Biosorption of Zn2+ and Pb2+ from aqueous solutions using native and microwave treated Flammulina velutipes stipe

Native stipe (NS) and microwave treated stipe (MTS) of Flammulina velutipes were utilized for the biosorption of Zn²⁺ and Pb²⁺ ions from aqueous solution. The effects of pH, contact time, and initial concentration on the biosorption were studied for each metal separately. The desired pH of aqueous solution was found to be 6.0 for the removal of Zn²⁺ ions and 5.0 for the removal of Pb²⁺ ions. The percent removal of both metals was found to increase with the increase in contact time; biosorption equilibrium was established in about 60 min. The maximum biosorption of Zn²⁺ and Pb²⁺ ions from single component systems can be successfully described by Langmuir and Freundlich models; the biosorption kinetics can be accurately described by a second-order kinetic model. The present data from these studies confirms that the native and microwave treated forms of Flammulina velutipes stipe have the potential to be used for the biosorption of Zn²⁺ and Pb²⁺ ions from aqueous solution. The metal biosorption capacities of NS for Zn²⁺ and Pb²⁺ were 58.14 and 151.51 mg g^?1, respectively, while the biosorption capacities of MTS for the both metals were 95.24 and 172.41 mg g^?1, respectively.     

High-performance inductive couplers based on novel Ce3+ and Co2+ ions co-doped Ni-Zn ferrites

High-performance inductive couplers require Ni-Zn ferrites of high saturation magnetization, Curie temperature, permeability and application frequency. However, for inductive couplers some of these properties run against each other in one ferrite. To balance these requirements, in this work, novel Ni-Zn ferrite ceramics co-doped by Ce³⁺ and Co²⁺ ions with chemical formula Ni_0.4Zn_0.5Co_0.1Ce_xFe_2-xO₄ (x = 0–0.06) were designed and fabricated by a molten salt method. For the acquired ferrites, both Ce³⁺ and Co²⁺ ions could come into the lattices. The initially doped Co²⁺ ions would cause a slightly decreased grain size and dramatically reduced the specimen densification, but the further added Ce³⁺ ions could effectively inhibit the density reduction, while the grain size continues to dwindle. The additional Ce³⁺ ions would generate a foreign CeO₂ phase in the acquired specimens. The sole doping of Co²⁺ ions would aggrandize the saturation magnetization of ferrites, but the introduction of Ce³⁺ ions would cause its decrease. However, with an appropriate doping level, the Ce³⁺ and Co²⁺ ions co-doped ferrites could preserve a relatively high saturation magnetization, while the Curie temperature and cut-off frequency of the ferrites are dramatically augmented, although the permeability would be somewhat reduced. The as-acquired ferrites were simulated to apply in inductive couplers, revealing that the devices manufactured by the Ni_0.4Zn_0.5Co_0.1Ce_xFe_2-xO₄ ferrites had significantly high maximum operating frequency, compared with that of the one manufactured by pure Ni_0.5Zn_0.5Fe₂O₄ ferrite.     

Characterization of Adsorptive Capacity and Investigation of Mechanism of Cu2+, Ni2+ and Zn2+ Adsorption on Mango Peel Waste from Constituted Metal Solution and Genuine Electroplating Effluent

Abstract

The present study reports the potential of mango peel waste (MPW) as an adsorbent material to remove Cu²⁺, Ni²⁺, and Zn²⁺ from constituted metal solutions and genuine electroplating industry wastewater. Heavy metal ions were noted to be efficiently removed from the constituted solution with the selectivity order of Cu²⁺ > Ni²⁺ > Zn²⁺. The adsorption process was pH-dependent, while the maximum adsorption was observed to occur at pH 5 to 6. Adsorption was fast as the equilibrium was established within 60 min. Maximum adsorption of the heavy metal ions at equilibrium was 46.09, 39.75, and 28.21 mg g for Cu²⁺, Ni²⁺, and Zn²⁺, respectively. Adsorption data of all the three metals fit well the Langmuir adsorption isotherm model with 0.99 regression coefficient. Release of alkali and alkaline earth metal cations (Na⁺, K⁺, Ca²⁺, Mg²⁺) and protons H⁺ from MPW, during the uptake of Cu²⁺, Ni²⁺, and Zn²⁺, and EDX analysis of MPW, before and after the metal sorption process, revealed that ion exchange was the main mechanism of sorption. FTIR analysis showed that carboxyl and hydroxyl functional groups were involved in the sorption of Cu²⁺, Ni²⁺, and Zn²⁺. MPW was also shown to be highly effective in removing metal ions from the genuine electroplating industry effluent samples as it removed all the three metal ions to the permissible levels of discharge legislated by environment protection agencies. This study indicates that MPW has the potential to effectively remove metal ions from industrial effluents.     

