16065-83-1

Basic information

• Product Name: CHROMIUM(III)
• Synonyms: TRIVALENTCHROMIUM;Chromium (III), insoluble salts
• CAS NO: 16065-83-1
• Molecular Formula: Cr+3
• Molecular Weight: 52.00
• Mol File: 16065-83-1.mol
• Article Data: 86

Chemical Properties

• Melting Point: 1470 °C
• Appearance: /
• CAS DataBase Reference: CHROMIUM(III)(CAS DataBase Reference)
• NIST Chemistry Reference: CHROMIUM(III)(16065-83-1)
• EPA Substance Registry System: CHROMIUM(III)(16065-83-1)

Safety Data

• Hazardous Substances Data: 16065-83-1(Hazardous Substances Data)

Usage

General Description

Chromium(III) is a chemical element with the symbol Cr and atomic number 24. It is a hard and lustrous metal that is commonly found in various minerals, including chromite. Chromium(III) compounds are often utilized in industrial processes, such as in the production of stainless steel, as well as in the manufacturing of pigments and dyes. This chemical element is also an essential trace mineral for the human body and is involved in numerous physiological processes, including glucose metabolism and insulin function. However, excessive exposure to chromium(III) compounds can pose health risks, leading to respiratory issues, skin irritation, and potential carcinogenic effects. Therefore, it is essential to handle and use chromium(III) compounds with care to minimize the potential for harmful effects on human health and the environment.

InChI:InChI=1/Cr/q+3

Upstream product

• 99-09-2 3-nitro-aniline 
• 84-65-1 9,10-phenanthrenequinone 
• 14683-12-6 Te(VI) 
• 13907-47-6 dichromate anion 
• 7440-66-6 zinc 
• 63-68-3 L-methionine 
• 13907-45-4 chromate(VI) ion 
• 932-90-1 Benzaldoxime 
• 106-51-4 p-benzoquinone 
• 14683-12-6 tellurium(IV) 
• 60764-48-9 i-propylpentaaquochromium(III) 
• 18540-29-9 chromium (VI) 
• 74-99-7 prop-1-yne 
• 155026-88-3 superoxochromium(III) ion 

Downstream Products

• 13907-45-4 chromate(VI) ion 
• 18540-29-9 chromium (VI) 
• 15723-28-1 chromium(IV) 
• 16397-91-4 manganese(II) 
• 18898-57-2 chromium(III) diethyldithiocarbamate 
• 22541-79-3 chromium (II) 
• 127621-10-7 {Cr(C₁₈H₁₄N₃O₃S)3} 
• 15279-76-2 {Cr(C₆H₅N₂O₂)3} 
• 74344-71-1 tetraphenylporphyrinatochlorochromium 
• 41509-53-9 tris(ethylenediamine)chromium(III) 

Relevant articles and documents

Kinetics and mechanism of the oxidation of l-methionine by aqueous solution of chromium(VI)

The kinetics of the reduction of Cr(V1) by l-methionine (represented by RSCH3) have been studied in aqueous perchloric acid. The data are consistent with the rate law: -d[Cr(VI)] dt = (k1 + k2[H+]2[RSCH3])[Cr(VI)] with k1 = (3.1 ± 0.5) x 10-4 s-1; k2 = 12.3 ± 1.1 mol-3 dm9 s-1 at I = 1.0 mol dm-3 (NaClO4), [H+] = 40.04-0.10 mol dm-3 and T 25.1°C. The corresponding activation parameters are ΔH1* = 26.2 ± 0.4 kJ mol-1; ΔS1* = -224± 1 JK-1 mol-1; ΔH1* = 33.9±0.01 KJ mol-1; ΔS1* -111±1 JK-1 mol-1. The above rate is very much slower than those of other related reactions. This is interpreted in terms of a rate-determining CrS bonded intermediate which undergoes hydrolysis after electron transfer to yield Cr(III) and methionine sulphoxide. The significance of pathways involving second-order substrate dependence is also discussed.

