Colorimetric detection of Cr(VI) in water using tetramethyl benzidine (TMB) as an indicator.

Hexavalent chromium (CrVI) poses a serious risk to both human and environment health. Hence, a simple, robust, and efficient analytical method must be developed to monitor the presence of Cr(VI) in the environment. The current investigation concentrated on the colorimetric detection of Cr(VI) using TMB as indicator in the presence of H2O2. The study found that Cr(VI) reacts with H2O2 to generate hydroxyl radicals which oxidize TMB in a concentration dependent manner. Under optimized conditions, the method obtained a good linearity range (0.025-0.5 mg/L, r2 = 0.9944) with LOD and LOQ of 0.009 mg/L and 0.029 mg/L, respectively. The technique was further improved by the addition of EDTA in the sample preparation protocol to reduce the false positive result by the presence of ions like Cu2+, Fe3+, etc. The study recorded improved Cr(VI) recoveries (81.73-111.40 %) at different fortification levels (0.1-0.5 mg/L). Under optimized conditions, the EDTA added method obtained a good linear response (r2 = 0.9952) with a detection limit of 0.023 mg/L which is less than the prescribed limits by WHO (0.05 mg/L) and US EPA (0.1 mg/L) for drinking water. The developed analytical method is very simple without use of any nanomaterial and the results with natural water samples show that it has the potential for real-time detection of Cr(VI) in the environment.

Recovering chromium from electroplating sludge using an integrated technology of bipolar membrane electrodialysis and H2O2 oxidation.

Chromium electroplating produces Cr(III)-containing electroplating sludge (EPS) in large volumes, which is easily oxidised to Cr(Ⅵ) and is harmful to the environment and human health. This study recovered Cr(III) as Na2CrO4 from EPS using an integrated bipolar membrane electrodialysis (BMED)-H2O2 oxidation technology. During the treatment process, Cr(III) was oxidised to Cr(VI) using H2O2 in an alkaline environment, BMED was used to separate and recover Cr(VI). Experimental results showed that H2O2 dosage and pH affected Cr(III) oxidation-the highest Cr(III) oxidation ratio of 68.4% was observed when H2O2 dosage and pH were 5.5 mL and 12.0, respectively. The current density, solid/liquid ratio and sludge particle size affected Cr(III) recovery, energy consumption and current efficiency. Under a current density of 20.0 mA/cm2, solid/liquid ratio of 1.0:45 and sludge particle size of 100 mesh, 58.2% of Cr(III) was recovered. When the number of the equipped EPS compartments was increased from one to two and three, the specific energy consumption decreased from 1.04 to 0.87 and 0.81 kW·h/g, respectively, but the current efficiency remained almost constant. After EPS treatment, the Cr(III) remaining in the sludge was mainly in the residual state, which is less environmentally harmful. The obtained Na2CrO4 had similar properties according to X-ray diffraction analysis. Thus, the proposed integrated technology effectively recovers Cr(III) from EPS and other chromium-containing solid wastes.

Combined impact of antibiotics and Cr(VI) on antibiotic resistance, ARGs, and growth of Bacillussp. SH-1: A functionl analysis from gene to protease.

The simultaneous selection of antibiotic resistance genes (ARGs) induced by heavy metals and antibiotics has emerged as a growing environmental problem. This study investigated the combined effects of chromium (Cr(VI)) and antibiotics on the ARGs of Bacillus cereus SH-1. As Cr(VI) concentration increased, it triggered reactive oxygen species oxidative stress in SH-1, increased antioxidant enzyme activity, enhanced plasmid conjugative transfer, and reduced the efficiency of Cr(VI) removal by SH-1. Antibiotic resistance varied with increasing tetracycline and amoxicillin minimum inhibitory concentrations (MICs), whereas azithromycin and chloramphenicol MICs decreased with Cr(VI) induction. The overexpression of eight genes of the HAE-1 family of efflux pumps was detected using metagenomics and proteomics. Co-contamination with Cr(VI) and antibiotics has led to the emergence and spread of antibiotic-resistant bacteria. Therefore, resistance gene contamination resulting from Cr(VI)-polluted environments cannot be overlooked.

