CdSO4 Solution Research Articles

One-Step Photochemical Preparation of CdS/Poly(MMA-co-MAA) Composite with Enhanced Photocatalytic Activity.

This paper presents a one-step photochemical method for the preparation of CdS/Poly(MMA-co-MAA) composite photocatalyst, based on the concept of simultaneous photocatalytic polymerization of organic monomers during UV-light induced formation of CdS. The preparation is carried out in an aqueous solution of Na2S2O3, CdSO4, methyl methacrylate (MMA) and methacrylic acid (MAA), under a UV lamp. The continuously formed CdS particles with photocatalytic activity act the role of initiator to directly initiate the copolymerization of MMA and MAA, resulting in the in situ formation of the composite and full contact of the CdS particles with the oxygen-containing groups in the polymer. Taking the photocatalytic degradation of methylene blue as a case study, the composite exhibited significantly higher activity under simulated solar light compared to the pure CdS. By analysis on various data, the enhanced photocatalytic activity is attributed to the enhanced visible light absorption, and especially the high electron-hole separation efficiency caused by the electrostatic interaction between photogenerated holes and carbonyl oxygen atoms with negatively charged features. Furthermore, the composite displays excellent sunlight activity and recyclability, suggesting its potential for practical applications. Such a one-step construction strategy relying only on photo-energy is green, low-cost and promising in obtaining high-performance semiconductor/polymer composite photocatalysts.

Assessment of herbaceous ornamental plant species as potential remediation agents for cadmium contaminated environments

Industrial development has led to the pollution of lands with Cadmium (Cd), resulting in the contamination of edible crops and posing significant health risks to humans and animals. To address this issue, the selection of non-edible ornamental plants has been considered. In this study, a lab-scale experiment was conducted using five different ornamental plant species: Tabermaeontana divaricata L., Syngonium podophyllum Schott, Asparagus setaceus (Kunth) Jessop, Catharanthus roseus (L.) G. Don. and Portulaca grandiflora Hook. These plant species were treated 100 mL of 5 mg L−1 CdSO4 solution, continuing for 30 days in hydroponic medium with replenishment with same solution on every 3rd day. The main objective was to identify ornamental plant species with high tolerance and remarkable Cd translocation and accumulation power. The plants were evaluated based on their Tolerance Index (TI), Translocation factor (TF) and Bioaccumulation Factor (BAF) toward Cd in the hydroponic medium. P. grandiflora exhibited high tolerance to Cd with 95 % TI and S. podophyllum (TI – 85 %) and T. divaricata (TI – 62 %) showed limited tolerance while C. roseus and A. setaceus were found to be more sensitive. Moreover, Cd presence was also found to induce a hormetic response in P. grandiflora, T. divaricata, and S. podophyllum. Based on their TF and BAF values, P. grandiflora (TF-5.45; BAF-0.86) and S. podophyllum (TF-4.49; BAF-0.85) were identified as potential candidates for phytoextraction, while T. divaricata (TF-0.007; BAF-4.34) showed potential as a phytostabilizer of Cd. These findings propose for the utilization of these ornamental plants for the remediation of the Cd-contaminated soil and water, with the harvested biomass potentially serving as bio-ore for recovery of Cd.

Hydrometallurgical recycling of critical metals from spent Ni-Cd batteries with emphasis on the separation of Cd2+ over Ni2+ using D2EHPA