Excellent photoreduction performance of Cr(vi) over (WO4)2--doped metal organic framework materials

A new conductive metal-organic-framework (MOF) photocatalyst, (WO4)2-doped bismuth terephthalate (referred to as nNa2WO4BiBDC), was synthesized and characterized by varying the precursor molar ratio (n = 0.1, 0.3, 0.4, and 0.5) of Na2WO4/Bi(NO3)3 in the presence of terephthalic acid through a one-pot solvothermal process. This study found that doping (WO4)2- into BiBDC enhanced the separation of photo-generated carriers, improved the photocatalytic properties of bismuth terephthalate (BiBDC), and enabled the application in Cr(vi) reduction under UV light irradiation with the synergic effect from citric acid acting as a hole scavenger. Among all the precursor ratios of Na2WO4/Bi(NO3)3 used, 0.4Na2WO4BiBDC has the optimum performance, leading to triple gain in reduction efficiency for undoped BiBDC. The synthetic strategy to dope (WO4)2- into a layered MOF as a viable option for modification of MOFs was demonstrated in this study. Finally, the photoreduction of Cr(vi) by (WO4)2-doped bismuth terephthalate enables a new promising wastewater treatment option. This journal is

Highly efficient and bifunctional Cd(II)-Organic Framework platform towards Pb(II), Cr(VI) detection and Cr(VI) photoreduction

Lead and chromate/dichromate are widely used in manufacturing industry, but Pb(II) and Cr(VI) ions pose fatal threats to human health and the water ecological environment. It is thus highly desirable to develop novel and valid strategies for rapid detection and effective decontamination of these heavy metal ions. Design and assembly of luminescent Metal-Organic Framework (LMOFs) for effective recognition and removal of Pb(II) and/or Cr(VI) from water provide a feasible avenue to address this issue. Herein, a novel Cd(II)-MOF, [(Cd3L2)]·(solvent)x (labeled as compound 1) with bright blue fluorescence was assembled under the solvothermal reaction of triangular ligand 5'-(5-carboxy-1H-benzo [d]imidazole-2-yl)-[1,1':3′,1″-terphenyl]-4,4″-dicarboxylic acid (H3L) and Cd(NO3)2. Given that the unique structure features of 3D stacking framework, i. e. strong π···π conjugative effects of organic linkers, plentiful free imidazole N atoms and carboxyl O atoms, Cd-MOF of 1 was deliberately deployed as bifunctional platform to sense Pb(II)/Cr(VI) and photochemically reduce Cr(VI) to Cr(III). Notably, 1 emits durable bright blue fluorescence and performs rapid quenching sense for Pb2+, Cr2O72? and CrO42?, with ultra low detection limits of 1.89, 4.83 and 2.84 ?ppb, respectively. Moreover, highly toxic Cr(VI) could be rapidly and thoroughly reduced to Cr(III) ions by 1 under the irradiation of mercury lamp, with reliable recycling ability. The possible photoluminescence, quenching and photocatalytic reduction mechanisms also were tentatively proposed.

Synthesis and Characterization of CeO2 Nanoparticles via Solution Combustion Method for Photocatalytic and Antibacterial Activity Studies

CeO2 nanoparticles have been proven to be competent photocatalysts for environmental applications because of their strong redox ability, nontoxicity, long-term stability, and low cost. We have synthesized CeO2 nanoparticles via solution combustion method using ceric ammonium nitrate as an oxidizer and ethylenediaminetetraacetic acid (EDTA) as fuel at 450°C. These nanoparticles exhibit good photocatalytic degradation and antibacterial activity. The obtained product was characterized by various techniques. X-ray diffraction data confirms a cerianite structure: a cubic phase CeO2 having crystallite size of 35 nm. The infrared spectrum shows a strong band below 700 cm-1 due to the Ce-O-Ce stretching vibrations. The UV/Vis spectrum shows maximum absorption at 302 nm. The photoluminescence spectrum shows characteristic peaks of CeO2 nanoparticles. Scanning electron microscopy (SEM) images clearly show the presence of a porous network with a lot of voids. From transmission electron microscopy (TEM) images, it is clear that the particles are almost spherical, and the average size of the nanoparticles is found to be 42 nm. CeO2 nanoparticles exhibit photocatalytic activity against trypan blue at pH 10 in UV light, and the reaction follows pseudo first-order kinetics. Finally, CeO2 nanoparticles also reduce CrVI to CrIII and show antibacterial activity against Pseudomonas aeruginosa.

