Initial Peroxide Concentration Research Articles

Green synthesis of TiO₂ phases for efficient photocatalytic degradation of oxytetracycline in real aquaculture wastewater

The increasing use of antibiotics, particularly oxytetracycline (OTC), in aquaculture has raised concerns about environmental pollution and the spread of antibiotic-resistant bacteria. This study investigates the photocatalytic removal of OTC in real aquaculture wastewater using green-synthesized titanium dioxide (TiO₂) derived from Neem leaves. Three phases of TiO₂ were successfully synthesized, namely anatase, rutile, and brookite, with their properties evaluated using XRD, FESEM, photocurrent response, EIS, and photoluminescence. Among the phases studied, Neem-Anatase TiO2 demonstrated superior performance, achieving 86.63 % ± 2.7 % antibiotic degradation in pure OTC aqueous solution. With a band gap of 3.15 eV, Neem-Anatase TiO₂ exhibited light absorption capability 1.5 and 6 times greater than Neem-rutile (3.4 eV) and Neem-brookite (3.71 eV), respectively. Neem-Anatase TiO₂ maintained a 69.3 % ± 1.2 % degradation efficiency over four recycling cycles, and hole radicals was determined as the primary radical species involved in the photocatalytic process. In real aquaculture water, the Neem-Anatase TiO2 OTC degradation performance could achieve 69.63 % ± 3.4 % after optimizing experimental parameters including the initial Neem-Anatase TiO2 dosage (0.6 mg/mL), initial OTC concentration (10 ppm), pH (pH 6) and hydrogen peroxide concentration (5 mM) using the Design Expert software. Factors contributing to the reduction of OTC removal efficiency in aquaculture water include the screening and scavenging effect by the dissolved solids, organic and inorganic components in the water. This work demonstrates the potential of green-synthesized TiO₂, particularly the anatase phase, as a sustainable solution for antibiotic pollution in aquaculture wastewater thereby mitigating environmental impacts and limiting antibiotic resistance in aquatic ecosystems.

DEGRADATION KINETICS OF TEXTILE AZO DYE REACTIVE ORANGE-16 BY GAMMA IRRADIATION

Gamma radiation have become attention since their high potential for degrading compounds, especially organic pollutants. In this research, gamma radiation was studied for degrading the Reactive Orange-16 (RO-16) dye, a toxic and carcinogenic pollutant. The radiolytic degradation process was studied in a batch reactor with a gamma-ray dose rate of 2.930 kGy/h. The effect of experimental variable such as initial peroxide concentration, initial pH, initial dye concentration, and addition of inorganic anion were studied. The highest degradation rates were achieved at a peroxide concentration ranging from 2 to 4 mM. In contrast, the higher peroxide concentration indicated the slower degradation process caused by the scavenging effect of the peroxide. Degradation of 88% RO-16 dye with 0.1 mM initial concentration, was achieved at 2.0 kGy irradiation dose and 97.4% degradation in the presence of 4 mM peroxide. The dose constant (d) for those degradation processes was 1.0657 kGy-1 and 1.8420 kGy-1 respectively. The degradation was more efficient in acid pH. The degradation process increased with lower initial dye concentrations. The degradation of RO-16 dye by gamma-ray was inhibited by the presence of inorganic anions in the following sequence: NO3-→ CO32− → HCO3− → CH3COO-→ Cl-.

Effect of plasma-activated water on planktonic and biofilm cells of Vibrio parahaemolyticus strains isolated from cutting board surfaces in retail seafood markets.

This research aimed to analyze cutting board surfaces in seafood markets to find Vibrio parahaemolyticus, assess the isolates' ability to form biofilms, generate and evaluate characteristics of plasma-activated water (PAW), and compare the effect of PAW on planktonic and biofilm cells of the isolated V. parahaemolyticus strains. A total of 11V. parahaemolyticus strains were isolated from 8.87% of the examined cutting boards. Biofilm-forming ability was evaluated for these isolates at temperatures of 10°C, 20°C, and 30°C using crystal violet staining. Four strains with the highest biofilm potential were selected for further analysis. The pH of the PAW used in the study was 3.41±0.04, and the initial concentrations of hydrogen peroxide, nitrate, and nitrite were 108±9.6, 742±61, and 36.3±2.9µM, respectively. However, these concentrations decreased significantly within 3-4 days during storage at room temperature. PAW exhibited significant antimicrobial effects on V. parahaemolyticus planktonic cells, reducing viable bacteria up to 4.54 log CFU/ml within 20 min. PAW also reduced the number of biofilm cells on stainless steel (up to 3.55 log CFU/cm2) and high-density polyethylene (up to 3.06 log CFU/cm2) surfaces, although to a lesser extent than planktonic cells. PAW exhibited significant antibacterial activity against V. parahaemolyticus cells, although its antibacterial properties diminished over time. Furthermore, the antibacterial activity of PAW against biofilm cells of V. parahaemolyticus was less pronounced compared to the planktonic cells. Therefore, the actual effectiveness of PAW in seafood processing environments can be affected by biofilms that may form on various surfaces such as cutting boards if they are not cleaned properly.

