Initial Concentration Research Articles

Elaboration of a green and highly dispersible Co-MOFs induced Co-doped C3N5 photocatalyst: Applications and mechanistic insights into activated perxymonosulfate degradation of antibiotics

In recent years, metal-organic frameworks (MOFs) as metal-based carbon materials have been widely concerned with the application of activated perxymonosulfate(PMS) to degrade antibiotics. However, constructing MOFs-derived materials with excellent dispersion, highly exposed metal active sites, and environmental friendliness remains a challenge. This paper reports for the first time the in-situ formation of nitrogen-rich Co-doped C3N5 (Co-C3N5) materials using a cobalt-based metal-organic framework (Co-MOFs), which has highly dispersed metal sites that are conducive to the activation of PMS. The forbidden bandwidth value of Co-C3N5 photocatalyst is as low as ∼1.20 eV, which could completely degrade chlortetracycline hydrochloride (CTC) with the initial concentration of 30 mg/L within 6 min under a light source of 50 W LED lamp. The results indicate that efficient photoelectron separation and transport are key factors in the activation and degradation of CTC by PMS, involving both free radical and non-free radical degradation processes. Meanwhile, the skeletal structure of MOFs and the triazine ring of C3N5 were retained, enhancing the stability of the photocatalyst and reducing the leaching of cobalt Finally, the seed germination experiment of Chinese cabbage showed that the treated CTC could increase the root length of Chinese cabbage seedlings by 10.1∼42.9%, which proved that the materials had no toxic effect on environment and could provide carbon and nitrogen source for plant growth. Based on this, this study proposes a novel approach for the development of MOFs-derived carbon photocatalysts that exhibit excellent dispersion and highly exposed metal active sites.

Bioreactor study of the metabolic repertoire and morphology of actinomycete Streptomyces rimosus ATCC 10970 under various initial concentrations of carbon and nitrogen sources

This work aims at investigating the influence of the initial concentrations of carbon (glucose) and organic nitrogen (yeast extract) sources on Streptomyces rimosus ATCC10970 secondary metabolism in the stirred tank bioreactors. Additionally, glucose utilisation, biomass formation, pH, redox potential and dissolved oxygen levels, and the morphological development of S. rimosus pseudomycelium were studied. Eighteen secondary metabolites were detected by mass spectrometry and identified with the use of the authentic standard, or putatively with the use of literature and database of secondary metabolites. Varied initial yeast extract concentration acted much stronger on the formation of secondary metabolites than glucose did. For example, oxytetracycline was not biosynthesised at high yeast extract concentration while the formation of three other metabolites was enhanced under these conditions. In the case of glucose its increasing initial concentration led to higher secondary metabolite levels with the exception of an unnamed angucycline. High initial yeast extract concentration also drastically changed S. rimosus pseudomycelial morphology from the pelleted to the dispersed one. Ultimately, the cultivation media with the varied initial levels of carbon and nitrogen sources were proved to have the marked effect on S. rimosus secondary metabolism and to be the simplest way to either induce or block the formation of the selected secondary metabolites.

Functionalized cellulose nanocrystals extracted from date pits as agricultural waste for the efficient remediation of molybdenum from groundwater: Performance and mechanistic studies

The adsorption technique has proven to be an excellent option for treating contaminated water. This work was designed to investigate the efficient remediation of molybdenum (Mo(VI)) from groundwater by using a novel adsorbent composed of date pits (DP) modified by manganese oxide/cellulose nanocrystal (CNC) composite (MnO2/CNC@DP). The physicochemical properties of the adsorbent were examined by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope with energy-dispersive X-ray spectroscopy techniques (SEM/EDX), X-ray diffraction (XRD), and transmission electron microscopy (TEM) to study the functional group on the adsorbent surface, surface morphology and chemical composition, and the crystallinity behavior. The performance of prepared (MnO2/CNC@DP) toward Mo(VI) was studied using synthetic solutions and real groundwater samples. Also, the effect of pH, temperature, and initial Mo concentration on the adsorption process was investigated. Moreover, various adsorption isotherm models were calculated, and the thermodynamics of adsorption was studied. The recovery experiments for Mo(VI) saturated MnO2/CNC@DP were conducted by using acidic and alkaline solutions. At the optimum pH of 2, the adsorption capacity increased with increasing the initial concentration of Mo(VI), and Qmax was 30 mg/g at 35 °C. The removal of Mo(VI) from real groundwater was 88.42% The negative values of Gibbs energy (ΔG°) demonstrated that the adsorption is spontaneous, and the experimental data followed the Langmuir isotherm model. Moreover, Mo(VI) can be desorbed from the MnO2/CNC@DP surface by using 1.0M HCl. The proposed mechanisms for the adsorption of Mo(VI) by MnO2/CNC@DP were dominated by electrostatic attraction and inner-sphere complexation. As a result of the research, MnO2/CNC@DP is a promising adsorbent with a high potential for removing Mo(VI) from groundwater. Furthermore, This research provides new knowledge into the modification of date pits using different metal oxides/cellulose nanocrystal particles. Furthermore, the results suggest an excellent chance of employing the efficiently produced adsorbent MnO2/CNC@DP for sustainable groundwater treatment from additional contaminants.

