Evaluation Of Cr Research Articles

Synthesis, Characterization, Thermal aspects, Density Functional Theory study and in-vitro antibacterial evaluation of Cr(III) complexes based on Pyrazolone Phenylhydrazone Ligands

Synthesis, Characterization, Thermal aspects, Density Functional Theory study and in-vitro antibacterial evaluation of Cr(III) complexes based on Pyrazolone Phenylhydrazone Ligands

Study on Low‐Cycle Fatigue Behavior and Life Prediction of Cr–Ni–Mo–V Gun Steel at Room Temperature and 600 °C

ABSTRACTIn this paper, the low‐cycle fatigue fracture behavior and life prediction of Cr–Ni–Mo–V gun steel at room temperature and 600 °C are studied. The results indicated that at room temperature and 600 °C, the Cr–Ni–Mo–V gun steel exhibited obvious monotonic softening and cyclic softening. This behavior could be attributed to the formation of dislocation networks, dislocation walls, dynamic recovery, and dynamic recrystallization. As the temperature increased, the failure mode gradually shifted from mixed transgranular and intergranular fractures to intergranular fractures possibly owing to the reduced grain boundary strength and easy oxidation of the grain boundary at high temperatures. In addition, the fatigue life prediction model considering the influence of temperature is established by using the energy dissipation quadratic function, offering a practical method to improve the fatigue performance evaluation of Cr–Ni–Mo–V gun steel at various temperature.

Anticancer, Antioxidant and Antimicrobial Evaluation of Cr (III) and Rh(III) Complexes Derived from A New Mannich Base

The Mannich base ligand was synthesized in an ethanol medium through a condensation reaction of 2-mercaptobenzimidazole and ciprofloxacin at room temperature. Subsequently, several metal complexes of this ligand were prepared. To characterize both the base ligand and the metal complexes, various techniques were employed, including elemental analysis, FT-IR spectroscopy, UV-Vis spectroscopy, molar conductivity measurements, magnetic moment determination, and melting point analysis. The results were shown that the metal complexes formed have the formula [Cr(L)2Cl2] Cl.H2O and [Rh(L)2(H2O)2] Cl3.H2O, where L= mannich base ligand. Based on spectroscopic analytical, coordination with metal ions involves the 'N' donor atom of mannich base and 'N' atom of piprizaing ring, and two complexes are A six-coordinated octahedral structure is suggested. Molar conductivity of these complexes showed that they were electrolytic in nature. In this study, the anticancer and antioxidant potential of the Mannich base ligand and its metal complexes were investigated against MDA-MB-231 cell lines and using the DPPH free radical scavenging assay. Moreover, the in vitro efficacy of the ligand and its complexes against Gram-negative bacteria (E. coli) and Gram-positive bacteria (Staphylococcus aureus), as well as the fungal strain Candida albicans, was evaluated using the disc diffusion method. The results indicated that Cr (III) and Rh(III) complexes demonstrated the highest levels of cytotoxicity against MDA-MB-231 cell lines, enhances antioxidant and antimicrobial activity more than the free ligand. These findings suggest that these metal complexes may have promising applications in the development of novel anticancer, antioxidant and antimicrobial agents.

Amine-functionalized cellulose-silica composites for the remediation of hexavalent chromium (Cr IV) in contaminated water