Adsorption of toxic metals from greywater using coconut husk biochar and spent green tea.

The discharge of wastewater into ground and surface waters can cause human and ecological health problems, hence eco-friendly, sustainable and cost-effective methods for removing toxic metals from wastewater are required. The study employed coconut husk biochar and spent impra ginseng flavoured green tea to adsorb cadmium (Cd), chromium (Cr) and lead (Pb) from greywater. The adsorption capacity of coconut husk biochar ranged from 88.70 % to 98.20 % for cadmium, 78 %-96 % for chromium and 95.71 %-99.29 % for lead whilst the spent impra ginseng flavoured green tea ranged from 94.03 % to 96.87 % for cadmium, 52 %-74 % for chromium and 98.52 %-99.48 % for lead. The maximum adsorption capacity (Qe) of coconut husk biochar ranged from 235.64 to 1132.40 mg/g for Cd, 1.31-8.80 mg/g for Cr and 58.85-415.80 mg/g for Pb. Lead demonstrated the highest affinity for the binding of coconut husk biochar and spent impra ginseng flavoured green tea adsorbent with a trend of Pb > Cd > Cr. Coconut husk biochar and spent impra ginseng flavoured green tea adsorbent were suitable for the toxic metals adsorption in the greywater. Cr showed different removal efficiencies where coconut husk biochar showed more effective removal than spent impra ginseng flavoured green tea. The application of coconut husk biochar and spent impra ginseng flavoured green tea in wastewater treatment is a green technology means and can lead to zero pollution of freshwater.

"Efficient novel fungal-enriched biochar formulation for hexavalent chromium bioremediation".

Chromium (Cr), a key element in industrial processes such as leather tanning, poses severe environmental hazards, particularly its hexavalent form, Cr(VI), which is highly toxic and prevalent in tannery effluents/sludge. The persistence and toxicity of Cr(VI) necessitate the development of effective remediation strategies to mitigate its environmental impact. This study investigated the potential of Trichoderma yunnanense (NBRICRF_97) and its combination with 0.5% sugarcane bagasse biochar (SBC) for the reduction of Cr(VI). The results demonstrated that T. yunnanense alone achieved a 91.04% reduction of 50 mg L-1 Cr(VI) within 72 h. Combined with 0.5% SBC, the reduction efficiency increased to 99.65% within 48 h. However, the efficiency decreased at higher concentrations (200 mg L-1). The combination also improved fungal growth and increased extracellular ChrR enzyme activity (13.07 U mg-1 protein compared to the control). Total glutathione activity was boosted by 161.07% at 100 mg L-1 Cr(VI). Antioxidant enzymes (SOD, POD, CAT) and proline mitigated oxidative stress and FTIR analysis revealed changes in fungal cell wall functional groups (-OH and -NH) upon Cr(VI) exposure. SEM-EDX confirmed chromium deposition on fungal surfaces. These results underscore the Cr(VI) detoxification capabilities of T. yunnanense and the synergistic benefits of SBC, suggesting a promising bioremediation strategy for Cr(VI)-contaminated environments. The integration of T. yunnanense with SBC offers a sustainable and cost-effective approach for the bioremediation of Cr(VI)-contaminated sites, with potential for implementation in large-scale environmental cleanup efforts.

Marginal bone loss and soft tissue health around two-implant mandibular overdenture retained with milled versus selective laser melted cobalt chromium bar: a randomized clinical trial.

