H2O2 Dosage Research Articles

Tertiary/quaternary treatment of urban wastewater by UV/H2O2 or ozonation: Microplastics may affect removal of E. coli and contaminants of emerging concern

The aim of this study was to investigate the interference of polyethylene microplastics (MPs) on ultraviolet irradiation/hydrogen peroxide (UV/H2O2) and ozonation processes in the inactivation of E. coli bacteria (tertiary treatment) and removal of contaminants of emerging concern (CECs) (quaternary treatment) from simulated and real secondary treated urban wastewater. Three pharmaceuticals were investigated as model CECs, namely carbamazepine, sulfamethoxazole and trimethoprim. Experimental results showed that disinfection efficiency of UV/H2O2 treatment decreased (2.4, 1.8 and 1.3 log reductions of E. coli, initial H2O2 dose of 30 mg/L, 2.5 min treatment) as the initial concentration of MPs was increased (0.25, 0.5 and 1.0 g/L, respectively). Similarly, an increase in MPs concentration (0.25, 0.5 and 1.0 g/L) reduced the inactivation (4.7, 4.1 and 3.7 log reductions) of the target bacteria after 60 min of ozonation treatment. Although the disinfection efficiency of both treatment processes was negatively affected by the presence of MPs, UV/H2O2 was more effective than the ozonation, despite ozonation being investigated at high doses to better discriminate the effect of MPs. Noteworthy, CECs degradation by UV/H2O2 under realistic operating conditions was affected to some extent by MPs, while a lower effect was observed for ozonation, at not realistic ozone dose.

Enhanced photocatalytic performance of milkvetch-derived biochar via ZnO–Ce nanoparticle decoration for reactive blue 19 dye removal

In this research, the photocatalytic removal of reactive blue 19 (RB19) dye is investigated employing zinc oxide/cerium (ZnO@Ce) nanoparticles decorated with biochar under LED irradiation. Synthesis of ZnO@Ce nanoparticles decorated with biochar was performed utilizing the co-precipitation procedure and, then, the texture and morphology of the fabricated nanocomposite were analyzed using energy dispersive X-ray (EDX), field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), and Fourier transform infrared (FTIR) spectroscopy techniques. Moreover, FE-SEM images demonstrate that ZnO–Ce nanoparticles were successfully decorated on the surface of biochar. The specific surface areas of biochar and biochar/ZnO–Ce were 519.75 and 636.52 m2/g, respectively. To achieve the maximum yield in the removal of RB19 dye, the effects of operating variables including dye concentration, LED lamp power, biochar@ZnO–Ce catalyst dose, pH and H2O2 dose were explored. Besides, the maximum percentage of RB19 dye removal was 96.47% under optimal conditions, i.e. catalyst dosage of 100 mg, H2O2 dosage of 1 mL, pH of 9, initial dye concentration of 5 ppm, LED power of 50 W, and reaction time of 140 min. Furthermore, the kinetic analysis reveals that the removal of RB19 dye follows the pseudo-first order kinetic model, with calculated values of a reaction rate constant of 0.045 min−1 and a correlation coefficient of R2 = 0.99, respectively. Moreover, the reusability and recyclability of biochar@ZnO/Ce nanocatalyst was promising over five runs, with only a 6.08% decrease in RB19 dye removal efficiency. Therefore, it can be concluded that the biochar @ZnO/Ce photocatalyst can be promisingly applied for the removal of azo dyes in aqueous solutions.

Singlet oxygen is also involved in the formation of hypoiodous acid during the transformation of phenolic pollutants by peracetic acid in the presence of iodide