Effect of a brush tip on in-office bleaching gels in an attachable syringe: Hydrogen peroxide penetration, bleaching efficacy and amount of gel expended

ObjectiveEvaluate the penetration of hydrogen peroxide (HP) into the pulp chamber, bleaching efficacy (BE) and amount of gel expended during in-office bleaching using an applicator brush tip and conventional tip from different commercial brands. Materials and Methods104 human premolars were randomly distributed into thirteen groups (n = 8) according to the commercial brand: DSP White Clinic 35 % Calcium (DW), Nano White 35 % (NW), Total Blanc One-Step 35 % (TS), Whiteness HP Blue 35 % (WB), Potenza Bianco Pro SS 38 % (PB), Opalescence XTra Boost 40 % (OB), no bleaching (negative control), and application method: applicator brush tip and conventional tip for all groups. Initial HP concentration (%) was determined via titration and pH was measured with digital pH meter. Concentration (µg/mL) of HP into the pulp chamber was measured using UV–Vis spectrophotometry, the BE (ΔE*ab, ΔE00 and ΔWID) was evaluated with a digital spectrophotometer, and the amount of gel expended was evaluated using a precision analytical digital balance. Statistical analysis included two-way ANOVA, Tukey's, and Dunnett's test. Comparison between HP into the pulp chamber vs BE was performed with Person's correlation (α = 0.05). ResultsBrush tip demonstrated a low amount of HP in the pulp chamber compared to the conventional method for all bleaching gels (p < 0.0003), as well as lower amount of gel expended (p < 0.002). The brush tip did not result in a significant difference in BE compared to the conventional (p > 0.05). No correlations were found between both factors (p > 0.05). ConclusionBrush tip showed lower penetration of HP in the pulp chamber and a reduced volume of spent gel when compared to the conventional tip, for all commercial brands. Clinical relevanceBrush tip is recommended for bleaching gels in an attachable syringe due to its ability to reduce the penetration of HP into the pulp chamber and minimize the amount of bleaching gel used.

Heterogeneous Photo-Fenton-like Degradation of Oxytetracycline Containing Wastewater

Oxytetracycline (OTC) is a commonly used antibiotic. It can be absorbed to a limited extent by both humans and animals, so it can be detected at various levels in different water sources. Its presence in rivers or water and wastewater streams can pose serious problems for human and environmental health, and therefore, it needs to be treated. OTC degradation was studied using iron-doped g-C3N4 through a photo-Fenton-like oxidation process under simulated sunlight. In this study, the effects of key reaction parameters such as pH (3, 6, 9), catalyst amount (0-0.8 g/L), initial hydrogen peroxide concentration (HP, 0-20 mM) on the degradation of oxytetracycline were studied. The optimal reaction conditions for OTC degradation were found to be pH=6, catalyst amount of 0.4 g/L, and HP of 10 mM. Subsequently, the temperature effect was examined at the optimum reaction conditions. Based on the results, at 25, 35, and 45 °C, OTC degradation was found to be 51.1%, 60.8%, and 76.7%, respectively. The kinetic study conducted revealed that the observed reaction follows a second-order reaction kinetic model. In addition, the activation energy of observed reaction was found to be 86.96 kJ/mol.

