Na2SO4 Concentration Research Articles

Different in cytoskeleton reorganization in tobacco root cells in the original samsun variety and a transgenic line with FeSOD1 overexpression under salinity

The aim of the study was to study the state and reaction of cytoskeletal elements - microtubules and actin laments, in root cells of Samsun tobacco plants and its transgenic line expressing the FeSOD1 gene from Arabidopsis thaliana with the pea rbcS leader sequence for the localization of the gene product in chloroplasts encoding Fe-dependent superoxide dismutase, constitutively inducing intracellular oxidative stress, by increasing the H2O2 pool for a long-term e ect of moderate concentrations of NaCl and Na2SO4. The main hypothesis was to identify the positive protective e ect of controlled constant oxidative stress on the stability of the most sensitive system that provides growth by division and growth by extension - the tubulin cytoskeleton and e ective intracellular transport and structural stability - the actin lament system. Localization of the microtubule cytoskeleton and actin laments using antibodies to tubulin clone DM1α and actin clone 10-B3 by transmission electron microscopy and immunocytologically, detected by treatment with the second antibodies conjugated with Alexa-488, made it possible to establish signs of reorganization and disassembly of the actin lament network under the action of NaCl and Na2SO4 as in control and in transgenic plants. At the same time, in transgenic plants, di erences can be noted even without exposure, which indicates the e ectiveness of this method for stimulating a protective response. These data suggest that the state of the system of the tubulin cytoskeleton and actin laments may be an indicator of the resistance of FeSOD1 transgenic plants to salinity. A relationship has also been established between the reorganization of the cytoskeleton and vacuolization, especially with Na2SO4.

Remediation of 2,4-dichlorophenol-contaminated soil by electrokinetic delivery of persulfate technology.

2,4-Dichlorophenol (2,4-DCP) is difficult to degrade rapidly in the environment due to its stable chemical properties, so it was easy to lead to serious chlorophenol pollution in soil. Consequently, a remediation method which is efficient, safe, and economical is required. In this study, electrokinetic (EK) remediation was used to transfer sodium persulfate (Na2S2O8) into soil to degrade 2,4-DCP, and the effect of several factors (including the addition location of Na2S2O8, applied voltage, and running time) on the remediation efficiency was explored. The concentration of Na2S2O8, residual efficiency of 2,4-DCP and distribution characteristics of pH, and electrical conductivity were analyzed. The results showed that the cathode was the optimal position to add Na2S2O8. Under this condition, Na2S2O8 was uniformly distributed in the whole soil column through electromigration. The optimal removal efficiency of 2,4-DCP in soil by adding Na2S2O8 was approximately 26% when the voltage gradient was 1.0V/cm and the operating time was 9days, which was mainly due to the degradation of S2O82-.

Finite Modeling and Simulation of the Effects of Neutral Electrolytic Pickling Process Parameters on EN 1.4404 Steel Strips

Surface treatment via neutral electrolytic pickling (NEP) aims to remove oxide layers and scaling from stainless steel. The objective of this study was to investigate the factors that affect the energy efficiency of the process. This study developed a COMSOL Multiphysics model for the distribution of current across a bipolar steel strip by controlling the following parameters: Na2SO4 concentration, temperature, electrode-to-strip distance, and inter-electrode distance. Full factorial measurements of the electrolyte’s conductivity as well as the steel strip’s and the electrode’s polarization were conducted to provide data for the NEP model. Galvanostatic pulse measurements were performed to calculate transient times during pickling. According to the model, an applied voltage of less than 11 V was insufficient to polarize the steel strip to the potentials needed on both the anodic and cathodic sides. A higher voltage of 11–15 V resulted in anodic current densities of 600–1600 A m−2 and cathodic current densities of 700–2000 A m−2 on the steel strip. These current densities are within the range of previous experimental studies and industrial practices. The model showed that when a steel strip acts as a bipolar electrode, the current’s efficiency decreases, as only a fraction of the strip facing the anodes or cathodes is polarized sufficiently. The galvanostatic tests showed that anodic polarization of the steel strip is easier than cathodic polarization. The slow polarization in the cathodic direction can be improved by using a higher current density. The time needed to polarize stainless steel indicates that the strip’s velocity should be less than 1 m s−1 to give enough time for polarizing the steel strip.