Preparation of magnetic DTPA-modified chitosan composite microspheres for enhanced adsorption of Pb(II) from aqueous solution

In this study, magnetic DTPA-modified chitosan composite microspheres (MDCM) were prepared by reverse emulsion-double crosslinking method (carbodiimide followed by glutaraldehyde) for removal of Pb(II) from aqueous solution. The obtained magnetic adsorbents were characterized by FTIR, SEM, XRD, VSM, BET, and 13C NMR. The effects of the pH, contact time, initial concentration, and competitive metal cations (Na(I), Ca(II), or Mg(II)) on Pb(II) adsorption were investigated. The results revealed that MDCM exhibited high removal performance over a wide pH range and in the presence of competitive metal cations. The maximum adsorption capacity of MDCM for Pb(II) is 214.63 mg g−1 at pH 3, which is higher than most recently reported magnetic adsorbents. Adsorption kinetics and isotherms can be described by the pseudo-second-order model and Langmuir model, respectively. In addition, MDCM is easy to regenerate and can be reused five cycles with high adsorption capacity. Finally, the adsorption mechanism was further revealed by FTIR and XPS analysis. Overall, MDCM has practical application potential in removing Pb(II) from contaminated wastewater due to its high adsorption efficiency, good reusability, and convenient magnetic separation.

Towards liquid EPR dosimetry using nitroxides in aqueous solution.

Objective. Water-equivalent dosimeters are desirable for dosimetry in radiotherapy. The present work investigates basic characteristics of novel aqueous detector materials and presents a signal loss approach for electron paramagnetic resonance (EPR) dosimetry.Approach. The proposed principle is based on the radiation dose dependent annihilation of EPR active nitroxides (NO·) in aqueous solutions. Stable nitroxide radicals (3-Maleimido-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (MmP), 3-Carbamoyl-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (CmP)) in aqueous solutions containing dimethyl sulfoxide (DMSO) as an additive were filled in glass capillaries for irradiation and EPR readout. Radiation doses ranging from 1 to 64 Gy were applied with a clinical 6 MV flattening filter free photon beam. EPR readout was then performed with a X-band benchtop spectrometer. The dose response, temporal stability and reproducibility of the samples' EPR signal amplitudes as well as the influence of the nitroxide concentration between 10 and 160μM on the absolute signal loss were investigated using MmP. CmP was used to examine the dependence of the dose response on DMSO concentration between 0 and 10 vol%. An indirect effect model was fitted to the experimental data assuming irradiation induced radical reactions as the underlying mechanism.Main results. For an initial MmP concentration of 20μM, absolute EPR signal loss is linear up to a dose of 16 Gy with a yield G(-NO·) of approximately 0.4μmol J-1. Within five weeks upon sample irradiation to doses between 0 and 32 Gy relative EPR signal fluctuations were on average (126 readouts) below 1% (1σ). For c(MmP) ≥ 20μM, absolute signal loss is only weakly dependent on c(MmP), whereas it increases strongly with increasing c(DMSO) in the range 0-5 vol%. An indirect effect model is applicable to describe the reaction mechanism resulting in the observed dose response curve.Significance. Liquids consisting of nitroxides in aqueous solution and small amounts of DMSO (2 vol%) show promising basic characteristics for application as water-equivalent EPR dosimeter materials in radiotherapy. The EPR signal loss is based on an indirect effect mediated by diffusing radicals originating from the radiolysis of the water/DMSO mixture.