ABSTRACT The present study is comprised of a hydrometallurgical process investigated for the recovery of critical metals viz. nickel (Ni) and cadmium (Cd) from spent Ni-Cd batteries with a focus on solvent extraction of Cd-ions. The leaching performed at 5 (w/v)% pulp density using 2.0 M H2SO4 with 7 (v/v)% H2O2 for 6 h duration at 90°C yielded the maximum leaching efficiency of >91% Ni and >99% Cd along with a significant quantity of Fe (>87%). Iron was subjected to hydrolytic precipitation to its complete removal (below 10 ppm in the solution) from the leach liquor at a pH of ~3.5. After that, the Ni-Cd-containing solution was contacted with di-(2-ethylhexyl) phosphoric acid (D2EHPA) to study the extraction behavior as a function of extractant concentration, equilibrium pH, and organic-to-aqueous (O:A) phase ratio. At an equilibrium pH of 3.3, a significant quantity of Ni (>18%) was co-extracted with ~73% Cd by contacting 20 (v/v)% D2EHPA, which was completely scrubbed by contacting 15 g/L CdSO4 solution at an O:A ratio of 2. The scrubbed organic containing 14.4 g/L Cd was then recovered by stripping with 1.5 M H2SO4 solution at an O:A ratio of 1, yielding >99% Cd into the aqueous phase. Further, Ni was recovered from the raffinate by adding soda ash at Na2CO3:Ni2+ ratio = 2.5, temperature = 50°C, and time = 1 h, which was analyzed to be NiCO3.2Ni(OH)2 with purity >99.9%. The experimental results showed the potential of hydrometallurgical tools for the recovery of critical metals from spent Ni-Cd batteries.

Extracellular biosynthesis of cadmium sulphide quantum dot using cell-free extract of Pseudomonas chlororaphis CHR05 and its antibacterial activity

Abstract For the first time a novel aquatic bacterium belonging to strain of Pseudomonas chlororaphis was developed for the synthesis of cadmium sulfide quantum dots. The cadmium sulfate solution incubated with cell-free extract (CFE) of P. chlororaphis strain CHR05 to generate cadmium sulfide nanoparticles (CdSNps) which were characterized with combined spectroscopy and microscopy analyses. The preliminary confirmation on the formation of CdSNps was done by UV–vis and fluorescence analyses with the absorption and emission spectra at 435 and 475 nm, respectively. EDX pattern shows that the CdSNps are composed of the elementals Cd and S. Also, XRD analysis of the purified nanoparticles confirmed the formation of CdSNps. FE-SEM, TEM, and DLS analyzed the size and morphology of the CdSNps. The biosynthesis of CdSNps with the strategy of cell free extract was investigated under optimum conditions. After 24 h of incubation, the results showed that the novel isolated strain can produce spherical CdSNps with an average size of 6.7 ± 2.4 nm, after exposure to CdSO4 solution (2.5 mM) at pH 7.5 and 30 °C. The antibacterial activity CdSNps against some Gram-positive and -negative bacteria were determined using agar well diffusion method and microplate method which has growth-inhibitory effect all on tested bacteria.

Potential Pulse ALD for Room Temperature Fabrication of Stoichiometric CdTe Nanofilms

Deposition of thin film compound semiconductors with good control over stoichiometry, crystallinity and thickness is essential for a range of diverse applications such as solar cells, photocatalysis, thermoelectrics, photodetectors, etc. In this work, nanometer-thick cadmium telluride (CdTe) films with exceptional control over its stoichiometry were electrodeposited onto Au substrates using a novel potential pulse atomic layer deposition (PP-ALD) process. The films were electrodeposited from an acidic aqueous solution of CdSO4 and TeO2 at room temperature using a flow cell electrodeposition set-up. Deposition potential and effect of solution flow were first investigated to optimize the codeposition process. Potential pulses were then subsequently introduced to achieve atomic layer deposition of CdTe. X-ray diffraction (XRD), Scanning electron microscope (SEM), Electron probe microanalysis (EPMA), Energy Dispersive X-Ray Analyzer (EDX) were used to characterize resulting CdTe films. XRD studies of the films showed the evolution of a much sharper peak corresponding to CdTe cubic (111) than is customarily observed for CdTe thin films grown at room temperature. The optimized PP-ALD method was also used to deposit CdTe on Au nanowire-array electrodes. Initial results show high-quality CdTe deposits conformally coated on Au nanowire arrays, which could open pathways for ultrathin light absorber solar energy conversion devices.

