Oxidation-reduction Potential Research Articles

P-033 Impact of the sperm reactive oxygen species on Intrauterine Insemination outcome

Abstract Study question Does sperm reactive oxygen species values affect the pregnancy rate after Intrauterine Insemination (IUI)? Summary answer Sperm reactive oxygen species values affect pregnancy rate and can be used as a predictive marker for IUI outcome. What is known already Oxidative stress resulting from excessive production of reactive oxygen species (ROS) can profoundly affect the sperm and subsequent functional sperm integrity. Diagnostics to measure semen oxidative stress have been added to the 6th edition of the WHO laboratory manual for examining and processing of human semen, under advanced examinations. Although a semen analysis has classically been used as the gold standard for determining a man’s fertility, basic sperm analysis alone cannot accurately predict infertility since between 6 and 27 % of men with normal semen parameters are infertile. Determination of oxidative stress in diagnosing infertility may contribute to better outcomes. Study design, size, duration This study was based on semen analyses of 50 male patients whose samples were used for IUI treatment between November 2022 and January 2023. The oxidation-reduction potential was measured using novel galvanostat-based technology, the MiOXSYS System. Briefly, 30 μL of liquefied semen at room temperature were applied to the MiOXSYS sensor. Both absolute ORP (mV) and normalized sORP values ( mV/10 6 sperm/ml) based on sperm concentration were calculated. Participants/materials, setting, methods Sperm analysis were performed according to the WHO laboratory manual sperm criteria (Sixth edition 2021). All participants followed a period of 3–5 days of sexual abstinence and had a diagnosis of unexplained infertility (normozoospermia). Ovarian stimulation for IUI cycle was initiated on the 5th day of menstruation by using recombinant gonadotropins. Clinical pregnancy was determined based on the Beta-hCG values. For statistical comparison between group values the Mann-Whitney U test was used. Main results and the role of chance According to the guidelines of the World Health Organization, all participants included in the study had normal BMI (21.85±3.80 kg/m2). The average age of the female patients included in the study was 33.9 ± 3.1 years while the average age of the male patients was 37.8 ± 4.8 years. Out of the 50 patients, 32% (N = 16) got pregnant. For the study propose sperm ORP and sORP values were compared between patients based on the pregnancy outcome. Statistical analysis showed a significant difference in ORP values. Patients with a positive pregnancy outcome after IUI had a lower ORP value compared to patients where IUI was not successful [25.65 [6.7-52.6] mV vs. 40.2 [6.3-109.8] mV, respectively, p = 0.02]. Additionally, normalized values according to the sperm concentration (sORP) were also significantly different between those groups [ 0.37(0.17-1.44) mV/10 6 sperm/ml vs. 0.88(0.13-20.81) mV/10 6 sperm/ml, respectively p = 0.006]. Due to the above-mentioned significant difference logistic regression analysis were performed, and the obtained results confirm that sperm ORP (p = 0.02) as well sORP (p = 0.016) significantly affects the pregnancy rate after the IUI procedure. Limitations, reasons for caution The limitation of the presented study was a relatively small patient cohort. Additionally, pregnancy was determined based on the beta hCG values, therefore future research should link ORP values and live birth rate as well. Wider implications of the findings In the present study suggests ORP as an additional parameter with diagnostic value to identify the best therapeutic approach concerning IUI in couples that show minimal or no impairments of the WHO semen parameter. Trial registration number not applicable

A New Slurry for Photocatalysis-Assisted Chemical Mechanical Polishing of Monocrystal Diamond