Heterogeneous photochemical uptake of SO2 on typical brown carbon species: A significant sulfate source

The heterogeneous reactions of SO2 on organic aerosols (OA) have been proposed as a significant source of sulfates. The photochemical conversion of SO2 to sulfates on the surface of light-absorbing OA, i.e., brown carbon (BrC), remained slight understanding. Herein, the photochemical uptake of SO2 on typical BrC species, including aromatic carbonyl compounds (ACs), polycyclic aromatic hydrocarbons (PAHs) and phenols (PHs), was systematically investigated by a flow tube reactor. Light can significantly promote the uptake of SO2 on all BrC species used here, especially for ACs. The initial and steady-state uptake coefficients (γi and γss) of SO2 exhibited positive relationships with the light intensity, whereas they negatively correlated with the initial SO2 concentration. Significant sulfate formation was clearly observed with in situ attenuated total internal reflection infrared (ATR-IR) spectrometer, and H2O and O2 had obvious enhancement effects on the sulfate production. Photoinduced •OH, which primarily originated from •O2− that was generated through an electron transfer process on BrC under irradiation, was determined to be a key driver for the oxidation of SO2 to sulfates. Finally, SO2 lifetime and sulfate formation rate were evaluated on the basis of experimental results, highlighting potential contributions of BrC photochemistry to atmospheric SO2 loss and sulfate sources.

Remediation of pesticides, acetamiprid and imidacloprid from aqueous solutions using cellulose derived from sawdust of Populus nigra

Abstract In this study a low cost and easily available Black Poplar Sawdust (Populus nigra L.) was converted into an efficient adsorbent for the removal of acetamiprid (AMR) and imidacloprid (ICR) pesticides from aqueous solutions. The effect of adsorption effecting parameters including initial pesticides concentration, variations in the adsorbent amount, time of contact, and pH were investigated to understand the adsorption process of both pesticides. Further the kinetic, thermodynamic, and isotherm models were used to get an insight into the process of adsorption taking place. The results of the study suggested that the isotherm data align effectively with both the Langmuir and Temkin isotherm models (both pesticides). The maximum adsorption capacity (q m) for AMR was found to be 25.22 mg g−1, while for ICR, it was 25.65 mg g−1. Furthermore, the adsorption kinetics were best described by the pseudo-second-order model with value of R 2 = 0.9934 & 0.9964 respectively for AMR and ICR. The thermodynamic analysis confirmed the spontaneity and feasibility of the adsorption process, evident from the negative ∆G° values at different temperatures. The thermodynamics parameter values also suggested that the adsorption process is physisorption and exothermic due to the negative ∆H° value. From the results it was concluded that the devised adsorbent could be effectively used in reclamation pesticides contaminated water subjected to further verifications through testing against other pesticides.

The unreasonable effectiveness of the total quasi-steady state approximation, and its limitations

In this note, we discuss the range of parameters for which the total quasi-steady-state approximation of the Michaelis–Menten reaction mechanism holds validity. We challenge the prevalent notion that total quasi-steady-state approximation is “roughly valid” across all parameters, showing that its validity cannot be assumed, even roughly, across the entire parameter space — when the initial substrate concentration is high. On the positive side, we show that the linearized one-dimensional equation for total substrate is a valid approximation when the initial reduced substrate concentration s0/KM is small. Moreover, we obtain a precise picture of the long-term time course of both substrate and complex

Chitosan-vermiculite composite adsorbent: Preparation, characterization, and competitive adsorption of Cu(II) and Cd(II) ions

The cost-effective removal of heavy metal ions represents a significant challenge in environmental science. In this study, we developed a straightforward and efficient reusable adsorbent by amalgamating chitosan and vermiculite (forming the CSVT composite), and comprehensively investigated its selective adsorption mechanism. Different techniques, such as Fourier-transform infrared spectroscopy (FTIR), zeta potential analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer, Emmett, Teller (BET) analysis were employed for this purpose. The prepared CSVT composite exhibited a larger surface area and higher mesoporosity increasing from 1.9 to 17.24 m2/g compared to pristine chitosan. The adsorption capabilities of the CSVT composite and pristine chitosan for Cu(II) and Cd(II) species were systematically examined. Due to its porous structure and increased surface area, the CSVT composite demonstrated superior adsorption ability when compared to pristine chitosan. The maximum adsorption capacities of Cu(II) and Cd(II), determined by Langmuir adsorption isotherms in batch experiments, were found to be 116.22 and 147.64 mg/g, respectively, under initial pH conditions of 8 and an initial concentration of 250 mg/L. The thermodynamic analysis revealed that the adsorption process for both metal ions is spontaneous, endothermic physisorption, and thermodynamically favorable. These findings collectively affirm the CSVT composite as a highly promising adsorbent for the efficient and selective removal of Cu(II) and Cd(II) from aqueous solutions.