Radiation-induced reduction of Cd2+ ions in aqueous solution

Cadmium metal is formed in deaerated aqueous solutions of CdSO4 containing СН3ОН on irradiation with accelerated electrons. The yield of the metal is (1.7 ± 0.2) × 10−2 g kGy−1 absorbed dose. The metal precipitation and hydrogen evolution processes were studied as functions of reactant concentrations and absorbed doses, and a scheme of radiation-induced chemical transformations was proposed and substantiated. The method can be promising for the preparation of pure and amorphous transition metal precipitates from aqueous solutions of metal salts and for treatment of waste water containing these toxic metals.

CdS nanodots preparation and crystallization in a polymeric colloidal nanoreactor and their characterizations

Cadmium sulfide (CdS) nanodots in polymeric colloidal reactors were prepared by seeded inverse emulsion polymerization and then crystallized solvothermally. The cadmium sulfate (CdSO4)-polyacrylamide (PAM) seeds were synthesized by inverse miniemulsion polymerization with CdSO4 solution as a co-stabilizer. The prepared CdSO4-PAM particles were used as polymeric colloidal reactors for the formation of CdS-PAM by feeding the mixed solution of sodium sulfide (Na2S) and acrylamide. The effects of the feeding rate on the size, distribution and morphologies of particles were investigated. The influences of the solvothermal treating temperature and time on the crystallite size were characterized. The CdS was well formed and then crystallized in the PAM colloidal reactors. The crystals growth mechanism was taken under consideration. The crystallite size was calculated by the X-ray diffraction (XRD) data, and their morphologies were observed by transmission electron microscopy (TEM). The small CdS crystals showed a blue-shift on the spectra of ultraviolet visible absorption and fluorescence emission. The small CdS crystals displayed the desired property of photocatalytic degradation.

Molecular Heterogeneity of Lectins in Wheat Seedlings under the Action of Stevioside and Heavy Metals.

The effect of the diterpene glycoside stevioside and high concentrations of heavy metals on the molecular heterogeneity of lectins was studied in seedlings of Kazanskaya 560 winter wheat cultivar. Stevioside induced the emergence of a new 45-kDa lectin. Cultivation of wheat seedlings in CdSO4 and ZnSO4 solutions resulted in the emergence of the protein with Mr = 88 kDa. We detected the presence of both lectins in seedlings during combined treatment with stevioside and heavy metals.

In situ optical and Raman spectroscopic observations of the effects of pressure and fluid composition on liquid–liquid phase separation in aqueous cadmium sulfate solutions (≤400 °C, 50 MPa) with geological and geochemical implications

This study presents the first description of liquid–liquid phase separation in a vapor-saturated CdSO4 solution at temperatures above 222.2°C in fused silica capillary tubing, in which a sulfate-rich liquid (Srich) phase separates from an initially homogeneous aqueous solution and coexists with the remaining sulfate-poor liquid (Spoor) phase and a vapor phase. This phase behavior is characterized by a lower critical solution temperature (∼222.2°C), which is a macroscale property of polymer mixtures. In situ Raman spectroscopy shows an increase in Cd2+–SO42− associations with increasing temperature, especially in the immiscible Srich phase. Phase behavior observations and in situ Raman spectroscopic analyses confirm our previous conclusion that strong ion associations are responsible for the liquid–liquid phase separation in inorganic solutions. The effects of pressure and the fluid composition on liquid–liquid phase separation are also investigated. The temperature of liquid–liquid phase separation increases almost linearly with pressure at a rate of ∼0.5°C/MPa and decreases with the addition of methanol. Both decreases in pressure and increases in the methanol concentration decrease the dielectric constant of the solutions, favoring the Cd2+–SO42− interaction and thus liquid–liquid phase separation. The capillary size also exerts a strong influence on liquid–liquid phase separation because the immiscible Srich phase is more stable in fused silica capillary tubing with an inner diameter of ≤300μm. Therefore, liquid–liquid phase separation can occur in hydrothermal fluids hosted in porous rocks/sediments, especially those that are rich in low-dielectric-constant components and/or at low pressures.Liquid–liquid phase separation may play an important role in the formation of Mississippi-valley-type ore deposits because the ore-forming fluids are enriched in low-dielectric-constant components. The occurrence of liquid–liquid phase separation can promote the enrichment of Zn and S in fluids and accelerate thermochemical sulfate reduction as well as the mineralization of sphalerite. In addition, liquid–liquid phase separation may contribute to the enrichment and transport of metals in other hydrothermal systems because it significantly increases the capability of fluids to carry certain components. Finally, we observe crystallization within the Srich droplet, confirming that large clusters and separated dense liquids can act as precursors for crystallization. Therefore, crystallization through liquid–liquid phase separation can represent an important mechanism of nucleation and crystal growth in hydrothermal fluids.