Diamond needs to have a perfectly smooth surface due to the growing requirements in the fields of electronic semiconductors, optical windows and high-fidelity loudspeakers. However, the polishing of diamonds is highly challenging due to their exceptional hardness and chemical stability. In this study, a new polishing slurry is prepared for the proposed photocatalysis-assisted chemical mechanical polishing (PCMP) approach to obtain an ultra-smooth surface for large-area diamond. The analyses and experimental findings revealed the significance of the photocatalyst, abrasive, electron capture agent and pH regulator as essential components of the PCMP slurry. TiO2 with a 5 nm pore size and P25 TiO2 possess improved photocatalysis efficiency. Moreover, diamond removal is smooth under the acidic environment of H3PO4 due to the high oxidation–reduction potential (ORP) of the slurry, and, during the methyl orange test, P25 TiO2 exhibits reasonable photocatalytic effects. Moreover, in 8 h, a smooth surface free of mechanical scratches can be obtained by reducing the surface roughness from Ra 33.6 nm to Ra 2.6 nm.

Freezing degradation of the anticonvulsant oxcarbazepine by bromate in water ice under sunlight irradiation

Ice plays a crucial role in contaminant transformation in seasonally ice-covered waters. In this study, the characteristics and mechanisms of an emerging contaminant oxcarbazepine (OXC) degradation by a disinfection by-product bromate (BrO3–) in ice were explored via combined experiments and theoretical calculations. Results showed that 74.0 % and 86.4 % of OXC was degraded by BrO3– in ice after 140 min in dark and 120 min under solar irradiation, respectively, while the reaction was negligible in water. The oxidation-reduction potential of BrO3– solution at 1000 μmol L−1 was 56.9 % higher than that at 50 μmol L−1. The oxidation-reduction potential of BrO3– solution at pH 2 was 14.8 %–109.5 % higher than those at other pH values. Enhanced OXC degradation by BrO3– in ice could be attributed to increased BrO3– oxidation capacity resulting from locally elevated BrO3– and H+ concentrations. Hypobromous acid (HOBr), •OH, and Br• generated by direct photolysis under solar irradiation further promoted the OXC degradation in ice. Br• formed by the direct photolysis of accumulated HOBr under solar irradiation caused the generation of bromine-containing degradation products. Bromine-containing degradation products possessed higher potential toxicities, which could contribute to increase the secondary pollution of water environment.

Microbial community dynamics in a feedback-redox controlled bioreactor process that enabled sequential selenate, nitrate and sulfate removal, and elemental selenium recovery

Oxidation reduction potential (ORP) feedback-control by ethanol-dosing was recently proved effective in facilitating a two-stage fluidized bed reactor (FBR) process to remove selenate, nitrate, and sulfate from wastewater, and recover high-purity elemental Se without the formation of carcinogenic SeS. However, further optimization requires knowledge on the relationship between microbial community composition and process performance. Here, changes of microbial communities during the reduction of selenate and nitrate in the first FBR (FBR1) under various ORP conditions (−240 to −520 mV vs. Ag/AgCl), sulfate reduction in subsquent FBR (FBR2) and sulfide oxidation in sulfide oxidation reactor (SOR) were examined. Based on 16S rRNA gene sequencing, high ORP (stage i without sulfate: >−360 mV; stage ii with sulfate: >−440 mV) and elevated sulfate at ORP ≤ −480 mV (stage iii) in FBR1 altered the microbial communities both on fluidized carrier and bulk liquor. Selenate reducers (Geoalkalibacter and Geovibrio genera) were impacted at ORP > −360 mV (stage i) or >−440 mV (stage ii), when selenate removal in FBR1 declined. However, nitrate reducers (Caenispirillum and Paracoccus genera) were not affected in the FBR1, and facilitated ~100 % nitrate removal. At ORP ≤ −480 mV, selenate reducers were readily enriched in FBR1. In the FBR2, the major sulfate reducing genera were Desulfomicrobium, Desulfovibrio and Desulfuromonas, whereas the dominant sulfide-oxidating genera in SOR were Paracoccus, Thiobacillus and Acholeplasma. This study suggested that both nitrate- and selenate-reducing communities could remain active under elevated sulfate concentrations, enabling sequential oxyanions removal and elemental Se recovery from wastewater.