Thio-groups decorated covalent triazine polyamide (TTPA) for Hg2+ adsorption: Efficiency and mechanism

In this work, the thio-modified covalent triazine polyamides, TTPA-1 (1.5/1) and TTPA-2 (1/1), were successfully synthesized from the diester containing S and melamine, and applied to the adsorption of Hg2+ in the aqueous solution. We have systematically investigated the factors that can affect the adsorption process, such as the dosage of the adsorbent, the contact time, the temperature of the heavy metal solution, the initial concentration of the ions, the pH, the co-existing substances, and the desorption. The pseudo-second-order kinetic model can describe the adsorption of Hg2+ well, and the equilibrium adsorption time is 180 min, respectively. The most appropriate adsorption isotherm model is Langmuir, and the maximum Hg2+ adsorption capacities calculated at 25°C are 685 (TTPA-1) and 657 (TPPA-2) mg g−1. Repeatable experiments have shown that it can be reused more than 10 times without any loss. The adsorption mechanism of TTPA-1 (-2) was elucidated by combining experimental results, spectral characterization (SEM and XPS, etc.) and the density-functional-theory (DFT) calculations. These results indicate that TTPA-1 (-2) could have a good potential for the removal of the Hg2+ metal ions from wastewater.

Characterization and photodegradation of methylene blue dye using bio-synthesized cerium oxide nanoparticles with Spirulinaplatensis extract

Increasing concern about environmental pollution attracts researchers to develop eco-friendly, low-cost, and sustainable approaches for green biosynthesis of nanoparticles to overcome pollutants. This study focuses on the green synthesis of ceria NPs using Spirulinaplatensis extract as a stabilizing and reducing agent. Characterization measurements, such as optical properties, X-ray diffraction, SEM, TEM, and FT-IR spectroscopy, confirmed the successful synthesis of crystalline and stable ceria NPs with well-defined morphological features. The calculated bandgaps energy of pure ceria, green CeO2@Sp 2:1, and CeO2@Sp 1:1 were 3.3, 3.15, and 2.94 eV, respectively. The as-synthesized and green ceria NPs showed an excellent degradation efficacy of MB dye under UV irradiation. Furthermore, the green ceria NPs showed high photodegradation efficiency of MB dye (R% = 86.2 and 88.8%) than pure ceria (R% = 76.4%) at certain specific conditions (pH = 11, contact time = 90 min, catalyst dose = 0.3 g/L and MB dye initial concentration = 100 mg/L). The isothermal constants confirmed that the degradation of MB dye is well-fitted with the Freundlich isotherm model (R2 > 0.99) better than the Langmuir model (R2 < 0.8). The kinetics models revealed a rapid degradation rate of MB dye, which follows pseudo-second-order models with Ce values ranging from 83.33 to 89.29 mg/g, with R2 > 0.99. These results indicated the potential applicability and promising avenue for developing advanced ceria NPs for wastewater treatment applications.

Photochemical oxidation of VOCs and their source impact assessment on ozone under de-weather conditions in Western Taiwan

The application of statistical models has excellent potential to provide crucial information for mitigating the challenging issue of ozone (O3) pollution by capturing its associations with explanatory variables, including reactive precursors (VOCs and NOX) and meteorology. Considering the large contribution of O3 in degrading the air quality of western Taiwan, three-year (2019–2021) hourly concentration data of VOC, NOX and O3 from 4 monitoring stations of western Taiwan: Tucheng (TC), Zhongming (ZM), Taixi (TX) and Xiaogang (XG), was evaluated to identify the effect of anthropogenic emissions on O3 formation. Owing to the high-ambient reactivity of VOCs on the underestimation of sources, photochemical oxidation was assessed to calculate the consumed VOC (VOCcons) which was followed by the source identification of their initial concentrations. VOCcons was observed to be highest in the summer season (16.7 and 22.7 ppbC) at north (TC and ZM) and in the autumn season (17.8 and 11.4 ppbC) in southward-located stations (TX and XG, respectively). Results showed that VOCs from solvents (25–27%) were the major source at northward stations whereas VOCs-industrial emissions (30%) dominated in south. Furthermore, machine learning (ML): eXtreme Gradient Boost (XGBoost) model based de-weather analysis identified that meteorological factors favor to reduce ambient O3 levels at TC, ZM and XG stations (−67%, −47% and −21%, respectively) but they have a major role in accumulating the O3 (+38%) at the TX station which is primarily transported from the upwind region of south-central Taiwan. Crucial insights using ML outputs showed that the finding of the study can be utilized for region-specific data-driven control of emission from VOCs-sources and prioritized to limit the O3-pollution at the study location-ns as well as their accumulation in distant regions.