Nucleation and growth study of SnS nanostructures prepared by electrodeposition method

SnS nanostructures were prepared using the electrodeposition technique in aqueous solutions containing 0.1M of SnSO4 and Na2SO4. Three concentrations (0.05M, 0.10M, and 0.15M) of Na2SO4 were tested. The electrodeposition of SnS nanostructures on ITO substrates was investigated by cyclic voltammetry, chronoamperometry, SEM microscopy, and X-ray diffraction techniques. The concentration-dependent nucleation and growth mechanisms of electrodeposited SnS were analyzed using current transients. For the concentrations (0.05M and 0.10 M), the SnS films follow 3D growth in instantaneous nucleation mode. For a concentration of 0.15M, the SnS films start with progressive nucleation before switching to the instantaneous nucleation mode. The SnS nanostructures produced were found to be polycrystalline with an orthorhombic structure. XRD measurement shows that the preferred orientation of SnS nanostructures is in the (111) and (101) directions for the lower concentrations. SEM images reveal the 3D growth model of the samples, which is consistent with the electrochemical analysis.

Y-mediated optimization of 3DG-PbO2 anode for electrochemical degradation of PFOS

In our previous study, the three-dimensional graphene-modified PbO2 (3DG-PbO2) anode was prepared for the effective degradation of perfluorooctanesulfonat (PFOS) by the electrochemical oxidation process. However, the mineralization efficiency of PFOS at the 3DG-PbO2 anode still needs to be further improved due to the recalcitrance of PFOS. Thus, in this study, the yttrium (Y) was doped into the 3DG-PbO2 film to further improve the electrochemical activity of the PbO2 anode. To optimize the doping amount of Y, three Y and 3DG codoped PbO2 anodes were fabricated with different Y3+ concentrations of 5, 15, and 30 mM in the electroplating solution, which were named Y/3DG-PbO2-5, Y/3DG-PbO2-15 and Y/3DG-PbO2-30, respectively. The results of morphological, structural, and electrochemical characterization revealed that doping Y into the 3DG-PbO2 anode further refined the β-PbO2 crystals, increased the oxygen evolution overpotential and active sites, and reduced the electron transfer resistance, resulting in a superior electrocatalytic activity. Among all the prepared anodes, the Y/3DG-PbO2-15 anode exhibited the best activity for electrochemical oxidation of PFOS. After 120 min of electrolysis, the TOC removal efficiency was 80.89% with Y/3DG-PbO2-15 anode, greatly higher than 69.13% with 3DG-PbO2 anode. In addition, the effect of operating parameters on PFOS removal was analyzed by response surface, and the obtained optimum values of current density, initial PFOS concentration, pH, and Na2SO4 concentration were 50 mA/cm2, 12.21 mg/L, 5.39, and 0.01 M, respectively. Under the optimal conditions, the PFOS removal efficiency reached up to 97.16% after 40 min of electrolysis. The results of the present study confirmed that the Y/3DG-PbO2 was a promising anode for electrocatalytic oxidation of persistent organic pollutants.

Corrosion Behavior of 20G Steel in Saline (Na2SO4) Circumstances at High Temperature/Pressure

Abstract To study the corrosion characteristic of 20G steel in saline circumstances with sodium sulfate (Na2SO4), a series of corrosion experiments are implemented on a novel setup. The corroded steel samples are analyzed by X-ray photoelectron spectroscopy and X-ray diffraction. The results indicate that the effect of salinity on corrosion products in the gas phase is greater than that in the liquid phase. FeOOH is easier to form in the liquid phase than in the gas phase. The salinity of steam could promote the generation of Fe2O3. The relative content of Fe2O3 within the corrosion products that contained Fe in the gas/liquid phase increases from 49.68%/36.30% (Na2SO4 concentration in solution, c = 0) to 95.70%/74.55%, separately (c = 4 g L−1). The salinity has an inhibiting effect on the generation of FeOOH. In deionized water, the relative contents of FeOOH within the corrosion products that contained Fe are 36.01% (gas phase) and 56.43% (liquid phase), respectively. FeOOH hardly occurs as c = 4 g L−1. For corroded surfaces in Na2SO4 deposit, the main compositions detected are iron oxides (Fe2O3 and Fe3O4) and iron (Fe).