The heavy metal ions (Cu2+, Zn2+, Cd+) toxic compounds influence on triticale plants growth

The presence of the heavy metals toxic compounds (CuSO4 · 5H2O, ZnSO4 · 7H2O and 3CdSO4·8H2O) in water and soil can be observed by their negative effects on the germination and growth process for different vegetable (barley, oat, maize) who are used for human and animal consumption. This paper it aims the determination of germination and growth inhibition negative effects for triticale plants in the heavy metals ions presence by ecotoxicological laboratory tests. The triticale plants was chosen for their different characteristics to the other grasses respectively: a very good resistance for a wide range of diseases, an accelerated growth and a very good tolerance for aluminum ions presents in acid soils. The determinations were conducted step by step, first, we put the triticale grains in contact with the heavy metal solutions with different concentration then for 3 days we noticed the triticale germination inhibition effects and finally we noticed the growth inhibition process for triticale plants respectively in 7th and 9th day from the start of the experiment. At the end of the tests we can conclude that the triticale roots have a very great sensibility to a CuSO4 solutions compared to the effects for their stalks. A positive effect for triticale stalks we can see for low CuSO4 solution concentrations thus for 5 mg Cu/l the growth is 19,44%. A positive effect for triticale roots it can see for low ZnSO4 solution concentrations so for 5 – 15 mg Zn/l the growth is 24,4%. In the presence of the CdSO4 solution all the processes are inhibited (germination and growth for triticale plants) even for a low concentrations for this toxic.

EFFECT OF CADMIUM AND LEAD IONS ON THE GROWTH AND CONTENT OF PROLINE IN PLANTS OF TRITICALE (Triticosecale Wittm.)

We studied the effect of CdSO4 and Pb(NO3)2 salts in 10-5M, 10-4M and 10-3M concentrations on some physiological indices of growth and development in plants of triticale (Triticosecale Wittm.) cultivar PRAG-530. It is shown that both of the metal salts inhibited germination energy and this effect increased along with salt concentration. It was found that the changes in growth rates, biomass accumulation and accumulation of proline by above- and underground organs of plants cannot be described as a monotonic dose-response dependence, but they are consistent with the paradoxical effect that an increase in the metal dose resulted in a decrease of its damaging effects, whereas a reduction of the metal dose, on the contrary, increased its damaging effect. In particular, it was found that the exposure of triticale plants for 8 days in Pb(NO3)2 solutions stimulated growth processes in terms of length and weight of the shoot and the root system. Interestingly, the toxic 10-4M lead concentration was more favorable for the seedlings than the 10-5M concentration. The response of triticale seedlings grown on CdSO4 solutions was the same, except for the salt concentration of 10-3M, when growth in shoots was inhibited and that in roots was completely suppressed. It is shown that the plants responded to stress caused by lead and cadmium metal salts with substantial accumulation of proline in leaves and roots, and the compound had the protective function. These results indicate that triticale plants are resistant to heavy metals, lead and cadmium, and that cadmium is more toxic to them than lead.

