Binary Metal Systems Research Articles

Competitive biosorption of Pb(II), Cr(III), and Cd (II) from synthetic wastewater onto heterogeneous anaerobic biomass in single, binary, and ternary batch systems

Biosorption of lead, chromium, and cadmium ions from aqueous solution by dead anaerobic biomass (DAB) was studied in single, binary, and ternary systems with initial concentration of 50 mg/l. The metal-DAB affinity was the same for all systems. The main biosorption mechanisms were complexation and physical adsorption of metallic cations onto natural active functional groups on the cell wall matrix of the DAB. It was found that biosorption of the metallic cations onto DAB cell wall component was a surface process. The main functional groups involved in the metallic cation biosorption were apparently carboxyl, amino, hydroxyle, sulfhydryl, and sulfonate. These groups were part of the DAB cell wall structural polymers. Hydroxyle groups (–OH) were responsible for 37, 52, and 31% of the removal of Pb(II), Cr(III), and Cd(II) by DAB through complexation mechanisms; whereas carboxylic groups (C=O) were responsible for 21, 14, and for 34%of the removal of Pb(II), Cr(III), and Cd(II), respectively. Biosorption data were fitted to four isotherm models. Langmuir model was best fitted to the experimental data than Freundlich, Sips, and Redlich–Peterson models for single system. While for binary and ternary metal systems, extended Langmuir model were fitted experimental data better than interaction factor, a combination of Langmuir–Freundlich and Redlich–Peterson models. The maximum uptake capacities were 54.92, 34.78, and 29.99 mg/g for Pb(II), Cr(III), and Cd(II), respectively. Optimum pH was found to be 4.

Reaction diffusion and interdiffusion in some binary metallic systems

This paper reviews studies from the Münster laboratory on multiphase and interdiffusion performed on several binary metallic systems. Optical microscopy and electron microprobe analysis were used to study interdiffusion and growth of the intermetallic layer(s) in infinite diffusion couples. Both methods have resolutions at the micron level. Thus, the results summarised in this paper concern the diffusion-controlled regime of the reaction diffusion process. We first remind the reader of some of the basics of multiphase diffusion and interdiffusion. Then we discuss results reported for the following systems: cobalt–niobium, nickel–niobium, nickel–aluminium and magnesium–aluminium. In the case of Co2Nb we also compare interdiffusion and tracer diffusion of the components. Multiphase diffusion experiments also contain information about solid–solid equilibria of the phase diagram(s).

Thermodynamic properties of binary metallic systems containing intermetallic compounds

If the thermodynamic activity of the components in a binary metallic system A-B, which contains intermetallic compounds (AmB or ABl, where m, l = 1, 2, 3, …), is calculated on the basis of ideal associated solutions, reasonable accuracy may be obtained by means of the assumption that the chemical composition and thermodynamic properties of the associates are the same as for the intermetallic compounds.

Synergistic effect in the simultaneous removal of binary cobalt–nickel heavy metals from effluents by a novel e-waste-derived material

Simultaneous removal of heavy metals coupled with high adsorption capacity of an adsorbent material is an ultimate target in industry for the purification of wastewater. A novel adsorbent prepared from an electronic waste-based material has been used for this purpose. The results exhibit very high removal capacities of the adsorbent for both cobalt and nickel in the single-component systems. These capacities have been compared with those of three widely-used industrial adsorbents and it has been shown that the removal capability of this novel material is well above those of the industrial ones. Moreover, the effect of pH has also been explored and it has been shown that the pH value has a drastic effect on the metal removal capacity at pH values lower than 3. Furthermore, a synergistic effect of two metals has been observed and studied in the binary metal system. The results indicate that not only the simultaneous presence of the two metals does not reduce the adsorption capacity, but also enhances their removal from the effluent.Moreover, the adsorption equilibrium modeling for the single and binary systems have been presented and it has been inferred that the Langmuir-type models can fit the single component experimental data, while the binary system can be fitted only by the modified extended Freundlich model.

Removal of Cu(II) and Fe(III) from aqueous solutions by dead sulfate reducing bacteria

The biosorption properties of dead sulfate reducing bacteria (SRB) for the removal of Cu(II) and Fe(III) from aqueous solutions was studied. The effects of the biosorbent concentration, the initial pH value and the temperature on the biosorption of Cu(II) and Fe(III) by the SRB were investigated. FTIR analysis verified that the hydroxyl, carbonyl and amine functional groups of the SRB biosorbent were involved in the biosorption process. For both Cu(II) and Fe(III), an increase in the SRB biosorbent concentration resulted in an increase in the removal percentage but a decrease in the amount of specific metal biosorption. The maximum specific metal biosorption was 93.25 mg·g−1 at pH 4.5 for Cu(II) and 88.29 mg·g−1 at pH 3.5 for Fe(III). The temperature did not have a significant effect on biosorption. In a binary metal system, the specific biosorption capacity for the target metal decreased when another metal ion was added. For both the single metal and binary metal systems, the biosorption of Cu(II) and Fe(III) onto a SRB biosorbent was better represented by a Langmuir model than by a Freundlich model.