The temporal and spatial evolution of green finance and carbon emissions in the Pearl River Delta region: An analysis of impact pathways

The issue of carbon emissions has become increasingly urgent in tandem with the rapid growth of the economy in the Pearl River Delta region. This paper uses kernel density estimation and standard deviation ellipses based on Pearl River Delta data from 2012 to 2021 to explore the spatiotemporal evolution trends of green financing and carbon emissions. Additionally, it uses a spatial Durbin model to examine the spatial effects of green finance on carbon emissions. The results indicate the following: Firstly, over the years, green finance shows an overall increasing trend, with an internal spatial pattern characterized by higher levels in the northeast and lower levels in the southwest. In contrast, carbon emissions are decreasing, with an internal spatial pattern characterized by higher levels in the southwest and lower levels in the northeast. Secondly, more and more green financing initiatives are aiming towards the Pearl River Delta's northeast, suggesting a more significant concentration of such initiatives there than elsewhere. At the same time, carbon emissions seem to converge on the southwest of the Pearl River Delta, which could indicate that this area generally has greater carbon emission levels. Finally, the spatial effect results reveal that improving green finance levels can significantly inhibit carbon emission levels in the Pearl River Delta region. Evidence of spatial spillover effects indicates that the carbon emissions in neighboring areas are influenced to some extent. This study on green finance and carbon emissions' spatiotemporal characteristics and spatial impact gives a development path and theoretical support for sustainable development goals in the global economy.

Study of acid hydrolysis and submerged fermentation parameters in second generation ethanol production using cassava waste

Biofuels are an alternative to reduce the environmental impacts caused by the use of petroleum-based fuels. Second generation ethanol comes from lignocellulosic materials that are little used or discarded in the environment, including agro-industrial waste. These residues are rich in sugars that can be converted by ethanol-producing microorganisms. In this context, the present work uses cassava waste (Manihot esculenta Crantz) obtained during the processing of starch as a raw material for the production of cellulosic ethanol, as well as evaluating different parameters in acid hydrolysis and during submerged fermentation using the strain Saccharomyces cerevisiae ATCC 26602. Experiments of acid hydrolysis of these residues with sulfuric acid in concentrations of 0.5% to 5.0% (v/v) were carried out. The results demonstrated that 2.0% H2SO4 for 10 min. reaction at 121 ºC/1.1 atm in an autoclave reached the highest release of reducing sugars present in the residue (131.09 g.L-1). The ideal conditions for alcoholic fermentation using yeast were pH 6.5, temperature of 35 ºC, without rotation and initial reducing sugar concentration of 50 g.L-1, resulting in 21.23 g.L-1 of ethanol with productivity of 1.86 g.L-¹.h-¹ and theoretical yield of 96.5% after 12 hours of fermentation. The results indicated that the cassava waste serve as a potential substrate for the production of second generation ethanol. Thus, this study provides data on the most suitable conditions for the use of these industrial wastes aiming at the generation of a renewable fuel, an increasingly attractive feature for the world, where the economic and environmental concern is growing.

Isomorphic Insertion of Ce(III)/Ce(IV) Centers into Layered Double Hydroxide as a Heterogeneous Multifunctional Catalyst for Efficient Meerwein-Ponndorf-Verley Reduction.