Electrochemical synthesis, cathodoluminescence, and optical absorption of CdS and Cd1–х Zn х S (0 < x ≤ 0.017) films

Using electrochemical deposition from an aqueous solution of Na2S2O3 and CdSO4, with a cadmium anode, we have grown CdS films on tin dioxide substrates (cathode). The CdS films have been shown to be polycrystalline, with the wurtzite structure. From the optical absorption and cathodoluminescence spectra of the films, we have determined their band gap at 298 and 78 K. With a zinc anode, we obtained polycrystalline Cd1–хZnхS (0 < x ≤ 0.017) films with the wurtzite structure. The Cd0.983Zn0.017S films have a larger band gap and higher luminescence intensity than do the CdS films.

Fabrication of metal sulfide porous foams via electrodeposition and galvanic replacement reaction

A simple and non toxic method is reported for fabrication of metal sulfide foams such as Cu2S, Ag2S and CdS. The presented method is mainly based on the electrochemical fabrication of metal foam and galvanic replacement reaction. Cu2S and Ag2S foams are synthesized by immersing as-fabricated Cu and Ag foams in aqueous sulfide solution. Furthermore, another method is used for fabrication of Ag2S foam based on immersing of as-prepared Cu2S foam in AgNO3 solution. Electrodeposition of CdS on as-fabricated Cu foam electrode is performed potentiostatically using a two electrode setup in an aqueous solution of CdSO4, EDTA, and Na2S2O3. The synthesis process is rapid and convenient. The as-fabricated foams were characterized through XRD, BET, SEM and EDX analysis. The obtained data revile fabrication of Cu2S, Ag2S and CdS foams with porous and ramified walls and high surface area. The applicability of as-fabricated Cu2S in the photodegradation of methylene blue is reported, as a proof of concept. The proposed approaches demonstrate a practical route toward preparation of porous metal sulfide foams via electrodeposition and galvanic replacement.

The dynamics of photosynthetic parameters of Phaseolus vulgaris and Vicia fabo under strong cadmium stress

One of the most toxic metals is cadmium, which inputs include those from commercial fertilizers, sewage sludge and other wastes used as soil amendments and also atmospheric deposition. The aim of this experiment was to study the dynamics of photosynthetic parameters of bean (Phaseolus vulgaris L.) and broad bean (Vicia fabo L.) under strong cadmium stress effect. Plants were sown in a neutral (pH 6.0–6.5) peat substrate, when 2nd true leaf unfolded, growth substrate was watered with 6 mM concentration CdSO4 solution. Gas exchange parameters (photosynthetic rate (Pn), transpiration rate (Tn), intercellular CO2 concentration (Ci) and water use efficiency (WUE)) were measured every day with portable photosynthesis system LI-6400. Content of photosynthetic pigments was analyzed in acetone extract using a spectrophotometer on the last 5th day of the experiment. On the first day of treatment the Pn of Cd treated P. vulgaris plants decreased only by 4.3% and statistically insignificant, while Pn of V. fabo decreased by 35.9% (p

Cation-exchange-induced single-crystal-to-single-crystal transformations of a nanoporous coordination complex

Abstract Use of a rigidly conjugated clamp-like bis-pyridyl-bis-amide ligand N,N-bis-(3-pyridyl)isophthalamide (L), complex [CoLCl2]2 (1) with porous macrocycle structure was obtained under solvothermal conditions. When single crystals of 1 were immersed into the methanol solution of HgCl2 and CdSO4, new crystals of a bimetallic macrocyclic complex [HgLCl2]2 (2) and a two-dimensional (2D) corrugated sheet complex [CdLSO4(H2O)2]n (3) were attained, respectively. All these phenomena are observed through single crystal to single crystal (SCSC) transformations along with the metal–ligand bond breaking and the new metal–ligand bond formation. In addition, the determination of Scanning Electron Microscope (SEM) and Energy-Dispersive X-ray Spectrometry (EDS) reveals that the exchange is a recurrent dissolving-exchange-crystallization process of solvent-mediated mechanism.