BACKGROUND: To assess marginal bone loss and soft tissue health around two-implant mandibular overdenture retained with milled versus selective laser-melted cobalt chromium (Co-Cr) bars. METHOD: This research was set to be a parallel, triple-blinded, randomised controlled trial. Twenty completely edentulous patients received new conventional complete dentures according to conventional techniques. Two implants were placed at mandibular canine areas bilaterally, and patients were randomly allocated into two equal groups: the milled Co-Cr bar group and the selective laser melted (SLM) Co-Cr bar group. Marginal bone loss (MBL), modified plaque index (mPI), modified gingival index (mGI), and probing depth (PD) were evaluated at 0-month (baseline), 6-month, and 12-month follow-up visits. Repeated measures ANOVA test and Bonferroni's post-hoc test were used for parametric data as PD, while for non-parametric data as MBL, mGI, and mPI, Mann-Whitney U test and Friedman's test were used. A P-value ≤ 0.05 was set as the statistical level of significance. The study protocol was approved by the Faculty Research Ethics Committee at Minia University (636 4/10/2022). Registration for the clinical trial was made retrospectively on clinicaltrials.gov with ID NCT06401200 at 04/30/2024. RESULTS: The follow-up period (one year) was completed without a dropout. Regarding MBL, no statistically significant difference was found between the two groups throughout the study. However, the milled group showed significantly increased MBL from 0- to 6-month follow up period. In both groups, mPI increased significantly from 0- to 6-months post-loading. On the other hand, no statistically significant difference between the two groups was found regarding mPI and mGI throughout the study follow-up periods. The PD was significantly lower in the milled compared to the SLM group at the 6- and 12-month follow up period. CONCLUSION: Two-implant mandibular overdenture retained with milled or SLM Co-Cr bar can provide an acceptable treatment option for completely edentulous patients regarding marginal bone loss and soft tissue outcomes.

Chromium and Palmitic Acid Supplementation Modulate Adipose Tissue Insulin Sensitivity in Postpartum Dairy Cows.

Periparturient dairy cows exhibit intense lipolysis driven by reduced dry matter intake, enhanced energy needs, and the loss of adipose tissue (AT) insulin sensitivity. Extended periods of low insulin sensitivity and negative energy balance induce lipolysis dysregulation, leading to increased disease susceptibility and poor lactation performance. Chromium (Cr) supplementation improves systemic insulin sensitivity, while palmitic acid (PA) increases energy availability for milk production. However, the effect of supplementing Cr and PA alone or in combination on insulin sensitivity in AT is unknown. Thirty-two multiparous cows were used in a randomized complete block design experiment and randomly assigned to one of 4 diets fed from 1 to 24 DIM. Diets included: control, no supplementation (CON, n = 8); Cr (Cr-propionate at 0.45 ppm Cr/kg DM, n = 8); PA (1.5% DM, n = 8); or Cr+PA (n = 8). Plasma samples were collected at -13 ± 5.1 d prepartum (PreP), and 14.4 ± 1.9d (PP1) and 21 ± 1.9d (PP2) after calving for albumin, BHB, BUN, calcium, cholesterol, glucose, nonesterified fatty acids (NEFA), total protein, iron, transferrin, triglycerides, and oxylipids quantification. Subcutaneous AT (SCAT) explants were collected at PreP, PP1 and PP2 and incubated in the presence of the lipolytic agent isoproterenol (ISO = 1 µM, BASAL = 0 µM) for 3 h. The antilipolytic effect of insulin (1µL/L) on SCAT explants was evaluated during ISO stimulation (IN+ISO). Lipolysis was quantified by glycerol release in the media (nmol glycerol/mg AT). Macrophage infiltration and adipocyte size were measured using hematoxylin and eosin-stained AT sections and immunohistochemistry. Cr tended to reduce postpartum NEFA concentrations when compared with CON, PA, and Cr+PA. Likewise, Cr increased the percentage of large adipocytes (>9000 µm2) postpartum compared with other diets. In line with higher lipid content, Cr-fed cows had higher ex-vivo BASAL lipolysis at PP2 when compared with PA and Cr+PA. ISO induced higher lipolysis at PP1 and PP2 but it was not affected by Cr and PA. IN+ISO reduced lipolysis by 29.91 ± 11% in Cr compared with ISO. In contrast, IN+ISO did not affect ISO lipolysis in CON, PA, and Cr+PA. Plasma transferrin was reduced by Cr. At PP2, PA cows had 3.3-fold higher macrophage infiltration in SCAT when compared with CON and Cr. Plasma 9-HODE and 9-oxoODE were increased by Cr+PA. PA increased plasma 13-oxoODE and Cr increased the ratio of 13-HODE:13-oxoODE. PA increased 5-iso Prostaglandin F2α-VI. Our results demonstrate that supplementing Cr during the immediate postpartum enhances SCAT insulin sensitivity and lipid accumulation. Further studies should determine the effects and mechanisms of action of Cr and PA on AT lipogenesis, adipogenesis, and their impact on lactation performance.