Quality Assessment and Monitoring of River Water Using IoT Infrastructure

The quality assessment of water is a challenging task due to extensive experimental requirements. However, the process of water quality monitoring can be automated with the help of Internet of Things (IoT) devices using sensor probes. This paper presents the IoT infrastructure-based river water quality monitoring and assessment. Experiments were performed to assess the water quality during different months and seasons for the Ganga river and Sangam (confluence of Ganga and Yamuna rivers) at Prayagraj, Uttar Pradesh, India. The data samples were collected for 15 months continuously using the Libelium smart water kit. The Smart Water IoT (SWIoT) kit was equipped with sensors to assess specific parameters like pH, dissolved oxygen, temperature, conductivity, and oxidation-reduction potential. An algorithm is also presented that harnesses PCA and factor analysis for feature selection and weight assignment for river water quality assessment. Further water quality is quantified using the water quality index that helps to categorize the water quality for different usages. The results corroborate that the water quality of the Ganga River was found to be better than the Sangam site most of the time, owing to the higher level of pollution in Yamuna River. Additionally, the water quality of both rivers were found to be suitable for irrigation and fisheries but not for drinking purposes, considering the average oxygen levels.

The response of C/N/S cycling functional microbial communities to redox conditions in shallow aquifers using in-situ sediment as bio-trap matrix

ABSTRACT Microbial communities are fundamental components driving critical biogeochemical carbon (C), nitrogen (N) and sulfur (S) cycles in groundwater ecosystems. The reduction-oxidation (redox) potential is one important environmental factor influencing the microbial community composition. Here, we developed a bio-trap method using in-situ sediment as a matrix to collect aquifer sediment samples and evaluate the response of microbial composition and C/N/S cycling functions to redox variations created by providing sole O2, joint O2 and H2, and sole H2 to three wells. Illumina sequencing analyses showed that the microbial communities in the bio-trap sediment could respond quickly to redox changes in the wells, demonstrating that this bio-trap method is promising for detecting microbial variation in the aquifer sediment. The microbial metabolic functions related to C, N and S cyclings and organic pollutants degradation were predicted by the Kyoto Encyclopedia of Genes and Genomes (KEGG) approach. It was found that the joint O2 and H2 injection produced medium oxidation-reduction potential (ORP -346 and -614 mV) and enhanced more microbial functions than sole O2 or H2, which mainly include oxidative phosphorylation, most carbon source metabolism, various pollutants degradation, and nitrogen and sulfur metabolism. Moreover, the functional genes encoding phenol monooxygenase, dioxygenase, nitrogen fixation, nitrification, aerobic and anaerobic nitrate reductase, nitrite reductase, nitric oxide reductase, and sulfur oxidation increased. These findings tell us the contaminant bioremediation and N, S metabolism can be promoted by adjusting ORP realised by injecting joint O2 and H2.

ASSESSMENT BY MACROINVERTEBRATES OF THE ECOLOGICAL QUALITY OF SHALLOW LAKE WITH RICH SAPROPEL SEDIMENTS

In this research, the ecological quality of the Lake Vēveru (Latvia, Rēzekne district) according to macroinvertebrates was investigated. The Lake Vēveru has a large sapropel deposit. The Lake Vēveru is relatively little affected by human economic activity, the only moderate impact is sapropel mining in the lake in 2009-2012, it is planned to resume industrial sapropel mining in the lake. During the period of sapropel removal, a decrease in the transparency of water is noted due to the nutrient flow into the water mass, pH increases, the habitat of planktonic and benthic organisms is disturbed. Macroinvertebrates samples were collected and analyzed using standard methods in the open pelagic and littoral zones of the lake in different seasons. The ecological quality of the lake was assessed in accordance with the requirements of the European Water Framework Directive in Latvia. To characterize the ecological status of the lake the Latvian Lake Macroinvertebrate Multimetric Index was used. According to the Ecological Quality Ratio (EQR) the lake indicates a good ecological status of the water. However, a moderately low species diversity index indicates the dominance of certain taxa. In general, macroinvertebrates species that are often and widely found in Latvia and are environmentally tolerant have been found in the lake. Water temperature, pH, conductivity, dissolved oxygen, oxidation reduction potential, chlorophyll-α were measured with a HACH OTT DS5 Probe. Water transparency was measured using a Secchi disc.