The Effect of Different Bleaching Techniques Using 6% Hydrogen Peroxide: Penetration Inside the Pulp Cavity, Bleaching Efficacy and Toxicity

Abstract This in vitro study aimed to quantify the penetration of hydrogen peroxide (HP), bleaching efficacy (BE) and toxicity in larvae in different bleaching techniques using 6% HP. Sixty maxillary premolars were divided in six groups (n = 10): Pola Luminate (PL), VivaStyle Paint On PIus (VS), PolaDay (PD), White Class (WC) and Whiteness HP Automixx (AM). A group not exposed to bleaching agents was evaluated as a control group (CG). Previously, the initial HP concentration in the bleaching agents was determined via titration and pH was measured with a digital pH meter. The concentration (µg/mL) of HP inside the pulp cavity was assessed using UV-Vis spectrophotometry. The BE (ΔE* ab and ΔE00) was evaluated with a digital spectrophotometer. The toxicity was evaluated in larvae model. Data from HP penetration and color change were evaluated for a one-way ANOVA and the Tukey’s test, as well as Kaplan-Meier death curve for toxicity (α = 0.05). VS, PD and AM had an initial concentration lower than that the manufacturers reported. VS had a more acidic pH. PL and WC showed a significantly lower HP amount inside the pulp cavity when compared to VS (p = 0.001). Regarding BE, no significant difference was observed for ΔE* ab (p = 0.38), and ΔE00 (p = 0.42). No toxicity was observed when all 6% HP was compared to GC (p &gt; 0.05). All 6% HP products tested showed bleaching efficacy, low penetration into the pulp chamber and were non-toxic to Tenebrio molitor larvae.

Sintered magnesium ferrite particles in decolorization of anthraquinone dye AV 109: Combination of adsorption and fenton process

Magnesium ferrite (MgFe2O4) particles were synthetized by sol-gel method and used in the decolorization of the Acid Violet 109 (anthraquinone dye, AV109) water solutions' by combination of adsorption and heterogeneous Fenton process. The material's morphology and elemental analysis of the surface were revealed by Scanning electron microscopy and Energy Dispersive Spectroscopy (SEM/EDS). The X-Ray Diffraction (XRD) technique was used to analyze the crystallographic phase. In the first part of the decolorization experiment, the adsorption ability of the synthesized particles was investigated. During the adsorption study influence of pH was investigated. In the second part of the decolorization experiment, the effects of the various parameters on the Fenton process were studied such as the initial concentrations of hydrogen peroxide, dye, and magnesium ferrite particles. Influence of magnesium ferrite particles structure, pH value and reaction temperature were also investigated. The decolorization reaction was followed by UV-Visible (UV-Vis) spectrophotometry. At optimal conditions, the dye decolorization was 99.1% (55.4% by adsorption and 43.7% by the Fenton process). Both the adsorption and the Fenton process obey second-order kinetics.

Sintered magnesium ferrite particles in decolorization of anthraquinone dye AV109: Combination of adsorption and fenton process

Magnesium ferrite (MgFe2O4) particles were synthetized by sol-gel method and used in the decolorization of the Acid Violet 109 (anthraquinone dye, AV109) water solutions' by combination of adsorption and heterogeneous Fenton process. The material's morphology and elemental analysis of the surface were revealed by Scanning electron microscopy and Energy Dispersive Spectroscopy (SEM/EDS). The X-Ray Diffraction (XRD) technique was used to analyze the crystallographic phase. In the first part of the decolorization experiment, the adsorption ability of the synthesized particles was investigated. During the adsorption study influence of pH was investigated. In the second part of the decolorization experiment, the effects of the various parameters on the Fenton process were studied such as the initial concentrations of hydrogen peroxide, dye, and magnesium ferrite particles. Influence of magnesium ferrite particles structure, pH value and reaction temperature were also investigated. The decolorization reaction was followed by UV-Visible (UV-Vis) spectrophotometry. At optimal conditions, the dye decolorization was 99.1% (55.4% by adsorption and 43.7% by the Fenton process). Both the adsorption and the Fenton process obey second-order kinetics.

A performance comparison of photo-fenton decolorization of methylene blue by using bentonite/iron composites prepared by liquid phase and solid phase ion exchange method

Nowadays, there is a wide range of pollutants present, which requires the treatment of wastewater. The photo-Fenton method has been recognized as valuable in this area. In this study, iron/bentonite composites were created using both liquid phase and solid phase iron exchange techniques, and they were utilized as a photocatalyst for the degradation of methylene blue through photo-Fenton process. Various factors affecting the photocatalytic decolorization were investigated, including the initial concentration of the dye, weight of the catalyst, pH of the solution, and concentration of hydrogen peroxide. The decolorization efficiency of the iron/bentonite composites prepared using the solid phase and liquid phase ion exchange approaches was found to be 99% and 95%, respectively. Based on the data, it can be concluded that the performance of both catalysts was almost equally influenced by the initial dye concentration, catalyst weight, solution pH, and hydrogen peroxide concentration. Moreover, the solid phase ion exchange method demonstrated greater reusability compared to the liquid phase ion exchange method. Consequently, it can be stated that the solid phase ion exchange approach is a suitable and straightforward alternative to the conventional liquid phase ion exchange method for producing a photo-Fenton catalyst.