Investigations of the divalent metal ions Zn2+, Co2+, Ni2+ doped ultra-wide temperature stable BBNN system

Multi-component BaTiO₃–Bi_0.5Na_0.5TiO₃–Nb₂O₅ (BBNN) system doped with divalent metal ions (Zn²⁺, Co²⁺, Ni²⁺) was prepared by the conventional solid–state method.The X-ray diffraction patterns revealed all samples exhibited perovskite (P4mm) single phase. The dielectric properties and micro-mechanisms were discussed and validated. Novel theories, based on the characteristics of the different kinds of dielectric polarization, are proposed to explain the dielectric anomalies in the dielectric system. The relationships between microstructure and the dielectric properties were investigated systematically for the first time. The samples doped with 15 mol% Zn²⁺/Co²⁺presented good dielectric properties of an ultra-broad temperature stable range (from −50 and >300), high dielectric constant (ε~1925 for Zn²⁺/ ε~1341 for Co²⁺) and low dielectric loss (tan δ<0.02) were obtained. These features made the ceramics system have high practical values for miniaturization and harsh environments applications.     

Tricalcium phosphate doped with Mg2+ and combinations of Mn2+, Zn2+ and Fe3+: A DoE study on sintering,mechanical, microstructural and biological properties

Bioactive ceramics such as tricalcium phosphate (TCP) doped with metal ions are often used to replace natural bone in orthopedic and dental function, both in structural and coating applications. Although the addition of different ions to TCP has been correlated with improved mechanical performance, as well as pro-osteogenic and osteointegrative biological activities, the effect of combining different ions in single biomaterial formulations is poorly described. Here, design of experiments (DoE) was used to assess the effect of the addition of three metallic ions - Mn²⁺, Zn²⁺ and Fe³⁺ - to TCP doped with 10 mol% Mg²⁺, in combinations comprising one, two and three ions with varying ratios. Our results showed that the TCP could be doped by combinations of metallic ions and β-TCP and hydroxyapatite constitute the main crystalline phases. Additionally, the simultaneous effect of metal ions influenced the structural and physical properties of the TCP composite. Overall, for up 1 mol% of Mn²⁺, up to 3.75 mol% of Zn²⁺ and more than 2 mol% of Fe³⁺, compositions 2 and 6, a dense microstructure and good defined grain boundaries improve the mechanical properties. Furthermore, the ion-doped TCP composites, namely the one prepared from equal amounts of substituting ions besides Mg2+, did not elicit a cytotoxic effect indicating that these materials could be of interest for tissue engineering applications.     

A sensitive Schiff-base fluorescent indicator for the detection of Zn2+

A Schiff-based fluorescence probe benzene-1,2-dicarbaldehyde bis-benzoyl hydrazide (L) was designed and synthesized. Its sensing behavior toward metal ions has been investigated by absorption and fluorescence spectroscopy. Indicator L showed high selectivity to Zn²⁺ in various solvents, whereas other metal ions failed to induce response. Especially Cd²⁺, which has similar chemical properties with Zn²⁺, can be distinguished from Zn²⁺ obviously.     

