Ratio Of Cd Research Articles

Bioavailability of heavy metals bounded to PM2.5 in Xi'an, China: seasonal variation and health risk assessment.

Studying the characteristics and health risks of heavy metals in atmospheric fine particulate matter (PM2.5) is a crucial component of understanding atmospheric pollution in China. Integrated 24 h PM2.5 samples were collected in winter and summer 2016 in Xi'an, China. The pollution levels, speciation, and health risks of seven PM2.5-bound metal elements (Al, As, Cd, Cr, Ni, Pb, and Zn) were investigated in this study. The average concentration of PM2.5 was 50.1 ± 30.4 μg m-3 and was higher in winter than in summer. Significant seasonal variations in the elements were also observed. The average concentration ratios of Al, As, Cd, Cr, and Pb decreased in summer by 17.5%, 6.4%, 42.5%, 34.1%, and 61.4% compared with their concentrations in winter, respectively, whereas Ni and Zn increased by 37.7% and 7.6% in summer. The soluble and exchangeable fraction (F1) accounted for large proportions of Cd and Pb concentrations, indicating their greater hazard to the environment and human health. Al, As, and Cr mainly existed in the residual state (F4), which had relatively high stability in particulate matter. Ni was consistently distributed in different forms (F1-F4). The bioavailability evaluation indicated that Pb, Cd, Ni, and Zn were potential bioavailable element which exhibited strong biological toxicity. Although the concentration of Pb was very low, its BI value was the highest. The carcinogenic and non-carcinogenic risks of Cr and As were relatively high, and thus require attention from the government and environmental management departments.

Immobilization of cadmium by Burkholderia sp. QY14 through modified microbially induced phosphate precipitation

Microbially induced phosphate precipitation (MIPP) is an advanced bioremediation technology to immobilize heavy metals. An indigenous bacterium QY14 with the function of mineralization isolated from Cd contaminated farmland soil was identified as Burkholderia ambifaria. The minimum inhibitory concentration value for QY14 was 550 mg/L for soluble Cd concentration. This study found that the addition of 10 mM Ca2+ during MIPP process could significantly increase the removal ratio of Cd, and the maximum removal ratio of Cd with 10 mM Ca2+ and without Ca2+ in solution was 99.97% and 76.14%, respectively. The increase of acid phosphatase activity and the formation of precipitate containing calcium caused by 10 mM Ca2+ addition contributed the increase of Cd removal efficiency. The results of SEM-EDS, FTIR and XRD showed that Cd was removed by forming Cd containing hydroxyapatite (Cd-HAP). In addition, the dissolution experiment showed the Cd release ratio of Cd-HAP (0.01‰ at initial pH 3.0 of solution) was lower than Cd-absorbed HAP, indicating that Cd was more likely removed by the formation of Ca10−xCdx(PO4)6(OH)2 solid solution. Our findings revealed MIPP-based bioremediation supplied with 10 mM Ca2+ could increase the Cd removal and could potentially be applied for Cd remediation.

Capture effect of Pb, Zn, Cd and Cr by intercalation-exfoliation modified montmorillonite during coal combustion

Raw montmorillonite (MMT) was modified by intercalation-exfoliation method to improve the capture capacity of heavy metals (Pb, Zn, Cr and Cd) during coal combustion. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) Spectroscopy and Brunner-Emmett-Teller (BET) indicated that intercalation agents cetyltrimethylammonium bromide (CTAB) and sodium dodecyl benzene sulfonate (SDBS) could be successfully inserted into the interlayer of MMT during the intercalation step, additionally exfoliation process could peel off the MMT into fine flakes. The co-combustion of coal and MMTs was conducted in a tube furnace from 900 to 1300 °C. Results indicated that with the increase of temperature, the retention ratio of Pb, Zn and Cd gradually decreased, especially higher than 1200 °C with a great capture capacity reduction, whereas for Cr, it rose first and then decreased. The capture performance of modified MMT on Pb, Zn and Cr was obviously improved. However, for Cd, adverse effect was observed, of which the capacity was even worse than that of raw MMT in some cases. According to the mechanism analysis, the intercalation-exfoliation modification of MMT primarily enhances the chemisorption of heavy metals by exposing more active sites, which facilitates the fixation of heavy metals in the form of aluminosilicates.