Adsorption method for Hexavalent chromium (Cr(VI) removal from domestic and industrial wastewater is widely desirable due to public health concern of the heavy metal. The purpose of this study was to investigate the evaluation of Cr(VI) adsorption using a novel adsorbent: amine-functionalized cellulose-silica composite derived from banana fibers. We employed the in-situ sol–gel method to create cellulose-silica silane functionalized composites, analyzing them through different characterization techniques such as Attenuated total reflectance- Fourier transform infrared spectroscopy (ATR-FTIR), X-ray Diffraction Analysis (XRD), Thermo gravimetric analysis (TGA)/differential thermogravimetric (DTG), Brunauer–Emmett–Teller (BET), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) techniques. ATR-FTIR depicted key organic constituents in raw banana pseudo stem fibers (BF) and the formation of SiO bonds in BCSiO2 composite, and further enhanced by the grafting of N-[3-(trimethoxysilyl)propyl ethylenediamine (DAPTMS) onto the BC-SiO2 surface in BC-SiO2-DAPTMS. XRD and TGA/DTG analyses revealed changes in crystallinity and thermal stability, while BET analysis showcased altered surface area and pore characteristics in BC-SiO2-DAPTMS (2 %). SEM and TEM imaging provided visual evidence of structural modifications and improved dispersion in BC-SiO2-DAPTMS composites. The impact of composite weight, contact time, and pH on Cr(VI) removal rates was examined, revealing optimal performance at slightly acidic pH 4 value (80.7 %) and enhanced efficiency with increased contact time of 65 min (86.66 %), composite weight of 1 g (82.62 %), and initial concentration was for 0.8 mg/l (80 %). The kinetics and isotherms analyzed using pseudo second order (PSO) and pseudo first order (PFO) models, highlight the composite’s efficiency. The Freundlich model was found to better fit the adsorption isotherm data, while the PSO model described the kinetics more accurately. These insights contribute to optimizing the BC-SiO2-DAPTMS (2 %) composite for efficient Cr(VI) ion removal in water treatment applications.

Distribution and Comprehensive Risk Evaluation of Cr, Cd, Fe, Zn, and Pb from Al Lith Coastal Seawater, Saudi Arabia

Seawater contamination is a global challenge due to its hazardous effects on marine organisms and human health. Twenty-three surface seawater samples were collected from the Al Lith intertidal area along the Saudi Red Sea coast to evaluate the ecological risks and document the potential sources of Cr, Cd, Fe, Zn, and Pb. Contamination factor (CF), contamination degree (Cd), water quality index (WQI), and heavy metal pollution index (HPI), as well as multivariate tools were applied. The average concentrations of HMs (μg/L) had the following order: Zn (6.616) > Pb (0.284) > Cd and Cr (0.268) > Fe (0.197). CF results showed moderate contamination of seawater with Cd and low contamination of Cr, Fe, Zn, and Pb. However, 26.09% of the samples showed considerable contamination with Cd. Average Cd values revealed low contamination with HMs, while 17.39% of the samples showed moderate contamination. HPI average values indicated medium pollution of Al Lith seawater, while 13 samples reported high pollution. The higher HPI values were reported in samples characterized by higher concentrations of HMs, particularly Cd and Zn. Correlation matrix and principal component analysis suggested anthropogenic sources for Pb and Zn, mostly from industrial and agricultural effluents, landfilling, and domestic wastewater, apart from their natural sources.

Seasonal Variation of Heavy Metals in the Bivalves of a Major Fish Landing Centre in Mumbai

One of the most prevalent environmental contaminants found in aquatic ecosystems and its associated biota is considered to be heavy metals. The current study evaluated the heavy metal concentrations of Copper (Cu), Iron (Fe), Cadmium (Cd), Zinc (Zn), Manganese (Mn), Cobalt (Co), Chromium (Cr), Arsenic (As), Nickel (Ni), and Lead (Pd) in the soft tissues of M.casta and Paphia malabarica species seasonally for one year. The soft tissue of the two species were digested using a microwave digestion system (CEM-MARS-5) using nitric acid and perchloric acid. Evaluation of Cu, Ni, Cr, Mn, Co, Fe, and Zn was done using ICP-OES while for estimation of Pd, Cd and As, ICP-MS was used. During the study, Fe, Mn and Zn content dominated the whole soft tissues of both species. The findings demonstrated that the pre-monsoon season had higher amounts of the most examined heavy metals, whereas the monsoon season had the lowest quantities of these metals in the soft tissues of both species.

Cellular absorption and cytotoxic mitigation of heavy metals in mining vegetables in southwest China: Mechanistic insights and health implications