Antimicrobial properties of co-doped tricalcium phosphates Ca3-2x(MˊMˊˊ)x(PO4)2 (M = Zn2+, Cu2+, Mn2+ and Sr2+)

The substituted (Ca²⁺/Cu²⁺), and co-substituted (Cu²⁺/Zn²⁺), (Cu²⁺/Sr²⁺), and (Sr²⁺/Mn²⁺) β-tricalcium phosphate (β-TCP)-based Ca_3-2x(MˊMˊˊ)_x(PO₄)₂ (M = Zn²⁺, Cu²⁺, Mn²⁺ and Sr²⁺) solid solutions have been synthesized using solid-state route. The powder X-ray diffraction study shows the formation of β-TCP-type structure as the main phase in all solid solutions. The crystal structures and chemical compositions were approved using Fourier-transform infrared (FT-IR) absorption spectra and energy-dispersive X-ray spectrometry (EDX) data, respectively. The unit cell parameters and volume of as-synthesized samples directly depend on the radius of the incorporated ions. The limits of the single-phase solid solutions were found based on the possible occupation of the crystal sites in β-TCP structure. For the divalent ions with small radii, such as Cu²⁺ or Zn²⁺, the limit composition was found as Ca_2.571Mˊ_0.429–xMˊˊ_x(PO₄)₂ for Mˊ and Mˊˊ – Cu²⁺ and Zn²⁺. The enlargement of the unit cell by incorporation of Sr²⁺ allows to extend the limit of solid solutions up to Ca_2.5Sr_0.5–xMˊ_x(PO₄)₂ for Mˊ – Cu²⁺ or Mn²⁺. The antibacterial properties were studied on 4 bacteria (S. aureus, P. aeruginosa, E. coli and E. faecalis) and 1 fungus (C. albicans). It has been showed that co-doped Ca_2.5Sr_0.25Cu_0.25(PO₄)₂ sample exhibits the highest antimicrobial activity resulting in 92%, 96% and 96% inhibition growth rate for S. aureus, P. aeruginosa and E. faecalis, respectively. The antimicrobial properties are strongly related to the occupation of the crystal sites in the β-TCP structure by doping ions.     

Effect of magnesium carbonate on the uptake of aqueous zinc and lead ions by natural kaolinite and clinoptilolite

Adsorption behavior of Zn²⁺ and Pb²⁺ ions on kaolinite and clinoptilolite, originating from natural resources, was studied as a function of contact time and concentration. Zn²⁺ and Pb²⁺ ions are quickly adsorbed on both minerals and the uptake of the latter is more favored. The uptake of both ions was then examined on kaolinite–MgCO₃ and clinoptilolite–MgCO₃ mixtures over a metal ions range from 1 to 10 000 mg/L. The sorption behavior of Zn²⁺ and Pb²⁺ on pure MgCO₃ was also studied. MgCO₃ is much more effective in the retention of Zn²⁺ and Pb²⁺ ions, in particular at higher concentrations. The large increase in the retarded amounts of both ions was associated with formation of the hydroxy-carbonate phases; namely hydrozincite for Zn²⁺, and cerussite and hydrocerussite in the case of Pb²⁺.     

Influence of the Metal Ions Cr3+, Fe3+, Ni2+ and Cu2+ on the Stability and Oxygen Consumption of Acrylic and Methacrylic Acid

For the safe and trouble‐free operation of a manufacturing plant and the safe storage of acrylic, as well as methacrylic monomers, it is important to know the polymerization stability as a function of the process parameters (temperature, oxygen concentration, and impurities, e.g., metal ions). Contamination with metal ions can be caused by the corrosion of steel units. Therefore, the influence of the metal ions Cr³⁺, Fe³⁺, Ni²⁺ and Cu²⁺ in the concentration range of 0–10 ppm (g g^–1) on the polymerization behavior and the oxygen consumption of acrylic and methacrylic acid were examined in this work. It was shown that Cr³⁺, Ni²⁺, and Cu²⁺ ions extend the inhibition period of acrylic acid (AA) and methacrylic acid (MAA) and reduce the O₂ consumption. Fe³⁺ ions, however, cause a decrease of the inhibition period and in the case of AA an increase of the O₂ consumption, which leads, in the end, to a faster unintentional polymerization. Therefore, alloys which contain iron should be avoided as far as possible in the construction of AA plants. Fe³⁺‐ions show the opposite influence towards MAA, here the presence of Fe³⁺ shows a stabilizing effect.     

