Changes In Redox Potential Research Articles

Redox Imaging Using Cardiac Myocyte-Specific Transgenic Biosensor Mice.

Changes in redox potentials of cardiac myocytes are linked to several cardiovascular diseases. Redox alterations are currently mostly described qualitatively using chemical sensors, which however do not allow quantifying redox potentials, lack specificity, and the possibility to analyze subcellular domains. Recent advances to quantitatively describe defined redox changes include the application of genetically encoded redox biosensors. Establishment of mouse models, which allow the quantification of the glutathione redox potential (EGSH) in the cytoplasm and the mitochondrial matrix of isolated cardiac myocytes and in Langendorff-perfused hearts based on the use of the redox-sensitive green fluorescent protein 2, coupled to the glutaredoxin 1 (Grx1-roGFP2). We generated transgenic mice with cardiac myocyte-restricted expression of Grx1-roGFP2 targeted either to the mitochondrial matrix or to the cytoplasm. The response of the roGFP2 toward H2O2, diamide, and dithiothreitol was titrated and used to determine the EGSH in isolated cardiac myocytes and in Langendorff-perfused hearts. Distinct EGSH were observed in the cytoplasm and the mitochondrial matrix. Stimulation of the cardiac myocytes with isoprenaline, angiotensin II, or exposure to hypoxia/reoxygenation additionally underscored that these compartments responded independently. A compartment-specific response was also observed 3 to 14 days after myocardial infarction. We introduce redox biosensor mice as a new tool, which allows quantification of defined alterations of EGSH in the cytoplasm and the mitochondrial matrix in cardiac myocytes and can be exploited to answer questions in basic and translational cardiovascular research.

The Influence of Peripheral Substituent Modification on P(V), Mn(III), and Mn(V)(O) Corrolazines: X-ray Crystallography, Electrochemical and Spectroscopic Properties, and HAT and OAT Reactivities.

The influence of remote peripheral substitution on the physicochemical properties and reactivity of phosphorus and manganese corrolazine (Cz) complexes was examined. The substitution of p-MeO for p-t-Bu groups on the eight phenyl substituents of the β-carbon atoms of the Cz ring led to changes in UV-vis transitions and redox potentials for each of the complexes. The oxygen atom transfer (OAT) and hydrogen atom transfer (HAT) reactivity of the Mn(V)(O) complexes was also influenced by p-MeO substitution. The OAT reactivity of Mn(V)(O)(MeOP8Cz) (MeOP8Cz = octakis(p-methoxyphenyl)corrolazinato(3-)) with triarylphosphine (PAr3) substrates led to second-order rate constants from 10.2(5) to 3.1(2) × 10(4) M(-1) s(-1). These rates of OAT are slower than those seen for Mn(V)(O)(TBP8Cz) (TBP8Cz = octakis(p-tert-butylphenyl)corrolazinato(3-)). A Hammett study involving para-substituted PAr3 substrates reveals a Hammett ρ-value for Mn(V)(O)(MeOP8Cz) that is more negative than that observed for Mn(V)(O)(TBP8Cz), consistent with a less electrophilic Mn center. The HAT reactivity of Mn(V)(O)(MeOP8Cz) with C-H substrates was examined and revealed second-order rate constants from 6.8(5) × 10(-5) to 1.70(2) × 10(-1) M(-1) s(-1). The rate constants varied with the C-H bond strength of the substrate. Slightly faster HAT rates with C-H substrates were observed with Mn(V)(O)(MeOP8Cz) compared to Mn(V)(O)(TBP8Cz), indicating that the basicity of the putative [Mn(IV)(O)](-) intermediate likely compensates for the more negative redox potential in the driving force for HAT. In addition, the complete, large-scale synthesis of the para-phenyl-substituted porphyrazines RP8PzH2 (R = p-tert-butylphenyl (TB), p-methoxyphenyl (MeO), and p-isopropylphenyl) and corrolazines RP8CzH3 (TBP8CzH3 and MeOP8CzH3) is presented. The crystal structures of the monoprotonated, metal-free corrolazine [(TBP8CzH3)(H)](+)[BArF](-), P(V)(OMe)2(MeOP8Cz), and Mn(III)(MeOP8Cz)(MeOH) are presented. This work provides the first insights into the influence of electronic substituent effects on the corrolazine periphery.

Changes in oxidation-reduction potential during milk fermentation by wild lactic acid bacteria.