Kinetic Salt Effects on the Reaction between the Cobalt(III) Ion, Co(sep)3+, and the Hexa-aquochromium(II) Ion

Highly specific effects are shown by different salts on the title reaction.Some salts increase the rate by a factor between ca. two and four, whereas for others the increase is between 30 and over a 1000 times.This is attributed to the formation of highly reactive ion pairs (or triplets), whose formation constants have been evaluated, in some cases, from the kinetic data at constant ionic strength.These ion pairs involve essentially the CrII reactant, and their high reactivity is related to the rate of formation of the precursor complex and/or to the rate of electron transfer within the precursor complex.

Construction of Hierarchical Hollow Co9S8/ZnIn2S4 Tubular Heterostructures for Highly Efficient Solar Energy Conversion and Environmental Remediation

Visible-light-responsive hierarchical Co9S8/ZnIn2S4 tubular heterostructures are fabricated by growing 2D ZnIn2S4 nanosheets on 1D hollow Co9S8 nanotubes. This design combines two photoresponsive sulfide semiconductors in a stable heterojunction with a hierarchical hollow tubular structure, improving visible-light absorption, yielding a large surface area, exposing sufficient catalytically active sites, and promoting the separation and migration of photogenerated charges. The hierarchical nanotubes exhibit excellent photocatalytic H2 evolution and CrVI reduction efficiency. Under visible-light illumination, the optimized Co9S8/ZnIn2S4 heterostructure provides a remarkable H2 generation rate of 9039 μmol h?1 g?1 without the use of any co-catalysts and CrVI is completely reduced in 45 min. The Co9S8/ZnIn2S4 heterostructure is stable after multiple photocatalytic cycles.

Kinetics and mechanism of the vanadium(IV) oxidation of the (hydroxymethyl)chromium(III) ion

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The enhanced properties in photocatalytic wastewater treatment: Sulfanilamide (SAM) photodegradation and Cr6+ photoreduction on magnetic Ag/ZnFe2O4 nanoarchitectures

Ag/ZnFe2O4 nanoarchitectures composed of ZnFe2O4 nanoparticles loading onto Ag nanowires were fabricated by hydrothermal method. The Ag/ZnFe2O4 nanocomposites possessed excellent performanc

Regulation of band edge and specific surface area of BixInyOCl microsphere for excellent photocatalytic performance

In order to solve the problem of low efficiency of existing photocatalyst in wastewater treatment, BiOCl and BixInyOCl solid solution photocatalysts with different indium element content were prepared by one-step solvothermal method. The solid solution of indium element greatly affects the porous structure and specific surface area of BiOCl, and the specific surface area of BiInOCl-0.5 is 9.26 times that of BiOCl, which provides abundant active sites for photocatalytic reaction. Furthermore, after indium element solid solution, the conduction band and valence band potentials of BiOCl shift towards negative and positive, respectively, enhancing the redox capacity of the photogenerated electrons and holes. Thus, BiInOCl shows excellent photocatalytic performances for reduction of Cr(VI), degradation of norfloxacin, dyes and even industrial cotton pulp wastewater. This provides a possibility for the practical application of photocatalytic technology in industrial wastewater treatment.