Peracetic acid (PAA) has been used as a disinfectant/oxidant in wastewater treatment. However, considering that the presence of iodide (I−) would induce the iodinated products in wastewater, the effect of I− on the transformation of phenolic pollutants by PAA was investigated. Herein, the presence of I− enhanced the transformation of phenolic pollutants (bisphenol S (BPS), bisphenol A (BPA), and p-hydroxybenzoic acid (p-HBA)) by PAA. Furthermore, hypoiodous acid (HOI) was reactive species in the PAA/I− system based on radical quenching experiments and electron spin resonance. In this system, PAA, together with 1O2 that was produced in PAA oxidized I− into HOI. Increasing PAA and I− dose promoted the transformation of phenolic pollutants but the promoting effect was less significant at higher dosage. The increase in H2O2 dose retarded the transformation of phenolic pollutants because of HOI being quenched by H2O2. In a wide range of pH (pH 4.0–10.0), the transformation of BPS, BPA, and p-HBA was pH-dependent and most effective at pH 7.0. The presence of chloride and bromide accelerated the transformation of phenolic pollutants by PAA/I− due to the formation of HOCl and HOBr. Furthermore, HOI substitution was the primary reaction pathway in the transformation of BPS, BPA, and p-HBA by PAA/I−. Finally, the transformation products of phenolic pollutants during the PAA/I− posed higher cytotoxicity compared to the parent pollutants. Overall, our findings improved the understanding of the chemical behavior of PAA in the presence of I− and suggested that the generation of iodinated products raised concerns for water safety.

The ability of drinking water treatment sludge to degrade methylene blue in water through combined adsorption/photo Fenton-like process

In the present study, drinking water treatment sludge (DWTS) was reused as a catalyst in advanced oxidation processes for the removal of methylene blue (MB) from aqueous solutions. After determining their chemical and mineralogical compositions by X-ray Powder Diffraction (XRD), BET surface area, scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), Inductively Coupled Plasma (ICP), and FT-IR spectra. DWTS has been used as a heterogeneous photo Fenton-Like catalyst for the oxidation of MB under different parameters, including pH (3-6), H2O2 concentration (9.79-29.37 mM), and dose (1-2.5 g/L). The results showed that within 180 min and under UV light irradiation, more than 86% of MB having a concentration of 50 mg/L were removed using a catalyst loading of 1.5 g/L, a H2O2 dosage of 23.17 mM and a solution pH of 5. The DWTS has a satisfactory stability as the catalyst is stable and have very less iron leaching property.

Preparation of PrFexCo1–xO3/Mt catalyst and study on degradation of 2-hydroxybenzoic acid wastewater by catalytic wet peroxide oxidation

In this study, the perovskite nanocomposite PrFexCo1–xO3(Pr(S)) was successfully synthesized by the sol–gel method; PrFexCo1–xO3/Al-pillared montmorillonite (Pr(S)/Mt) catalysts were prepared by impregnation (D) method and solid-melting (G) method, respectively, with Pr(S) as the active component and Al-pillared montmorillonite as the carrier. The catalysts were applied to treat the 2-hydroxybenzoic acid (2-HA)-simulated wastewater by catalytic wet peroxide oxidation (CWPO) technique, and the chemical oxygen demand (COD) removal rate and the 2-HA degradation rate were used as indicators to evaluate the catalytic performance. The results of the experiment indicated that the solid-melting method was more conducive to preparing the catalyst when the Co/Fe molar ratio of 7:3 and the optimal structural properties of the catalysts were achieved. The influence of operating parameters, including reaction temperature, catalyst dosage, H2O2 dosage, pH, and initial 2-HA concentration, were optimized for the degradation of 2-HA by CWPO. The results showed that 97.64% of 2-HA degradation and 75.23% of COD removal rate were achieved under more suitable experimental conditions. In addition, after the catalyst was used five times, the degradation rate of 2-HA could still reach 76.93%, which implied the high stability and reusability of the catalyst. The high catalytic activity of the catalyst was due to the doping of Co into PrFeO3, which could promote the generation of HO·, and the high stability could be attributed to the loading of Pr(S) onto Al–Mt, which reduced the leaching of reactive metals. The study of reaction mechanism and kinetics showed that the whole degradation process conformed to the pseudo-first-order kinetic equation, and the Langmuir–Hinshelwood method was applied to demonstrate that catalysis was dominant in the degradation process.