Oxidation-reduction potential (E h) is a fundamental physicochemical property of lactic acid bacteria that determines the microenvironment during the cheese manufacture and ripening. For this reason the E h is of growing interest in dairy research and the dairy industry. The objective of the study was to perform a comprehensive study on the reduction activity of wild lactic acid bacteria strains collected in different periods (from 1960 to 2012) from Italian dairy products. A total of 709 strains belonging to Lactococcus lactis, Enterococcus durans, E. faecium, E. faecalis and Streptococcus thermophilus species were studied for their reduction activity in milk. Kinetics of milk reduction were characterised by the minimum redox potential (E h7) and time of reaching E h7 (t min), the maximum difference between two measures (Δmax) and the time at which these maximum differences occurred (t*). Broad diversity in kinetic parameters was observed at both species and strain levels. E. faecalis and L. lactis resulted to be the most reducing species, while S. thermophilus was characterised by the lowest reducing power while the greatest heterogeneity was pointed out among E. durans and E. faecium strains. Considering the period of collection (1960-2012) we observed that the more recently isolated strains generally showed less reducing activity. This trend was particularly evident for the species E. durans, E. faecium and L. lactis while an opposite trend was observed in E. faecalis species. Data reported in this research provide new information for a deeper understanding of redox potential changes during milk fermentation due to bacterial growth. Gain knowledge of the redox potential of the LAB cultures could allow a better control and standardisation of cheesemaking process.

Transcriptional responses in Lactococcus lactis subsp. cremoris to the changes in oxygen and redox potential during milk acidification.

Milk acidification and metabolic activity of the starter cultures are affected by oxygen; however, molecular factors related to the redox changes are poorly defined. The objective of the study was to investigate transcriptional responses in Lactococcus lactis subsp. cremoris CHCCO2 grown in milk to the shifts of oxygen and redox potential (Eh7 ). Transcriptomic studies were performed with the use of Illumina HiSeq 2000 mRNA sequencing and validated by the real-time quantitative PCR. In total 105 differentially expressed genes were assigned functional gene names. Most of the differentially expressed genes were detected during aerobic reduction phase. Upregulated genes were implicated in lactose utilization, glycogen biosynthesis, amino sugar metabolism, oxidation-reduction, pyrimidine biosynthesis and DNA integration processes. Genes of purine nucleotide biosynthesis and genes encoding amino acid, multidrug resistance and ion ABC transporters were mostly downregulated, while oligopeptide transporter genes were reduced during oxygen depletion and induced at minimum Eh7 . Understanding of gene responses in starter cultures to the changes of oxidation-reduction state is important for the better control and reproducibility of dairy fermentations. We applied mRNA sequencing by Illumina HiSeq 2000 to investigate gene expression profile in a dairy strain of Lactococcus lactis subsp. cremoris during milk acidification. Novelty of this study lies in linking transcriptional responses to oxygen depletion and the changes of redox potential with the fermentation kinetics and clarification of molecular factors specifically expressed in milk which might be essential for bacterial performance and the final quality of cheeses.

Poly(3-octylthiophene) nanoparticles for turn-on fluorescent sensor

A novel concept of optical fluorescent sensing using conducting polymer nanostructures poly(3-octylthiophene) as an optical receptor is proposed. A conducting polymer was encapsulated within polymeric nanospheres obtained from poly(maleic anhydride-alt-1-octadecene) in a simple procedure, resulting in formation of core-shell nanostructures. In the presence of carboxyl groups at the outer shell of nanospheres the conducting polymer undergoes spontaneous oxidation (e.g. by oxygen dissolved in the solution), leading to decrease of native fluorescence of poly(3-octylthiophene). Thus obtained core-shell nanospheres are sensitive to changes of the solution redox potential, due to dependence of poly(3-octylthiophene) emission spectra on its oxidation state. The decrease in redox potential is accompanied with increase of emission intensity of the conducting polymer core, which allows application of nanospheres as turn-on probe for reducing agents. The sensitivity and selectivity of obtained nanoprobes can be fine-tuned taking the advantage of the presence of charged groups in the shell layer of the nanostructures obtained. As a model analyte, ascorbic acid was chosen. A linear response was recorded, with increase of emission intensity for increasing ascorbic acid concentration, within the range from 10−6 to 0.1M.