Fe (hydr)oxides and organic colloids mediate colloid-bound chromium mobilization in Cr(VI) contaminated paddy soil.

The association of chromium (Cr) with colloidal particles transport in contaminated sites can affect hexavalent chromium (Cr(VI)) migration and transformation, which is an important mechanism for Cr pollutants in soil and groundwater systems. Here, we investigated colloid and particle-bound Cr migration and transformation effects on rice Cr accumulation during different rice growth stages and different redox conditions in Cr(VI) contaminated soil by pot experiment. Results showed that 13-29% of soil Cr was water dispersible colloid-bound (100-1000 nm) form during rice growth. Using transmission electron microscopy - energy dispersion spectroscopy and asymmetric flow field - flow separation, we identified colloid-bound organic matter (OM) and iron (Fe), most likely in the form of Fe (hydr)oxides - clay composites, as the primary Cr carrier. Specifically, colloid-bound Cr was mainly associated with 125-350 nm soil particle size. Under different redox conditions, colloid- and nanoparticle-bound Cr concentration decreased with increasing nanoparticles zero-valent iron (nZVI) dose. Soil reoxidation promoted the colloid- and nanoparticle-bound Cr release due to the weakly crystalline Fe-(hydr)oxides reprecipitation. Further quantitative analysis showed that colloid-bound Cr concentrations were positively correlated with colloid-bound Mn concentrations during the whole rice growth soils. Most important of all, Cr content in rice grain was positively correlated with colloid-bound Cr significantly. This study provides a quantitative and size-resolved understanding of particle-bound Cr in paddy soils, highlighting the importance of colloid-bound Cr and Fe interactions in Cr geochemical cycle of paddy soil.

Decoding trace element speciation in mushrooms: Analytical techniques, comprehensive data review, and health implications.

This review focuses on trace element speciation in edible mushrooms, providing information on analytical methods, available literature data, and health risk assessment. All steps of analytical procedures were presented, including extraction, separation and quantification. It compiles fragmented literature data on trace element speciation, focusing on arsenic, chromium, selenium, mercury, and antimony. Key findings include non-bioaccumulative chromium, the prevalence of Sb(V), mercury accumulation in contaminated sites, diverse arsenic and selenium speciation. Safe intake limits by agencies like USEPA indicate low risk for Cr(VI) and Sb but significant hazards from mercury and methylmercury, especially in contaminated areas: about 10 % of samples exceed safe limits for inorganic arsenic, and selenium enrichment often surpasses safety thresholds. The review underscores the need for standardized methods, speciation analyses of all toxicologically relevant species, and research on cooking impacts to improve health risk evaluations: establishing safe conditions for mushroom consumption remains a far-fetched goal.

Ecological risk of Cd and Cr in the black rock series should be noticed: Based on the study of enrichment mechanism, occurrence form in the Lower Cambrian Lujiaping formation.