Stable Layered Semiconductive Cu(I)-Organic Framework for Efficient Visible-Light-Driven Cr(VI) Reduction and H2 Evolution

Metal-organic frameworks (MOFs) have gained tremendous attention in the fields of environmental restoration and sustainable energy for their potential use as photocatalyst. Herein, a new two-dimensional (2D) Cu(I)-based MOF material showing a narrow forbi

Constructing Ag2O nanoparticle modified TiO2 nanotube arrays for enhanced photocatalytic performances

Currently, the silver-based semiconductor modified TiO2 nanotube arrays (TiO2 NTA) for the improved photocatalytic treatment of industrial waste water have been a hot topic. The simple synthesis and environmental application of photocatalysts with excellent photocatalytic ability is still a big challenge. Herein, We reported the successive ionic layer adsorption and reaction (SILAR) preparation of Ag2O nanoparticles on TiO2 NTA surfaces. The different deposition cycles were performed to investigate the influence of Ag2O deposition amounts on the photoelectrochemical activity. Results revealed that the S-10 fabricated with 10 SILAR cycles had the impressive photocatalytic and photoelectric conversion performances. The visible light photovoltage and photocurrent of S-10 electrode were ?0.20 V and 463.2 μA/cm2. Moreover, the photocatalytic degradation efficiencies of MO, RhB and MB dyes achieved 67.40percent, 59.19percent and 93.89percent, respectively. Further increasing the irradiation time, the mineralization degree of organic dyes were improved up to 71.28percent, 60.31percent, and 92.58percent after 6 h solar irradiation. Cr(VI) ions were also dramatically removed by photocatalysts. The remarkable photocatalytic performance of Ag2O/TiO2 NTA would exhibit attractive prospect in the industrial waste water purification.

Photo-reduction of heavy metal ions and photo-disinfection of pathogenic bacteria under simulated solar light using photosensitized TiO2 nanofibers

We report the photosensitization of electrospun titania nanofibers, with a mean diameter of 195 nm, by low bandgap silver sulfide nanoparticles of 11-23 nm mean size with the aim of treating heavy metal ions and pathogenic bacteria simultaneously under simulated solar light irradiation. The 17 nm Ag2S/TiO2 nanofibers showed 90% photocatalytic reduction of Cr(vi) at pH of 3 with a pseudo-first order rate constant of 0.016 min-1 which is significantly better than the previously reported for Ag-Ag2S/TiO2 composite particles. The antibacterial capability of the Ag2S/TiO2 nanofibers was evaluated via photo-disinfection of the Gram-positive and Gram-negative bacterial strains. The smallest sized 11 nm Ag2S/TiO2 nanofiber showed the best bactericidal efficiency of 100% and 90.6% against Gram-negative E. coli and Gram-positive S. aureus after 1 h of irradiation, respectively, whereas, only 50% E. coli and 41% S. aureus were found to be inactivated in dark. Furthermore, a UV-O3 treatment of the 11 nm Ag2S/TiO2 nanofibers remarkably enhanced the antibacterial activity where 89% E. coli and 81% S. aureus were inactivated in just 10 min of the irradiation. Enhanced photocatalytic activity is attributed to the efficient charge separation and transfer and reduced electron-hole recombination induced by the effective heterojunction formation between TiO2 and the optimally sized Ag2S nanoparticles. The disinfection nature of the Ag2S nanoparticles, role of the generated hydroxyl species under irradiation, and the cell wall damage mechanism is also discussed. This study demonstrates the potential use of these multifunctional composite TiO2 nanofibers for water remediation.