Influence of redox potential on the accumulation of poly(3-hydroxybutyrate) by Bacillus megaterium.

The main goal of the present study was to evaluate the oxidation-reduction potential (ORP) on the production of poly(3-hydroxybutyrate) (P(3HB)) by Bacillus megaterium. Each microorganism has an optimal ORP range, and changes to the culture medium's ORP may redistribute the cell's metabolic flux, as such, the measurement and control of the ORP profile allows one to, in a way, manipulate the microbial metabolism, affecting the expression of certain enzymes and allowing for better control over the fermentative process. The ORP tests were carried out in a fermentation vessel coupled with an ORP probe, containing 1L of mineral medium added with agroindustry byproducts (60% v/v of confectionery wastewater, and 40% v/v of rice parboiling water). The system's temperature was kept at 30°C, with an agitation speed of 500rpm. The vessel's airflow rate was controlled via a solenoid pump based on the ORP probe's data. Different ORP values were evaluated to verify their impact on biomass and polymer production. Cultures using OPR levels of 0mV displayed the highest amounts of total biomass (5.00gL-1) when compared to -20mV and -40mV (2.90g L-1 and 0.53g L-1, respectively). Similar results were also found for P(3HB)-to-biomass ratio, with polymer concentration being reduced when using ORP levels below 0mV and with a maximum amount of polymer-to-biomass ratio of 69.87% after 48h of culture. Furthermore, it was possible to observe that the culture's pH can also affect total biomass and polymer concentration, albeit to a lesser extent. Thus, when considering the data found during this study, it is possible to observe that ORP values can greatly impact B. megaterium cell's metabolism. Furthermore, the measurement and control of ORP levels may be an invaluable asset when trying to maximize polymer production under different culture conditions.

Valorization of whey-based side streams for microbial biomass, molecular hydrogen, and hydrogenase production.

Side streams of the dairy industry are a suitable nutrient source for cultivating microorganisms, producing enzymes, and high-value chemical compounds. The heterotrophic Escherichia coli and chemolithoautotroph Ralstonia eutropha are of major biotechnological interest. R. eutropha is a model organism for producing O2-tolerant [NiFe]-hydrogenases (Hyds) (biocatalysts), and E. coli has found widespread use as an expression platform for producing recombinant proteins, molecular hydrogen (H2), and other valuable products. Aiming at developing suitable cultivation media from side streams of the dairy industry, the pre-treatment (filtration, dilution, and pH adjustment) of cheese (sweet) whey (SW) and curd (acid) whey (AW), with and without the use of ß-glucosidase, has been performed. Growth parameters (oxidation-reduction potential (ORP), pH changes, specific growth rate, biomass formation) of E. coli BW25113 and R. eutropha H16 type strains were monitored during cultivation on filtered and non-filtered SW and AW at 37°C, pH 7.5 and 30°C, pH 7.0, respectively. Along with microbial growth, measurements of pH and ORP indicated good fermentative growth. Compared to growth on fructose-nitrogen minimal salt medium (control), a maximum cell yield (OD600 4.0) and H2-oxidizing Hyd activity were achieved in the stationary growth phase for R. eutropha. Hyd-3-dependent H2 production by E. coli utilizing whey as a growth substrate was demonstrated. Moreover, good biomass production and prolonged H2 yields of ~ 5mmol/L and cumulative H2 ~ 94mLg/L dry whey (DW) (ß-glucosidase-treated) were observed during the cultivation of the engineered E. coli strain. These results open new avenues for effective whey treatment using thermostable β-glucosidase and confirm whey as an economically viable commodity for biomass and biocatalyst production. KEY POINTS: • Archaeal thermostable β-glucosidase isolated from the metagenome of a hydrothermal spring was used for lactose hydrolysis in whey. • Hydrogenase enzyme activity was induced during the growth of Ralstonia eutropha H16 on whey. • Enhanced biomass and H2 production was shown in a genetically modified strain of Escherichia coli.