Collaborative Effect of In-Plasma Catalysis with Sequential Na2SO3 Wet Scrubbing on Co-Elimination of NOx and VOCs from Simulated Sinter Flue Gas

Sinter flue gas produced by the iron-ore sinter process in steel plants is characterized by a large gas volume and complex components. Among the major air pollutants, preliminary emissions of volatile organic compounds (VOCs) and nitrogen oxides (NOx) exhibit an inevitable contribution to secondary aerosol and ozone formation. Herein, oxidation–absorption collaborative technology for in-plasma catalysis with sequential Na2SO3 wet scrubbing, aiming at co-elimination of NOx and VOCs from sinter flue gas, is proposed. Experimental parameters, including plasma discharge status, NO initial concentration, gas feed flux, Na2SO3 concentration, pH value, and absorption ions, were systematically investigated. The VOC and NOx removal performance of the integrated system was further investigated by taking simulated sinter flue gas as model pollutants. The results showed that the collaborative system has satisfactory performance for TVOC and NO removal rates for the effective oxidation of in-plasma catalysis and Na2SO3 absorption. The integration of plasma catalysis with Na2SO3 scrubbing could be an alternative technology for the co-elimination of sinter flue gas multi-compounds.

Investigation into the electrochemical advanced oxidation of p-arsanilic acid: Peculiar role of electrolytes and unexpected formation of coupling byproducts

Although banned in some countries, p-arsanilic acid (ASA) is still widely used as feed additive in poultry production. As a result, ASA is usually released into the aquatic environment without any treatments. Although ASA exhibits low toxicity, it can be transformed into highly toxic aromatic amines and inorganic arsenic species (As (V) as H2AsO4− and HAsO42−) under natural environmental conditions. Hence, it is necessary to develop efficient technologies for its removal or degradation. In this contribution, electrochemical advanced oxidation technology with boron-doped diamond (BDD) had been initially used to degrade ASA pollutants. A five-level central composite rotatable design (CCRD) was implemented to optimize the various influencing factors involved, among applied current density, NaCl concentration, Na2SO4 concentration and NaHCO3 concentration on the oxidation efficiency; the latter was assessed in terms of ASA degradation percentage. The results obtained highlighted the unique and important roles of electrolytes during the electrolytic oxidations. Meanwhile, the major degradation byproducts detected were also strongly dependent on the electrolyte adopted. In particular, several oligomer byproducts with novel structures were initially identified in BDD-treated ASA solutions. Two different electrochemical transformation pathways of ASA on BDD anode were thus proposed. This study demonstrated the effectiveness of BDD technology in the degradation of ASA, as well as the potential minor risk of its application in actual ASA wastewater treatment.

Effect of chemical species and temperature on the stability of air nanobubbles

The colloidal stability of air nanobubbles (NBs) was studied at different temperatures (0–30 °C) and in the presence of sulfates, typically found in mining effluents, in a wide range of Na2SO4 concentrations (0.001 to 1 M), along with the effect of surfactants (sodium dodecyl sulfate), chloride salts (NaCl), and acid/base reagents at a pH range from 4 to 9. Using a nanobubble generator based on hydrodynamic cavitation, 1.2 × 108 bubbles/mL with a typical radius of 84.66 ± 7.88 nm were generated in deionized water. Multiple evidence is provided to prove their presence in suspension, including the Tyndall effect, dynamic light scattering, and nanoparticle size analysis. Zeta potential measurements revealed that NBs are negatively charged even after two months (from − 19.48 ± 1.89 to − 10.13 ± 1.71 mV), suggesting that their stability is due to the negative charge on their surface. NBs were found to be more stable in alkaline solutions compared to acidic ones. Further, low amounts of both chloride and sulfate dissolved salts led to a reduction of the size of NBs. However, when high amounts of dissolved salts are present, NBs are more likely to coalesce, and their size to be increased. Finally, the investigation of the stability of air NBs at low temperatures revealed a non-monotonic relationship between temperature and NBs upon considering water self-ionization and ion mobility. This research aims to open a new frontier towards the application of the highly innovative NBs technology on the treatment of mining, mineral, and metal processing effluents, which are challenging aqueous solutions containing chloride and sulfate species.