Kinetics and mechanism of the chromic oxidation of 3-O-methyl-d-glucopyranose

The oxidation of 3-O-methyl-d-glucopyranose (Glc3Me) by CrVI in acid medium yields CrIII, formic acid and 2-O-methyl-d-arabinose as final products when a 50-times or higher excess of Glc3Me over CrVI is used. The redox rea

A size tunable bimetallic nickel-zinc nitride as a multi-functional co-catalyst on nitrogen doped titania boosts solar energy conversion

To enable high-efficiency solar energy conversion, rational design and preparation of low cost and stable semiconductor photocatalysts with associated co-catalysts are desirable. However preparation of efficient catalytic systems remains a challenge. Here, N-doped TiO2/ternary nickel-zinc nitride (N-TiO2-Ni3ZnN) nanocomposites have been shown to be a multi-functional catalyst for photocatalytic reactions. The particle size of Ni3ZnN can be readily tuned using N-TiO2 nanospheres as the active support. Due to its high conductivity and Pt-like properties, Ni3ZnN promotes charge separation and transfer, as well as reaction kinetics. The material shows co-catalytic performance relevant for multiple reactions, demonstrating its multifunctionality. Density functional theory (DFT) based calculations confirm the intrinsic metallic properties of Ni3ZnN. N-TiO2-Ni3ZnN exhibits evidently improved photocatalytic performances as compared to N-TiO2 under visible light irradiation.

Controlled growth of single-crystalline Bi.333(Bi6S9)Br nanorods under hydrothermal conditions for enhanced photocatalytic reduction of Cr (VI)

The rational design of composition and structure of the photocatalytic materials is especially critical for the practical application of photocatalytic technology. Herein, uniform single-crystal Bi.333(Bi6S9)Br nanorods were synthesized for the first time using a one-pot hydrothermal method. By prolonging the hydrothermal reaction time, the evolution process of Bi.333(Bi6S9)Br from nanoparticles to short nanorods, and finally to long nanorods was observed. Bi.333(Bi6S9)Br nanorods can effectively inhibit the recombination of photogenerated electron-hole pairs and effectively adsorb of Cr (VI) due to the presence of surface defects and unique structure, thereby promoting the photocatalytic activity. Bi.333(Bi6S9)Br nanorods exhibited excellent photocatalytic performance as well as promising recyclability in rapidly reducing aqueous Cr (VI) to Cr (III) under visible light. The degradation rate of Cr (VI) reached 90.96percent within 60 min, and the structure of Bi.333(Bi6S9)Br did not change after six photocatalytic cycles. The photocatalytic reaction mechanism of nanorods was proposed based on the band structure of Bi.333(Bi6S9)Br and electron spin resonance radical scavenging assay.

Boosting the photoreduction activity of Cr(vi) in metal-organic frameworks by photosensitiser incorporation and framework ionization

It is mandatory to decontaminate Cr(vi) species from water streams due to their high toxicity. The photoreduction of hazardous Cr(vi) to nontoxic Cr(iii) is a very promising approach to control Cr(vi) pollution. Although some MOFs and their composites have been employed as photocatalysts to reduce toxic Cr(vi), their catalytic activities are always limited by inefficient visible light absorption and inferior Cr(vi) adsorption performances. Herein, cationic Ru-UiO-dmbpy(1) that is decorated with a high density of cationic charges and also embedded with catalytically competent and visible light harvesting moieties (i.e. Ru(bpy)3) was successfully synthesized by a sequential mix-and-match and ionization process. The presence of Ru(bpy)3 moieties makes Ru-UiO-dmbpy(1) an excellent visible-light harvester, extending the absorption edge from 420 nm for pristine UiO-bpy to about 780 nm for Ru-UiO-bpy/Ru-UiO-dmbpy(1). Driven by ion exchange, Ru-UiO-dmbpy(1) shows a large adsorption rate constant (k2) of 1.33 × 10-2 g mg-1 min-1 in the adsorption of Cr2O72-, which is 8.26 times that of pristine UiO-bpy and 6.27 times that of the non-ionization counterpart Ru-UiO-bpy(1) under the same adsorption conditions. The equilibrium Cr2O72- uptake capacity of Ru-UiO-dmbpy(1) reaches 101.8 mg g-1, which is about 1.98 and 1.81 times that of UiO-bpy and Ru-UiO-bpy(1), respectively. With an efficient visible light absorption ability and superior Cr(vi) adsorption performance, Ru-UiO-dmbpy(1) shows a reaction rate constant (k1) of 0.011 min-1 in the photoreduction of Cr(vi) without any sacrificial agents under visible light illumination, which is much larger than those of pristine UiO-bpy (0.003 min-1) and its non-ionization counterpart Ru-UiO-bpy(1) (0.007 min-1) under the same conditions. The result unambiguously demonstrates that the Cr(vi) photoreduction activity could be largely enhanced by photosensitiser introduction and framework ionization. To further evaluate the catalytic performance of Ru-UiO-dmbpy(1), Cr(vi) reduction was also investigated in the presence of various sacrificial agents. Remarkably, a high Cr(vi) photoreduction rate of 6.4 mgCr(VI) gcatalyst-1 min-1 was obtained when benzyl alcohol was used as a sacrificial agent, which is a record value among those reported for MOF-based photocatalysts. This journal is