The existing health risk assessment models often rely on total concentrations of contaminants, neglecting cellular absorption, leading to an overestimation of risks due to a lack of toxicological verification. In this study, the content, bioaccessibility, and health risk evaluation of Cr, Ni, Cu, and As in vegetables from mining areas in Southwest China were examined. The cytotoxicity and gastric absorption of heavy metals and underlying mechanisms as well as the toxic mitigation approach after consumption of risky vegetables were explored. Our results showed that the heavy metals in cabbage, celery, and garlic seedlings were within the safety limit, even though grown in contaminated soils. The bioaccessibility of As, Cu, Ni, and Cr in vegetables in the gastric phase is from 6.92% to 81.15%, with mint having the highest bioaccessible concentrations of Cr (32.7 μg/kg), Cu (540.1 μg/kg), and As (103.9 μg/kg). The Hazard Quotient and Hazard Index values of the bioaccessible metals suggested an unacceptable cancer risk. Besides, the vegetable extracts increased cell apoptosis and tight junction disruption. Unexpectedly, the high-risk mint extract with the greatest bioaccessibility didn't cause cytotoxicity but inhibited cell apoptosis and enhanced cellular tight junction, evidenced by the upregulation of Zonula Occludens-1, Occludin, and Claudin 3, and a decrease in cellular heavy metal uptake. Furthermore, the mint extract could alleviate garlic seedling extract-induced cytotoxicity, indicating that the special substance in mint has protective effects. Taken together, special components in vegetables, cellular uptake, and toxicity of heavy metals should be considered in the accurate assessment of health risks.

Oxidation of chromium(Ⅲ): A potential risk of using chemical oxidation processes for the remediation of 2-chlorophenol contaminated soils

Chemical oxidation processes are widely used for the remediation of organically contaminated soils, but their potential impact on variable-valence and toxic metals such as chromium (Cr) is often overlooked. In this study, we investigated the risk of Cr(Ⅲ) oxidation in soils during the remediation of 2-chlorophenol (2-CP) contaminated soils using four different processes: Potassium permanganate (KMnO4), Modified Fenton (Fe2+/H2O2), Alkali-activated persulfate (S2O82−/OH−), and Fe2+-activated persulfate (S2O82−/Fe2+). Our results indicated that the KMnO4, Fe2+/H2O2, and S2O82−/Fe2+ processes progressively oxidized Cr(III) to Cr(Ⅵ) during the 2-CP degradation. The KMnO4 process likely involved direct electron transfer, while the Fe2+/H2O2 and S2O82−/Fe2+ processes primarily relied on HO• and/or SO4•- for the Cr(III) oxidation. Notably, after 4 h of 2-CP degradation, the Cr(VI) content in the KMnO4 process surpassed China's 3.0 mg kg−1 risk screening threshold for Class I construction sites, and further exceeded the 5.7 mg kg−1 limit for Class II construction sites after 8 h. Conversely, the S2O82−/OH− process exhibited negligible oxidation of Cr(III), maintaining a low oxidation ratio of 0.13%, as highly alkaline conditions induced Cr(III) precipitation, reducing its exposure to free radicals. Cr(III) oxidation ratio was directly proportional to oxidant dosage, whereas the Fe2+/H2O2 process showed a different trend, influenced by the concentration of reductants. This study provides insights into the selection and optimization of chemical oxidation processes for soil remediation, emphasizing the imperative for thorough risk evaluation of Cr(III) oxidation before their application.

Microwave-assisted functionalized biosorbent preparation using seed gum of Tamarindus indica: characterization and evaluation of Cr(VI) removal potency from tannery effluents

Microwave-assisted functionalized biosorbent preparation using seed gum of Tamarindus indica: characterization and evaluation of Cr(VI) removal potency from tannery effluents

Evaluation of Cr(VI) Removal from Tanning Effluents Using Magnetic Nanoparticles of Fe3O4 Synthesized with Olea europaea Bone Extract.

The tanning industry generates effluents with high chromium content, which require treatment prior to discharge into the sewage system. This article explores the use of magnetic magnetite nanoparticles (MNPs) to remove Cr(VI) from aqueous solutions, such as tanning effluents. The MNPs were synthesized by coprecipitation reaction using the Olea europaea extract as a reducing agent. Subsequently, they were characterized by dynamic light scattering spectroscopy (DLS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). MNPs with irregular morphology and diameters ranging from 73.28 to 162.90 nm were obtained. Cr(VI) removal was performed using jar test methodology, and its efficiency was evaluated in the laboratory for different initial Cr(VI) (mg/L) concentration and nanoparticle (g/L) concentration. A kinetic study was developed and indicated that the equilibrium adsorption mechanism corresponds to a pseudo-second-order model. Furthermore, the isotherm analysis revealed that chromium adsorption best fits the Langmuir isotherm. Finally, Cr(VI) removal rates from 85% to 100% were achieved in tanning and retanning effluents.