A waste-free biorefinery pathway to the valorisation of Chinese hickory shell through alkaline hydrogen peroxide pretreatment

Efficiently harnessing the intrinsic value of lignocellulose requires the integration of multifarious capacities within a zero-waste biorefinery. Chinese hickory shell, a food industry byproduct, remains largely untapped. Unleashing their full potential as a valuable biomass resource has become an urgent challenge. This study utilises the alkaline hydrogen peroxide pretreatment for Chinese hickory shell, exploring the effect of H2O2 dosage, alkali concentration, and temperature on lignocellulosic fractionation. Under optimal conditions, nearly complete removal of lignin and hemicelluloses is achieved, with cellulose enzymatic hydrolysis up to 98.1%, surpassing the original material by over 15-fold. Simultaneously, hemicelluloses transformed into high-value organic acids, yielding 33.5%. Notably, fractionated lignin is abundant in aryl ether linkages after AHP, facilitating subsequent transformation into aromatic chemicals. Through AHP, efficient fractionation of Chinese hickory shell is achieved, yielding fermentable glucose, organic acids, and lignin enriched with high aryl ether content. This research emphasises the pivotal role of comprehensive Chinese hickory shell utilisation in elevating the revenue of zero-waste biorefinery, sparking the production of valuable products from biomass waste streams, and further contributing to establishing resource-efficient biorefineries.

Enhanced degradation of metformin using surface-coated vortex diodes

The present work successfully demonstrates, for the first time, complete degradation of metformin using newer surface-coated vortex diode (SCVD) with copper and nickel coating to provide catalytic activity in the conventional hydrodynamic cavitation (HC) for significantly enhanced degradation efficiency. The SCVDs have dual functionality and the efficacy of catalytic cavitation reactors get enhanced using process intensifications of the type H2O2 addition, pH modification, and combined approach of HC+ pH+ H2O2 apart from the advantage of low pressure drop for the vortex flow based cavitation in vortex diode (ΔP of 1 bar). Complete, 100%, degradation of metformin (MTF) was achieved within 5 min with integration of optimized H2O2 dose and exceptionally high synergistic index value over 300, indicating extraordinary synergy for both Cu and Ni-SCVD. Acidic condition promote degradation and a complete degradation with a high 43–48% mineralization was observed using HC+ pH 4+ (1:200) H2O2 with less intermediates formation. The SCVDs reveal remarkable enhancement of ∼9800% in per-pass degradation and 1400–3400% in cavitational yield as compared to conventional cavitation process under similar conditions. The newer SCVDs with catalytic activity can provide more cost-effective solutions for industrial and real-life applications.

Removal of refractory organic compounds from bio-treated landfill leachate using a Fe0-H2O2-MoS2 process under continuous operation mode

Fe0 and MoS2 can synergistically activate H2O2 to generate free radicals for the removal of refractory organic compounds. This study aims to evaluate the Fe0-H2O2-MoS2 process for the removal of refractory organic compounds from bio-treated landfill leachate (BTL) under continuous operation mode. The results show that the dosage of H2O2, Fe0 and MoS2 all affect the removal effect of the Fe0-H2O2-MoS2 process on refractory organics during continuous operation. The removal rates of total organic carbon, absorbance at 254 nm and chroma at an initial pH of 3, [H2O2] of 5 mM, Fe0 of 0.4 g/L, MoS2 of 0.4 g/L and reaction time of 60 min were 65.83%, 85.11% and 93.14%, respectively. The Fe0-H2O2-MoS2 process can not only effectively destroy the complex structure of refractory organic compounds in the BTL treatment but also reduce the biological toxicity of BTL to a certain extent. In addition, a high organic removal rate can still be maintained during the long-term dynamic reaction process. Therefore, the Fe0-H2O2-MoS2 process has excellent performance in removing refractory organic compounds from BTL under continuous operation conditions.

Study on the performance test of Fe–Ce–Al/MMT catalysts for phenol-containing wastewater

In this study, a series of Fe–Ce–Al/MMT catalysts were prepared, characterized by XRD, SEM and N2 adsorption/desorption, and treated with phenol-containing wastewater. The results showed that the optimal Fe–Ce–Al/MMT catalyst with a molar ratio of (Fe + Ce)/(Fe + Ce + Al) of 5.5% has better grain development, more regular appearance, more uniform particle distribution, specific surface area of 180.9 m2/g and pore volume of 0.1858 cm3/g. The optimum technological conditions obtained by single factor test are as follows: initial pH value was 4, dosage of H2O2 was 13 mL/L, dosage of Fe2+ was 3500 mg/L, reaction temperature was 60 °C, and reaction time was 180 min. Under these conditions, the phenol removal rate was 98.21%. Based on the single factor test, the response surface test was carried out, and the results are as follows: initial pH value was 3, dosage of H2O2 was 15.64 mL/L, dosage of Fe2+ was 4884.37 mg/L, reaction temperature was 53.05 °C, and reaction time was 217.1 min. Under these conditions, the phenol removal rate was up to 98.75%.