Fabrication of CuO/ZnO composite films with cathodic co-electrodeposition and their photocatalytic performance

CuO/ZnO composite films with different atomic Cu/Zn ratios were for the first time fabricated on indium tin oxide (ITO)-coated glass substrates via a cathodic co-electrodeposition route from baths containing Zn(NO 3)2 and Cu(CH3COO)2. The obtained composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Hexavalent chromium (Cr(VI)) was used as a model pollutant to evaluate their photocatalytic activity. For a bath containing Zn(NO3)2 with a certain concentration, the concentration of Cu2+ ions added into this bath play an important role in fabrication of CuO/ZnO composite films. When the Cu2+ concentration in a bath is lower, the obtained composite is a Cu-doped ZnO film. The electrodeposited CuO/ZnO composite films show higher photocatalytic activity towards reduction of Cr(VI) compared to pure ZnO both under UV and under UV-vis light illumination. Furthermore, the photocatalytic activity of CuO/ZnO composite films is related to their atomic Cu/Zn ratios. The mechanism of CuO/ZnO composite films for improvement in photocatalytic activity was also discussed.

New insights on the mechanism of oxidation of d-galacturonic acid by hypervalent chromium

The pollutant CrVI is known to be very carcinogenic. In conditions of excess of CrVI, oxidation of d-galacturonic acid (Galur), the major metabolite of pectin, yields d-galactaric acid (Galar) and CrIII. The redox reaction takes place through a multistep mechanism involving formation of intermediate CrII/IV and CrV species. The mechanism combines one- and two-electron pathways for the reduction of CrIV by the organic substrate: CrVI → Cr IV → CrII and CrVI → CrIV → CrIII. This is supported by the observation of the optical absorption spectra of CrVI esters, free radicals, CrO 22+ (superoxoCrIII ion) and oxo-CrV complexes. CrIV cannot be directly detected; however, formation of CrO22+ provides indirect evidence for the intermediacy of CrII/IV. CrIV reacts with Galur much faster than Cr V and CrVI do. The analysis of the reaction kinetics via optical absorption spectroscopy shows that the CrIV-Galur reaction rate inversely depends on [H+]. Nevertheless, high [H+] still does not facilitate accumulation of CrIV in the Cr VI-Galur mixture. CrVI and the intermediate CrV react with Galur at comparable rates; therefore the build-up and decay of CrV accompany the decay of CrVI. The complete rate laws for the CrVI, CrV and CrIV-Galur redox reaction are here derived in detail. Furthermore, the nature of the five-co-ordinated oxo-CrV bischelate complexes formed in CrVI-Galur mixtures at pH 1-5 is investigated using continuous-wave and pulsed electron paramagnetic resonance (EPR) and density functional theory (DFT).

