Cadmium Phosphate Research Articles

Structural and electrical characterization of cadmium phosphate glasses doped with different concentration of sodium chloride

Structural and electrical characterization of cadmium phosphate glasses doped with different concentration of sodium chloride

Improving the removal performance of cadmium from wastewater by phosphate-modified sludge biochar: A mineral dissolution-precipitation perspective

To improve the removal performance of sludge biochar (BC) for heavy metal Cd2+ in wastewater, phosphate-modified sludge biochar (PBC) was prepared by impregnation-pyrolysis. Batch removal experiment was conducted to research the impact of initial solution pH, coexisting ions, contact time, reaction temperatures, and Cd2+ concentrations on the adsorption capacity of adsorbent. The outcome indicated that PBC exhibited excellent Cd2+ removal efficiency at pH 5-7. Compared to the original biochar, phosphate-modified biochar had a stronger resistance to ion interference. The models of pseudo-second-order and Langmuir well described the adsorption processes of Cd2+ on BC and PBC. The maximum adsorption capacities of PBC for Cd2+ were 163.93mg/g, significantly higher than that of BC (72.94mg/g). Adsorption mechanism analysis suggested that Cd2+ removal involved complexation, electrostatic attraction, cation-π interactions, and co-precipitation. According to the semi-quantitative analysis of the mechanism, the leading mechanism for Cd2+ removal by PBC was precipitation (79.94%), whereas the primary mechanisms for Cd2+ removal by BC were complexation (42.57%) and precipitation (48.85%). The strategy of converting highly mobile Cd2+ in aqueous solutions into insoluble cadmium phosphate precipitates using phosphate-modified sludge biochar can be an ideal approach for removing Cd2+ from wastewater.

A2Cd(PO3)4 (A = K, Rb, Cs): Series of cadmium polyphosphates with infinite 1[(PO3)4]ꝏ chains and deep ultraviolet transparency windows

In the work, three cadmium polyphosphate crystals, A2Cd(PO3)4 (A = K, Rb, Cs), have been obtained via the high-temperature solution reaction with spontaneous crystallization technique. The compounds all crystallize in the P21/n space group and exhibit similar structural characteristics, including one-dimensional (1D) 1[(PO3)4]ꝏ chains and unique three-dimensional (3D) 3[Cd4P24O84]ꝏ frameworks. Especially, all of them exhibit deep ultraviolet (deep-UV) transparency windows, which is rare for cadmium phosphates containing d10 electrons. The UV-Vis-NIR diffuse reflectance spectra indicate that their cutoff edges are below 200 nm and have potentiality as deep-UV or UV short-wavelength optical materials. The investigation turns out that the dimensional distribution is closely related to the ratio of P/M in the asymmetric unit in cadmium phosphates. Additionally, the structure-function correlation was investigated through theoretical calculations. This work offers a valuable insight for the subsequent exploration of cadmium-based deep-UV optical materials.

Cadmium phosphates Cd2(PO4)OH and Cd5(PO4)2(OH)4 crystallizing in mineral structures