A Comprehensive and Sustainable Recycling Process for Different Types of Blended End-of-Life Solar Panels: Leaching and Recovery of Valuable Base and Precious Metals and/or Elements

The production of photovoltaic modules is increasing to reduce greenhouse gas emissions. However, this results in a significant amount of waste at the end of their lifespan. Therefore, recycling these solar panels is important for environmental and economic reasons. However, collecting and separating crystalline silicon, cadmium telluride, and copper–indium–gallium–selenide panels can be challenging, especially in underdeveloped countries. The innovation in this work is the development of a process to recycle all solar panel waste. The dissolution of all metals through the leaching process is studied as the main step of the flowchart. In the first step of leaching, 98% of silver can be recovered by 0.5 M nitric acid. Then, the second and third step involves the use of glycine for base metal dissolution, followed by the leaching of valuable metals with hydrochloric acid. The effect of parameters such as the initial pH, acid concentration, solid/liquid ratio, and hydrogen peroxide concentration is studied. The results show that up to 100% of Cu, Pb, Sn, Zn, Cd, In, Ga, and Se can be recovered under optimal conditions. The optimal conditions for the dissolution of Cu, Zn, and Cd were a glycine concentration of 0.5 M, a temperature of 25 °C, a solid/liquid ratio of 10 gr/L, and 1% of hydrogen peroxide. The optimized glycine concentration for the leaching of lead and tin was 1.5 M. Indium and gallium were recovered at 100% by the use of 5 M hydrochloric acid, S/L ratio = 10 gr/L, and T = 45 °C. Separation of selenium and tellurium occurred using 0.5 M HCl at a temperature of 60 °C. Additionally, for the first time, a general outlook for the recycling of various end-of-life solar panels is suggested.

Gerçek Tekstil Atıksularının Perovskite/Aktif Karbon Kompozit Katalizör Varlığında Elektrokoagülasyon ve Fenton Benzeri Oksidasyondan Oluşan Hibrit Sistem Kullanılarak Son Arıtımı

A hybrid wastewater treatment method was used to improve the quality of the treated wastewater for possible reuses. Real textile wastewater was subjected to electrocoagulation and Fenton like oxidation sequentially. In the Fenton like oxidation process the performances of BiFeO3/RHAC and BiNiO3/RHAC (RHAC: Rice husk based activated carbon) catalysts were compared. BiNiO3/RHAC was determined to be more effective in total organic carbon removal. A parametric study was carried out in the presence of the selected BiNiO3/RHAC catalyst to investigate the effect of the catalyst loading, pH and the oxidant dosage on total organic carbon removal. The most suitable reaction conditions were determined as 1.5 g/L of catalyst loading, pH 7, and 2 mM initial hydrogen peroxide concentration. 17% and 15.7% total organic removal efficiencies were achieved in electrocoagulation and Fenton like oxidation processes, respectively, whereas the cumulative removal efficiency was 32.7%.

Suppression of nitrite oxidizing bacteria by hydrogen peroxide for energy reduction in municipal wastewater treatment

This paper investigated the application of hydrogen peroxide (H2O2) for achieving partial nitrification in mainstream municipal wastewater treatment process. The investigation was carried out in both bench-scale and pilot-scale sequencing batch reactor systems using primary effluent as feed from municipal wastewater treatment plant. H2O2 played a dual role of: (1) inhibitor for nitrifying microorganisms, and (2) supplemental oxygen source. Bench scale studies were carried out at various doses of initial hydrogen peroxide concentrations (10,25,50,100 mg/L). It was found that at a concentration of 50 mg/L and above ammonia removal reduced by more than 80% implying significant impact on both ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB). After an acclimatization period of 18 days at a dose of 50 mg/L H2O2, complete nitrification was observed with about 30% nitrite accumulation in the effluent which showed NOBs were impacted more significantly than AOBs. It was also observed from the long-term pilot-scale study that the inhibitory impact on NOBs is almost double the impact of on AOBs which facilitated partial nitrification resulting a nitrite accumulation ratio up to 60% in the effluent at 2 mg/L DO and 15 days SRT.Peroxide dosing resulted in an energy savings of 12–15% compared to a control reactor. It was also shown that by reducing the DO from 2 to 1 mg/L, additional power saving of 15% is achievable. Therefore, the proposed approach is an efficient method for aeration energy savings and can be easily implemented in existing wastewater treatment plants.