Incorporation of selectivity factor in modeling binary component adsorption isotherms for heavy metals-biomass system

The single and binary biosorption of copper and lead ions from aqueous solution using a low cost agro-based resource (i.e. rice straw) has been demonstrated in this work. The biosorption experiments were performed in a static mode. Experimental parameters affecting the sorption process namely biosorbent dose, pH, and temperature were studied. Two empirical adsorption models (i.e. Langmuir and Freundlich) were used for the evaluation of biosorption equilibrium data in single system. Both models were able to correlate experimental data satisfactorily. The adsorptivity of solute (KL) and maximum sorption capacity of the solid (qm) were increased at higher temperatures. For binary metal system, we modified the adsorption parameters of extended-Langmuir model (i.e. KL-bin and qm-bin) by introducing selectivity factor of the solute (S). It was found that the modified extended-Langmuir model with incorporation of solute’s selectivity factor gave good correlation results against binary adsorption data with reasonable fitted parameter values. The feasibility and biosorption performance of rice straw in sequestering copper and lead ions was also tested using real effluent along with its regeneration possibility.

<I>Phase Diagram of the Iridium-Rhenium System</I>

Department of Chemistry, Center for Materials Science and Nanotechnology, University of Oslo, PO Box 1033 Blindern, N-0315 Oslo, Norway Email: kirill.yusenko@smn.uio.no The experimental data on the binary metallic iridiumrhenium system available to date are inconsistent. The present work summarises recent experimental data on the Ir-Re system with the aim of allowing the correct solidus parts of the equilibrium phase diagram to be constructed. The examination of data obtained by different synthetic methods and thermodynamic calculations has revealed that the maximum solidphase solubilities at 2000oC of Re in Ir and Ir in Re are 20 at% and 68 at%, respectively. The binary phase diagram proposed in this paper serves as a reliable model for representing the available experimental data.

Influence of variable fluxes and sorption properties on Mn2+ transport under single, binary, and multiple metals through lateritic aquifer

Contamination of underlying aquifers in gold mining areas is usually a great concern and prevention plans need to be implemented. To assess the potential risk of heavy metal contamination, the simulation of heavy metal transport was carried out using variable leachate fluxes and chemical nonequilibrium two-site sorption parameters derived from column experiments. This study applied a numerical model, called the HYDRUS-2D, to simulate the transport of Mn 2+ under a single metal and multi-metal systems with 2 variable leachate fluxes (0.002 and 0.0026 m/day) through a lateritic aquifer approximately 5 km downgradient of the tailing pond. This model could be used as an environmental monitoring tool for gold mining management. The model assumed that the compacted clay layer of the tailing storage facility (TSF) has cracked and this led to Mn 2+ and some other elements to contaminate the shallow groundwater. The simulations showed that the time needed to reach from contamination to the Thailand drinking water standard at a specific location for Mn 2+ in a multi-metal system was faster than those in the binary metal system and single metal system, respectively. With increasing leachate flux from 0.002 to 0.0026 m/day (30% increase), the time to reach the drinking water standard at well no. 1 (1 km downgradient, the nearest well to the source) was about 57 and 106 years (17 and 19% decrease, respectively) for Mn 2+ under the multi-metal and single metal systems. In addition, the timing of the heavy metal contamination leached from the tailings may be a source of pollution for over hundreds to thousands of years. As indicated by the simulation results, the predicted impacts of contamination of the TSF on the groundwater quality in the lateritic aquifer indicate that sorption parameters and leachate fluxes should be carefully monitored. These visible descriptions should be used as management tools for planning well installations under field conditions.

Electron work function in alloys with alkali metals

The electron work function in alloys and compounds containing alkali metals, which are of interest for the designing of new photocathode materials and further development of the theory of electron emission, is studied. It is shown that a number of applied and theoretical issues in this field are poorly understood. These are the temperature and concentration dependences of the electron work function in binary metallic systems, the surface activity of components that are inactive in alloys with alkali metals, and some others.