Dynamics and control mechanisms of inorganic nitrogen removal during wetting-drying cycles: A simulated managed aquifer recharge experiment

Managed aquifer recharge (MAR) systems can be operated intermittently through wetting-drying cycles to simultaneously improve the water supply and quality. Although MAR can naturally attenuate considerable amounts of nitrogen, the dynamic processes and control mechanisms of nitrogen removal by intermittent MAR remain unclear. This study was conducted in laboratory sandy columns and lasted for 23 d, including four wetting periods and three drying periods. The hydraulic conductivity, oxidation reduction potential (ORP), and leaching concentrations of ammonia nitrogen and nitrate nitrogen of MAR systems were intensively measured to test the hypothesis that hydrological and biogeochemical controls play an essential role in regulating nitrogen dynamics at different stages of wetting-drying cycles. Intermittent MAR functioned as a sink for nitrogen while providing a carbon source to support nitrogen transformations; however, it occasionally became a source of nitrogen under intense flushes of preferential flow. Nitrogen dynamics were primarily controlled by hydrological processes in the initial wetting phase and were further regulated by biogeochemical processes during the subsequent wetting period, supporting our hypothesis. We also observed that a saturated zone could mediate nitrogen dynamics by creating anaerobic conditions for denitrification and buffering the flush effect of preferential flow. The drying duration can also affect the occurrence of preferential flow and nitrogen transformations, which should be balanced when determining the optimal drying duration for intermittent MAR systems.

Feasibility of soil oxidation-reduction potential in judging shear behaviour of hydrocarbon-contaminated soil

This study investigates the indicative role of oxidation-reduction potential (ORP) and pH of hydrocarbon-contaminated soils on their shear characteristics, contributing to safer and more efficient ex-situ remediation and management processes. The presence of hydrocarbons alters the soil's shear strength by affecting the hydration shell thickness, fluid's dielectric properties, and ion/electron exchange, as well as the soil's electrochemical force, which in turn affects the ORP and pH. The relationship between hydrocarbon concentrations in contaminated soils (0.1–15%) and corresponding ORP/pH values could be fitted linearly with a good correlation coefficient r (0.978), highlighting the potential of ORP/pH as an indicator for pollutant occurrence. Furthermore, the relationships between ORP/pH and shear strength, as tested in our study and obtained after processing from relevant literature sources, exhibited a strong fit (r = 0.976–0.995). The Mohr-Coulomb criterion modified using the ORP/pH parameter was established, which could improve the fitting effect of these relationships (r = 0.988–0.996), verifying the reliability of the novel criterion and application feasibility of ORP/pH. In future research, this modified criterion can be employed to conveniently assess the shear strength of contaminated soil by considering the shear behaviour of virgin soil and the ORP/pH values of the contaminated soil.

Study of Total Dissolved Solids (TDS) and Total Suspended Solids (TSS) in Estuaries in Banten Bay Indonesia

The estuaries of Banten Bay have sandy sediment, and their main activity is fisheries. In order to maintain fishery productivity, good water quality is required. The sandy sediment in this location can affect water conditions at the point of the residue content. This study aims to reveal solids content in the estuaries of Banten Bay. A survey was conducted in four estuaries, namely Karangantu, Wadas, Cengkok, and Pamong. TDS were measured in situ in April and October 2021. TSS was analyzed in May, July, and October 2013, as well as in April and October 2021. Other physical and chemical parameters were analyzed in the laboratory or in situ. The results were compared with the standard for sea aquatic biota. Furthermore, the regression method was used to determine the correlation of TSS and TDS with other parameters. The physical and chemical parameters that affect TDS and TSS were analyzed using Principal Component Analysis (PCA). The results show that TSS correlated with Oxidative Reductive Potential (ORP) and turbidity. PCA showed that TSS correlated with TDS, nitrate, ammonium, ORP, water depth, and water current. Although TSS exceeded the threshold, sufficient dissolved oxygen and higher nutrient still maintained water quality for fisheries in four estuaries.