Nano-CuOx for ciprofloxacin effective removal via wet peroxide oxidation catalysis and its practical application in wastewater

Using Cu(NO3)2·3H2O as active material and citric acid (CA) as complexing agent, heterogeneous catalyst nano-CuOx was prepared by sol-gel method. The catalytic wet peroxide oxidation (CWPO) reaction system was established accordingly. The system was used to treat ciprofloxacin (CIP) in simulated wastewater and real wastewater. The effects of the molar ratio of metal salt to CA, calcination temperature, H2O2 dosage, reaction temperature, and catalyst dosage on the physicochemical structure and the properties of CWPO were investigated. The results showed that when the molar ratio of CA to metal salt (Cu(NO3)2·3H2O) was 1.8, the calcination temperature was 500 °C, the concentration of H2O2 was 10 mmol · L–1, the reaction temperature was 95 °C, and the dosage of catalyst was 1 g · L–1, CWPO system has the best degradation effect on CIP. At thses optical conditions, the removal rate reached 86.8%, chemical oxygen demand (COD) removal rate reached 54.9%, and the recycling rate of the catalyst was very good. The refractory organics in actual pharmaceutical wastewater could be oxidized by this system as well, and the COD removal rate reaches 47%. The degradation mechanism of CIP showed that the main functions of the CWPO system were ·O2– and ·OH radicals. The possible degradation pathways were determined by ion chromatography to be intermediate products generated from piperazine ring cleavage, defluorination, decarboxylation, and quinoline hydroxylation of CIP. The catalyzing mechanism was investigated in detail; some useful information was obtained in this work.

Experimental study of microwave-catalytic oxidative degradation of COD in livestock farming effluent by copper-loaded activated carbon

ABSTRACT The problem of massive discharge of livestock wastewater is becoming more and more severe, causing irreversible damage to the ecological environment, and how to treat livestock wastewater efficiently and rapidly deserves to be studied in depth. In this work, CuO/granular activated carbon (GAC) loaded catalysts were prepared and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption/desorption techniques, and X-ray energy spectroscopy (EDS). The results showed that CuO was successfully attached to the GAC surface with good adsorption performance. The effects of catalyst dosage, H2O2 dosage, initial pH, microwave power and microwave irradiation time in different reaction systems on the degradation efficiency of chemical oxygen demand (COD) in wastewater were investigated, and the orthogonal experiments were used to explore the importance ranking of these factors. The highest degradation rate of COD was found to be enhanced by 12.1% in the reaction system of CuO/GAC, and the initial pH had the greatest effect on the COD removal rate. The combined MW/catalyst/H2O2 method used in this work provided a rapid and effective degradation of COD in wastewater, which can be helpful for reference in other microwave catalytic oxidation studies.