Enhanced Photocatalytic Degradation of the Antidepressant Sertraline in Aqueous Solutions by Zinc Oxide Nanoparticles

Antidepressants are one of the main pollutants in the aquatic environment. They are being widely studied due to their widespread use, possible health effects, and partial removal from wastewater treatment plants by conventional methods. Photocatalysis is an effective and ecologically beneficial method in wastewater treatment. In the present study, the photocatalytic degradation of sertraline hydrochloride (SERT) in water using nano-sized zinc oxide (ZnO-NPs) was investigated. The ZnO-NPs were synthesized from zinc gluconate as a precursor by the sol–gel method. The crystal structure, morphology, surface charge, and textural properties were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analyses, transmission electron microscopy, Fourier-transform infrared spectroscopy, zeta potential, and N2 adsorption–desorption measurements. The removal of SERT in water was explored by different processes: H2O2/UV, ZnO-NPs/H2O2/UV, and ZnO-NPs/UV. Our results indicate that the combination of both UV illumination and the ZnO-NP as a catalyst was necessary for the efficient degradation of the drug. Nearly complete removal of SERT (98.7%) was achieved in 30 min with the ZnO-NPs/UV process at room temperature. The photodegradation of SERT follows first-order kinetics with a rate constant of 0.0678 min−1. The results reveal that SERT degradation with ZnO-NPs/UV is pH-dependent, as the maximum drug removal was achieved at pH 11. Initial drug concentration, catalyst dose, and hydrogen peroxide concentration were also crucial in the removal of SERT. Our findings indicate that the high specific surface area and porous structure of ZnO-NP enhance its photocatalytic performance toward photodegradation of SERT, i.e., ZnO-NP is an efficient nanophotocatalyst for the degradation of SERT under UV irradiation.

Rapid removal of methylene blue by a heterogeneous photo-Fenton process using economical and simple-synthesized magnetite–zeolite composite

A hetero-Fenton zeolite-supported Fe3O4 catalyst was synthesized using a simple impregnation–precipitation method. The structure, morphology, and components of the catalyst were characterized using various analytical methods (XRD, SEM, and ICP-MS). Subsequently, the catalyst was used to degrade the azo dye methylene blue (MB), via a heterogeneous photo-Fenton process under UV irradiation in an aqueous solution. This study investigated the influence of different parameters on MB decolorization efficiency, such as the initial concentration of hydrogen peroxide, amount of catalyst, initial dye concentration, and reusability of the catalyst. The removal efficiency was nearly 100% within only 5 min with an initial concentration of methylene blue of 50 mg L−1 under the following experimental conditions: a pH solution of 3, a catalyst of 0.6 g L−1, an H2O2 concentration of 66 mg L−1, and a UV lamp power of 6 W. Moreover, the Fe3O4/zeolite A catalyst (Fe/ZA) showed good stability in the photo-Fenton degradation of methylene blue after four consecutive cycles, implying that the Fe/ZA catalyst could be a potential wastewater treatment option. Furthermore, the findings of the reaction kinetics study demonstrate that the kinetics of the dye removal reaction can be fitted using the Langmuir–Hinshelwood model for heterogeneous catalytic reactions.