A new Zn2+ chemosensor based on functionalized 8-hydroxylquinoline

A new fluorescent Zn²⁺ chemosensor (3) based on functionalized 8-hydroxylquinoline has been synthesized and characterized. Compound 3 shows weak fluorescence in CH₃CN–HEPES buffer solution (50 mM, pH 7.2 v/v = 1:9), but the fluorescence is significantly enhanced upon binding to Zn²⁺ through a zinc(II)-catalyzed ester hydrolysis reaction to form a highly emissive zinc(II) complex. This suggests that 3 can be served as a typical “switch–on” chemosensor with high selectivity for Zn²⁺ over other metal ions.     

Synthesis and photoluminescence characterizations of Zn2+ and Tb3+ codoped CeO2 phosphors for temperature sensing applications

Cyan light-emitting Ce_0.985-xZn_xO₂:0.015 Tb³⁺ (x = 0 to 0.2) phosphors were synthesized using the ethylenediaminetetraacetic acid-assisted hydrothermal method. The X-ray diffraction and refinement analyses of the prepared phosphors indicated that the formed face-centered cubic structure remained intact even after the doping of large quantities of Zn²⁺ ions. However, the incorporation of Zn²⁺ ions increased the Ce³⁺/Ce⁴⁺ ratio, resulting in the enhancement of oxygen vacancies in the prepared phosphors. The generation of oxygen vacancies caused the evolution of a broad photoluminescence emission band ranging from 400 to 525 nm with a characteristic Tb³⁺ emission of approximately 543 nm. Two-emission regions in Ce_0.885Zn_0.1O₂:0.015 Tb³⁺ phosphors were utilized for measuring the fluorescence intensity ratio (FIR) as a function of temperature ranging from 303 to 523 K. At 523 K, the FIR values dropped to approximately 40% of the starting temperature value. The variation of FIR values followed the Boltzmann behavior. The Boltzmann fitting demonstrated the feasibility of the present phosphors for temperature sensor applications. The optimum absolute sensor sensitivity of Ce_0.885Zn_0.1O₂:0.015 Tb³⁺ phosphors was measured to be 0.0043 K⁻¹ at 398 K with a resolution of approximately 1 K⁻¹. Moderate temperature sensitivity, negligible hysteresis loop, and excellent reversibility revealed the suitability of Ce_0.885Zn_0.1O₂:0.015 Tb³⁺ phosphors for sensing the temperature in various electronic devices.     

Adsorption characteristics of metal ions by CO2-fixing Chlorella sp. HA-1

Single and binary metal systems were employed to investigate the removal characteristics of Pb²⁺, Cu²⁺, Cd²⁺, and Zn²⁺ by Chlorella sp. HA-1 that were isolated from a CO₂ fixation process. Adsorption test of single metal systems showed that the maximum metal uptakes were 0.767 mmol Pb²⁺, 0.450 mmol Cd²⁺, 0.334 mmol Cu²⁺ and 0.389 mmol Zn²⁺ per gram of dry cell. In the binary metal systems, the metal ions on Chlorella sp. HA-1 were adsorbed selectively according to their adsorption characteristics. Pb²⁺ ions significantly inhibited the adsorption of Cu²⁺, Zn²⁺, and Cd²⁺ ions, while Cu²⁺ ions decreased remarkably the metal uptake of Cd²⁺ and Zn²⁺ ions. The relative adsorption between Cd²⁺ and Zn²⁺ ions was reduced similarly by the presence of the other metal ions.     

Photoactive ternary Tb3+/Zn2+ centered hybrids with p-tert-butylcalix[4]arene functionalized Si–O bridge and polyvinylpyridine

A new multifunctional linkage Calix-AC-Si is derived from the modification of the p-tert-butylcalix[4]arene derivative with 3-(triethoxysilyl)-propyl isocyanate (TEPIC) and behaves as the first chelated ligand, and the organic polymer polyvinylpyridine (PVPD) is used as the second terminal ligand, whose ternary hybrids of metal ions (Tb³⁺ and Zn²⁺) are assembled and possess different luminescent properties. Especially the introduction of Zn²⁺ in the Tb³⁺ hybrid system can improve the luminescence of Tb³⁺.     