Metal Bioaccumulation by the Neotropical Clam Anomalocardia flexuosa to Estimate the Quality of Estuarine Sediments.

This investigation evaluated the bioaccumulation potential of the tropical estuarine bivalve Anomalocardia flexuosa for trace metals. To this aim, chemical and sedimentological analyses and bioaccumulation tests were performed. The sediments were mainly composed by fine-sands and mud, with variable levels of organic matter and CaCO3. Muddy sediments from a depositional site (P2) presented the highest concentrations of metals, despite SEM/AVS not indicating bioavailability. Bioaccumulation factors showed high ratios for Cd, Ni, and Zn, while associations between the contents of mud, organic matter, CaCO3 and metals in sediments and tissues of A. flexuosa were indicated by a principal component analysis. The SEM/AVS was not effective to predict the bioavailability through dissolved metals. The results showed that contaminants were bioavailable, while the performed bioaccumulation test proved to be a reliable technique for assessing sediment contamination in estuarine regions. Moreover, A. flexuosa was considered an adequate test organism for bioaccumulation studies.

Cadmium Bioavailability and Accumulation in Rice Grain are Controlled by pH and Ca in Paddy Soils with High Geological Background of Transportation and Deposition.

Cadmium (Cd) threatens rice quality and human health, yet this risk remains uncertain in paddy fields with high geological background of transportation and deposition. In this study, we collected 31 pairs of soil and rice grain samples in Doumen and Xinhui Districts in Guangdong province, China and investigated which factors controlled Cd bioavailability in soil and accumulation in rice. Soil samples were mostly acidic and contained a range of organic matter. Total Cd in soil varied from 0.10 to 1.03 mg kg- 1 and was positively correlated with those of calcium (Ca), manganese (Mn) and iron (Fe), suggesting that these elements shared same sources and Cd was most likely originated from parent material. The activity ratio (AR, CaCl2-extractable Cd/soil Cd) and bioconcentration factor (BCF, rice grain Cd/soil Cd) of Cd were negatively correlated with soil pH. The coupling relationship between soil and rice grain Cd could be described by a linear model, which was used to predict soil Cd threshold values to keep rice grain Cd concentration from exceeding the Chinese limit (0.2 mg kg- 1). In summary, Cd pollution was not very severe in the paddy soils of studied area but the risk could not be neglected when soil was acidified, which could increase Cd bioavailability and accumulation in rice grain.

A new route for preparing CdTe thin films by chemical bath deposition

Cadmium telluride (CdTe) is a binary II-VI direct band gap semiconducting material. Cadmium telluride is a promising electrochemical and photovoltaic material for thin film solar cells. It shows both p and n type conductivity. A nanocrystalline thin film of CdTe was deposited in homogeneous medium on nickel plate by chemical bath deposition method containing 0.01 M cadmium acetate and 0.02 M tellurium dioxide. The structural, compositional and optical analysis were studied by x-ray diffraction (XRD), energy-dispersive x-ray spectroscopy (EDS), scanning electron microscope (SEM), Fourier Transform infrared spectroscopy (FTIR) and Photoluminescence (PL).The diffraction peak observed at 2θ = 23.59° with (1 1 1) plane indicate the crystalline phase of CdTe film. The average crystalline size is measured to be 7 nm. Compositional analysis reveals the presence of both Cd and Te elements. The EDS Spectroscopy shows the ratio of Cd and Te is1:2 in case of as deposited film. The Photoluminescence peak is observed at 471 nm.

Cadmium isotope fractionation during Cd-calcite coprecipitation: Insight from batch experiment