Experimental corrosion resistance evaluation of Cr–Mo-Mn steel surface modified with titanium and nitrogen ions

Experimental corrosion resistance evaluation of Cr–Mo-Mn steel surface modified with titanium and nitrogen ions

In Situ Evaluation of Cr(VI) Bioavailability and Rhizosphere Effects in Reduced Cr-Contaminated Soil Based on Diffusive Gradients in Thin Films Technique

The transformation between Cr(III) and Cr(VI) occurs in Cr-contaminated soil, which can be regulated by root-soil interactions, under natural conditions. In situ investigation of the effectiveness of different reductants in reducing Cr(VI) to Cr(III), and thereby the reoccurrence risk in reduced Cr-contaminated soil, can improve the understanding of Cr biogeochemistry and toxicity. Traditional and high-resolution diffusive gradients in thin films (DGT) were used to measure Cr(VI) availability and rhizosphere effect controlling the chemical behaviors of Cr(VI) in the rice rhizosphere microdomain. The Cr(VI) concentration in the soil solution (Csoln) of the rhizosphere region varied according to the reductant type and followed the order: Molasses > CaS4 >Fe(II). Rice root activity increased the Csoln in the rhizosphere region by 2.16 μg/L, 1.90 μg/L, and 1.08 μg/L for Fe(II), CaS4, and Molasses treatments, respectively. The Cr(VI) concentration measured by DGT (CDGT) in the reduced Cr-contaminated soils increased from 0.96–1.17 μg/L in the bulk region to 1.23–1.76 μg/L in rhizosphere region. The variation in the effective concentration of Cr(VI) (CE) was similar to that of Csoln in the rice rhizosphere microdomain. Csoln accounted for 14.71–19.36% of the CE, further suggesting that bioavailable Cr(VI) mainly originated from the replenishment from the solid phase. The sequence of the average Cr(VI) flux in the reduced Cr-contaminated soil was Molasses, CaS4, and Fe(II). Except for Molasses, there was no obvious Cr(III) in Fe(II) and CaS4. For Fe(II), a higher phosphate flux in the rhizosphere microdomain hindered Cr(VI) uptake. High-resolution imaging provides a theoretical basis for the bioavailability evaluation and remediation of Cr-contaminated soil. Compared with CaS4 and Molasses, Fe(II) was the most effective reductant for remediating Cr-contaminated soils.

Evaluation of Cr (VI) retention in soils of varying carbonate in arid land (Djelfa – Algeria)

Pollution by Chromium (Cr) presents a serious problem that may affect both health and the environment. This study aims to evaluate the contribution of carbonates to chromium sorption/desorption in soils with different concentrations of carbonates in the Djelfa region. The retention study was based on three soils with different total limestone concentrations. A physico-chemical analysis of the soils, followed by a sorption study by modifying some sorption parameters, and finally a comparison of chromium retention. According to the findings, sorption followed pseudo-second-order kinetics with a good regression value R². The activation energies were 12.85 and 16.44 kJ mol-1, implying a physical sorption mechanism. The data agree with the Freundlich model.

Toluene-mercuric modified USEPA Method 3060A to eliminate interference of sulfide-based reductants with Cr(VI) determination

The validity of USEPA Method 3060A as universal Cr(VI) analysis method for remediated soil is controversial. We investigated soil Cr(VI) remediation performance by commonly used reductants (FeSO4, CaSx, Na2S) under different operating conditions (dosage, curing time and degree of mixing) using Method 3060A, and developed modified 3060A specific for sulfide-based reductants. Results showed that Cr(VI) was primarily removed during analysis stage rather than remediation stage. Thereinto, chemical dosage played a much more important role than curing time and degree of mixing. Besides, soil Cr(VI) concentration decreased to below the detection limit with residual reductant content increasing. Comparing standard and toluene-mercuric modified 3060A, Cr(VI) removal efficiency decreased from 100 % to 38.9–45.4 %, 67.1–68.8 % and 94.1–96.3 %, corresponding to mixing degree of 33 %, 67 % and 100 %, for treated soil using 1× and 2× the molar stoichiometric ratio of CaSx. Subsequently, the optimization mechanism was revealed. Elemental sulfur, remediation product of sulfide-based reductants, was removed from soil by toluene preventing its disproportionation to sulfide at Method 3060A stage. Sulfide was fixed by mercuric oxide in species of mercuric sulfide. This method also proved suitable for different types of soils. Therefore, an effective way for scientific evaluation of soil Cr(VI) remediation was provided in this study.