Efficient degradation of 2,4-dichlorophenol by heterogeneous electro-Fenton using bulk carbon aerogels modified in situ with FeCo-LDH as cathodes: Operational parameters and mechanism exploration

In this study, an in situ grown FeCo-Layered double hydroxide anchored to the surface of a bulk carbon aerogel (FeCo-LDH/CA) for contaminant degradation during the heterogeneous electro-Fenton (EF) process. The results exhibited that the FeCo-LDH/CA cathode achieved 100% of 2,4-dichlorophenol (2,4-DCP = 20 mg/L) degradation within 120 min at pH = 3, application current 20 mA, and Na2SO4 concentration 0.05 M. Moreover, the degradation efficiency was impressive in the range of pH = 2–9. The coexistence of the Fe (III)/Fe (II) and Co (III)/Co (II) as active sites on the cathode surface promoted the in-situ decomposition of H2O2 to form reactive oxygen species (ROS). •OH and O2- were confirmed to be the major degradation pollutants of ROS. Furthermore, density functional theory (DFT) was used to predict the reaction sites of 2,4-DCP, and its possible degradation pathways were proposed. The toxicity of intermediate products was evaluated and decreased after degradation. In addition, the eight cycle experiments and the degradation of other typical contaminants demonstrated the satisfactory stability and applicability of the synthetic cathode. This study presents the preparation of an efficient and stable EF cathode, further promoting the application of iron-based composites in wastewater treatment.

Highly efficient and reusable magnetic anion-exchange microbeads for reactive dye removal

A novel magnetic anion exchange microbead (NAEM) with excellent reuse and anti-fouling performance was developed, and used for removal of an reactive dye sunset yellow (FCF). The NAEM initial adsorption rate was 16.7-, 25.8-, 31.6-, and 31.6-fold that of commercial IRA-958, D201, A520, and IRA-900 resins, respectively. The adsorption of FCF on different anion-exchange resins appeared to be multilayered, implying physical adsorption also contributes to FCF removal. The polyacrylic resin matrix exhibited higher affinity than the polystyrene matrix towards FCF. The equilibrium adsorption capacity for FCF at 298 K was in the following order: NAEM (1.95 mmol/g) > IRA-958 (1.01 mmol/g) > D201 (0.85 mmol/g) > A520 (0.81 mmol/g) > MAER (0.78 mmol/g) > IRA-900 (0.59 mmol/g). NAEM reinforced the anti-interference capacity of FCF adsorption when the concentrations of NaCl or Na2SO4 were lower than 20 mmol/L. After 10 cycles of regeneration, the FCF adsorption capacity of NAEM was 1.76-, 2.79-, 2.81-, 3.05-, and 5.26-fold higher than MAER, IRA-958, D201, A520, and IRA-900, respectively. The high adsorption capacity and excellent reusability may facilitate the practical applications of NAEM in wastewater treatment against reactive dyes.

Q-Carbon as a Corrosion-Resistant Coating.

A newly discovered quenched form of carbon, widely known as Q-carbon, thin films are synthesized by the direct conversion of the amorphous carbon layer using the nanosecond pulsed laser annealing technique, and its corrosion-resistant properties, that is, potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy technique, are investigated. The unique microstructure and the existence of defects (sp2 content) in sp3-rich Q-carbon are highly desirable for efficient corrosion-resistant performance. The sp3 percentage of the as-grown Q-carbon is measured to be ∼80.5% from the D and G peaks of the Raman and C-1S X-ray photoelectron spectrum. The anti-corrosion properties with inhibition durability of Q-carbon thin films are systematically investigated in various concentrations of Na2SO4 solutions, and the corrosion potential, corrosion current, and corrosion rate of Q-carbon are determined to be -253 V, 30.1 × 10-5 A/cm2, and 0.00528, respectively, for 1 M Na2SO4 solution. Both series and contact resistance decrease from 5498.6 and 821.1 Ω to 698.8 and 124.3 Ω with an increase of Na2SO4 concentration from 0.1 to 1 M, respectively. The small shift of PDP curves toward more negative potential, the shrinkage of the radius of semicircular arcs in the Nyquist plot (Z″ vs Z'), and negligible loss in corrosion resistance (∼78%) are observed for Q-carbon thin film at the immersion time up to 48 h. The unique sp2-sp3 ratio, shorter bond length, compact atomic arrangement, and minimum porosity, along with the high adhesion strength, due to the ultrafast solid-liquid-solid growth route, of Q-carbon thin film on the substrate signify it as a better alternative compared to the existing corrosion-resistant materials.