Comparison of TiO2 powder suspensions and TiO2 ceramic membranes supported on glass as photocatalytic systems in the reduction of chromium(VI)

A comparative study of semiconductor particle suspensions and semiconductor membranes as photocatalytic systems is presented. Both suspensions of TiO2 powder and TiO2 ceramic membranes supported on glass act as photocatalysts for the reduction of chromium(VI) to chromium(III). In both cases, the overall kinetic characteristics were the same. The reaction rate increases as pH decreases, and the order of reaction with respect to Cr(VI) is 0.5 at low pH (2). For this pH no deactivation of the catalyst is noted. The efficiency of the suspended particles was ca. four times higher than that of the membrane system.

Magnetically Recyclable Fe3O4@ZnxCd1-xS Core-Shell Microspheres for Visible Light-Mediated Photocatalysis

Magnetically recyclable photocatalyst has drawn considerable research interest because of its importance in practical applications. Herein, we demonstrate a facile hydrothermal process to fabricate magnetic core-shell microspheres of Fe3O4@ZnxCd1-xS, successfully using Fe3O4@ZnS core-shell microspheres as sacrificed templates. The as-prepared magnetically recyclable photocatalysts show efficient photochemical reduction of Cr(VI) under irradiation of visible light. The photochemical reduction mechanism has been studied to illustrate the reduction-oxidation ability of the photogenerated electrons (e-) and holes (h+), which play an important role in the reduction of Cr(VI) to Cr(III) and oxidation of organic dyes. The as-prepared Fe3O4@Zn0.55Cd0.45S core-shell microspheres show good chemical stability and only a slight decrease in the photocatalytic activity after four recycles. In particular, the as-prepared photocatalysts could be easily recycled and reused by an external magnetic field. Therefore, this work would provide a facile chemical approach for controlled synthesis of magnetic nanostructures combined with alloyed semiconductor photocatalysts for wastewater treatment.

Single-phase Gd0.2La0.2Ce0.2Hf0.2Zr0.2O2 and Gd0.2La0.2Y0.2Hf0.2Zr0.2O2 nanoparticles as efficient photocatalysts for the reduction of Cr(VI) and degradation of methylene blue dye

We report for the first time the use of noble metal-free multi-component equiatomic oxide as photocatalysts with excellent performance for natural sunlight driven degradation of Cr(VI) and methylene blue dye. The multi-component oxide nanoparticles with a composition Gd0.2La0.2Ce0.2Hf0.2Zr0.2O2 and Gd0.2La0.2Y0.2Hf0.2Zr0.2O2 were synthesized by simple co-precipitation followed by peptization in acid to obtain nanoparticle sol and calcined at 500 °C. The nanopowders were characterized by x-ray diffraction (XRD), UV–Visible spectroscopy (UV–Vis), and high-resolution transmission electron microscopy (HRTEM). The complete (～100percent) reduction of Cr(VI) to Cr(III) was observed after 90 and 100 min for the calcined Gd0.2La0.2Ce0.2Hf0.2Zr0.2O2 and Gd0.2La0.2Y0.2Hf0.2Zr0.2O2 respectively, under exposure to natural sunlight. In addition, 70percent degradation of methylene blue is observed in 180 min. The effective photocatalytic activity of multi-component oxides can be attributed to their unique composition containing five components in equimolar amounts. The role of oxygen vacancies in photocatalytic reduction of Cr(VI) and the degradation of methylene blue is also discussed.

In situ growth of UIO-66-NH2 on thermally stabilized electrospun polyacrylonitrile nanofibers for visible-light driven Cr (VI) photocatalytic reduction