Cadmium (Cd) calcite coprecipitation experiments were conducted to constrain the possible Cd isotope fractionation mechanism under different conditions. The changes in Cd/Ca molar ratio, HCO3− concentration, addition of Mg2+, Na2EDTA, or ionic strength (INaNO3) did not affect the composition of the precipitation but resulted in substantial change in mineral morphology. Cd exhibited an apparent isotope fractionation in the process of coprecipitation with calcite, and the fractional coefficient αCaCO3-Cd(aq) was less than one, indicating that the solution is preferentially enriched in heavy isotopes. The Cd mainly existed in the form of Cd(H2O)62+ in the solution before the reaction and was dominated by Cd(NO3)2, CdNO3+, Cd(EDTA)2− at the end of the experiments. The different isotopic ratios of Cd between the liquid phase and the solid phase can be explained by changes in Cd speciation which have different bond lengths of CdO. Expect for the experiments with Na2EDTA and high ionic strength, the measured isotope ratios under different conditions plotted around the theoretical Rayleigh fractionation curve. This demonstrates that Cd isotopes almost reach equilibrium with Cd-calcite coprecipitation under the different experiment conditions and the Cd isotope fractionation mechanism is closely related to the thermodynamic isotope fractionation. In the experiment with Na2EDTA and high ionic strength, the formation of Cd(EDTA)2− and ion occlusion at surface sites inhibit Cd2+ entering the calcite and the isotopes of the solid and liquid phases do not reach equilibrium. As the result, obtained experiment data shift from the Rayleigh fractionation curve indicating the Cd isotope fractionation mechanism is closely related to the kinetic isotope effect. In general, the study results indicate that the Cd/Ca molar ratio, ionic strength, HCO3−, Na2EDTA, and Mg2+ concentrations of the solution can cause Cd isotope fractionation in different degrees during Cd-calcite coprecipitation. Cd isotope ratios might potentially provide important information on Cd mobilization and transportation in groundwater environment.

Rational design of chemical bath deposition technique for successful preparation of Mn-doped CdS nanostructured thin films with controlled optical properties

The introduction of a rational design for depositing internally-doped nanostructured thin films is of great importance for optoelectronics. In this presented work, Mn-doped CdS thin films with high purity in composition were prepared through the chemical bath deposition technique using a nucleation-doping strategy. This work focuses on an improved chemical design to eliminate mostly ignored property of conventionally doped nanoscale thin films. The synthesis strategy was initiated by the initial formation of MnS nuclei in a colloidal depositing solution followed by injection of cadmium precursor to diffuse into the initial nuclei and play the role of host CdS matrix which was the beginning of the deposition process. Upon optimization of the PL-emission, it was revealed that relative intensity of Mn2+-related peak to the excitonic peak has significantly increased (~100 times) in 80 °C, pH = 6, and precursor molar ratio of Cd:Mn:EDTA:S equal to 1:3:0.4:5, at deposition time of 300-min. The TRPL measurements further revealed the effective contribution of Mn-related midgap states with long-lived decay curve character, which confirms the success of the designed approach to reach internally doped thin films. It was found that the deposition temperature, amount of Cd/Mn/TA precursors, and deposition time are the most important experimental parameters in the proposed synthesis approach. Due to the versatility, generality, and colloidal advantages of this method, it can be extended to the other structures with various types of dopant agent.

Effect of cornstalk biochar on phytoremediation of Cd-contaminated soil by Beta vulgaris var. cicla L

Cadmium (Cd) contamination is the most common and extensive heavy metal pollution in the farmland of China. Phytoremediation is considered as a promising measure for Cd-contaminated soil remediation, but the remediation efficiency still needs to be enhanced. Biochar as an effective amendment medium is widely manufactured and studied for the soil remediation of heavy metals. In this study, a greenhouse pot trial was conducted to investigate the effects of cornstalk biochar on Cd accumulation of Beta vulgaris var. cicla L. (Beta vulgaris) in Cd contaminated soil. The Cd availability, speciation and nutrients in soil, biomass and Cd chemical forms in the Beta vulgaris root were studied to explore the mechanism that how the cornstalk biochar promoted Cd accumulation in Beta vulgaris. Biochar amendment reduced the DTPA-extractable Cd concentration and stimulated the growth of root. Compared to the Beta vulgaris without biochar treatment, the results of 5% biochar amendment showed that the root dry weight of Beta vulgaris increased to 267%, Cd accumulation in Beta vulgaris increased to 206% and the Cd concentration in leaves and roots increased by 36% and 52%, respectively. Additionally, after 5% biochar was applied to soil, the total content of organic matter-bound Cd and residual Cd increased by 38%, while the content of Fe–Mn oxides-bound Cd decreased by 40%. Meanwhile, Cd may mainly bind to the root cell wall and the ratio of NaCl-extracted Cd to HAc-extracted Cd increased to 166% with 5% biochar amendment. According to our study, Cd in soil can be removed by Beta vulgaris and phytoremediation efficiency can be improved with biochar amendment. The combination of phytoremediation and biochar amendment is a promising strategy for the Cd-contaminated soil remediation.