The heavy metals in soils developed from the black rock series originate from the parent rock, but their sources and enrichment mechanisms in the parent rock remain unclear. This study explores the enrichment mechanisms, occurrence forms, and ecological environmental effects of cadmium (Cd) and chromium (Cr) in the black rock series. Results revealed average concentrations of 1.15 mg/kg for Cd and 193.08 mg/kg for Cr. Cd showed moderate enrichment (CdEF=31.03), while Cr had slight enrichment (CrEF=4.42). Both metals were mainly in the residual fraction (44.22 % for Cd, 69.02 % for Cr), followed by the Fe-Mn oxide-bound fraction (24.07 % for Cd, 18.51 % for Cr). The Risk Assessment Code (RAC) indicated moderate risk for Cd (10 %≤RAC<30 %) and low risk for Cr (1 %≤RAC<10 %). The Secondary Phase to Primary Phase ratio (RSP) suggested mild Cd pollution (1 

Chromium cycle in Red Soil Critical Zone constrained by chromium isotopes.

Chromium (Cr) isotopic system has been used to trace Cr pollution in the modern surface environment and redox change in the paleoenvironment. However, the transformation mechanism of Cr in soil and the accompanied Cr isotopic fractionation have not been clarified clearly. Here we measured Cr isotopic compositions (δ53Cr) of two paddy field profiles from the Red Soil Critical Zone Observatory in South China. The δ53Cr values of the young paddy fields, which have been cultivated for about 20 years, range from -0.34 ‰ to -0.22 ‰. The old paddy fields have been cultivated for >100 years and have more positive Cr isotopic compositions than the young paddy fields, from -0.20 ‰ to -0.06 ‰. The results of three-step leaching experiments show that iron and manganese oxides are enriched in heavy Cr isotopes, while organic matters have much lower Cr isotopic compositions, likely resulting from back reduction of Cr(VI). Our results suggest that Cr isotopic fractionation during the oxidation of Cr(III) is not the only reason for the depletion of heavy isotopes during oxidative weathering, and the partial back-reduction of generated Cr(VI) by organic matter plays an important role in Cr isotopic fractionation during weathering. Comparison between the old and young paddy fields further indicates that cultivation can significantly affect the Cr cycle in red soils. Paddy fields could be a potential sink for the Cr(VI) contaminant, and soils with a long history of cultivation would be more susceptible.

Chromium(VI) Adsorption and Reduction in Soils under Anoxic Conditions: The Relative Roles of Iron (oxyhr)oxides, Iron(II), Organic Matters, and Microbes.

Chromium (Cr) transformation in soils mediated by iron (Fe) (oxyhr)oxides, Fe(II), organic matter (OM), and microbes is largely unexplored. Here, their coupling processes and mechanisms were investigated during anoxic incubation experiments of four Cr(VI) spiked soil samples with distinct physicochemical properties from the tropical and subtropical regions of China. It demonstrates that easily oxidizable organic carbon (EOC, 55-84%) and microbes (16-48%) drive Cr(VI) reduction in soils enriched with goethite and/or hematite, among which in dryland soils microbial sulfate reduction may also be involved. In contrast, EOC (38 ± 1%), microbes (33 ± 1%), and exchangeable and poorly crystalline Fe (oxyhr)oxide-associated Fe(II) (29 ± 3%) contribute to Cr(VI) reduction in paddy soils enriched with ferrihydrite. Additionally, exogenous Fe(II) and microbes significantly enhance Cr(VI) reduction in ferrihydrite- and goethite-rich soils, and Fe(II) greatly promotes but microbes slightly inhibit Cr passivation. Both Fe(II) and microbes, especially the latter, promote OM mineralization and result in the most substantial OM loss in ferrihydrite-rich paddy soils. During the incubation, part of the ferrihydrite converts to goethite but microbes may hinder the transformation. These results provide deep insights into the geochemical fates of redox-sensitive heavy metals mediated by the complicated effects of Fe, OM, and microbes in natural and engineered environments.

Sunlight-Driven Direct/Mediated Electron Transfer for Cr(VI) Reductive Sequestration on Dissolved Black Carbon-Ferrihydrite Coprecipitates.