Effect of NO2 substitution and solvent on UV-visible spectra, redox potentials and electron transfer mechanisms of copper β-nitrotriarylcorroles. Proposed electrogeneration of a Cu(I) oxidation state

Three copper triarylcorroles containing a [Formula: see text]-pyrrole nitro substituent were synthesized and characterized as to their spectral and electrochemical properties in nonaqueous media. The examined compounds are represented as [Formula: see text]-NO2(YPh)3CorCu, where Cor is the trianion of a triphenylcorrole and Y is a Cl, H or CH3 substituent at the para-position of the three meso-phenyl rings of the compound. The data from absorption spectra, electrochemistry and thin-layer spectroelectrochemistry are consistent with an initial assignment of Cu[Formula: see text]-Cor[Formula: see text] in CH2Cl2, DMF and pyridine and electrogeneration of a formal Cu(II) corrole with an unreduced macrocycle, represented as Cu[Formula: see text]-Cor[Formula: see text], after the first one-electron reduction in these solvents. The doubly reduced [Formula: see text]-nitrocorrole has a sharp Soret band at 439 nm and a well-defined Q-band at 611 nm in CH2Cl2. Similar absorption spectra are seen for the three examined doubly reduced nitrocorroles in DMF and pyridine, suggesting formation of a Cu(I) species with an unreduced macrocycle which is represented as Cu[Formula: see text]-Cor[Formula: see text]. Changes in redox potentials and absorption spectra of the nitrocorroles are examined as a function of solvent and substituents on the meso-phenyl rings of the compounds and comparisons are made between spectral and electrochemical data of the newly synthesized corroles and that of structurally related tetraarylcorroles lacking a [Formula: see text]-nitro group.

Chromium Release from a COPR-Contaminated Soil at Varying Water Content and Redox Conditions.

Many soils in the region of Kanpur, North India, are heavily affected by the leather industry and its upstream supplier sector, as indicated by elevated chromium (Cr) contents. Under reducing conditions-for instance, at water saturation after monsoon rain or flood irrigation-the dynamic and species distribution of Cr may be affected due to changes in redox potential (E). In this study, the influence of E on the speciation and release of Cr from a contaminated agricultural soil was investigated. A soil sample that was affected by hyperalkaline leachate from chromite ore processing residue, was taken and packed in soil columns, and subjected to a saturation-drainage-saturation cycle. After initial water saturation, the E dropped slowly to minimum values of around ‒100 mV (calculated to pH 7), while E was controlled by CrO/CrO(s), or CrO/(Fe,Cr)OOH redox couples. Soil drainage resulted in a quick return to oxidizing conditions; i.e., E > 300 mV. The Cr species distribution and release showed a clear trend with E. At the beginning of the experiment, under oxidizing and weakly reducing conditions (E range from >100 to 300 mV), Cr(VI) was released in particular. However, under moderately reducing conditions (E range from 100 to -100 mV), Cr was gradually immobilized and irreversible sequestered via reductive precipitation. The results presented in this study provide an improved understanding of the mobility of Cr(VI) in contaminated soils at varying water contents, which is essential for the evaluation of environmental risks in this region.

Minimizing photodecomposition of flavin adenine dinucleotide fluorescence by the use of pulsed LEDs.

Dynamic alterations in flavin adenine dinucleotide (FAD) fluorescence permit insight into energy metabolism-dependent changes of intramitochondrial redox potential. Monitoring FAD fluorescence in living tissue is impeded by photobleaching, restricting the length of microfluorimetric recordings. In addition, photodecomposition of these essential electron carriers negatively interferes with energy metabolism and viability of the biological specimen. Taking advantage of pulsed LED illumination, here we determined the optimal excitation settings giving the largest fluorescence yield with the lowest photobleaching and interference with metabolism in hippocampal brain slices. The effects of FAD bleaching on energy metabolism and viability were studied by monitoring tissue pO2 , field potentials and changes in extracellular potassium concentration ([K+ ]o ). Photobleaching with continuous illumination consisted of an initial exponential decrease followed by a nearly linear decay. The exponential decay was significantly decelerated with pulsed illumination. Pulse length of 5 ms was sufficient to reach a fluorescence output comparable to continuous illumination, whereas further increasing duration increased photobleaching. Similarly, photobleaching increased with shortening of the interpulse interval. Photobleaching was partially reversible indicating the existence of a transient nonfluorescent flavin derivative. Pulsed illumination decreased FAD photodecomposition, improved slice viability and reproducibility of stimulus-induced FAD, field potential, [K+ ]o and pO2 changes as compared to continuous illumination.