The development of highly active acid-base catalysts for transfer hydrogenations of biomass derived carbonyl compounds is a pressing challenge. Solid frustrated Lewis pairs (FLP) catalysis is possibly a solution, but the development of this concept is still at a very early stage. Herein, stable, phase-pure, crystalline hydrotalcite-like compounds were synthesized by incorporating cerium cations into layered double hydroxide (MgAlCe-LDH). Besides the insertion of well-isolated cerium centers surrounded by hydroxyl groups, the formation of hydroxyl vacancies near the aluminum centers, which were formed by the insertion of cerium centers into the layered double hydroxides (LDH) lattice, was also identified. Depending on the initial cerium concentration, LDHs with different Ce(III)/Ce(IV) ratios were produced, which had Lewis acidic and basic characters, respectively. However, the acid-base character of these LDHs was related to the actual Ce(III)/Ce(IV) molar ratios, resulting in significant differences in their catalytic performance. The as-prepared structures enabled varying degrees of transfer hydrogenation (Meerwein-Ponndorf-Verley MPV reduction) of biomass-derived carbonyl compounds to the corresponding alcohols without the collapse of the original lamellar structure of the LDH. The catalytic markers through the test reactions were changed as a function of the amount of Ce(III) centers, indicating the active role of Ce(III)-OH units. However, the cooperative interplay between the active sites of Ce(III)-containing specimens and the hydroxyl vacancies was necessary to maximize catalytic efficiency, pointing out that Ce-containing LDH is a potentially commercial solid FLP catalysts. Furthermore, the crucial role of the surface hydroxyl groups in the MPV reactions and the negative impact of the interlamellar water molecules on the catalytic activity of MgAlCe-LDH were demonstrated. These solid FLP-like catalysts exhibited excellent catalytic performance (cyclohexanol yield of 45%; furfuryl alcohol yield of 51%), which is competitive to the benchmark Sn- and Zr-containing zeolite catalysts, under mild reaction conditions, especially at low temperature (T = 65 °C).

Removal of malachite green from wastewater using date seeds as natural adsorbent; isotherms, kinetics, Thermodynamic, and batch adsorption process design

This research explores the feasibility of using date seeds (DS), an agricultural waste, for the adsorption of malachite green (MG) dye from synthesized wastewater. The characterization of the DS before and after adsorption was accomplished by FTIR, SEM, BET, and EDX measurements. Batch adsorption experiments were investigated for MG dye adsorption from aqueous solution onto the DS. The effect of different parameters such as solution pH, adsorbent dose, contact time, temperature, and the initial dye concentration were studied. The optimum pH, adsorbent dose, temperature, and contact time for the dye removal were found to be 5, 0.1 g, 25 °C, and 30 min, respectively. The equilibrium studies for the data with Langmuir, Freundlich, and Temkin isotherms showed that Freundlich isotherm is the best model to describe the adsorption of MG onto the DS particles which has a heterogeneous surface. It was found that the adsorption process follows a pseudo-second-order kinetic model which revealed that the intra-particle diffusion stage is the rate-controlling stage for the process. The thermodynamic parameters ΔG, ΔS, and ΔH suggest the possibility of chemisorption and physisorption simultaneously and indicate the exothermic and spontaneous characters of the adsorption of MG dye on DS with negative values of ΔH and ΔG.

Synergistic potential in spinel ferrite MFe2O4 (M = Co, Ni) nanoparticles-mediated graphene oxide: Structural aspects, photocatalytic, and kinetic studies

The existence of artificial dyes in water is a significant environmental concern, as it can lead to poor water quality. Photodegradation is becoming an increasingly popular method for treating water contaminated with dyes. In this study, the photodegradation of Reactive Red 66 and Reactive Red 120 dyes, as well as textile wastewater, was investigated under UV and visible light irradiation. To enhance the photoresponse of the MFe2O4 (M = Co, Ni) nanoparticles, modifications were made by incorporating graphene oxide. The MFe2O4 nanoparticles and MFe2O4/GO nanocomposite photocatalysts were subjected to several characterization techniques, including FT-IR, Raman spectroscopy, XRD, DRS, zeta potential, VSM, TGA, DSC, BET, SEM, and EDAX analysis. Experiments were conducted to optimize several key parameters involved in the photodegradation process, including pH, photocatalyst dosage, initial dye concentration, and irradiation time. The removal efficiency of Reactive Red 66 and Reactive Red 120 dyes using CoFe2O4 nanoparticles was found to be 86.97 and 82.63%, respectively. Also, the removal percentage of these dyes using CoFe2O4/GO nanocomposite photocatalyst was 95.57 and 90.9% for Reactive Red 66 and Reactive Red 120, respectively. Experiments found that NiFe2O4 nanoparticles removed 90.92% of Reactive Red 66 dye and 84.7% of Reactive Red 120 dye. The NiFe2O4/GO nanocomposite photocatalyst showed even higher removal efficiencies, degrading 97.96% of Reactive Red 66 and 93.44% of Reactive Red 120. After three days of exposure to visible light irradiation, the removal percentage of Reactive Red 66 using MFe2O4 and MFe2O4/GO nanocomposite was investigated.