Synergistic effect of Fenton oxidation and adsorption process in treatment of azo printing dye: DSD optimization and reaction mechanism interpretation

ABSTRACT The main challenges to overcome within the Fenton process are the acidic pH as an optimal reaction condition, sludge formation in neutral pH medium and high toxicity of treated printing wastewater due to the generation of contaminating by-products. This research discusses the catalytic activity of homogeneous (FeSO4/H2O2) and heterogeneous (Fe2(MoO4)3/H2O2) Fenton processes in treatment of Yellow azo printing dye in synthetic aqueous solution and real printing effluent, with an integration of adsorption on functionalized biochar synthesized from wild plum kernels. The definitive screening design (DSD), was used to design the experiment. Independent variables were initial dye concentration (20–180 mg L−1), iron concentration (0.75–60 mg L−1), pH (2–10) and hydrogen peroxide concentration (1–11 mM). Higher decolourization efficiency of 79% was obtained within homogeneous Fenton treatment of printing wastewater, in comparison to heterogeneous Fenton treatment (54%), after a reaction time of 60 min. Same trend of mineralization degree was established: COD removal was 59% and 33% for homogeneous and heterogeneous Fenton process, respectively. The application of adsorption treatment has achieved significant advantages in terms of toxicity reduction (95%) and decolourization efficiency (90% of TOC removal and 22% of dye removal) of treated samples, even at neutral pH medium. Degradation mechanisms within Fenton and adsorption processes were proposed based on the qualitative gas chromatography/mass spectrometry analysis, physico-chemical properties of dye degradation products and functionalized biochar. Overall, the homogeneous Fenton/adsorption combined process can be potentially used as a treatment to remove azo dyes from contaminated water.

Comparative study using design experiment to assess an anionic dye degradation in aqueous solution through the application of different advanced oxidation processes

AbstractThis study aims to compare the anionic dye degradation (Titan yellow dye: DY9) in synthetic solution using three advanced oxidation processes, namely, Fenton process (FP) (H2O2/Fe2+), photo‐Fenton process (PhFP) (UV/H2O2/Fe2+), and photocatalytic process (PhCP) (TiO2/UV). To perform this study, design of experiments methodology was applied. A full factorial design was used to investigate the effect of operating parameters on the degradation yield. For each process, four parameters were considered, for “FP” and “PhFP,” the initial dye concentration ([DY9]0), the ratio R1 = [H2O2]/[Fe2+], the ratio R2 = [DY9] / [Fe2+], and the pH of solution and for “PhCP,” the initial dye concentration (([DY9]0), initial concentration of hydrogen peroxide [H2O2], dose of titanium oxide [TiO2], and the pH of solution. The averages of degradation yield obtained are 47.1%, 56.7%, and 68.5% for “FP,” “PhFP,” and “PhCP,” respectively. Main and interaction effects plots were constructed. An interaction index (In (%)) was defined, which allowed to quantify the impact of the interaction on the response. Three regression models were proposed and validated on basis of analysis of variance (ANOVA) and statistical criteria as corrected Akaike Information Criterion (AICc), Mallows Cp statistic, coefficient of determination (R2), and adjusted coefficient of determination (R2adj). These models showed that the “PhCP” model was the most statistically significant, including more interaction effect terms. Iso‐responses curves were plotted to predict the optimal conditions for each process. To achieve a full degradation of DY9, the predicting optimal conditions were expressed on intervals.

ВОДА, АКТИВИРОВАННАЯ СВЧ-ПЛАЗМОЙ, КАК РЕГУЛЯТОР РОСТА ХВОЙНЫХ

The reduction of the world's forests threatens a global ecological catastrophe. The contribution of forests and phytoplankton of the seas and oceans in the processes of photosynthesis, responsible for maintaining oxygen in the Earth's atmosphere, is divided equally at a ratio of forest and water surface areas of 9:71. The protection and restoration of lost forests, in Russia coniferous forests, is a paramount task. The problem of forest restoration is being solved at the government level. Decree of the Government of the Russian Federation dated 21.09.2020 No. 1509 «On the peculiarities of the use, protection, protection, reproduction of forests ...». The effect of plasma-activated water (PAW) on the stimulation of seed germination, the development of conifers in the early stages of their growth was studied. PAW was obtained using UHF plasmotron generating plasma in the atmosphere. PAW contains solutions of hydrogen peroxide and nitrogen oxides, which are necessary for plant life. VAP solutions were tested by the concentration of hydrogen peroxide. The initial concentration of hydrogen peroxide was 8·10-3 M. The seeds of fir and larch were germinated on filters moistened with water in the control, in the experiment with VAP solutions. The most effective VAP solution was a solution with a hydrogen peroxide concentration of 2·10-6 M, which provided an increase in the germination of larch and fir seeds by 25 and 30%, respectively, compared with the control. The germinated seeds were placed in transparent culture vessels on sand, which was moistened once with water in the control, in the experiment with VAP solutions. The vessels were closed. Seedlings were grown in stressful isolation conditions. We tested the development remotely. By the 30th day, 5% of the seedlings survived in the control and 40-45% of the seedlings survived in the experiment.