Study of dynamics of electro-chemical properties of submerged soils

Wetland rice systems in Asia make a major contribution to global rice supply. The system is also able to maintain soil fertility on a sustainable basis. The essential components of wetland rice culture comprise cultivation of land in the flooding, puddling and transplanting of rice seedlings into puddled rice paddies, and growing the rice crop under flooding. The wetland rice system, growing rice in submerged soils has a great ameliorative effect on chemical fertility: largely by bringing pH in the neutral range, resulting in better availability of plant nutrients and accumulation of organic matter. Submergence bring a lot changes in redox potential which in turn gives the idea of reduction of nutrients to release to soil solution to make available to plant. This article revealed the dynamic changes of soil pH, electrical conductivity and Redox potential on submergence.

ChemInform Abstract: Biogeochemical Transformations of Mercury in Solid Waste Landfills and Pathways for Release

AbstractReview: 143 refs.

Nanoparticles of Fluorescent Conjugated Polymers: Novel Ion-Selective Optodes.

A novel type of ion-selective nano-optode is proposed, in which a conjugated polymer is used as optical transducer and nanoprobe material. Thus, contrary to most of the proposed optodes, the response does not require presence of pH-sensitive dye in the sensor. The conjugated polymer nanosensor material is in partially oxidized form-it is bearing positive charges and its emission is quenched. The receptor is an optically silent uncharged ionophore selective for the analyte cation. When a binding event occurs, positive charges are formed in the nanosphere, leading to a decrease in the oxidation state of the polymer, in the absence of redox potential change, resulting in increased emission. This general approach herein proposed results in a simple sensor, benefitting from a novel optical transduction mechanism and high lipophilicity of the polymer matrix that results in linear responses over a broad concentration range of analyte. For the model system studied, the linear dependence of emission intensity on the logarithm of analyte (K(+)) concentration was obtained for a broad range from 10(-5) M to 0.1 M.

Geochemical control processes and potential sediment toxicity in a mine-impacted lake.

Geochemical parameters and major ion concentrations from sediments of a freshwater lake in the town of Åtvidaberg, southeastern, Sweden, were used to identify the geochemical processes that control the water chemistry. The lake sediments are anoxic, characterized by reduced sulfur and sulfidic minerals. The hypothesis tested is that in sulfidic-anaerobic contaminated sediments, the presence of redox potential changes creates a favorable condition for sulfide oxidation, resulting in the release of potentially toxic metals. The acid volatile sulfide (AVS) contents ranged from 5.5 μmol/g to 16 μmol/g of dry sediment. Comparison of total mine tailing metals (∑mine tailing metals) with simultaneously extracted metals (SEM) in sediments indicates that up to 20% of the ∑mine tailing metals are bound to the solid phase as AVS. Consequently, the AVS and SEM analysis classified all sediment samples as potentially toxic in terms of heavy metal concentrations (i.e., SEM to AVS ratio distribution > 1). Evaluation of hydrogeochemical data suggests that calcite dissolution, iron (III) oxyhydroxysulfate mineral jarosite (H-jarosite) precipitation, hematite precipitation, and siderite precipitation are the most prevailing geochemical processes that control the geochemical interactions between the water column and sediment in a mine-impacted lake. The geochemical processes were verified and quantified using a chemical equilibrium modeling program, Visual MINTEQ, Ver 3.1, beta. The identified geochemical processes create an environment in which the characteristics of sulfate-rich waters and acidic-iron produce the geochemical conditions for acid mine drainage and mobilization of toxic metals.

Exploring Oxidation State Dependent Conformational Changes of Cytochrome C on Cardiolipin Containing Liposomes

¬A combination of circular dichroism, absorption and fluorescence spectroscopies were used to study the binding of oxidized and reduced cytochrome c to cardiolipin (CL) containing liposomes with different CL content as a function of cardiolipin concentration. Recently, our group provided evidence for a two-step binding process of the oxidized (ferricytochrome) state to CL containing liposomes. The second step of binding converts a native-like to a more unfolded structure in which M80 is replaced either by a lysine of a histidine as axial ligand. The conversion into this more unfolded conformation was found to be partially inhibited in the presence of NaCl. Currently we are investigating whether the initial binding and/or the equilibrium between the two membrane bound conformers depends on pH. Our work with the reduced (ferrocytochrome) state has revealed a dependence on NaCl for stability. In the absence of NaCl and at aerobic environment, the protein becomes oxidized upon binding to CL containing liposomes. When NaCl is added to the solution, it stabilizes the reduced state on the liposome surface and inhibits the auto-oxidation. At anaerobic conditions and in the absence of NaCl, the protein undergoes a notable conformational change, but clearly maintains its reduced state. This shows that the obtained oxidation of the protein involves the reduction of molecular oxygen. We are in the process of exploring the pH dependence of the underlying change of the protein's redox potential.

