electrocatalysis.

Simultaneous pretreatment with ultraviolet light and alkaline H2O2 to promote enzymatic hydrolysis of corn stover

Pretreatment processes are essential for the preparation of biofuels from lignocellulosic feedstocks. Based on alkaline H2O2 pretreatment, photocatalytic alkaline H2O2 pretreatment (U-AHP) was investigated to examine the effects of reaction time, alkali concentration, and H2O2 concentration on the enzymatic digestion of corn stover. The optimum process conditions were determined by orthogonal tests: 1% NaOH, 2% H2O2, and reaction time of 8 h. Under these conditions, the lignin removal efficiency of UH-AHP was 90.2% and the saccharification yield was 94.7%. Furthermore, FT-IR, XRD, and SEM analyses showed that U-AHP pretreatment caused structural damage to the maize straw and increased the crystallinity of the cellulose, and it was speculated that the U-AHP pretreatment reaction was a complex mechanism, which might be a multiple synergistic reaction. This study shows that U-AHP pretreatment is a simple, green and effective method to promote lignin removal.

Boosting alkaline photocatalytic H2O2 generation by incorporating pyrophosphate on g-C3N4 for effective proton shuttle and oxygen activation

A novel pyrophosphate-based proton shuttle strategy has been proposed to boost on-site photocatalytic H2O2 generation in alkaline waters for organic pollutant treatment. Pyrophosphate-incorporated g-C3N4 (PCN) photocatalyst was prepared by facile thermal polymerization to address the issue of lack of protons in alkaline conditions. The PCN shows a record-high alkaline H2O2 synthesis rate (e.g. 1071.7 μmol gcat−1 h−1 at pH 9) under visible light together with an apparent quantum yield (ΦAQY) of 8.7 % (at 420 nm). Mechanism study demonstrates that the pyrophosphate could serve as proton shuttle to effectively adsorb and provide protons, and act as advanced active sites for O2 adsorption and activation to promote O2 reduction, which greatly benefits the capture of nearby protons by the activated O2 to form H2O2. This work provides a promising approach to prepare photocatalysts with superior alkaline H2O2 synthesis efficiency for on-site treatment of organic pollutants.

Efficient separation of cellulose from bamboo by organic alkali

This study focuses on the effective separation of cellulose from bamboo through a two-step process. Several organic alkalies 2-pyrrolidinone, ethylurea, dibutylamine, N-methylformamide and tetramethyl guanidine were used to remove lignin and isolate cellulose from massive bamboo. The results showed that tetramethyl guanidine can effectively remove lignin and hemicellulose while retaining almost all the cellulose in the residual solid. The removal of lignin and hemicellulose achieved 86.0 and 84.0% after heating for 3 h at 150 °C, respectively. Subsequently, the final removal of lignin and hemicellulose increased to 91.5 and 93.8%, respectively, after a simple alkaline H2O2 bleach treatment. Interestingly, the loss of cellulose was very small after two-step treatments, and 96.9% of the component was still retained. The crystallinity increased from 69.8–75.2% in X-ray diffraction graphs due to the removal of lignin and hemicellulose. The Scanning electron microscopy images indicated that the diameter of cellulose bundles decreased from 80–100 µm to about 50 µm after organic alkali treatment, and then the fiber bundle was completely separated into a single long fiber with a diameter of about 10 µm after H2O2 bleaching. The Fourier transform infrared spectroscopy spectra confirmed the high selective removal of lignin and hemicellulose. Two-dimensional 1H-13 C Heteronuclear singular quantum correlation were analyzed to investigate the lignin structure and found that only the signals of –OCH3, Cγ–Hγ in β-O-4’ (Aγ) and β-β’ (Cγ) structures and C5-H5 in guaiacyl (G5) did not disappear after two-step treatment.