Adsorption Efficiency of Bentonite Clay and Parrotia persica During Acid Mine Drainage Treatment for the Removal of Turbid Material

We conducted jar tests on the efficacy of using various mixtures of pulverized bentonite clay and Parrotia persica plant to treat AMD from a mine in Mogale City, South Africa without adding alkalinity. Two nearly identical sets of experiments were conducted using the same materials after they were rinsed using distilled and potable waters, respectively, to remove impurities, and then dried in an oven at 60 °C for 24 h, after which they were pulverized again. The pH, electrical conductivity, oxidation reduction potential, turbidity, and metal concentrations were measured before and after the experiments. The samples were treated in a jar test using standard procedures, i.e. rapid and slow mixing and settling for 1 h. The results showed that increasing the concentration of P. persica relative to the bentonite improved treatment effectiveness and that the highest turbidity removal (> 96.8%) was produced by rinsing the mixtures with potable water, drying them, and then pulverizing them again. Potentially toxic metals were removed by more than 93.7%. The morphological structure of the SEM micrographs indicate that the removal mechanism involves both physical and chemical phenomena and that the clay and P. persica are both important, particularly to the physical aspects.

Benthic macroinvertebrates community to response environmental factors in a crater lake (Case study: Lake Menjer, Indonesia)

Lake Menjer is one of the crater lakes located in the highland of Central Java, Indonesia, which has received multiple stressors from anthropogenic activities. Benthic macroinvertebrates as a key indicator for water quality were little known there. Thus, this present research aimed to identify benthic macroinvertebrate structures and to understand the response of this community to water quality in Lake Menjer. Samplings were conducted twice, one week each in August and October 2019 at five sites. Sampling in August represented the condition of the dry season, while in October represented the rainy season. Some groups were identified into the family and others into the genus level. Water quality variables were measured directly on the site, including water clarity, pH, dissolved oxygen (DO), conductivity, total dissolved solids (TDS), and oxidation-reduction potential (ORP). Meanwhile, the level of total nitrate (TN), total phosphate (TP), nitrite, and chlorophyll-a were analyzed separately. A total of 4312 benthic macroinvertebrates composed of eleven taxa belonging to eight families were recorded, namely Chironomidae (22.85%), Tubificidae (73.50%), Lumbricullidae (0.68%), Thiariidae (0.21%), Planorbidae (0.45%), Lymnaeidae (0.21%), Unionidae (0.92%), and Corbiculidae (1.13%). The number of taxa varied between 1 to 3 in each station. Mollusk was the best-represented group with five families. Meanwhile, Tubificidae was shown as the predominant family in abundance both in August (3879 ind/m2) and October (2008 ind/m2). Shannon-Wiener index ranged nearly similar between the two seasons, 0.17 to 0.91 in August and 0.0 to 0.91 in October. ANOSIM CAP6 result illustrated that there was an insignificant difference in benthic macroinvertebrates abundance (P below 0.05) among sampling sites in Lake Menjer. This community was mostly homogenous. Bray-Curtis analysis using MVSP shows similarities in the taxa compositions between the sites. The analysis between water quality and macroinvertebrates which was performed by Canonical Correspondence Analysis shows that nine taxa tended to correlate with the level of TN, DO, and conductivity. Meanwhile, the other two taxa had a relationship with water clarity, temperature, level of TP, nitrite, and chlorophyll-a.