Cadmium ion-chlorophyll interaction – Examination of spectral properties and structure of the cadmium-chlorophyll complex and their relevance to photosynthesis inhibition

Chlorophyll was shown to spontaneously form a complex with cadmium, which is incorporated at the central position of the chlorophyll molecule porphyrin ring, where it replaces magnesium. The rate of complex formation depended on the ratio of Cd2+ ions to chlorophyll concentration in the solution. In solutions with chlorophyll concentration of C = 1 × 10−5 M and Cd2+ concentrations of C = 1 × 10−5 M, C = 1 × 10−3 M and C = 9 × 10−3 M, Cd-Chl complex formation was completed after 200 h, 50 h and 33 h, respectively.The formation of Cd-Chl complex followed the second order over all substrates reaction order, first order over Cd2+ concentration and first over Chl concentration. The pseudo second order reaction rate constant k, when Cd2+ concentration was equal Chl concentration have been obtained as k = 1.510 ± 0.023 × 10−4 M−1min−1.Quantum chemistry computations showed that Cd-chlorophyll complex existed in two conformations in the methanol solution with cadmium ion placed either below or above the coordination plane.Two times smaller overlap integral of the Chl fluorescence spectrum with the Cd-Chl absorption spectrum IChl,Cd-Chl= 2.4223 × 10−13 cm3/M in comparison with the overlap integral of the Chl fluorescence spectrum with the Chl absorption spectrum IChl,Chl= 4.6210 × 10−13 cm3/M (twice lower probability of energy transfer Chl∗ → Cd-Chl than Chl∗ → Chl) and lower Förster critical distance for resonance energy transfer: RoChl→Cd-Chl= 46.773 Å, RoChl→Chl= 52.086 Å, indicated that in plants intoxicated with cadmium, taken up from the contaminated soil, the energy transfer between Chl and Cd-Chl in antennas will be disturbed, which may be one of the reasons for the inhibition of photosynthesis.

Synthesis and characterization of solution-processable Cd1–xZnxS nanorods for photocatalytic degradation of tetracycline

Photocatalytic degradation of broadband antibiotics like tetracycline (TC) under visible-light irradiation is considered as an efficient and cost-effective protocol for eliminating it from the aqueous medium. In this study, highly efficient solution-processable Cd1−xZnxS photocatalysts were synthesized using a simple solvothermal route where zinc acetate and cadmium acetate were used as precursors. Composition-tunable alloyed nanorods with bandgap energy tunability ranging from UV (3.7 eV) to Vis (2.5 eV) were synthesized and structural and optical characterization was performed thoroughly. With the increase of Zn content in the Cd1−xZnxS crystal, the 1LO phonon shifts notably towards higher wavenumber. The performance of Cd1−xZnxS nanorod photocatalyst is strongly related to the ratio of Cd and Zn. The Cd0.75Zn0.25S sample exhibits the highest photocatalytic degradation rate constant compared to the other family members. The scavenger experiment revealed that the holes are the main responsible species, whereas hydroxyl radicals have weak roles and electrons have mild effects for the photocatalytic degradation of TC. Our study gives new insight towards the designing of ternary photocatalytic materials for efficient removal of antibiotics from aqueous solution.

Virological and immunological efficacy of metabolically favorable antiretroviral therapy regimens in HIV patients who had no previous treatment