Hydrogen Peroxide Affects the Electroretinogram of Isolated Perfused Rat Retina

Purpose To evaluate the effects of H2O2 as an oxidant on the electroretinogram (ERG) in isolated rat retina. Methods Retinas were isolated from rat eyes and perfused with a nutrient solution. ERGs were recorded every 3 min. Once the signal was at a steady state, H2O2 was added to the perfusion solution. Results H2O2 caused instantaneous and transient changes in amplitudes and implicit times of the ERG, followed by changes in retinal survival curves. H2O2 0.2 mM produced a rapid increase in b-wave amplitude, followed by a return to the initial value and a survival curve above the control (without H2O2). A slight increase in a-wave was observed, followed by a decrease and a recovery above the control. The slow PIII decreased and then recovered to the initial value. H2O2 0.6 mM induced a small increase in b-wave amplitude, followed by a rapid decrease without recovery. The a-wave and slow PIII decreased rapidly without recovery. The implicit times of the a-wave and b-wave increased moderately with a low dose of H2O2, whereas they significantly increased with a high dose. Whatever the dose, the slow PIII implicit time increased significantly, followed by a return to the initial value. Barium increased the a-wave and b-wave, and then H2O2 reduced the two waves with a stronger effect on the a-wave. Aspartate and barium isolated the fast PIII, which decreased after H2O2 application. Conclusions H2O2 affects retinal function as shown by ERGs in isolated rat retina. The response differs with the dose of H2O2, suggesting that mechanisms underlying the action at low doses might be different from those at high doses. Our results also suggest an effect of H2O2 on ionic currents and/or neurotransmitter releases involved in the generation of the ERG and indicate a more pronounced effect on photoreceptors than on postsynaptic cells.

Fe2O3/coal fly ash Fenton-like catalyst for the elimination of organic pollutants in wastewater: Kinetic, mechanism, and application feasibility

Fe2O3/CFA was prepared by loading Fe2O3 on the surface of raw coal fly ash (RCFA), and then used as a Fenton-like catalyst to treat refractory organic wastewater. The characterization results of SEM-EDX, XRD, XPS, XRF, and BET test indicate that Fe2O3 is successfully loaded on the surface of RCFA, while the adsorption performance is not significantly affected. Under optimal treatment conditions of p-nitrophenol (PNP) simulated wastewater (H2O2 dosage = 8 mmol/L, Fe2O3/CFA loading = 6 g/L, pH = 3, and T = 303 K), the removal rate of PNP reaches 97.7 % at 50 min. There exist hydroxyl radicals (·OH), superoxide radicals (∙O2−) and singlet oxygen (1O2) in the Fenton-like system, and ·OH is the primary reactive oxygen species in the removal of PNP·H2O2 dosage, Fe2O3/CFA loading, and pH (i.e., [H+]) show different effects on the generation rate constant of hydroxyl radicals (k·OH), and the corresponding mathematic equation is k∙OH=6.51∙e−640.0T∙[H2O2]1.313∙[Fe2O3/CFA]1.093∙[H+]0.815. The Fenton-like process includes heterogeneous and homogeneous catalytic processes, and it is driven by the synergistic catalysis of multiple metallic elements; Fe and other metallic elements play major and auxiliary roles, respectively. In the advanced treatment of real coking wastewater, the catalytic capacity of Fe2O3/CFA can maintain 91.7 % in its 4th use, and the treatment cost is ¥4.15/ton, which can be decreased by further optimizing the preparation process of Fe2O3/CFA.

Synthesis of Cu Nanoparticles Incorporated Mesoporous C/SiO2 for Efficient Tetracycline Degradation.

In this study, a Cu NPs-incorporated carbon-containing mesoporous SiO2 (Cu/C-SiO2) was successfully synthesized through a grinding-assisted self-infiltration method followed by an in situ reduction process. The obtained Cu/C-SiO2 was then employed as a Fenton-like catalyst to remove tetracycline (TC) from aqueous solutions. TEM, EDS, XRD, N2 adsorption-desorption, FTIR, and XPS methods were used to characterize the crystal structure, morphology, porosity, chemical composition, and surface chemical properties of the catalyst. The effects of initial TC concentration, catalyst dosage, H2O2 dosage, solution pH, HA addition, and water media on the TC degradation over Cu/C-SiO2 were investigated. Scavenging and electrochemical experiments were then carried out to analyze the TC degradation mechanism. The results show that the Cu/C-SiO2 can remove 99.9% of the concentrated TC solution (C0 = 500 mg·L-1), and it can be used in a wide pH range (R.E. = 94-99%, pH = 3.0-11.0). Moreover, hydroxyl radicals (•OH) were detected to be the dominant reactive species in this catalytic system. This study provides a simple and promising method for the synthesis of heteroatom-containing mesoporous catalysts for the decomposition of antibiotics in wastewater.

Catalytic polymerization of bisphenol A using a horseradish peroxidase immobilized microporous membrane reactor.