Single crystals of two basic cadmium phosphates, dicadmium orthophosphate hydroxide, Cd2(PO4)OH, and pentacadmium bis(orthophosphate) tetrakis(hydroxide), Cd5(PO4)2(OH)4, were obtained under hydrothermal conditions. Cd2(PO4)OH adopts the triplite [(Mn,Fe)2(PO4)F] structure type. Its asymmetric unit comprises two Cd, one P and five O sites, all situated at the general Wyckoff position 8 f of space group I2/a; two of the O atoms are positionally disordered over two sites, and the H atom could not be localized. Disregarding the disorder, distorted [CdO6] polyhedra form a tri-periodic network by edge-sharing with neighbouring [CdO6] units and by vertex-sharing with [PO4] units. The site associated with the OH group is coordinated by four Cd atoms in a distorted tetrahedral manner forming 1 ∞[(OH)Cd4/2] chains parallel to [001]. The oxygen environment around the OH site suggests multiple acceptor atoms for possible O—H...O hydrogen-bonding interactions and is the putative reason for the disorder. Cd5(PO4)2(OH)4 adopts the arsenoclasite [Mn5(AsO4)2(OH)4] structure type. Its asymmetric unit comprises five Cd, two P, and twelve O sites all located at the general Wyckoff position 4 a of space group P212121; the H atoms could not be localized. The crystal structure of Cd5(PO4)2(OH)4 can be subdivided into two main sub-units. One consists of three edge-sharing [CdO6] octahedra, and the other of two edge- and vertex-sharing [CdO6] octahedra. Each sub-unit forms corrugated ribbons extending parallel to [100]. The two types of ribbons are linked into the tri-periodic arrangement through vertex-sharing and through common [PO4] tetrahedra. Quantitative structure comparisons are made with isotypic M 5(XO4)2(OH)4 crystal structures (M = Cd, Mn, Co; X = P, As, V).

Ultralong Nanowires of Cadmium Phosphate Hydroxide Synthesized Using a Cadmium Oleate Precursor Hydrothermal Method and Sulfidation Conversion to Ultralong CdS Nanowires.

Ultralong nanowires with ultrahigh aspect ratios exhibit high flexibility, and they are promising for applications in various fields. Herein, a cadmium oleate precursor hydrothermal method is developed for the synthesis of ultralong nanowires of cadmium phosphate hydroxide. In this method, water-soluble cadmium salt is used as the cadmium source, water-soluble phosphate is used as the phosphorus source, and sodium oleate is adopted as a reactant to form cadmium oleate precursor and as a structure-directing agent. By using this method, ultralong nanowires of cadmium phosphate hydroxide are successfully synthesized using CdCl2, sodium oleate, and NaH2PO4 as reactants in an aqueous solution by hydrothermal treatment at 180 °C for 24 h. In addition, a new type of flexible fire-resistant inorganic paper with good electrical insulation performance is fabricated using ultralong nanowires of cadmium phosphate hydroxide. As an example of the extended application of this synthetic method, ultralong nanowires of cadmium phosphate hydroxide can be converted to ultralong CdS nanowires through a convenient sulfidation reaction. In this way, ultralong CdS nanowires are successfully synthesized by simple sulfidation of ultralong nanowires of cadmium phosphate hydroxide under mild conditions. The as-prepared ultralong nanowires of cadmium phosphate hydroxide are promising for applications as the precursors and templates for synthesizing other inorganic ultralong nanowires and have wide applications in various fields.

Spectral and Up conversion Properties of Ho3+ ions doped Zinc Lithium Lead Soda lime Cadmium Phosphate Glasses

Abstract: Glasses samples containing Ho3+ in zinc lithium lead sodalime cadmium phosphate (35- x)P2O5:10ZnO:10Li2O:10PbO:10CaO:10Na2O:15CdO:xHo2O3. (where x=1, 1.5,2 mol %) have been prepared by melt-quenching method. The amorphous nature of the prepared glass samples was confirmed by X-ray diffraction. Optical absorption, Excitation and fluorescence spectra were recorded at room temperature for all glass samples. Judd-Ofelt intensity parameters Ωλ (λ=2, 4 and 6) are evaluated from the intensities of various absorption bands of optical absorption spectra. Using these intensity parameters various radiative properties like spontaneous emission probability (A), branching ratio (β), radiative life time (τR) and stimulated emission cross–section ( σp) of various emission lines have been evaluated.