Surface runoff horizontally distributed chromium (Cr) pollution into various surface environments. Sunlight is a vital factor for the Cr cycle in the surface environment, which may be affected by photoactive substances such as ferrihydrite (Fh) and dissolved black carbon (DBC). Herein, sunlight-driven transformation dynamics of Cr species on DBC-Fh coprecipitates were studied. Under sunlight, the removal of aqueous Cr(VI) by DBC-Fh coprecipitates occurred through sunlight-driven reductive sequestration including adsorption, followed by surface reduction (pathway 1) and aqueous reduction, followed by precipitation (pathway 2). Additionally, coprecipitates with a higher DBC content exhibited a more effective reduction of both adsorbed (kapp,S_red) and aqueous Cr(VI) (kapp,A_red). Photoelectrons facilitated Cr(VI) reduction through direct electron transfer; notably, electron donating DBC promoted the production of photoelectrons by consuming photogenerated holes. Photogenerated Fe(II) species (mineral-phase and aqueous Fe(II)) mediated electron transfer for Cr(VI) reduction, which was reinforced via a ligand-to-metal charge transfer (LMCT) process between DBC-organic ligands and mineral Fe(III). Furthermore, ·O2- also mediated Cr(VI) reduction, although this impact was limited. Overall, this study demonstrates that photoelectrons and photogenerated electron mediators play a crucial role in Cr(VI) reductive sequestration on DBC-Fh coprecipitates, providing new insights into the geochemical cycle of Cr pollution in sunlight-influenced surface environments.

Ecological implications of chromium-contaminated effluents from Indian tanneries and their phytoremediation: a sustainable approach.

Industrial activities are paramount to sustaining the economy in a rapidly developing nation and global powerhouse like India. Leather industries are important in the country's economic map due to the high revenue and employment generation opportunities. Several of these industries contribute largely to environmental pollution. The pollution of the environment is mainly caused by improper disposal of the tannery effluents that are highly rich in hexavalent chromium, a potent human carcinogen. Hexavalent chromium imparts toxic effects on the biotic components, which include plants, animals, and humans. The review portrays the current status of the Indian leather tanning sector and its impact on the Indian economy. The process of chromium tanning and its adverse effects on the environmental biotic components have been briefly discussed. Phytoremediation of these effluents using suitable hyperaccumulating plants has been suggested as an eco-friendly and cost-effective approach for the sustainable restoration of the polluted environment. The mechanism behind the remediation approach and the factors influencing it have been detailed. The manuscript briefly discusses some important advancements in the field of phytoremediation and emerging technologies and concludes by emphasizing further research for sustainable management of tannery wastes.

Sight of Aged Microplastics Adsorbing Heavy Metal Exacerbated Intestinal Injury: A Mechanistic Study of Autophagy-Mediated Toxicity Response.

Contaminant-bearing polystyrene microplastics (PSMPs) may exert significantly different toxicity profiles from their contaminant-free counterparts, with the role of PSMPs in promoting contaminant uptake being recognized. However, studies investigating the environmentally relevant exposure and toxic mechanisms of aged PSMPs binding to Cr are limited. Here, we show that loading of chromium (Cr) markedly alters the physicochemical properties and toxicological profiles of aged PSMPs. Specifically, Cr-bearing aged PSMPs induced severe body weight loss, oxidative stress (OS), autophagy, intestinal barrier injury, inflammation-pyroptosis response, and enteropathogen invasion in mice. Mechanistic investigations revealed that PSMPs@Cr exacerbated the OS, resulting in intestinal barrier damage and inflammation-pyroptosis response via overactivated Notch signaling and autophagy/cathepsin B/IL-1ß pathway, respectively, which ultimately elevated mortality related to bacterial pathogen infection. In vitro experiments confirmed that autophagy-mediated reactive oxygen species (ROS) overproduction resulted in severe pyroptosis and impaired intestinal stem cells differentiation alongside the overactivation of Notch signaling in PSMPs@Cr-exposed organoids. Overall, our findings provide an insight into autophagy-modulated ROS overproduction within the acidic environment of autophagosomes, accelerating the release of free Cr from PSMPs@Cr and inducing secondary OS, revealing that PSMPs@Cr is a stable hazard material that induces intestinal injury. These findings provided a potential therapeutic target for environmental MPs pollution caused intestinal disease in patients.