Removal Of Sumifix Yellow EXF Reactive Azo Dye By Electro-Fenton Method

Reactive dyes can be found in large quantities in textile industry wastewater due to their widespread use for dyeing cotton fabrics and their durable nature. In the treatment of wastewater containing dyestuffs in this class, advanced treatment methods have become necessary due to the inadequacy of conventional treatment methods and their disadvantages. For this reason, electro-Fenton, an electrochemical advanced oxidation method, is a strong alternative as a treatment technology that provides complete disintegration of dye molecules. In this study, the electro-Fenton method was used to treat model wastewater containing the reactive azo dye Sumifix Yellow EXF. The electro-Fenton process is based on the in situ generation of hydroxyl radicals (⦁OH), a strong oxidant, using Fe2+ and H2O2 released at the electrodes or added from outside. In the electrochemical cell used, carbon fiber was used as the cathode and iron was used as the anode. While Fe2+ ion was produced at the anode, H2O2 was added to the cell externally. In the experiments carried out at room temperature, a 250 mL glass beaker was used as a reactor. In the study, the optimization of the parameters was achieved by using the classical experimental design method. According to this method, one parameter is changed and other parameters are kept constant. In order to achieve the highest dyestuff removal, experiments were conducted by varying the voltage (5–10 V), H2O2 concentration (9–74 mM), Na2SO4 concentration (6–25 mM), and pH (3-5), and the impact of these factors on dye removal and energy consumption was evaluated. It was found that for the best dye removal, voltage is 7.5 V, the H2O2 concentration is 74 mM, the Na2SO4 concentration is 25 mM and the optimum pH value is 4. At these values, 98.14% removal at 30 minutes was achieved with an energy consumption of 7.98 Wh/L. The electro-Fenton method was found to be a highly effective approach for wastewater treatment and environmental remediation, showing remarkable dye removal efficiency with reasonable energy consumption under optimized conditions.

Removal of diazinon from aqueous solutions using alternating current in a three-dimensional electrochemical system containing MC/Fe3O4 nanocomposites

This study aims to determine diazinon removal using a three-dimensional electrochemical system supplied with alternating current (AC), which uses Fe3O4 magnetite nanoparticles immobilized on microbial cellulose (MC). The nanocomposites are used as catalysts to activate persulfate and produce sulfate radicals for diazinon removal. The surface properties and morphology of MC/Fe3O4 nanocomposites were determined by Fourier Transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscopes (FE-SEM), Thermo-Gravimetric Analysis (TGA), and X-Ray Diffraction (XRD) techniques. The studied variables were initial pH (3–9), diazinon concentration (10–40 mg/l), persulfate concentration (0.5–0.8 mmol/l), Na2SO4 concentration (0.1–0.7), MC/Fe3O4 nanocomposite concentration (01–0.3 g/l), voltage (1–7 V), and time (0−60). The obtained results indicated that the 3D electrochemical system could lead to complete removal in the presence of the MC/Fe3O4 catalyst in optimal conditions (10 mg/l initial diazinon concentration, 0.5 g/l Na2SO4, pH of 3 ± 0.5, 0.7 mmol/l PS, 0.25 g/l MC/Fe3O4, and 5 V AC) during 60 min. The energy consumption in this system was calculated 0.35 KW h/m3. The role of each process involved in diazinon removal and the reaction kinetics were also provided in this study.

Precipitation of Rare Earth Element from Indonesian Coal Fly Ash Using Sodium Sulfate

The rare earth element is a critical element in many industrial sectors. Due to unbalanced supply and demand, it is necessary to look for an alternative source. Coal ash is a waste product of power plant combustion. Previous research revealed that coal ash contained levels of rare earth elements. This research uses coal fly ash from the Paiton power plant. The objectives of this study were to determine the effect of the Na2SO4 concentration, stirring rate, and temperature on the recovery of REE concentrate. The experiment was conducted in four steps: (1) alkaline leaching, the process was carried out for 2 hours at 90°C with fly ash solid to 8 M NaOH solution ratio of 1:4 to break the aluminosilicate bonds. (2) Acid leaching of residue for 4 hours at 90°C in 3 M HCl. (3) Precipitation of residue to remove the impurities such as Fe using 1 M NaOH at pH 5. (4) Precipitation of filtrate from process (3) using Na2SO4 to produce REE concentrate precipitates. The best condition to obtain the highest REE residue is conducting recovery at the concentration of 20% Na2SO4, stirring rate of 500 rpm, and temperature of 50°C, with a yield of 88.72%.