Synthesis, characterization and photocatalytic studies of Ag+, Cu2+ and Sn2+ doped layered Li2Cd(PO3)4

The use of semiconducting compounds for environmental remediation has been one of the priorities in the energy and environment fields. Metal phosphates constitute a class of materials with wide range of properties and applications. Lithium cadmium phosphate (Li2Cd(PO3)4) and Ag+, Cu2+ and Sn2+ doped Li2Cd(PO3)4 were prepared. All the materials were characterized by powder XRD, IR, Raman, SEM-EDS, XPS, UV-Vis DRS, and PL spectra. The IR and Raman spectra indicated the characteristic PO3 vibrations. The photocatalytic activity of as-synthesized materials was evaluated in the decomposition of methylene blue under visible light irradiation. The ion-doped samples have shown higher photocatalytic activity compared to pristine Li2Cd(PO3)4. This can be attributed to the higher separation efficiency of photoinduced electron-hole pairs. The participation of reactive species was investigated by scavenger experiments and found that superoxide radicals played key role in the MB degradation. The recyclability and the chemical stability of catalyst were also presented.

Cadmium phosphates with two types of fundamental building units and a wide ultraviolet transparency window.

Owing to diverse crystal structures and intriguing properties, metal phosphates have attracted much attention in recent studies. In this work, two cadmium phosphates, KCd6P7O24 and KCd3P3O11, were obtained by the high-temperature solution method. In the crystal structure, both the title compounds contain two types of P-O fundamental building units. Thermal and spectral analyses were carried out on the title compounds, indicating that both of them have good thermal stability and short UV cut-off edges. In addition, the relationship between the electronic structures and optical properties was studied by theoretical calculations.

Phosphorus Regulates the Level of Signaling Molecules in Rice to Reduce Cadmium Toxicity.

Phosphorus treatment can reduce Cd accumulation and Cd toxicity in rice, but alterations in the internal regulatory network of rice during this process have rarely been reported. We have removed the effect of cadmium phosphate precipitation from the hydroponic system, treated a pair of different Cd-response rice varieties with different levels of phosphorus and cadmium and examined the changes in physiological indicators and regulatory networks. The results demonstrated that phosphorus treatment significantly reduced Cd accumulation in both types of rice, although the antioxidant systems within the two types of rice produced opposite responses. Overall, 3 mM phosphorus treatment to Cd-N decreased the expression of OsIAA17 and OsACO1 by 32% and 37%, respectively, while increasing the expression of OsNR2 by 83%; these three genes regulate the synthesis of auxin, ethylene, and nitric oxide in rice. IAA and NO levels in rice shoots increased by 24% and 96%, respectively, and these changes contribute to Cd detoxification. The cadmium transporter genes OsHMA2, OsIRT1, and OsABCC1 were significantly down-regulated in Cd-N roots after triple phosphorus treatment. These data suggest that phosphorus treatment can reduce Cd accumulation and enhance Cd resistance in rice by affecting the expression of signaling molecules.

Immobilization of heavy metals by microbially induced carbonate precipitation using hydrocarbon-degrading ureolytic bacteria

Crude oil contamination introduces multiple threats to human health and the environment, most of which are from toxic heavy metals. Heavy metals cause significant threats because of their persistence, toxicity, and bio-accumulation. Biomineralization, performed through many microbial processes, can lead to the immobilization of heavy metals in formed minerals. The potential of the microbially carbonate-induced precipitation (MICP) in removal by biomineralization of several heavy metals was investigated. A collection of diverse 11 bacterial strains exhibited ureolytic activity and tolerance to heavy metals when growing in Luria-Bertani (LB) and urea medium. Determination of the minimum inhibitory concentrations (MIC) revealed that heavy metal toxicity was arranged as Cd > Ni > Cr > Cu > Zn. Three hydrocarbon-degrading bacterial strains (two of Pseudomonas aeruginosa and one of Providencia rettgeri) exhibited the highest tolerance (MIC > 5 mM) to Cu, Cr, Zn, and Ni, whereas Cd exerted significantly higher toxicity with MIC <1 mM. At all MICP conditions, different proportions of calcium carbonate (calcite) and calcium phosphate (brushite) were formed. Pseudomonas aeruginosa strains (QZ5 and QZ9) exhibited the highest removal efficiency of Cr (100%), whereas Providencia rettgeri strain (QZ2) showed 100% removal of Zn. Heavy metal complexes were found as well. Cd removal was evidenced by the formation of cadmium phosphate induced by Providencia rettgeri bacterial activity. Our study confirmed that hydrocarbon-degrading ureolytic bacteria not only can tolerate heavy metal toxicity but also have the capability to co-precipitate heavy metals. These findings indicate an effective and novel biological approach to bioremediate petroleum hydrocarbons and immobilize multiple heavy metals with mineral formation. This is of high importance for ecological restoration via stabilization of soil and alleviation of heavy metal toxicity.