The objective : to study efficacy and safety of metabolically favorable antiretroviral therapy regimens ( ART ), their effect on HIV RNA levels, levels of CD 4, CD 8 T lymphocytes, and the ratio of CD 4/ C D 8 in HIV patients who had no previous treatment. Subjects and methods . The study included 80 patients with HIV infection who no received ART previously, 67 of them – without clinical manifestations of HIV infection, 13 – with HIV associated diseases. The virological and immunological efficacy of three ART regimens was evaluated: rilpivirine + emtricitabine + tenofovir ( RPV + FTC + TDF ); dolutegravir, emtricitabine, tenofovir ( DTG , FTC , TDF ); raltegravir, etravirine, lamivudine ( RAL , ETR , 3 TC ) during the first 6 months of treatment. Results . By the end of the 6th month of ART , the rate of decrease of viral load compared to the initial level increased in the series RPV + FTS + TDF < RAL , ETR , 3 TC < DTG , FTC , TDF . The number of CD 4 T-l ymphocytes and the ratio of CD 4/ C D 8 increased in all three ART regimens; the number of CD 8 T-l ymphocytes varied depending on the treatment regimen, the presence or absence of clinical manifestations. The assessment of ART efficacy should be based on the clinical signs of HIV infection. To assess treatment efficacy, it is necessary to control the viral load and three immunological parameters: the number of CD 4, CD 8 T-l ymphocytes, and the ratio of CD 4/ C D 8.

Study on the effects of polymer modifiers and phloem girdling on cotton in cadmium-contaminated soil in Xinjiang Province, China

The effects of two liquid modifiers (polyacrylate compound modifier and organic polymer compound modifier) and phloem girdling (stem girdling and branch girdling) on cadmium (Cd) content, Cd transport, and photosynthetic parameters of cotton (Xinluzao 60) in Cd-contaminated soil (40 mg kg −1) were studied through barrel experiment. The results showed that the distribution ratios of Cd in stem, leaves, and bolls, leaf net photosynthetic rate (Pn), leaf stomatal conductance (Gs), leaf transpiration rate (Tr), and chlorophyll content were decreased after girdling; and the application of modifiers reduced the Cd content and the Cd transported to the shoot, while alleviating photosynthetic damage caused by girdling. In general, our results indicated that the inhibition of carbohydrate supply caused by girdling reduced the photosynthetic capacity of cotton, while the applications of the two liquid modifiers decrease the influence to cotton photosynthesis. Moreover, Cd and modifiers may be transported to the shoot through both phloem and xylem.

A stepwise microwave synergistic pyrolysis approach to produce sludge-based biochars: Feasibility study simulated by laboratory experiments

A stepwise microwave synergistic pyrolysis (SMSP) approach is proposed as a new way to relieve disposal problems of the sewage sludge. Here the sludge is first pre-pyrolyzed by a conventional heating stage, and then rapidly pyrolyzed by a microwave-induced heating stage without any extra microwave absorbers or blending needed. Under simulated process pyrolysis conditions, the dried sludge, intermediate and final sludge-based biochar samples were prepared in the laboratory. Their chemical composition, microstructure and morphology, and leaching toxicity of heavy metals were carefully characterized and analyzed by various techniques such as proximate and ultimate analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET), and scanning electron microscope equipped with energy-dispersive x-ray spectroscopy (SEM-EDX). Results showed that the pre-pyrolytic biochar can be rapidly heated up to 1100 °C within 5 min under microwave irradiation. The pre-pyrolytic stage increased the carbonization and ash enrichment degree of the sludge which itself acted as a good microwave absorber while achieving a quick temperature rise under microwave irradiation. The ash remaining ratio and the specific surface area of the biochar derived from the SMSP approach (labelled as SBC2) are increased by 6.46% and 16.17% respectively, compared with the conventional biochar sample (SBC1). And SBC2 still had diverse surface functional groups kept after SMSP. The residual ratios of Ni, Cu, Zn, Pb, Cr and Cd in SBC2 was more noticeable than in SBC1 but the leaching ratios quite the contrary. Vitrification is also well proved by the increment of quartz peak detected by XRD tests, and the formation of melted glassy spheres with elemental composition of Si, Ca, Al observed by SEM-EDX. It can favorably increase solidification level and decrease leaching toxicity of heavy metals in the SBC2. The feasibility of this proposed SMSP concept has been positively supported by our experimental results. The properties of the sludge-based biochar produced from the SMSP approach also show great potential to be utilized as precursors to produce various adsorbents.