Production of eco-friendly UHPC with high durability and resistance to harsh environmental conditions using copper mine tailings

In recent years, constructing environmentally friendly buildings, also known as green buildings, has become a crucial aspect of sustainable development principles. This experimental study investigates the partial replacement of Portland cement with Sungun copper mine tailings (SCMT) for the production of eco-friendly UHPC. The research includes resistance testing against sulfate attack at a 5% Na2SO4 concentration at 30, 90, and 180 days, with SCMT replacement ratios ranging from 5% to 30%. Furthermore, the mechanical properties of eco-friendly UHPC are examined. The study also assesses the mass loss and compressive resistance of UHPC after exposure to an HCl acid solution for 30 and 90 days. The resistance of UHPC to chloride penetration is evaluated using the rapid chloride migration test (RCMT). Additionally, capillary water absorption and microstructural properties of eco-friendly UHPC are studied through SEM analysis. The results indicate that UHPC with partial cement replacement by SCMT had improved mechanical properties, durability, and microstructure. The compressive strength reduction in eco-friendly UHPC mixtures due to acid attack was minimal when 10% SCMT was used as a replacement for cement after being immersed in HCl acid for 90 days. Furthermore, the mixture that contained 10% SCMT demonstrated lower penetration for chloride ions, Which referred to an improvement of 17.6%, compared to the control mixture. In addition, the results of the tests demonstrated that the incorporation of SCMT in UHPC at a rate of 5%–15% had a beneficial impact on the resistance of UHPC to sulfate attack when exposed to a 5% Na2SO4 concentration. This study demonstrates the potential of sustainable UHPC production with SCMT as a suitable alternative to cement in aggressive environments containing acids, sulfates, chlorides, and similar compounds.

Rapid photocatalytic gold recovery from industrial cyanide-based gold plating wastewater via TiO2/WO3 nanocomposites: Role of mixed hole scavengers and operating conditions

A rapid photocatalytic gold recovery from the industrial cyanide-based gold plating wastewater was carried out via TiO2/WO3 nanocomposites synthesized by hydrothermal method. Effects of different weight ratios of TiO2 and WO3 in nanocomposites, types of hole scavenger (Na2S2O3, C2H5OH, Na2S2O3/C2H5OH), concentrations of Na2S2O3 (0–100 mM) and photocatalyst loading (1–4 g/L) were examined. The preliminary results demonstrated that the employed wet chemical process induced a well formation of TiO2/WO3 nanocomposites with better textural properties as well as a more negative band position than the pristine WO3. The presence of mixed hole scavengers of Na2S2O3 and C2H5OH played a crucial role on the photocatalytic gold recovery from the cyanide-based gold plating wastewater. A more stable form of gold cyanide ([Au(CN)2]-) was altered to a less stable form ([Au(S2O3)2]3-) by the addition of Na2S2O3. At the end, approximately 85.9 % and 98.2 % of gold were respectively recovered within 180 and 300 min via the T6/WO3 nanocomposite in the presence of 10 mM Na2S2O3 and 20 vol% C2H5OH at photocatalyst loading of 2 g/L and light intensity of 3.20 mW/cm2. The photocatalytic gold recovery was significantly improved via the 1st reused T6/WO3 nanocomposite, in which 99.9 % of gold was recovered within 180 min. The obtained results can pave the way for the design of novel TiO2/WO3 nanocomposites for gold recovery as well as the strategy of waste management for the practical operation.