Investigate the structure, mechanical, and optical properties of a novel cadmium phosphate glass containing vanadium oxide

Novel cadmium phosphate glasses doped with vanadium oxide (V2O5) were prepared by the melt-annealing technique. The P–O–P vibration revealed a connection between the phosphorus atoms and oxygen atoms in the Q1-Q2 joint mode. The VO or O3VO bonds were linked with P–O bonds in Q1 mode. The addition of V2.O5 to the glass network reduced the density from 4.935 g/cm3 for the base glass to 4.564 g/cm3 (10% V2O5). The molar volume, Vm values were derived from the glass density, ρ and used to estimate the Poisson’s ratio, σ, Young’s modulus, E, shear modulus, G, and bulk modulus, K, which were affected by the V2O5 ratio. The optical transition decreased from 2.668 eV for the base sample to 1.364 eV for the 5% V2O5-doped sample. The static refractive index, no, and the non-linear optical parameters were estimated and discussed in terms of the impact of V2O5.

Spectroscopic and optical investigations on Er3+ ions doped alkali cadmium phosphate glasses for laser applications

Alkali cadmium phosphate glasses doped with erbium ions were prepared by traditional melt - quenching technique. The FTIR and Raman spectroscopies were performed and employed to investigate the structural changes of the glass network doped with different concentrations of Er3+ ions. The UV–Vis–NIR spectroscopy was used to investigate the optical absorption spectra, optical bandgaps, refractive indices, and related parameters. The Judd – Ofelt (J – O) theory was used to explain the structural changes and to determine the bonds nature in the studied glasses by calculating the intensity parameters Ω2, Ω4, and Ω6. The J – O intensity parameters followed the trend of Ω2 > Ω6 > Ω4 and were used to evaluate some radiative parameters such as electric and magnetic radiative transition probabilities, branching ratios, and radiative lifetimes for the excited levels of the Er3+ ions. The absorption and emission cross-sections for the 4I13/2 → 4I15/2 transition of Er3+ ions were studied, and the gain coefficient was calculated. The higher values of the branching ratios (≥ 0.5) and lifetimes of the present glasses indicate their good suitability for lasers and amplifiers applications.

Gamma Irradiation Shielding Responses of Zinc Cadmium Phosphate Glasses Co-Doped with 3d Transition Metal Ions Assessed Through FTIR and Spectral Analysis

Gamma Irradiation Shielding Responses of Zinc Cadmium Phosphate Glasses Co-Doped with 3d Transition Metal Ions Assessed Through FTIR and Spectral Analysis

Kinetics and equilibrium studies of cadmium removal from cadmium phosphate by exchange reaction with cation ions

In recent years the presence of cadmium in phosphates ores used in the fertilizers industry has generated a lot of discussion which has prompted governments and authorities to put in place regulations that limit the use of phosphates and derivatives with cadmium contents exceeding certain limits. This work focuses on the study of the exchange reaction between cations ions and cadmium as a technique for reducing the cadmium content in phosphates by hydrometallurgical processes. The study was carried out using a synthesized precipitate of cadmium phosphate. The solubility study of the cadmium phosphate in water shows that it’s a very stable precipitate while it’s was very soluble at acidic pH. The solubility results and values agreed with those theoretically predicted. The exchange between cadmium and zinc is a thermodynamically possible equilibrium reaction that have been confirmed by a X-ray fluorescence analysis. The experimental results showed that the studied reaction reaches equilibrium in 10 h and that interesting cadmium exchange efficiencies can be achieved, for an initial mass ratio Zn/Cd of 2, the cadmium exchange efficiency was 39% and 72%, respectively, after 4 h and 10 h. The exchange reaction between zinc ions and cadmium phosphate was found to be a kinetic equilibrium and slow process, best described by the product layer diffusion control model with a reaction rate constant $$k=0.0001 {\mathrm{mn}}^{-1}$$ . The calcium ions presence at high concentrations (> 0.5 M) in reaction medium was found to have a slight effect on cadmium exchange efficiency.