Extracellular Cysteine in Connexins: Role as Redox Sensors.

Connexin-based channels comprise hemichannels and gap junction channels. The opening of hemichannels allow for the flux of ions and molecules from the extracellular space into the cell and vice versa. Similarly, the opening of gap junction channels permits the diffusional exchange of ions and molecules between the cytoplasm and contacting cells. The controlled opening of hemichannels has been associated with several physiological cellular processes; thereby unregulated hemichannel activity may induce loss of cellular homeostasis and cell death. Hemichannel activity can be regulated through several mechanisms, such as phosphorylation, divalent cations and changes in membrane potential. Additionally, it was recently postulated that redox molecules could modify hemichannels properties in vitro. However, the molecular mechanism by which redox molecules interact with hemichannels is poorly understood. In this work, we discuss the current knowledge on connexin redox regulation and we propose the hypothesis that extracellular cysteines could be important for sensing changes in redox potential. Future studies on this topic will offer new insight into hemichannel function, thereby expanding the understanding of the contribution of hemichannels to disease progression.

Effects of chlorine dioxide on mitochondrial energy levels and redox status of ‘Daw’ longan pericarp during storage

Mitochondrial redox status and adenosine triphosphate (ATP) production play a central role in responding to physiological and environmental changes and metabolic control. Changes in mitochondrial redox potential are intimately associated with oxidative stress which could lead to plant senescence. This study aimed to demonstrate the involvement of an alteration of the redox status in energy production and fruit senescence of longan (Dimocarpus longan Lour. cv. Daw) during storage and to investigate the effects of gaseous chlorine dioxide (ClO2) both on the redox and the energy status and on delaying senescence. Fresh longan fruit were fumigated with 5, 10 and 25mg/L ClO2 for 10min and then stored in a cardboard box at 25°C with 82% relative humidity for 7 days. ATP content and energy charge (EC), and activities of respiratory enzymes such as succinate dehydrogenase (SDH) and cytochrome c oxidase (CCO) were found to be steadily decreased in the untreated group during storage. These reductions coincided with a decrease in the redox status as determined by pyridine nucleotide (NAD/NADH) and ubiquinone (Q/QH2) ratios and with fruit senescence including browning and the onset of disease symptoms. However, in the ClO2 fumigated fruit, ATP content, EC, SDH and CCO activities as well as NAD/NADH ratio were immediately and markedly increased after treatment. The effects can be seen through the fourth day of storage. The Q/QH2 ratio remained unchanged before rising after Day 4. Higher concentrations of ClO2 (10 and 25mg/L) were more effective than the lower one (5mg/L) in altering the redox balance and increasing energy production. The altered redox state and increased energy by ClO2 were found to be closely associated with a delay in fruit senescence during storage. These findings support the notion that energy production and redox balance involve directly in longan senescence and demonstrated that ClO2 could restore ATP and the redox balance, leading to reduction and delay in fruit senescence.

A 24 h Delay in the Redox Response Distinguishes the most Severe Stroke Patients from Less Severe Stroke Patients

Objective: Admission measures of stroke severity are often used to assess 30-90 day outcomes. Since some patients have a poor outcome by discharge, we sought to identify a biomarker that distinguishes severities as well as acute outcomes. Disruptions in the equilibrium of the redox system were used as an indicator of stroke severity and acute outcome. Methods: Oxidation reduction potential (ORP), a measure of the redox system, was assessed in plasma at admission and 24 h later in patients admitted with stroke symptoms (n=76). Overall differences in ORP between stroke patients and healthy controls were determined. Within stroke patients, changes in ORP as a function of hospital discharge status, modified Rankin scale and NIHSS were assessed using ANOVA and the ability to predict acute outcome in ischemic stroke patients based on ORP was compared to NIHSS using Receiver Operator Characteristics. Results: Stroke patients had higher ORP levels than healthy controls (p 146.6 mV at admission was associated with a 46 fold increased odds of a good acute outcome. Conclusion: ORP measured at admission identified patients which died or were discharged to hospice based on their lower ORP values. The lower ORP and subsequent increase 24 h later in the most severely affected patients may reflect a failure or a delay in engaging the redox system, a response that may, during acute stages, be beneficial.