Microscopic and macroscopic analysis of hexavalent chromium adsorption on polypyrrole-polyaniline@rice husk ash adsorbent using statistical physics modeling.

This paper contributed with new findings to understand and characterize a heavy metal adsorption on a composite adsorbent. The synthesized polypyrrole-polyaniline@rice husk ash (PPY-PANI@RHA) was prepared and used as an adsorbent for the removal of hexavalent chromium Cr(VI). The adsorption isotherms of Cr(VI) ions on PPY-PANI@RHA were experimentally determined at pH 2, and at different adsorption temperatures (293, 303, and 313 K). Multi-layer model developed using statistical physics formalism was applied to theoretically analyze and characterize the different interactions and ion exchanges during the adsorption process for the elimination of this toxic metal from aqueous solutions, and to attribute new physicochemical interpretation of the process of adsorption. The physicochemical structures and properties of the synthesized PPY-PANI@RHA were characterized via Fourier transform infrared spectroscopy (FTIR). Fitting findings showed that the mechanism of adsorption of Cr(VI) on PPY-PANI@RHA was a multi-ionic mechanism, where one binding site may be occupied by one and two ions. It may also be noticed that the temperature augmentation generated the activation of more functional groups of the composite adsorbent, facilitating the interactions of metal ions with the binding sites and the access to smaller pore. The energetic characterization suggested that the mechanism of adsorption of the investigated systems was exothermic and Cr(VI) ions were physisorbed on PPY-PANI@RHA surface via electrostatic interaction, reduction of Cr(VI) to Cr(III), hydrogen bonding, and ion exchange. Overall, the utilization of the theory of statistical physics provided fruitful and profounder analysis of the adsorption mechanism. The estimation of the pore size distribution (PSD) of the polypyrrole-polyaniline@rice husk ash using the statistical physics approach was considered stereographic characterization of the adsorbent (here PPY-PANI@RHA was globally a meso-porous adsorbent). Lastly, the mechanism of Cr(VI) removal from wastewater using PPY-PANI@RHA as adsorbent was macroscopically investigated via the estimation of three thermodynamic functions.

A novel organic chromo-fluorogenic optical sensor for detecting chromium ions.

Sensing trivalent chromium ion (Cr(III)) is widely applied in different areas, such as clinical analysis, marine, environmental monitoring, or even chemical industry applications. Cr(III) has a significant role in the physiological process of human life. It is classified as an essential micronutrient for living organisms. Herein, we developed and designed a novel optical Cr(III) ions sensor film. The investigated sensor has a relatively small dynamic range of 1.24 × 10-3 to 0.5 µM. We report a highly sensitive optical sensor film for Cr(III) ions based on diethyl 3,4-diaminothieno[2,3-b]thiophene-2,5-dicarboxylate (3D) probe. The optical characteristics of the chemical probe exhibit substantial emission at 460 nm under 354 nm excitation. Besides, the interaction of the Cr(III) ions with 3D involves a complex formation with a 2:1 (metal: ligand) ratio, which is convoyed by the main peak enhancement that centered at 460 nm of 3D, and the main peak is red-shifted to 480 nm. The easily discernible fluorescence enhancement effect is a defining characteristic of the complexation reaction between the 3D probe and Cr(III). On the basis of the substantial fluorescence mechanism caused by the formation of a (Cr(III)-3D complex, which inhibits the photo-induced electron transfer (PET) process, the devised optical sensor was proposed. This film exhibits exceptional sensitivity and selectivity due to its notable fluorescence properties, stock shift of less than 106 nm, and detection capabilities at a significantly low detection limit of 0.37 × 10-3 µM. The detection procedure is executed by utilizing a physiological pH medium (pH = 7.4) with a relative standard deviation RSDr (1 %, n = 3). In addition, the 3D sensor demonstrates a high degree of affinity for Cr(III), as determined by the calculation of its binding constant to be 1.40 × 106. We present an impressive optical sensor that is constructed upon a three-dimensional molecule.