Bisphenol A (BPA) is one of the most widely used chemical products, which is discharged into rivers and oceans, posing great hazards to organisms such as reproductive toxicity, hormone imbalance and cardiopathy induction. With the expansion harm of BPA, people have paid more attention to the environmental effects. In this paper, the degradation of BPA from the synthetic wastewater using the immobilization of horseradish peroxidase membrane reactor (HPR) was investigated. The immobilized HRP microporous membrane was prepared by the porous calcium alginate method. In addition, the reuse of the immobilized HPR membrane and the measurement of membrane flux showed that the membrane has good activity and stability. Finally, the experimental parameters including reaction time, pH, the concentration of BPA and the dosage of H2O2 were optimized to remove the BPA, and about 78% degradation efficiency of BPA was achieved at the optimal condition as follows: H2O2 to BPA molar ratio of 1.50 with an initial BPA concentration of 0.1 mol/L, the HPR dosage of 3.84 u/mL, the initial solution pH of 7.0, a temperature of 20 °C and a contact time of 10 min.

Neuroprotective effect of Cistus laurifolius on hydrogen peroxide-induced neurodegeneration in differentiated SH-SY5Y cells

Neuroprotective effect of Cistus laurifolius on hydrogen peroxide-induced neurodegeneration in differentiated SH-SY5Y cells
 
 Hamiyet ECIROGLU1*, Fatma YILDIZ1, Ersin YUCEL2
 ORCID: 0000-0002-3555-3946; 0000-0002-9270-9062; 0000-0001-8274-7578
 1Department of Medical Laboratory Techniques, Vocational School of Health Services, Alanya Alaaddin Keykubat University, Antalya, Turkey
 2Department of Biology, Faculty of Science, Eskisehir Technical University, Eskişehir, Turkey (ORCID: 0000-0001-8274-7578)
 
 
 Abstract
 Neurodegeneration is an important finding of various neurological diseases such as Alzheimer's Disease and Parkinson's Disease. MAP2 and Rbfox3/NeuN genes are also two important neuronal markers. In this study, our aim is to investigate the neuroprotective effect of Cistus laurifolius L. extract in neurodegeneration caused by H2O2 treatment in differentiated SH-SY5Y (f-SH-SY5Y) cells.
 In the study, the effects of H2O2 (62.5-1000µM) and Cistus laurifolius (15.62-1000mg/ml) doses on cell viability were determined by the MTT method. The effect of Cistus laurifolius in d-SH-SY5Y cells followed by H2O2 treatment on cell viability was determined by the MTT test. The effect of the extract on MAP2 and Rbfox3/NeuN gene expressions in 24-hour periods was evaluated by the RT-qPCR method.
 According to our findings, Cistus laurifolius extract significantly reduced cell viability in SH-SY5Y cells at 24 h and 48 h (p

Dual-functional biochar-supported iron trinitrophthalocyanine for tetracycline removal

Despite having superior catalytic activity for Fenton-like reactions, iron trinitrophthalocyanine’s large-scale application is still greatly hindered by its tendency to aggregate. This tendency reduces the surface volume of iron trinitrophthalocyanine and disperses its stability in solution. As a catalyst carrier, biochar can improve the catalyst’s efficiency in reaction and promote the separation of catalysts in water. In this study, we prepared a heterogeneous catalyst by combining immobilized iron trinitrophthalocyanine with amino (FeMATNPc) and oxidic biochar (O-BC), derived from Flueggea suffruticosa residue for the first time to remove tetracycline (TC). The Fourier transform infrared (FTIR) studies confirmed that FeMATNPc was loaded by biochar via direct bonding and π–π interaction. The optimal loading ratio of O-BC to FeMATNPc is 10:1. The distribution of FeMATNPc on the surface of O-BC increases the catalytic activity of H2O2. Its TC removal reached 51.6% after 60 min. The effect of H2O2 dosage on TC removal fitted the second-order kinetics. The highest removal (93%) was obtained when H2O2 dosing was 60 mM, pH = 7 and temperature was 45 °C. In the catalyzing process, TC was oxidized into small molecule compounds (such as H2O, CO2, and NH4+) through demethylation, ring opening, hydrogenation, and other steps. This work provides an efficient way to prevent the aggregation of iron trinitrophthalocyanine and remove pollutants in water.