Prediction and analysis of corrosion rate of 3C steel using interpretable machine learning methods

Machine learning has become increasingly important in materials science, particularly for predicting material properties as artificial intelligence and big data continue to converge rapidly. Studying the corrosion rate of 3 C steel in various seawater environments is the purpose of this study. As a first step, correlation coefficients were used to establish the significance of the features considered. Following the training of 46 sample sets, machine learning methods were utilized to determine the most accurate machine learning model based on errors in the test set. In the end, the SHAP interpretation technique was employed to clarify the model and facilitate feature visualization. Through local interpretability, the effect of distinct seawater environments on 3 C steel corrosion rates was examined using SHAP contribution values for single and multiple feature interactions. According to the results, the oxidation-reduction potential (ORP) had the greatest impact on corrosion rate, showing a positive correlation. As dissolved oxygen (DO), pH value, and temperature (T) declined in magnitude, salinity (Sal) had a comparatively minor effect on corrosion.

Effect of different NaCl concentrations on the structure-function relationship of citrus peel pectins modified by electrochemistry

In this study, the modified citrus peel pectins (CPPs) were successfully produced by electrochemistry with varying NaCl concentrations of 0, 0.01 % and 0.1 % w/v using an H-type cell at 40 mA current. After 4 h, the pH and oxidation-reduction potential (ORP) of oxidized CPP solution in the anodic region were 2.00– 2.52 and 371.17– 564.45 mV, respectively, due to the electrolysis of water, whereas those of reduced CPP solution in cathodic region were 9.46– 10.84 and − 202.77 ∼ −230.57 mV. The modified CPPs in the anodic region (A-0, A-0.01, and A-0.1) exhibited significantly higher weight-average molecular weights and methyl esterification degrees than those in the cathodic region (C-0, C-0.01 and C-0.1). In contrast, the K+, Mg2+, and Ca2+ contents of A-0, A-0.01, and A-0.1 were lower than those of C-0, C-0.01 and C-0.1 due to the electrophoretic migration. Furthermore, the antioxidant activities of A-0 and A-0.01 solutions were stronger than those of the C-0, C-0.01, and C-0.1, while rheological and texture properties of their hydrogels showed contradictory results. Finally, the potential structure-function relationships of CPPs were explored by combining PCA and correlation analysis. Overall, this study introduced a potential approach for pectin purification and functional low-methoxyl pectin manufacturing.

Effects of electrochemical intervention on the remediation of black-odorous water: insights into microbial community dynamics and functional shifts in sediments.

Black-odorous water is a severe environmental issue that has received continuous attention. The major purpose of the present study was to propose an economical, practical, and pollution-free treatment technology. In this study, the in situ remediation of black-odorous water was conducted by applying different voltages (2.5, 5, and 10 V) to improve oxidation conditions of the surface sediments. The study investigated the effects of voltage intervention on water quality, gas emissions, and microbial community dynamics in surface sediments during the remediation process. The results indicated that the voltage intervention can effectively increase the oxidation-reduction potential (ORP) of the surface sediments and inhibit the emissions of H2S, NH3, and CH4. Moreover, the relative abundances of typical methanogens (Methanosarcina and Methanolobus) and sulfate-reducing bacteria (Desulfovirga) decreased because of the increase in ORP after the voltage treatment. The microbial functions predicted by FAPROTAX also demonstrated the inhibition of methanogenesis and sulfate reduction functions. On the contrary, the total relative abundances of chemoheterotrophic microorganisms (e.g., Dechloromonas, Azospira, Azospirillum, and Pannonibacter) in the surface sediments increased significantly, which led to enhanced biochemical degradability of the black-odorous sediments as well as CO2 emissions.

DC magnetic field-assisted improvement of textile dye degradation efficiency with multi-capillary air bubble discharge plasma jet.