Catalytic effect of nano cadmium phosphate catalyst on the synthesis of some (E)-3,4-dimethoxyphenylprop-2-en-1-ones

Abstract Cadmium phosphate nanomaterial was applied for the synthesis of some (E)-3,4-dimethoxyphenylprop-2-en-1-ones through microwave irradiation. Investigations made by the authors for the study of catalytic action of the nano cadmium phosphate catalyst by means of obtained yields and reusability. In this method the obtained maximum yield was 90% and the catalyst effect was not appreciably changed up to 6th time. Influence of solvents on this process was studied using normal boiling technique. Reaction in ethanol medium gave high yield than other solvents but not more than microwave method. The synthesized (E)-3,4-dimethoxyphenylprop-2-en-1-ones were analyzed through spectroscopic technique, micro analysis, yields, and physical constants. These data are confirmed by the formation of the 2-propen-1-ones.

Lithium cadmium phosphate glasses doped Sm3+ as a host material for near-IR laser applications

Abstract Sm2O3 doped Lithium Cadmium Phosphate (LCP) glasses are synthesized by a classical melting method, and their molecular structures are investigated by X-ray Diffraction method (XRD). FT-IR spectra, UV–Vis–NIR spectra, and emission spectra of these glasses are collected and analyzed. The emission spectrum of the present glass shows four emission lines at wavelengths of 562 nm, 598 nm, 645 nm, and 706 nm. The dependence of electronic polarizability and optical basicity of the synthesized glasses on the refractive index and bandgap is investigated. Judd-Ofelt theory is used to evaluate oscillator strengths and JO intensity parameters of Sm3+-doped LCP glasses. The emission and absorption cross-sections of the 562 nm line, which is originated from 6P3/2 → 6F5/2 transition, are calculated. Other emission spectral lines (598 nm, 645 nm, and 706 nm) couldn't be originated from transitions to the ground level. This is due to the weakness of the absorption transitions in this spectral region, i.e., 550 nm–900 nm. The most probable suggestion that these lines are originated from the transitions 4G9/2 → 6F1/2, 4G9/2 → 6F5/2, and 6P3/2 → 6F11/2. Emission and absorption cross-sections of some transitions in the Near-infrared spectral region are evaluated. Laser gain of the 1.1 μm and 1.2 μm emission lines are obtained, where a positive gain is observed at population factors (P) ≥ 0.6 .

Dependence of the structure, optical, and dynamic properties of novel cadmium phosphate glass on vanadium content

Novel cadmium phosphate glass containing vanadium has been investigated as a non–linear optical material. The densities and molar volumes of the invert glasses were estimated using Archimedes method. The structural properties of the prepared glasses were examined via Fourier transform infrared spectroscopy as well as Raman spectroscopy. The optical transmittance was measured using UV–visible spectroscopy in the photon wavelength ranging from 200 nm to 800 nm to detect the optical absorption edge, optical transition, optical band gap, refractive index, and dielectric constant. Non-linear optical trends were deduced from the optical studies. The correlation between the structural and physical properties of such glasses has been investigated. Moreover, the role of cadmium as a glass former and vanadium content as a glass modifier and former have also been examined. The dynamic properties were experimentally calculated using a free vibration test and simulated with finite element analysis. The results revealed that vanadium content has an impact on dynamic behavior.