Effective extraction of nickel and cobalt from sintered nickel alloy via reduction roasting and leaching

In this work, a carbothermic reduction technique is developed to improve the extraction of valuable metals from sintered nickel alloys by atmospheric acid leaching. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) analyses indicate that NiO in the sintered nickel alloy and the NiO coated by Ni2O3 hinders further dissolution of nickel. Nickel oxides can be transformed into easily leached metallic nickel by carbothermic reduction. The reduction roasting was investigated and optimized by thermodynamic analysis, thermogravimetry-mass spectrometry, XRD, and response surface methodology (RSM). The results show that the leaching efficiencies of nickel and cobalt are respectively increased from 80.34% and 69.92% to 98.65% and 96.71% after the reduction roasting under the optimized conditions: 935 °C of temperature, 50 min of time, and 29.9% of carbon dosage. The leaching of nickel was optimized by single-factor test method and the optimum conditions have been established as: 150 g/L of H2SO4 concentration, 25% of H2O2 dosage, 10 mL/g of liquid–solid ratio, 400 rpm of stirring speed, 80 °C of temperature, and 80 min of time. The kinetic analysis of leaching process shows that the activation energies of nickel and cobalt leaching are 20.71 kJ/mol and 16.33 kJ/mol, respectively, indicating that the leaching process is an internal diffusion control process. This study provides a feasible and effective approach to extract nickel from sintered alloys.

Degradation of veterinary antibiotics by Fenton process: Products identification and toxicity assessment

The aim of the work was primarily to determine the relationship between the doses of Fenton's reagents and the effectiveness of the ecotoxicity removal of aqueous solutions containing selected antibiotics. The degradation process of ampicillin, doxycycline, and tylosin in an acidic environment in the presence of H2O2 and FeSO4 was studied. The effect of reagent doses on the degree of degradation and identification of antibiotic transformation products was measured by the UPLC qTOF method. The degree of mineralisation was determined based on changes in the concentration of total organic carbon. The ecotoxicity of products was determined with commercial MARA® and MICROTOX® bioassays, as well as against unselected microorganisms from polluted rivers and wastewater treatment plant effluent.It was found that the complete degradation of antibiotics and the simultaneous elimination of the toxicity of the Fenton process products required the use of a precisely defined amount of reagents. When an insufficient dose of reactants was used, the post-reaction solutions contained antibiotic derivatives showing antimicrobial activity. On the other hand, the toxicity of the post-reaction solution against to microbiocenoses was observed when too high doses of H2O2 were used in the process. This effect resulted from the presence of unreacted reagent or other unidentified peroxides.

Degradation of polyvinyl alcohol (PVA) in neutral conditions based on copper-manganese bimetallic catalyst.

There have been many studies on the degradation of polyvinyl alcohol (PVA) by the Fenton-like method, but the narrow acid-base (pH) range, poor degradation effect, and time-consuming of the Fenton-like method limit its development. Therefore, to improve the shortcomings of the Fenton-like method, the study aimed to synthesize copper-manganese bimetal oxide loaded catalysts (MnCuO@γ-Al2O3) through the impregnation calcination method, and its potential to activate hydrogen peroxide (H2O2) for the degradation of PVA was evaluated. The X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer Emmett Teller (BET), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) characterizations revealed the chemical composition, structure and morphology of the prepared MnCuO@γ-Al2O3, furthermore the synergistic mechanism was proposed. Results indicated that copper and manganese could successfully attach to γ-Al2O3 and reduce the specific surface area of γ-Al2O3, promoting the transformation of multivalent metals and the generation of oxygen vacancies. In addition, comparative experiments demonstrated that the PVA removal efficiency was significantly improved at the catalyst calcination temperature of 500 °C, reaction temperature of 70 °C, H2O2 dosage of 125 [Formula: see text], and catalyst dosage of 625 [Formula: see text]and more than 96% of PVA was removed within 20 min in neutral conditions. Lastly, four catalyst cycle degradation experiments of PVA were carried out, and the degradation effect could reach more than 96% in a certain time.