Axial DC magnetic field-assisted multi-capillary underwater air bubble discharge plasma jet has been used to study the productions of reactive oxygen species. Analyses of optical emission data revealed that the rotational (Tr) and vibrational temperatures (Tv) of plasma species slightly increased with magnetic field strength. The electron temperature (Te) and density (ne) increased almost linearly with magnetic field strength. Te increased from 0.53 to 0.59eV, whereas ne increased from 1.03 × 1015cm-3 to 1.33 × 1015cm-3 for B = 0 to B = 374 mT, respectively. Analytical results from the plasma treated water provided that the electrical conductivity (EC), oxidative reduction potential (ORP), and the concentrations of O3 and H2 O2 enhanced from 155 to 229 µS cm-1, 141 to 17mV, 1.34 to 1.92mg L-1, and 5.61 to 10.92mg L-1 due to the influence of axial DC magnetic field, while [Formula: see text] reduced from 5.10 to 3.93 for 30min treatment of water with B = 0 and B = 374 mT, respectively. The model wastewater prepared with Remazol brilliant blue textile dye and the plasma treated wastewater studied by optical absorption spectrometer, Fourier transform infrared spectrometer, and gas chromatography mass spectrometer. The results show that the decolorization efficiency increased ~ 20% after 5min treatment for the maximum B = 374 mT with respect to zero-magnetic field and, power consumption, and electrical energy cost reduced ~ 6.3% and ~ 4.5%, respectively, due to the maximum assisted axial DC magnetic field strength of 374 mT.

Substituent effect on the oxidation and reduction of electronically altered iron(II)-terpyridine derivatives – DFT study

Structure, reactivity, and redox properties play an important role in many biological processes. The structures of two types of series of related iron(II) compounds, namely iron(II)-terpyridine and iron(II)-tris-azinyl derivatives, were optimized in the gaseous as well as solvated states by means of density functional theory (DFT). From the optimized geometries of the molecules, their frontier orbital energies (ELUMO/EHOMO), electronic chemical potential (μ), electrophilicity index, (ω), Merz-Kollman electric potential, Gibbs Free energy, Mulliken and Natural Bond Orbital charges were determined. The DFT calculated reactivity parameters were related to the experimentally reported iron-based oxidation and ligand-based reduction potential of the series of iron(II)-terpyridine and tris-azinyl derivatives. Results obtained show that the relationship between the experimental and DFT calculated Fe(II/III) redox potential gave the most accurate relationship (R2 = 0.97), though a systematic error, depending on the choice of the reference system, was obtained. Relationships between the experimental iron-based oxidation (EFe(II/III)) or ligand-based reduction (ELigand) of the iron(II) complexes, and solvent phase calculated HOMO and LUMO energies respectively (R2 = 0.96 and 0.95 respectively), lead to more accurate relationships with higher R2 values than the relationships involving the gas phase calculations (R2 = 0.87 and 0.88 respectively). More relationships, that can be used to predict the oxidation and reduction of related iron(II) derivatives containing two substituted terpyridine or tris-azinyl analogues of the terpyridine ligand, were obtained to a high accuracy.

Impacts of Nanobubbles in Pore Water on Heavy Metal Pollutant Release from Contaminated Soil Columns.

This study investigated the release of heavy metals from polluted soil under the pore water flow containing nanobubbles (NBs) to simulate natural ebullition. Three types of NBs (CH4, H2, and CO2) were generated in water and characterized, including bubble size, zeta potential, liquid density, and tension. The flow rate used in column tests was optimized to achieve proper soil fluidization and metal desorption or release. The leachate chemistries were monitored to assess the effect of NBs on conductivity, pH, oxidation-reduction potential (ORP), and dissolved oxygen (DO). The results showed that NBs in the pore water flow were significantly more effective in releasing Pb compared to DI water, with CO2 NB water being the most effective and H2 NB water being the least effective. CO2 NB water was also used to rinse column soil contaminated with four different metals (Pb, Cu, Zn, and Cr), which exhibited different leaching kinetics. Moreover, a convective-dispersion-deposition equation (CDDE) model accurately simulated the leaching kinetics and explained the effects of NBs on the key parameters, such as the deposition rate coefficient (Kd), that affect the released metal transport. The findings could provide new insights into soil pollutant release under ebullition and soil remediation using water wash containing NBs.