Carbon nanotubes doped with nitrogen, modified with platinum or platinum-free for alkaline H2-O2 fuel cell

A series of cathodic and anodic catalysts for alkaline H 2 -O 2 fuel cells (FC) deposited on the surface of functionalized and nitrogen-doped carbon nanotubes (CNT) was synthesized and studied by various structural and electrochemical methods. It was established that, due to the minor defect structure, CNT NaOH (functionalized in alkali) exhibit high corrosion stability. A further increase in the activity in the oxygen reduction reaction (ORR) and the stability of CNTs is observed following their doping with nitrogen. The high activity of CNT NaOH+N is attributed to pyridine groups and the increased electrical conductivity of this catalyst. It was shown that CNT NaOH comprise effective substrates for hydrogen oxidation reaction catalysts. The PtMo/CNT NaOH system containing 12 wt.% Pt at a molar ratio of PtMo=1:1 is characterized by the highest catalytic activity among investigated anode platinum and non-platinum catalysts. The use of this catalyst made it possible to reduce the content of platinum to 0.1-0.2 mg/cm 2 , while preserving the characteristics that significantly exceed those of the active layer containing 60Pt/C (HiSPEC 9100) catalyst (0.6 mgPt/cm 2 ).

Carbon Nanotubes Doped with Nitrogen, Modified with Platinum or Platinum-Free for Alkaline H2-O2 Fuel Cell

Carbon Nanotubes Doped with Nitrogen, Modified with Platinum or Platinum-Free for Alkaline H2-O2 Fuel Cell

On the Highly Efficient Concurrent Scavenging of No and So2 in High Gravitational Fields by Aop with Fe(Ii)-Catalyzed Alkaline H2o2 Systems

On the Highly Efficient Concurrent Scavenging of No and So2 in High Gravitational Fields by Aop with Fe(Ii)-Catalyzed Alkaline H2o2 Systems

Effect of PANI–AC Composite on Electrochemical Synthesis of Hydrogen Peroxide by Alkaline H2–O2 Fuel Cell Reactor

Effect of PANI–AC Composite on Electrochemical Synthesis of Hydrogen Peroxide by Alkaline H2–O2 Fuel Cell Reactor

Valorization of pineapple peel and poultry manure for clean energy generation

AbstractThe quest for renewable energy generation is fast increasing globally due to environmental degradation by fossil fuels. The energy production from the anaerobic codigestion of pineapple peels (PPs) and poultry manure (PM) was assessed in the present study. Prior to digestion, the PPs were pretreated using a strong acid (sulfuric acid) and a low‐cost mild alkali hydrogen peroxide (H2O2) which was prepared via the adjustment of the pH of H2O2 to 11.5 by adding solution of 5 M NaOH. The physicochemical and structural parameters of the biomass, as well as microbial composition, were evaluated by using standard methodologies, while all structural changes to the biomass after pretreatment were determined using the Fourier transform infrared spectra. The application of alkaline H2O2 pretreatment removed 71.34% of lignin, reduced hemicellulose by 61%, but increased the cellulose content by 39%. The alkaline pretreated pineapple peel (Al‐P PP) was able to produce about 91% more biogas than the acid pretreated pineapple peel (Ac‐P PP) and 36% more than the two untreated biomass samples. The results of the economic assessment of pretreatment also showed that investment into the use of H2O2 for pretreatment is economically feasible with high net thermal and electrical energy gain, while that of acid pretreatment results in loses. Therefore, alkaline pretreatment application to PPs prior to digestion is hereby solicited in the biotechnological conversion of PPs/wastes for biogas and quality digestate which can be used as biofertilizers or soil enhancers especially in those regions where pineapple production is enormous.

A novel High-Gravity AOP process for enhanced NOx attenuation using alkaline H2O2 as a strong oxidizing reagent: Reaction mechanisms and kinetics

A novel High-Gravity Advanced Oxidation Process (HiGee-AOP) using basic H2O2 solution as a liquid oxidizing reagent was examined for enhanced NOx removal efficiency in this study. At ambient temperature and optimal conditions, the process achieved a 99% removal of the inlet 1000 ppm NO. Spectroscopic experiments and radical-quenching tests indicated that the nucleophilic hydroperoxyl anion (−OOH) dissociated from H2O2 was the strongest reactive oxygen species (ROS) responsible for NO oxidation in alkaline H2O2, producing peroxynitrite (ONOO−) as detected by Fluorescence Spectroscopy. A mass transfer model coupling the reaction kinetics and gas diffusion under high liquid-film renewal conditions was established to simulate the HiGee-AOP process for NO absorption, and it achieved a model-prediction accuracy of within 10% of experimental data. It is speculated that the improved NO removal efficiency by the HiGee-AOP/alkaline H2O2 process stems from the enhanced mass transfer of NO in the heterogeneous reaction system provided by HiGee and the strong affinity of −OOH to NO. Oxidation of NO by −OOH may proceed first to form the [NO⋯OOH]− intermediate due to a strong nucleophile–electrophile interaction, which is followed by an electron transfer within the intermediate producing ONOO− and ultimately as nitrate.