Photo-degradation of sugar processing wastewater by copper doped bismuth oxyiodide: Assessment of treatment performance and kinetic studies.

In this study, photo-Fenton-like oxidation method was evaluated for synthetic sugar industry wastewater using visible-light driven Cu-BiOI photocatalyst. Reaction conditions including initial pH, catalyst loading, initial hydrogen peroxide (H2O2) concentration, and temperature, were optimized. At these optimized conditions, the total saccharide concentration (TSC) and total organic carbon (TOC) removals were 56.20% and 30.67%, respectively whereas the maximum TSC and TOC removal reached up to 93.35% and 74.72% respectively by decreasing initial sucrose concentration. The kinetic study showed that the reaction order for sucrose and TOC oxidation was determined as 2 for pseudo-homogeneous power law models with respect to sucrose concentration and TOC, respectively.For heterogeneous models, Langmuir-Hinshelwood model based on the mechanism of adsorbed pollutant and oxidant on different catalytic sites was the best fit for oxidation of sucrose and other organic intermediates. According to the catalyst characterization studies, incorporation of copper was successful and Cu-BiOI possesses high photocatalytic activity accomplished by acid-assisted synthesis method.

Global sensitivity analysis to identify influential model input on thermal risk parameters: To cottonseed oil epoxidation

Thermal runaway is still an important cause of accident in chemical industry. To evaluate the risk of such events, thermal risk assessment, which is a part of process safety, must be done. This assessment determines the safe operating conditions of a process by evaluating the thermal risk of an exothermic system. Nevertheless, based on thermal risk assessment, it is not possible to know which model inputs have the most influence on the thermal risk parameters. The knowledge of the most influential model inputs on thermal risk parameters is important to establish adequate safety barriers. Global sensitivity analysis was used to evaluate the influence of model inputs and their interaction on thermal risk parameters. It was performed on the exothermic system: epoxidation of cottonseed oil by performic acid in semibatch mode under isoperibolic conditions. The maximum reaction temperature and the time to reach this maximum reaction temperature were chosen as thermal risk parameters. We have also studied the influence of model inputs on the temperature rise. In the operating conditions of this study, it appeared that two parameters have the most influence on maximum reaction temperature and the temperature rise: the initial concentration of hydrogen peroxide and the jacket temperature, and one parameter for the time to reach this temperature: the jacket temperature.

Treating High COD Dyeing Wastewater via a Regenerative Sorption-Oxidation Process Using a Nano-Pored Activated Carbon.

Nowadays, the structural complexity of dyes used in the textile industry and the widely adopted water-saving strategy in the dyeing processes often fail plants’ biological wastewater treatment units due to chemical oxygen demand (COD) overload. To alleviate this problems, this study investigated a regenerable adsorption–oxidation process to treat dyeing wastewater with COD around 10,000 mg/dm3 using a highly nano-pored activated carbon (AC) as a COD adsorbent, followed by its regeneration using hydrogen peroxide as an oxidizing reagent. In addition to studying AC’s COD adsorption and oxidation performance, its operational treatment conditions in terms of temperature and pH were assessed. The results firstly demonstrated that about 50–60% of the COD was consistently adsorbed during the repeated adsorption operation before reaching AC’s maximum adsorption capacity (qmax) of 0.165 g-COD/g-AC. The optimal pH and temperature during adsorption were 4.7 and 25 °C, respectively. Secondly, AC regeneration was accomplished by using an initial peroxide concentration of 2.5% (by wt %) and EDTA-Fe of 2.12 mmole/dm3. The reuse of the regenerated ACs was doable. Surprisingly, after the first AC regeneration, the COD adsorption capacity of the regenerated AC even increased by ~7% with respect to the virgin AC. Thirdly, the results of a five-consecutive adsorption–regeneration operation showed that a total of 0.3625 g COD was removed by the 5 g AC used, which was equivalent to an adsorption capacity (q) of 0.0725 (= 0.3625/5) g-COD/g-AC during each adsorption stage. Based on the obtained results, a regenerable COD adsorption–oxidation process using a nano-pored AC to treat the high-textile-COD wastewater looks promising. Thus, a conceptual treatment unit was proposed, and its potential benefits and limitations were addressed.