Screening and evaluation of Cr(VI) biosorption potential of metal-resistant bacteria isolated from Sukinda chromite mine soil of Odisha

Screening and evaluation of Cr(VI) biosorption potential of metal-resistant bacteria isolated from Sukinda chromite mine soil of Odisha

Heavy Metals in Sediments of Hulun Lake in Inner Mongolia: Spatial-Temporal Distributions, Contamination Assessment and Source Apportionment

The spatial and temporal distributions, contamination evaluation, and source apportionment of Cu, Zn, As, Pb, Cd, and Cr in the sediments of Hulun Lake were explored in this work. The pollution characteristics of six heavy metals were assessed by single factor pollution index (PI) and geo-accumulation index (Igeo). The sources of heavy metals in the surface sediments were analyzed by the positive definite matrix factorization (PMF) and Pearson correlation analysis. The sedimentary records of heavy metals in core sediments were reproduced by radioisotopes. The average concentrations of 6 heavy metals except Cd were lower than the corresponding background values. The spatial distributions of Cu, Zn, Cr, Cd and As were generally similar and showed higher abundances in the southwestern part of the lake. With the use and import of heavy metals, the concentration of heavy metals in core sediments increased with the fluctuation of years. The peak of heavy metal concentration was related to the high growth rate of gross domestic product in 2003-2008. The single factor pollution index and geo accumulation index results showed that the surface sediment was mainly polluted by Cd, followed by Zn and As. Natural parent material, agricultural activities and industrial activities were the main sources of heavy metal pollution in the sediments, accounting for 17.03%, 26.34%, and 56.63% of the total heavy metal accumulation, respectively. Pb was derived mainly from natural parent material. Cd and As were closely associated with agricultural activities. Cu and Zn were mainly attributed to industrial mining activities. Source apportionment of the ecological risks of heavy metals illustrated that industrial sources were the primary ecosystem risk sources (66.1%), followed by agricultural sources (23.75%) and natural sources (10.15%). The results will also provide reference data for future studies of heavy metals pollution in sediments from Hulun Lake and other lakes.

Network pharmacology-based and pharmacological evaluation of the effects of Curcumae Radix on cerebral ischemia–Reperfusion injury

Objective: This study aimed to investigate the network pharmacology of curcumae radix (CR, Yujin) and explore the mechanism of CR in the treatment of cerebral ischemia–reperfusion injury (CIRI). Materials and Methods: Network analysis and pharmacological evaluation were performed to explore the protective role of CR to treat CIRI. The potential target genes of the active components and CIRI were identified using SwissTarget Prediction, Bioinformatics Analysis Tool for Molecular mechANism of Traditional Chinese Medicine, GeneCards, and Online Mendelian Inheritance in Man. Furthermore, network analysis was performed using Cytoscape software. Gene ontology analysis and Kyoto Encyclopedia of Genes and Genomes enrichment analysis were performed using the R software. In vivo experiments were performed using the water extract of CR (WECR) on PC12 cells induced by hypoxia/reoxygenation (H/R) to simulate ischemia/reperfusion injury. Results: The results exhibited that 21 active compounds identified in CR were associated with 73 targets of CIRI. Functional analysis showed that multiple pathways, including response to stress, regulation of apoptotic process, and hypoxia-inducible factor 1 signaling pathway, were significantly enriched. In addition, STAT3, IL4, HIFIA, and CTNNB1 were predicted to be the most important genes among the 36 hub genes. Furthermore, WECR treatment significantly improved PC12 cell injury and decreased apoptosis levels in cells induced by H/R, with malondialdehyde contents reduced and superoxide dismutase or glutathione peroxidase levels increased. Conclusions: Network analysis and pharmacological evaluation of CR could provide valuable directions for further research on CR and improve comprehension of CIRI.

Coagulation characteristic and mechanism of Fe(III) salts toward typical Cr(III) complexes in wastewater treatment.