Leaching behaviors and speciation of cadmium from river sediment dewatered using contrasting conditioning

Chemical conditioning is an effective strategy for improved river sediment dewatering affecting both the dewatering efficiency and subsequent resource utilization of the dewatered cake. Two types of conditioning agents, polyaluminium chloride (PAC)/cationic polyacrylamide (PAM) (coagulation precipitation conditioning agent, referred to as P–P conditioning) and ferrous activated sodium persulfate (advanced oxidation conditioning agent, referred to as F–S conditioning) were examined. With increasing leach liquid to solid (L/S) ratio the concentration of Cd for the real time leachates from the dewatered cakes decreased, but the leaching ratio of Cd in both P–P and F–S dewatered cakes increased. With the same L/S, the leaching ratio was reduced for both types of conditioning, as compared to no conditioning, with the leaching ratio being least with F–S conditioning. The leaching ratio of Cd in the dewatered cake with L/S of 100 L kg−1 was reduced from 21.3% of the total Cd present for the un-conditioned sediment to 12.5% upon P–P conditioning and 11.6% upon F–S conditioning. Furthermore, the different conditioning methods affected the Cd speciation in the dewatered cakes reducing the easy-to-leach speciation of exchangeable and carbonate-bound Cd species and increasing the potential-to-leach speciation of iron-manganese oxide and organically bound Cd species and also the difficult-to-leach species. Risk assessment indicates that the risk due to Cd leaching from the dewatered cakes at L/S of 100 L kg−1 was reduced from high risk to medium risk after P–P and F–S conditioning with reduced bioavailability.

Mobility of metal(loid)s in Pb/Zn tailings under different revegetation strategies

Metal tailings are potential sources of strong environmental pollution. In situ remediation involves the installation of a plant cover to stabilize materials and pollutants. Whether metal(loid)s are effectively immobilized in remediated tailing ponds submitted to heavy rainfall remains uncertain. In this study, tailing materials were collected from bare tailings (control), grass-planted (G) and grass-shrub planted (GS) areas on a former Pb/Zn mine site. Batch column experiments were performed with three rainfall intensities of 0.36, 0.48, and 0.50 mL min−1 for 18 d in the lab. The pH, Eh, Cd, Pb, Zn and As concentration in leachate were recorded. Selected leached tailing materials were finally characterized. Results showed that leachates from control were strongly acidic (pH 3.11–4.65), and that Cd, Pb, Zn and As were quickly released at high rate (e.g., 945 mg L−1 Zn). During the experiment up to 4% Cd present in the material was released and almost 1% Zn. With material collected from the G area, leachates were even more acidic (2.16–2.84) with a rainfall intensity of 0.50 mL min−1 and exhibited a high redox potential (588–639 mV). However, concentrations of metals in leachates were much lower than that in the control, except for Zn (e.g., 433 mg L−1), and they tended to decrease with time. Cumulative leaching rate was still relatively high (e.g., 0.68% Cd; 0.75% Zn) during the first eight days (stage I). However, with the GS treatment, leachate pH gradually raised from acid to alkaline values (3.9–8.2) during stage I, then remained high until the end of the experiment (stage II). Also, amounts of elements released during the 18 d were low in general. The releasing ratios of Cd (R2 > 0.95), Pb (R2 > 0.95), As (R2 > 0.87), and Zn (R2 > 0.90) fitted well with a two-constant model. In conclusion, under subtropical climate with heavy rainfall, phytostabilization is effective but immobilization of metals is higher with a combination of grass and shrub than with only grass to reduce leaching of As and Zn.

Evaluation of deflection amplification factor for steel buckling restrained braced frames

In the common force-based design method prescribed in seismic codes, displacements of a structure under reduced seismic forces are amplified by a deflection amplification factor, Cd, to estimate inelastic displacements. The present study evaluates Cd for steel buckling restrained braced frames (BRBFs). For this purpose, six low-to mid-rise structures comprising 2- to 12-story BRBFs are considered, and nonlinear dynamic analyses are performed. Results indicate that the recommended Cd by ASCE 7 (i.e., Cd = 5.0) underestimates the inelastic maximum interstory drift ratio (IMIDR) of lower stories in BRBFs under the design earthquake. Furthermore, estimation of IMIDR in upper stories of mid-rise structures using Cd = 5.0 leads to acceptable results. Therefore, by applying the particle swarm optimization (PSO) algorithm, a new equation is proposed for Cd to more realistically estimate IMIDR in steel BRBFs under the design earthquake. In the case of roof displacement, the results show that for low-rise structures the recommended value of Cd = 5.0 significantly underestimates the inelastic maximum roof drift ratio (IMRDR). On the other hand, for taller structures Cd = 5.0 overestimates the IMRDR. Thus, another new equation is proposed using the PSO algorithm for CdRoof in order to better estimate the IMRDR. Moreover, effects of variation in strain hardening ratio on Cd and CdRoof are investigated. In the last part of this study, variations of the ratios of Cd and CdRoof to response modification coefficient (R) with ductility reduction factor (Rμ) are investigated.