Synthesis and spectroscopic investigations of calcium cadmium phosphate hydrate nanopowders via doping divalent (Mn2+) and trivalent (Fe3+) cations

Calcium Cadmium Phosphate Hydrate (CaCdPH) powders with transition metal ions (Mn2+ & Fe3+) as dopants are synthesized via solid state route. The prepared nanopowders phase was confirmed by using XRD analysis. The surface morphology was analyzed by recording their SEM images. The quantitative chemical analysis of CaCdPH: Mn2+ and CaCdPH: Fe3+ was confirmed from energy dispersive spectroscopy (EDS). From the optical and Electron paramagnetic resonance (EPR) spectra, the site symmetries of CaCdPH: Mn2+ and CaCdPH: Fe3+ are ascribed as distorted octahedral. Various EPR parameters such as spin Hamiltonian parameters (g-value), hyperfine (HF) parameter A, number of spins (N) and paramagnetic susceptibility (χ) are evaluated.

Synthesis and physical characterization of gamma irradiated cadmium phosphate glass modified by copper oxide

The irradiation of Cu-doped Cd-phosphate glass mediated by gamma rays shows the conversion of Cu2+ ↔ Cu+ ion with subsequent glass defects which leads to the loss of glass structure. The physical evaluations encompassing FTIR studies, X-ray diffraction analysis, UV spectrophotometer analysis, EPR, differential scanning colorimetry, and elastic properties are performed. The optical band gap (Eg) values for both direct and indirect transition and refractive index are evaluated for varying irradiation doses and correlated with the data obtained for optical spectra, ultrasonic wave velocities and elastic moduli. Further, the evaluations such as optical basicity and average electro negativity have been determined. The obtained optical basicity values increases with concurrent increase in the dose of radiation, however the values of electron negativity have not displayed such variations. After irradiation at various doses, there is a significant elevation in non-bridging oxygen (NBO) atoms which lead to decreased glass polymerization, reduced glass stability and aids the formation of copper ions aggregates. The above stated process highly alters the structure and optical properties of glass which is confirmed by the results of the optical absorption, FTIR and EPR spectral analysis. The force constant values and the bond strength between Cu–O are lower as compared to P–O, which further decreases the glass rigidity thus decrease in glass rigidity affects the ultrasonic velocity, Eg and Tg. The thermal stability values of studied glass decreased with subsequent increases in the dose of irradiation. Thus this glass displays specific optical characteristic and thus can be employed as a bandpass filters.

Cadmium resistance mechanisms of a functional strain Enterobacter sp. DNB-S2, isolated from black soil in Northeast China

Enterobacter sp. DNB-S2 is an efficient DBP-degrading bacterial strain, which was proved to be highly resistant to cadmium (MIC was 12.5 mM) and the involved mechanisms were verified in this study. The results showed the maximu values of extracellular adsorbed and intracellular accumulated Cd2+ contents accounted for 24.67% and 4.78% of the initial Cd2+ content in the medium. The extreme low intracellular Cd accumulation reduced the risk of cadmium interfering with normal cell metabolism. TEM exhibited cell structure of DNB-S2 kept intact even at high Cd concentrations. Some precipitation particles were formed inside cells, which were further identified to be Cd–O–P, Cd (OH)2, CdCO3, and CdS by XPS. Furthermore, Cd resistant genes were predicted on DNB-S2 genome, and the presence of 11 alkaline phosphatase encoding genes provided genetic basis for the formation of cadmium phosphate precipitation, which illustrated intracellular precipitation is one of the important intracellular Cd detoxification mechanisms in strain DNB-S2. Noteworthily, 8 efflux proteins were annotated possibly responsible for cadmium efflux and they were all predicted located on cytoplasmic membrane. In a word, integrity of cell structure, the formation of cadmium precipitation and efficient exclusion primarily constitute Cd tolerance mechanisms of strain DNB-S2. This strain exhibits promising application to the bioremediation of cadmium-DBP contaminated bites.