Copper-selective chelating resins. I. Batch extractions

Eleven novel metal ion-chelating resins based upon porous poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) have been prepared by direct reaction of the polymer with ligands containing an amino group. Those species involving a 2-pyridyl-2-imidazole and a 2-aminomethylpyridine proved to be the most interesting and, for comparison, polystyrene resin analogues of these were also produced. As expected from the literature, the above pyridine-containing ligands remained effective for the extraction of Cu²⁺ down to pH 2. Despite having superficially similar overall physical characteristics (particle size, surface area, porosity) the glycidyl methacrylate-based resins showed remarkably enhanced kinetic behaviour in the batch extraction of base metal ions such as Cu²⁺, with an extraction half life as low as ∼ 8 minutes, four times faster than a polystyrene-based analogue.In addition the glycidyl methacrylate-based resins displayed superior selectivity in the extraction of particular metal ions from feed liquors containing a mixture of metal ions. The most remarkable separation discovered was that of Cu²⁺ from Zn²⁺ where the glycidyl methacrylate-based species with the above ligands achieved essentially quantitative separation of Cu²⁺, even with Zn²⁺ present in 250 times excess. Extracted metal ions were rapidly and quantitatively eluted from these resins with 2 M H₂SO₄, and in the case of Cu²⁺ an acid strength of only 0.25 M was adequate.     

Solvent Extraction of Indium,Gallium, and Zinc Ions with Acidic Organophosphates having Bulky Alkyl Groups

The extraction equilibria of In³⁺, Ga³, and Zn²⁺ with bis(4‐ethylcyclohexyl)phosphoric acid (D4ECHPA), bis(4‐cyclohexylcyclohexyl)phosphoric acid (D4DCHPA), and bis(2‐ethylhexyl)phosphoric acid (D2EHPA) were investigated in acidic aqueous sulfate media. The order of extractability of metal ions is D4DCHPA > D2EHPA > D4ECHPA, which corresponds to the lipophilicity (log P) of the extractants. The separation factors, β_(In/Ga) and β_(Ga/Zn), of D4ECHPA and D4DCHPA are greater or comparable than that of D2EHPA, because of the steric hindrance of the bulky cyclohexyl groups. In³⁺ can be therefore separated from simulated liquor containing a high concentration of Zn²⁺ by D4DCHPA.     

Liquid membrane transport and separation of Zn2+ and Cd2+ from sulfate media using organophosphorus acids as mobile carriers

The transport and separation of Zn²⁺ and Cd²⁺ from binary sulfate solutions in a supported liquid membrane using di(2‐ethylhexyl)phosphoric acid (D2EHPA) and 2‐ethylhexylphosphonic acid mono‐2‐ethylhexyl ester (PC88A) as mobile carriers was studied. Batch solvent extraction experiments were conducted to obtain the reaction stoichiometries. Experiments were performed at different metal concentrations (1.4–14.5 mol m^?3), metal concentration ratios (0.4–9.2), pH (2–5), and carrier concentrations (0.1–0.6 mol dm^?3). A mass transfer model was proposed that considers diffusion in the aqueous feed and strip stagnant layers, and within the membrane. The interfacial reactions were assumed to approach equilibrium instantaneously. It was shown that the proposed model was applicable for binary Zn²⁺/Cd²⁺ systems (standard deviation, 5%). The larger separation factors of Zn²⁺ over Cd²⁺ with PC88A than D2EHPA under equilibrium (batch solvent extraction) and non‐equilibrium (liquid membrane) conditions were also evaluated and discussed. Copyright © 2003 Society of Chemical Industry     

Optimization of Opto-Electrical and Photocatalytic Properties of SnO<Subscript>2</Subscript> Thin Films Using Zn<Superscript>2+</Superscript> and W<Superscript>6+</Superscript> Dopant Ions