Electrocrystallization of cadmium on anodically formed titanium oxide

The electrocrystallization of Cd on previously anodized Ti substrates was studied by means of electrochemical techniques and SEM images in three different solutions of CdSO4 (2, 10, and 50 mM). Voltammetric characterization showed the typical behavior of metal electrodeposition on conducting substrates, and potentials for electrodeposition of Cd were identified. However, the response obtained at different potentials in current transients exhibited an abnormal behavior suggesting the influence of TiO2 on the process of electrocrystallization. The characterization of the obtained electrodeposits by SEM images allowed relating electrochemical with morphological changes, in particular, variations in the crystal size and shape as well as formation of presumably Cd branches on the substrate surface. This behavior only allowed the analysis of current transients of the electrodeposits obtained in 2 mM CdSO4 solution using general equation for diffusion-controlled 3D growth and relating parameters of Cd crystal growth on anodized Ti electrode with the observed morphological changes.

ChemInform Abstract: Studies on the Chemistry of [Cd(NH3)4](MnO4)2. A Low Temperature Synthesis Route of the CdMn2O4+x Type NOx and CH3SH Sensor Precursors.

Abstract[Cd(NH3)4](MnO4)2 (I) is synthesized from an aqueous solution of CdSO4, NH3, and NaMnO4 at 0 °C (86% yield).

Biosorption of aquatic cadmium(II) by unmodified rice straw

Cadmium is the most common toxic metal threatening safe rice supply. Rice straw has the potential to remove Cd from large-scale effluent contaminated by heavy metals since it exhibited a short biosorption equilibrium time of 5min, high biosorption capacity (13.9mgg−1) and high removal efficiency at a pH range of 2.0–6.0. The main Cd biosorption mechanism was Cd2+ ion exchange with K+, Na+, Mg2+ and Ca2+, together with chelation with functional groups such as CC, CO, OH and carboxylic acids. When 0.5% (w/v) rice straw was exposed to 50mgmL−1 CdSO4 solution with shaking at 150rmin−1 for 3h, about 80% of the aquatic Cd was absorbed and the Cd content in rice straw reached 8–10mgg−1, suggesting that the metal-enriched rice straw could become high quality bio-ore by virtue of the industrial mining grade of its metal content and easy metal recovery.

Propriedades óticas e microestruturais de filmes finos eletrodepositados de CdTe

Filmes finos de CdTe foram obtidos por eletrodeposição catódica, a partir de uma solução de CdSO4, H2SO4 e Te. Os filmes foram depositados à temperatura ambiente, sobre substratos de vidro cobertos com SnO2 ou In2O3:Sn. A influência do potencial de deposição nas propriedades microestruturais e óticas dos filmes foi investigada. Os valores de banda proibida dos filmes ficaram na faixa de 1,40 e 1,50 eV, próximos ao valor da banda do CdTe volumétrico. Um potencial de deposição ótimo foi determinado para cada substrato. O aquecimento do eletrólito a 50 ºC não foi suficiente para provocar grandes alterações na cristalinidade, mas promoveu a formação de filmes com menor quantidade de defeitos. Isto sugere que um tratamento térmico pós-deposição possa melhorar as propriedades destes filmes para aplicações fotovoltaicas.

An in situ photoelectrochemical determination of hydrogen sulfide through generation of CdS nanoclusters onto TiO2 nanotubes

A novel and facile photoelectrochemical method has been developed to detect H(2)S in water samples with high sensitivity and selectivity. The protocol is based on the photocurrent generated by CdS nanoclusters which are deposited onto TiO(2) nanotubes exposing in CdSO(4) solution with the gradual addition of Na(2)S, with low-cost, environment-friendly, theoretical and technical simplicity. The developed method shows a very broad linear range from 10(-8) M to 10(-3) M and a low detection limit of 0.31 nM (9.92 ppt), far lower than the ceiling value in drinking water provided by WHO. Furthermore, the present method has been applied for determination of H(2)S in water samples. The concentrations of H(2)S in water samples determined by the present method are in a good agreement with those monitored by traditional spectrophotometry.