Preparation and performance of cadmium sulfide/sulfonated poly(ether ether ketone) nanocomposite materials

We report a kind of cadmium sulfide (CdS)/sulfonated poly(ether ether ketone) (SPEEK) composite via in situ for the first time. It is a new type of nanocomposite possessing outstanding fluorescence property and thermostability. The SPEEK has the sulfonic radical side group and the degree of the sulfonation is 0.88. With the SPEEK dissolving in the N, N-dimethylformamide, cadmium acetate dihydrate (cadmium (Cd) source) was added to make the precursor for the reaction and then the thiourea (sulfur (S) source) was injected. We also investigated the effects of reaction time, the ratio of Cd/S, and the ratio of Cd/–SO3H. The ultraviolet–visible and photoluminescence spectroscopy and thermogravimetric analysis were used to characterize the property of the nanocomposite. The high resolution transmission electron microscope (HRTEM) was used to characterize the morphological of the composite. As the reaction time increases, the photoluminescence intensity declined and the fluorescence peak redshifted. When the reaction time was 1 min, the ratio of Cd/S was 1:2 and the ratio of Cd/–SO3H was 1:5, and the fluorescence properties of the nanocomposites were the best.

Characterization of Simultaneous Aerobic Denitrification and Dephosphorization Strain Cupriavidus sp. H29 and Its Application on Cadmium-Removing

A cadmium tolerant strain Cupriavidus sp. H29 could be applied on simultaneous removal of nitrate, phosphorus and cadmium. Response surface methodology (RSM) experiments showed that optimal removal ratios of nitrate, phosphate and Cd(II), which reached 98.89%, 75.23% and 85.01%, occurred at Cd(II) initial concentration of 30.00 mg/L, nitrate initial concentration of 55.20 mg/L, phosphate initial concentration of 50.00 mg/L, initial pH of 7.0 and C/N ratio of 6.0. Studies on gaseous product, precipitations and extracellular polymeric substances (EPS) indicated that the removal of Cd(II) occurred in the extracellular place. Through the coordinated complexation of EPS, strain H29 can achieve the bio-induced phosphate-cadmium removal. Moreover, studies on heated cells, resting cells, permeable cells, cells membrane and cytoplasm demonstrated that the removal of Cd(II) mainly taken place on the cells membrane. This study provided the theoretical basis for the subsequent research of synchronous removal of heavy metals and other pollutants.

Tuning the structural properties of cadmium-aluminum layered double hydroxide for enhanced photocatalytic dye degradation.

The distinctive layered structure, chemical stability and tunability of layered double hydroxides (LDHs) have led to extensive investigations in various areas of photocatalysis, including photocatalytic water splitting, carbon dioxide photoreduction, and degradation of organic pollutants. Here, a series of visible light active cadmium–aluminum layered double hydroxides (CdAl LDHs) with various Cd2+ : Al3+ ratios is synthesized via the reaction-diffusion framework (RDF) leading thereby to a hierarchal spherical structure of the LDH. The aim of this study is to develop an optimal CdAl LDH photocatalyst that is activated by solar light irradiation and tested for methylene blue (MB) degradation. The structural and physicochemical properties of the synthesized materials are determined by several imaging and spectroscopic techniques. The photocatalytic study reveals a strong dependence of the photocatalytic activity of the CdAl LDH on the cationic ratio with an optimal performance at a ratio Cd2+ : Al3+ equal to 3 : 1. A mechanism is proposed whereby the activity is ascribed to the formation of intermediate reactive oxidative species (ROS) during the photodegradation reactions and scrutinised by invoking different ROS quenchers and corroborated by density functional theory (DFT) calculations.