Corrosion of Chromium Coating Fabricated on Zircaloy-4 Substrate.

In the nuclear industry, coated cladding is a topical problem and it is chosen as the near-term and most promising ATF (Accident-Tolerant Fuel) cladding concept. The main objective of this concept is to enhance the accident tolerance of nuclear power plants and accordingly, the performance of cladding is expected to be improved. This work assesses the corrosion performance of a Zircalloy-4 alloy coated with a thin chromium coating by MS (magnetron sputtering), tested under a CANDU (CANada Deuterium Uranium) reactor primary circuit simulated condition (LiOH solution, 10 MPa, 310 °C, pH = 10.5). The anticorrosive performance is evaluated by a gravimetric analysis, a metallographic analysis, X-ray diffraction, electronic microscopy, and electrochemical methods. A four times less gain mass was noticed compared to uncoated Zircaloy-4, indicating a smaller corrosion rate. The SEM micrographs illustrate that the coatings are still adherent, and they are keeping the initial morphological characteristics during the autoclaving process. A SEM cross-section analysis shows values of the thickness of the coatings between 0.8 and 1.46 µm. By XRD, the presence of Cr2O3 oxide is identified. Electrochemical testing confirms good stability and good corrosion performance of Cr coating over time under autoclave conditions.

Glucose Metabolism-Modifying Natural Materials for Potential Feed Additive Development.

Glucose, a primary energy source derived from animals' feed ration, is crucial for their growth, production performance, and health. However, challenges such as metabolic stress, oxidative stress, inflammation, and gut microbiota disruption during animal production practices can potentially impair animal glucose metabolism pathways. Phytochemicals, probiotics, prebiotics, and trace minerals are known to change the molecular pathway of insulin-dependent glucose metabolism and improve glucose uptake in rodent and cell models. These compounds, commonly used as animal feed additives, have been well studied for their ability to promote various aspects of growth and health. However, their specific effects on glucose uptake modulation have not been thoroughly explored. This article focuses on glucose metabolism is on discovering alternative non-pharmacological treatments for diabetes in humans, which could have significant implications for developing feed additives that enhance animal performance by promoting insulin-dependent glucose metabolism. This article also aims to provide information about natural materials that impact glucose uptake and to explore their potential use as non-antibiotic feed additives to promote animal health and production. Further exploration of this topic and the materials involved could provide a basis for new product development and innovation in animal nutrition.

Electrochemical Sensor Based on Glassy Carbon Electrode Modified with Carbon Nanohorns (SWCNH) for Determination of Cr(VI) via Adsorptive Cathodic Stripping Voltammetry (AdCSV) in Tap Water.

In this study, a new and simple glassy carbon electrode modified with carbon nanohorns (SWCNH/GCE) was used for the determination of Cr(VI) in aqueous matrices via adsorptive cathodic stripping voltammetry (AdCSV). The modified electrode was characterized via field emission scanning electron microscopy and cyclic voltammetry, which revealed a homogeneous distribution of spherical agglomerates of SWCNH on the electrode surface. The modification increased the electrochemically active area from 0.10 cm2 ± 0.01 (GCE) to 0.16 cm2 ± 0.01 (SWCNH/GCE). The optimized analytical conditions were as follows: a supporting electrolyte (0.15 mol L-1 HCl), an accumulation potential of 0.8 V versus Ag/AgCl, and an accumulation time of 240 s. Validation of the analytical methodology was performed, obtaining a linear range between 20 and 100 µg L-1, a limit of detection of 3.5 µg L-1, and a limit of quantification of 11.6 µg L-1 with good accuracy and precision. The method was applied to the analysis of spiked tap water samples, and the results were compared using a flame atomic absorption spectrophotometer (FAAS) with no significant statistical differences.