Abstract  

A series of Zn²⁺ and W⁶⁺ doped tin oxide (SnO₂) thin films with various dopant concentrations were prepared by spray pyrolysis deposition, and were characterized by X-ray diffraction, atomic force microscopy, contact angle, absorbance, current density–voltage (J–V) and photocurrent measurements. The results showed that W⁶⁺ doping can prevent the growth of nanosized SnO₂ crystallites. When Zn²⁺ ions were used, the crystallite sizes were proved to be similar with the undoped sample due to the similar ionic radius between Zn²⁺ and Sn⁴⁺. Regardless of the dopant ions’ type or concentration, the surface energy has a predominant dispersive component. By using Zn²⁺ dopant ions it is possible to decrease the band gap value (3.35 eV) and to increase the electrical conductivity. Photocatalytic experiments with methylene blue demonstrated that with zinc doped SnO₂ films photodegradation efficiencies close to 30% can be reached.     

Effect of the solvent properties on the polarographic behaviour of the Zn2+ and Cd2+ complexes with glycine,N-acetyl and N-Benzoyl glycine

The polarographic behaviour of Zn²⁺ and CD²⁺ and their complexes with glycine, N-acetyl and N-benzoylglycine has been studied in DMSO, CH₃CN and DMF; the results have been compared with those previously obtained in H₂O and C₂H₅OH. The effect of the solvent properties on the reduction of those systems has been explained in terms of the electron pair donor (EPD) and of electron pair acceptor (EPA) strength of the solvent itself. The higher the donor number (DN), the more negative the E_{$\text{1}\text{2}$} value both of the free metal ions and the complexes. Moreover, the stability constants of the complexes, polarographically determined, seem to be related to the acceptor number (AN) of the solvent.     

Preparation and fluorescence properties of Zn2SnO4:Eu3+ orange emitting afterglow phosphor

In this study, an orange emitting afterglow phosphor of Zn₂SnO₄:Eu³⁺ was fabricated using the co-precipitation & hydrothermal method, and then annealed in Ar atmosphere at 1000 °C. X-ray diffraction, Raman spectra, EDX, fluorescence spectrometer, SEM and TEM were performed to characterize the target products. As revealed from the XRD analysis results, the fabricated product was the cubic inverse spinel structure Zn₂SnO₄ (JCPDS 24–1470) exhibiting high crystallinity. As confirmed by Raman and EDX spectra, the target product was Zn₂SnO₄:Eu³⁺. As Zn₂SnO₄:Eu³⁺ was excited at 347 nm, its fluorescence spectra showed the magnetic dipole emission at 589 nm and the electric dipole transition at 610 nm, complying with the transitions of Eu³⁺ ions from ⁵D₀→⁷F₁ and ⁵D₀→⁷F₂. Meantime, Zn₂SnO₄:Eu³⁺ phosphors displayed an orange afterglow, and its attenuating characteristics met the exponential equation. Moreover, the optimal doping amount of Eu³⁺ ions was 15 mol%, and the concentration quenching took place by the cross relaxation. The color coordinate of the product (x = 0.15) was determined as (0.522, 0.4635), and the color purity reached 98.3%.     

Improving the efficiency of dye-sensitized Zn2SnO4 solar cells: The role of Al ions

The dye-sensitized Zn₂SnO₄ solar cells were treated with Al³⁺ ions to enhance the power conversion efficiency for the first time. Usually, the surface treatment on photoanodes with Al³⁺ ions generated an overlayer of Al₂O₃. For Zn₂SnO₄ photoanode, another reaction pathway was found. The treatment with Al³⁺ ions led to decreasing open circuit voltage, and a 22.6% enhancement of efficiency. Mott–Schottky measurements revealed that the flat band of Zn₂SnO₄ had a positive shift owing to the introduction of Al³⁺ ions. XPS confirmed that Al³⁺ ions were introduced into the lattice of Zn₂SnO₄ and occupied the position of Sn⁴⁺, resulting in decreased conduction band edge. TEM demonstrated the size of Zn₂SnO₄ nanoparticles became larger due to the reaction of Al³⁺ with Zn₂SnO₄. Although the adsorption amounts of dyes lowered by 21%, the driving force for electron injection was greatly enhanced as a result of decreased conduction band edge, resulting in significantly enhanced cell efficiency.