Insights into the response of Anammox sludge to the individual and combined stress of neodymium and salinity and the role of hydroxylamine regulation

Neodymium (Nd(III)) and sulfate (Na2SO4) are commonly present in neodymium mining wastewater. However, the effects of their coexistence on microorganisms responsible for removing nitrogen from wastewater have been poorly reported. In this study, the combined inhibition of Nd(III) and Na2SO4 on anaerobic ammonium oxidation (Anammox) and its recovery were investigated in terms of performance, kinetics, Nd(III) distribution characteristics and sludge morphology. The results shown that ≥ 150 mg·L−1 Nd(III) or ≥ 3 g·L−1 Na2SO4 decreased specific Anammox activity (SAA), and intracellular Nd(III) was identified as the primary factor for individual Nd(III) inhibition. Furthermore, the combined inhibition of Nd(III) and Na2SO4 on Anammox was stronger than individual inhibition, but low doses of hydroxylamine (NH2OH) could restore the Anammox. Notably, the combined effect of low doses of Na2SO4 (1 g·L−1) and Nd III (10 mg·L−1) on the long-term performance of Anammox reactor was not significant. However, when the dose of Nd(III) was kept constant and the dose of Na2SO4 was increased to 7 g·L−1, the total nitrogen removal efficiency (TNRE) decreased by 56.88%. Following the elimination of inhibitors and the addition of 5 mg·L−1 NH2OH, the TNRE of the Anammox reactor was increased from 20.83% to 29.78%. The Hill, modified Michaelis-Menten, and modified Boltzmann models were able to properly describe the inhibition effects of Nd(III) and Na2SO4 and recovery process of Anammox. In addition, scanning electron microscopy (SEM) and energy-dispersive X-ray (EDS) analysis revealed that the content of extracellular polymeric substances (EPS) and neodymium increased with increasing Na2SO4 concentration.

The oxidation efficiency and the microbial community analysis of a novel bio-electro-Fenton system with Fe@Co/GF composite cathode

A dual-chamber motional bio-electro-Fenton (BEF) system with Fe@Co/GF as the cathode was constructed to simultaneously degrade levofloxacin and tetracycline wastewater in both cathode and anode chambers. With an external resistance of 10 Ω, an initial cathode pH of 3, a Na2SO4 concentration of 0.5 mol/L, an initial Fe2+ concentration of 0.01 mmol/L, an aeration rate of 3*4.5 L/min, an initial levofloxacin concentration of 20 mg/L in the cathode chamber, and an initial tetracycline concentration of 20 mg/L in the anode chamber, the total levofloxacin removal rate was 91.09 % and the total mineralisation rate was 90.47 % within 24 h when Fe@Co/GF was used as the BEF system's cathode. And the total removal rates of tetracycline, COD and TOC in the anode chamber were 64.54 %, 85.45 % and 75.12 % respectively within 72 h. The BEF system's maximum power density, current density, and voltage were 12.64 W/m3, 636.94 mA/m3, and 920 mV, respectively. Furthermore, high-throughput sequencing techniques were used to examine the microbial flora that was valuable in the BEF system. This study's BEF system was capable of long-term stability and has enormous potential for treating antibiotic effluent.

Construction of MXene/Ti membrane electrode with Ti3C2TX via electrophoretic deposition for high-efficient electrochemical degradation of antibiotic wastewater

The introduction of antibiotics into the environment leads to serious environmental problems and public health concerns. Along these lines, in this work, a facile strategy to fabricate the MXene/Ti membrane was developed by loading 2D ultrathin Ti3C2Tx nanosheets on the porous Ti membrane through electrophoretic deposition, which was used as anode material for the degradation of the tetracycline hydrochloride (TCH) wastewater in the electrocatalytic membrane reactor (ECMR). From the acquired degradation results, it was demonstrated that the removal efficiency of TCH and total organic carbon (TOC) was nearly 100 % and 90.4 % with the obtained MXene/Ti anode in the ECMR, respectively, under a temperature value of 20 °C, a current density of 0.8 mA cm−2, a residence time of 10 min, an electrolyte Na2SO4 concentration of 15 g L−1, a TCH concentration of 50 mg L−1, and a pH of 7.0 reaction conditions. These values were much higher than that of pristine Ti membrane anode and other reported electrochemical treatment processes, such as electrocatalysis, photo-electrocatalysis process etc. The excellent stability of the MXene/Ti anode was also demonstrated by performing 15 cycles test. The superior removal efficiency of TCH and the mineralization ability of antibiotics could be ascribed to the formation of 2D nanocomposites of Ti3C2Tx and TiO2. Our work paves the way for the utilization of MXene/Ti membrane electrodes and ECMR for the efficient removal of antibiotics from wastewater.