UIO-66-NH2 was successfully deposited on electrospun polyacrylonitrile (PAN) nanofibers treated by thermal oxidative stabilization (TOS) via a simple and effective in situ growth method. Owing to the formation of acridone rings, naphthyridinering rings and hydronaphthyridine rings during the TOS process, the thermally stabilized electrospun PAN (TSPAN) nanofibers were greatly improved in stability and heat resistance and could provide adequate nucleation points for MOFs growth, indicating an ideal MOFs deposition support without additional surface modifications. The results demonstrated that UIO-66-NH2 crystals distributed relatively uniform and dense on the TSPAN nanofibers with mass loading up to 28.1 ?wt%. Compared with powdered UIO-66-NH2, the formed UIO-66-NH2@TSPAN nanofibers showed enhanced visible light driven photocatalytic activity towards reduction of Cr(VI) due to the improvement of visible light response, more excellent photothermal conversion ability and the increase of exposed active sites. The photocatalytic reduction rate of Cr(VI) over UIO-66-NH2@TSPAN was up to 93% within 180 ?min and the rate constant (k ?= ?0.1362) was 2.3 times that of powdered UIO-66-NH2 (k ?= ?0.00576). Significantly, the mechanical flexibility and structural stability endowed the nanofibrous photocatalyst easy operation and outstanding reusable capability. The photocatalytic activity for Cr(VI) reduction still preserved 90% after five cycles. This work proposes a facile strategy for preparation of free-standing MOFs nanofibers and provides MOFs-based photocatalysts a new opportunitie for broad applications in water treatment.

Photocatalytic activities of g-C3N4, Bi3NbO7 and g-C3N4/Bi3NbO7 in photocatalytic reduction of Cr(Ⅵ)

The g-C3N4, Bi3NbO7 and g-C3N4/Bi3NbO7 photocatalysts were prepared. The phase, microstructure, element composition, optical and photochemical properties are revealed

Investigation and characterization of biosynthesized green adsorbent CuO NPs and CuO/Fe3O4 NCs using Adiantum C.V leaf for removal MO dye and Cr(VI) metal ions: thermodynamic, kinetic, and antibacterial studies

The removal and degradation of organic/inorganic pollutants from aqueous solutions have stimulated the interest of researchers in recent years using heterogeneous adsorbent nanocatalysts. In this study, the coupled CuO/Fe3O4 nanocomposite (NC) was prepared at one step with a simple, cost-effective, and eco-friendly method by Adiantum C.V leaf extract as a reducing agent. The crystallite sizes for the CuO and CuO/Fe3O4 samples were obtained of XRD results by the Williamson–Hall equation (about 32.26 and 24.49?nm) and the Scherrer equation (about 22.37 and 23.97?nm), respectively. The EDS results from CuO/Fe3O4 NCs indicated a mole ratio of 1:2 for CuO/Fe3O4. Catalytic activity studies of green synthesized CuO/Fe3O4 NCs (dosage: 0.1?g/L) have shown high removal efficiency for both methyl orange (MO) (1.2 × 10–5?M) and Cr(VI) (3.0 × 10–3?M) pollutants at alkaline pHs between a range of (3 and 10) with a contact time of about 110?min. The degradation extent of the MO and Cr(VI) pollutants was estimated by changes in the UV–vis absorbances set to at λmax = 465 and 542?nm, respectively. Adsorption kinetics for the degradation of both investigated pollutants followed the pseudo-first-order kinetics model. The kinetic result showed degradation rate was increased toward the increase in pH (3–10) and temperature (293–308?K). The calculated thermodynamic parameters (?G°, ?H°, and ?S°) demonstrate that the adsorption of MO and Cr(VI) on the surface of green NCs is thermodynamically possible and spontaneous as temperature rises. Therefore, the present approach provides a potential method for preparing heterogeneous nanocatalysts for a wide range of applications in the degradation and reduction in organic/inorganic pollutants. In addition, the antibacterial effect of nanomaterials against gram-positive and gram-negative bacteria was tested at different concentrations of NCs (0.001–0.025?g/mL), which was in good agreement with the catalytic adsorption results for the degradation of both pollutants due to generated free radicals in aqueous solution. Graphical abstract: Schematic of the possible mechanisms for the removal of MO dye and Cr(VI) metal ions from the aqueous solutions at different temperatures and pHs, using green synthesized CuO/Fe3O4 NCs by Adiantum C.V leaf extract in the present NaBH4.[Figure not available: see fulltext.]