Role of Glutathione System Redox Potential in Apoptosis Dysregulation in MCF-7 Breast Adenocarcinoma.

MCF-7 breast cancer cells and HBL-100 breast epithelial cells were cultured with N-ethylmaleimide, a blocker of SH groups. Changes in redox potential of the glutathione system, activities of glutathione reductase, glutathione peroxidase, and intensity of apoptotic cell death were evaluated. The results indicate that incubation with N-ethylmaleimide led to glutathione system imbalance, reduced tumor cell redox potential, and induced their programmed death, which seemed useful for prospective target therapy of tumor diseases.

Differential Thiol-Based Switches Jump-Start Vibrio cholerae Pathogenesis.

Bacterial pathogens utilize gene expression versatility to adapt to environmental changes. Vibrio cholerae, the causative agent of cholera, encounters redox-potential changes when it transitions from oxygen-rich aquatic reservoirs to the oxygen-limiting human gastrointestinal tract. We previously showed that the virulence regulator AphB uses thiol-based switches to sense the anoxic host environment and transcriptionally activate the key virulence activator tcpP. Here, by performing a high-throughput transposon sequencing screen invivo, we identified OhrR as another regulator that enables V.cholerae rapid anoxic adaptation. Like AphB, reduced OhrR binds to and regulates the tcpP promoter. OhrR and AphB displayed differential dynamics in response to redox-potential changes: OhrR is reduced more rapidly than AphB. Furthermore, OhrR thiol modification is required for rapid activation of virulence and successful colonization. This reveals a mechanism whereby bacterial pathogens employ posttranslational modifications of multiple transcription factors to sense and adapt to dynamic environmental changes.

Metal distribution and bioavailability in surface sediments from the Huaihe River, Anhui, China.

This study presents the total concentrations and chemical fractionations of metals (Cu, Pb, Zn, Ni, Fe, and Mn) in 54 surface sediment samples collected from the Huaihe River (Anhui Province) in eastern China. Compared with the average shale values, Zn and Pb exhibited the most substantial anthropogenic enrichment, especially in Fengtai and Huainan areas, the main industrial districts along the Huaihe River (Anhui Province). Low levels of Cu and Ni were observed in the sediments. Based on risk assessment code (RAC), the metals associated with weak acid soluble (F1) in the Huaihe River sediments followed the order: Mn > Zn > Cu > Pb > Ni > Fe. Manganese presented the most potential for releasing into the aqueous environment and can easily enter the food chain. Copper, zinc, nickel, and iron were found dominant in the residual fraction, implying that these four metals were strongly bound to the sediments. Lead showed a different partitioning pattern from that of other metals studied, with a large percentage in Fe-Mn oxide fraction, indicating that slight redox potential changes may make significant influence on the removability of Pb. Moreover, Cu in oxidizable (F3) and residual (F4) fractions presented high positive correlation with organic matter, which can explain the high percentage of Cu in these two fractions.

Modified synthesis of nanoscale zero-valent iron and its ultrasound-assisted reactivity study on a reactive dye and textile industry effluents

Synthesized nanoscale zero-valent iron (NZVI) particles were applied for the degradation of a reactive dye Remazol Black B 133 and textile effluent. XRD and HR-TEM analysis of the synthesized particles showed body centered cubic crystal packing. The aggregates were spherical in shape and the size of the particles ranged from 5 to 15 nm. The reactive dye solution was substantially degraded by NZVI particles using ultrasonic irradiation under various experimental conditions created by varying NZVI dosages (0.15–0.30 g/L), initial dye concentration (25–200 mg/L), and pH (2–13). Experimental results suggest that NZVI particles work best within the pH range of 4–10. A unit gram of NZVI was found to degrade a maximum of 749.2 mg of RB B 133 dye and more than 80% of the dye was removed within 15 min of reaction time. During the degradation process, an oxidation–reduction potential change from 196 to −577 mV was detected, indicating reductive condition is necessary for effective dye removal. FT-IR analysis of the end products of the degradation process indicated the presence of an amino (–NH2) group resulting from the breakdown of the azo (–N=N–) group. Results suggest that the degradation followed pseudo-first-order kinetics with respect to dye concentration. The effluents of two textile industries were collected, characterized, and treated with NZVI particles, which led to the significant fall below the standard scale of American Dye Manufacturing Institute (ADMI). This lowering of ADMI value indicates that the overall color removal efficiency is irrespective of any specific dye present in the effluent.