Detoxification of mustard gas, nerve agents and simulants by peroxomolybdate in aqueous H2O2 solution: Reactive oxygen species and mechanisms

To overcome the insufficient understanding of the detoxification mechanisms of Chemical Warfare Agents (CWAs) and simulants by a molybdate-activated hydrogen peroxide solution (MoO42−-H2O2), detoxification performances toward CWAs and simulants were tested. The detoxification efficacy toward mustard gas (HD), nerve agent GD and VX by using MoO42−-H2O2 was higher than that by using H2O2 activated/modified by sodium hydroxide, ammonia, bicarbonate, and borates, but the vesicant mustard sulfone (HDO2) was only formed when using MoO42−-H2O2 to detoxify HD. Although Reactive Oxygen Species (ROS) such as singlet oxygen (1O2), superoxide anion (O2−), H2O2 and peroxide anion (OOH−) were detected by electron spin resonance (ESR) and chemiluminescence (CL) in the 0.1 M MoO42−-1.0 M H2O2 solution, 95Mo NMR indicated that Mo(O2)42− was the dominant oxidant for the oxidation of sulfide to sulfoxide and then to sulfone. Oxidation of HD by Mo(O2)42− occurred on the HD-drop/water interface through a direct oxygen transfer mechanism without the participation of H2O molecules, and further oxidation of HD to HDO2 was inevitable in an aqueous MoO42−-H2O2 solution. 18O tracer experiments confirmed that OOH−-based perhydrolysis dominated the detoxification reaction of nerve agents in an alkaline H2O2 solution. Considering the balance of oxidation/nucleophilic reactivity for a practical decontaminant, pH 10.5–11 range was recommended as the ideal for the MoO42−-H2O2 system to detoxify CWAs.

A novel energetically efficient combinative microwave pretreatment for achieving profitable hydrogen production from marine macro algae (Ulva reticulate)

This study aims to enhance the hydrogen (H2) production from marine macro algae (Ulva Reticulate) by microwave combined with hydrogen peroxide (H2O2) under alkaline condition. Microwave (domestic type) (M) pretreatment of algal biomass at its optimal power (40%) resulted in 27.9% COD solubilization at 15 min time interval. When this optimal microwave power was combined with H2O2 (MH) an increment in COD solubilization was achieved at 24 mg H2O2/g macroalgae dosage. Under alkaline condition (pH 7–12), microwave and H2O2 combination (MHA) yielded better result than MH. At optimal alkaline condition (pH 10), MHA pretreatment shows a COD solubilization of 34%. Microwave in alkaline condition induces decomposition of H2O2 and more OH radical synthesis. This synergistically promotes solubilization. The MHA process considerably diminish time and specific energy required for biomass disintegration. Among the samples, highest H2 yield of 87.5 mL H2/g COD was observed for MHA.

Serbian aromatized wine “Bermet”: Electrochemical, chemiluminescent and spectrophotometric determination of antioxidant activity

Serbian aromatized wine ?Bermet? from grapes grown on Fruska Gora Mountain has been in production since the 15th century. Ten commercial Bermets produced according to the traditional procedure by different manufacturers, and six prepared within the scope of this study were assessed for antioxidant (AO) activity using electrochemical, chemiluminescent and spectrophotometric AO assays. Direct current polarographic assay based on the decrease of anodic current of [hydrogen(peroxido)(1-)]hydroxidomercury(II) complex formation in alkaline H2O2 solution at potential of mercury oxidation, chemiluminescent H2O2 scavenging assay, as well as commonly used spectrophotometric assays (2,2?-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) based Trolox equivalent antioxidant capacity (TEAC), 2,2-diphenyl-1- picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP)) were used. Total phenolic content (TPC) was determined by Folin?Ciocalteu assay. The results obtained were correlated using regression analysis, ANOVA and F-test. An integrated approach to AO capacity determination allowed a more comprehensive comparison between samples. The approach is based on the introduction of the relative antioxidant capacity index, calculated by assigning each AO assay equal weight, and by PCA analysis. In addition, the introduction of phenolic antioxidant coefficients, calculated as the ratio between individual AO capacity and TPC, enabled a better understanding of their relation.