Cr(III) complexes are typical pollutants in various industrial wastewater and pose a serious threat to the ecosystem and humans. The coagulation process is commonly used in water treatment plants, yet its removal characteristic and mechanism toward Cr(III) complexes have been rarely reported. In this study, the Fe(III) coagulation process was adopted for the evaluation of Cr(III) complex removal in terms of Cr residual concentration as well as floc size. The results showed that Fe(III) with a dose of 0.8mM removed more than 80% of total Cr for Cr3+ and Cr(III)-acetate, whereas poor removal rate (~ 50%) was obtained for Cr(III)-citrate under the same conditions. Neutral and alkaline conditions facilitated Cr(III)-acetate removal by Fe(III) coagulation, while limited influence was observed for Cr(III)-citrate with various pH. The main removal mechanism of Cr(III)-acetate was precipitation. Cr(III)-citrate elimination largely relied on the adsorption property and sweeping effect of Fe floc. Moreover, Cr(III)-acetate was easier to be separated from a solution since the generated floc sizes were 270μm. Flocs that formed in the Cr(III)-citrate treatment were only 0.3μm, resulting in separation difficulties during the coagulation process. The presence of Cr(III)-acetate and Cr(III)-citrate caused a significant decline in membrane flux. This study provided fundamental knowledge of Fe coagulation treatment in Cr(III) complex-containing wastewater.

Bioaccessibility and bioavailability evaluation of heavy metal(loid)s in ginger in vitro: Relevance to human health risk assessment

Ginger is a common spice in everyday diet. However, over time, it may absorb and accumulate heavy metal(loid)s (HMs) from the soil, posing a potential health risk to humans. In this study, we evaluated the pollution level, bioavailability, mobility evaluation, and health risk of Cr, Pb, Cd, and As in the soil–ginger system of five major ginger-producing cities in Shandong Province, China. Research indicated the concentrations of the Cr, Pb, Cd, and As in the soil were close to or even higher than background value, except Weifang. With the concentrations of Cr, Pb, Cd, and As in ginger being 0.08–0.47, 0.03–0.16, 0.002–0.03, and 0.006–0.028 mg/kg, the four HMs concentrations were within the limits of 0.1–0.5 mg/kg based on the Chinese health standard (GB2762–2017) of HMs in food. The bioavailability of HMs in soils was evaluated using diethylenetriaminepentaacetic acid (DTPA) and nitric acid (HNO3) extraction and the results showed that Pb and Cd have high bioavailability. Mobility evaluation of HMs from soil to ginger based on Pearson's correlation and the partial least squares–path method (PLS-PM) model showed that the soil's physicochemical properties influence the HMs migration process (especially Cd and Pb) in the soil–ginger system, and the PLS-PM model has good adaptability to Cd and Pb (gof > 0.5). The mean total carcinogenic risk (TCR) of bioaccessible gastric and intestinal HMs were 4.64 × 10−6 and 3.13 × 10−6, which were much lower than that of total HMs (2.60 × 10−5), indicating that existing models based on total HMs may overestimate the health risk of HMs. The bioaccessible concentrations should be considered to improve the accuracy of assessment results.

Enhanced carbon solubility in solvent for SiC rapid solution growth: Thermodynamic evaluation of Cr–Ce–Si–C system

The carbon dissolution in solvent plays a key role in the process of solution growth route for SiC single crystal, which could determine the growth rate and quality of the products. However, the carbon dissolving ability of binary alloy solvent still needs to be improved. Here, we demonstrate the improved carbon dissolution and enlarged carbon supersaturation in Cr–Ce–Si ternary solvent, showing great potential for SiC solution growth. The phase relations of Cr–Ce–Si–C system were determined by using CALPHAD method based on thermodynamic parameters of CeCr2Si2C. It is indicated that the Cr–Ce–Si ternary solvent shows much larger carbon solubility in temperature range from 1700 to 2000 °C compared to Cr–Si binary one. Furthermore, the carbon supersaturation in solvent is also significantly increased in low temperature range after the addition of Ce, leading to a rapid growth rate. Our work not only demonstrates the feasibility of adding Ce in the alloy solvent for rapid growth of SiC crystal, but also provides an example for investigating the C solubility in ternary solvent.