Enhanced chromium and nitrogen removal by constructing a biofilm reaction system based on denitrifying bacteria preferential colonization theory

Understanding the developmental characteristics of microbial communities in biofilms is crucial for designing targeted functional microbial enhancements for the remediation of complex contamination scenarios. The strong prioritization effect of microorganisms confers the ability to colonize strains that arrive first dominantly. In this study, the auto-aggregating denitrifying bacterial Pseudomonas stutzeri strain YC-34, which has both nitrogen and chromium removal characteristics, was used as a biological material to form a stable biofilm system based on the principle of dominant colonization and biofortification. The effect of the biofilm system on nitrogen and chromium removal was characterized by measuring the changes in the quality of influent and effluent water. The pattern of biofilm changes was analyzed by measuring biofilm content and thickness and characterizing extracellular polymer substances (EPS). Further analysis of the biofilm microbiota characteristics and potential functions revealed the mechanism of strain YC-34 biofortified biofilm. The results revealed that the biofilm system formed could achieve 90.56% nitrate-nitrogen removal with an average initial nitrate-nitrogen concentration of 51.9 mg/L and 40% chromium removal with an average initial hexavalent chromium Cr(VI) concentration of 7.12 mg/L. The biofilm properties of the system were comparatively analyzed during the biofilm formation period, the fluctuation period of Cr(VI)-stressed water quality, and the stabilization period of Cr(VI)-stressed water quality. The biofilm system may be able to increase the structure of hydrogen bonds, the type of protein secondary structure, and the abundance of amino acid-like components in the EPS, which may confer biofilm tolerance to Cr(VI) stress and allow the system to maintain a stable biofilm structure. Furthermore, microbial characterization indicated an increase in microbial diversity in the face of chromium stress, with an increase in the abundance of nitrogen removal-associated functional microbiota and an increasing trend in the abundance of nitrogen transfer pathways. These results demonstrate that the biofilm system is stable in nitrogen and chromium removal. This bioaugmentation method may provide a new way for the remediation of heavy metal-polluted water bodies and also provides theoretical and application parameters for the popularization and application of biofilm systems.

A Box-Behnken design-based chemometric approach to optimize the sono-photodegradation of hydroxychloroquine in water media using the Fe(0)/S2O82-/UV system.

The huge utilization of hydroxychloroquine in autoimmune infections led to an abnormal increment in its concentration in wastewater, which can pose a real risk to the environment, necessitating the development of a pretreatment technique. To do this, we are interested in researching how hydroxychloroquine degrades in contaminated water. The main goal of this investigation is to optimize the operating conditions for the sono-photodegradation of hydroxychloroquine in water using an ultrasound-assisted Fe(0)/ /UV system. To get adequate removal of HCQ, a chemometric method based on the Box-Behnken design was applied to optimize the influence of the empirical parameters selected, including Fe(0) dose, concentration, pH, and initial HCQ concentration. The quadratic regression model representing the HCQ removal rate (η(%)) was evolved and validated by ANOVA. The optimal conditions as a result of the above-mentioned trade-off between the four input variables, with η(%) as the dependent output variable, were captured using RSM methodology and the composite desirability function approach. For HCQ full decomposition, the optimal values of the operating factors are as follows: dose, 194.309 mg/L; Fe(0) quantity, 198.83 mg/L; pH = 2.017, and HCQ initial dose of 296.406 mg/L. Under these conditions, the HCQ removal rate, achieved after 60 min of reaction, attained 98.95%.

Physicochemical stability of pevonedistat at 50, 100 and 200 µg/mL diluted in 0.9% sodium chloride and at 10 mg/mL in partially used vials

ObjectivesPevonedistat is a new cytotoxic used in association with azacitidine for the treatment of acute myeloid leukaemia and high-risk myelodysplastic syndromes. The manufacturer indicates an 18-hour stability after dilution in...