Liquefaction of pineapple peel: Pretreatment and process optimization

This study explored the optimization of pretreatment of pineapple peel for biogas generation. Pretreatments were carried out sulfuric acid and alkaline hydrogen peroxide prior to anaerobic digestion while the response surface methodology (RSM) was used for optimization of the pretreatment procedures. The physical, chemical, proximate and structural compositions of the peels were determined prior to and at the end of the pretreatment procedures. The dynamics of microorganisms in the reactors were also evaluated by rapid molecular methods while the Fourier Transform Infra-red (FTIR) spectroscopy was employed in the identification of the chemical changes as a result of pretreatments. The use of H2O2 pretreatment caused enormous lignin solubilization in the pineapple peel. In comparison, biogas production was 67% more in the alkaline pretreated pineapple peel than the biomass treated with acid and also 51% over the untreated samples. The total biogas volume produced from the acidic pretreated, alkaline pretreated, not sifted untreated and sifted untreated samples are 194.2 ± 3.0, 587.5 ± 5.2, 287.8 ± 2.1 and 245.4 ± 3.1 respectively. Thus, the alkaline pretreated experiment used lower retention time to achieve maximum gas production in this study. The use of alkaline H2O2 on lignocelluloses has remained unpopular prior to this study. However, its usage in this study yielded better result than all the conventional treatments in terms of lignin solubilization and improvement in methane yield. Economically, the use of H2O2 for pretreatment is adjudged feasible because the 1504 kWh t−1 TS thermal energy gain obtained from the biogas produced by the alkaline treated peel exceeded the 921 kWh t−1 TS used in the pretreatment. This gives a net thermal energy of 583 kWh t−1 TS. Whereas, the investment into acidic pretreatment of pineapple peel may not be economically justified because the total thermal energy gain of −200 kWh t−1 TS was far lower than the 1236 kWh t−1 TS thermal energy that was consumed during the pretreatment giving a net thermal energy of −1436 kWh t−1 TS. Therefore, the use of mild alkaline pretreatment is advocated in biogas generation from pineapple peel and also for biofertilizer production mostly in localities of mass production.

Isolation of Cellulose from Wheat Straw and Its Utilization for the Preparation of Carboxymethyl Cellulose

Cellulose was isolated from wheat straw by the combined pretreatment including dilute acid hydrolysis, ethanol extraction, and alkaline H2O2 delignification. The effects of varying the parameters on carboxymethylation on isolated cellulose were investigated. Furthermore, the chemical structure of carboxymethyl cellulose (CMC) prepared from wheat straw was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscope analysis. The isolated cellulose is mainly composed of cellulose without hemicellulose and with minors of lignin and ash. The optimal conditions for carboxymethylation were base concentration, 20%; reaction temperature, 70°C; reaction time, 2 h; mass ratio of etherifying agent to cellulose, 1.75. Under the optimized conditions, CMC with high degree of substitution (0.88) and low viscosity (18 mPa·s) was synthesized. Chemical structural characterization showed the feasibility of the preparation of CMC from wheat straw. The constituents of wheat straw would be maximally utilized by the proposed method.

Integrated enzymatic and chemical treatment for single-stage preparation of cotton fabrics

Starch sized 100% cotton woven fabrics need desizing, scouring and bleaching treatments prior to coloration and finishing. Traditionally, alpha-amylase-based enzymatic desizing and combined scouring and bleaching with an alkali, surfactant and H2O2 are used. Constant research is conducted on combining the desizing, scouring and bleaching processes into a single step by many researchers. This paper aims at combining enzymatic desizing and alkaline H2O2 scouring cum bleaching with a surfactant and stabilizer. The treatment resulted in efficient desizing, scouring and bleaching, leading to excellent size removal, absorbency, seed/mote removal and whiteness index levels, and comparable tensile and tear strength levels to that of the two-step process. The dyeability aspects were comparable in terms of surface color strength ( K/ S), color difference ( ΔE) and fastness ratings. Around 50–75% savings in water, energy, power, time and effluent generation were reported. The chemical oxygen demand, biological oxygen demand, total dissolved solids, pH and turbidity values of the resulting effluent were found to be remarkably lower. The technology was also tested industrially and found to be successful.