Competitive sorption and desorption of cadmium and lead in paddy soils of eastern China

To assess the competitive sorption and desorption of cadmium (Cd) and lead (Pb), batch equilibrium experiments were performed using single- and binary-metal solutions in surface samples of three paddy soils from eastern China. Sorption isotherms were well fitted with one-metal and competitive Langmuir equation for single- and binary-metal system, respectively. The distribution coefficient (Kd) values were Kd single (Pb) > Kd binary (Pb) > Kd single (Cd) > Kd binary (Cd), indicating that Pb was stronger sorbed by these soils than Cd in binary metal system. Soils with high pH and clay content had the greatest sorption capacity as estimated by the maximum sorption parameter (Q). The co-existence of both metals reduces their tendency of sorption, whereas Cd sorption was affected to a greater extent than that of Pb. The Langmuir binding strength parameter (b) in binary sorption system was greater than that in single sorption system for all soils (b < b1), indicating that competition for sorption sites promote the retention of both metals into more specific sorption sites. Sorption of Cd and Pb decreased soil pH by 1.61 U for YRS, 1.39 U for PCS, and 0.91 U for SLS. The decreases of pH in binary metal system were greater than in single-metal system for three soils. Cadmium and Pb desorption increased with increasing Cd and Pb sorption saturation for all soils; however, Cd desorption ratio in binary metal system (dCd*) was much greater than Pb (dPb*), indicating that under the competitive sorption conditions, the sorbed Cd was more readily desorbed from the soils than the sorbed Pb.

Bioaccumulation and biosorption of copper and lead by a unicellular algae Chlamydomonas reinhardtii in single and binary metal systems: A comparative study

A comparative evaluation of bioaccumulation and biosorption of Cu (II) and Pb (II) ions by algal cells of Chlamydomonas reinhardtii was conducted in single and binary metal systems. Experiments were performed in solutions containing 5 × 10−7 M of free metal at 30 °C and pH 6. Algal cells were used in the concentration of 0.2 g/L. Both processes tend to be more important as contact time between heavy metals and algal cells increases. Under studied conditions, dead cells showed higher removal efficiency than living cells for both metal ions. Removal efficiency of Pb increases from 8% to 40% when comparing the results obtained by living cells and dead cells. For Cu (II) ions, the removal efficiency of dead cells was about 2 times higher than living cells (55% vs. 28%). Living cells showed similar bioaccumulation capacity for both ions. Synergistic and antagonistic effects between copper and lead were observed in binary metal systems which imply that bioaccumulation process is much more dynamic than assumed in the equilibrium models. In contrast, dead algal cells showed a higher affinity for Pb (II) ions compared to Cu (II) ions and no competitive effect was observed in the biosorption of copper and lead by the inert cells in binary metal mixtures. Biosorption of Cu (II) and Pb (II) seems to occur at different binding sites on the surface of algal biomass. The obtained results showed that the mostly advantageous process of metal ions binding is biosorption and the biomass of C. reinhardtii is suitable for the development of an efficient and economic biosorbent for the removal of heavy metals from aqueous environments.

Regeneration performance of carbon nanotube by binary metallic oxide electrodes electrokinetic system

This study was aimed to investigate the regeneration performance of carbon nanotube saturated with 150mgL−1 of nonylphenol (NP) by binary metallic oxide electrodes-electrokinetic (BMOEEK) system under potential gradient of 2Vcm−1 for 8h of treatment. Twenty experiments were conducted with four processing fluids of de-ionized water (DW), citric acid (CA), NaOH, and NaCl in a Pyrex glass cylindrical cell. An inert electrode of carbon (C) and three binary metallic electrodes of PbO2/Ti (PT), PbO2–Co/Ti (PCT), and PbO2–SnO2+Sb2O3/Ti (PSST) were investigated in this study. Results showed that higher electroosmotic permeability (6.2–26.3×10−6cm2V−1s−1) was found in BMOEEK-CA, -NaOH, and -NaCl systems than in BMOEEK-DW system (0.8–1.4×10−6cm2V−1s−1). A significant detached Pb2+ was found in BMOEEK systems with PT electrode. The best CNT regeneration efficiency of 71.4–80.0% was found in BMOEEK-NaCl system with PSST electrodes, which was 1.4–1.6 times greater than in BMOEEK-DW system. This might be resulted from both hypochlorite (OCl−) generation in anode reservoir by disassociation of NaCl and less Pb2+ detached from electrode with coating of Co and insulated layer of SnO2+Sb2O3. For BMOEEK-NaOH and -NaCl systems, the degradation of NP is much more prominent than the combined removal by electroosmosis and electromigration and for the other two systems, the removal percentage is significant. It is concluded that both binary metallic electrode and processing fluid definitely played key roles in enhancing the regeneration performance of CNT. The electrode characteristics (progressive cyclic voltammogram, and SEM micrograph with EDS), electrokinetic behavior (specimen pH and current density), and regeneration mechanism in investigated systems would also be discussed in this study.

Prediction and Hydrogen Acceleration of Ordering in Iron-Vanadium Alloys

Ab initio calculations of binary metallic systems often predict ordered compounds in contrast to empirical reports of solid solutions or disordered phases. These discrepancies are usually attributed to slow kinetics that retains metastable structures at low temperatures. The Fe-V system is an example of this phenomenon, in which we predict two ordered stable ground states, Fe3V and FeV3, whereas a disordered σ phase is reported. We propose to overcome this difficulty by hydrogen absorption, which facilitates metal atom mobility through vacancy formation and separation between the two elements due to their opposite affinities towards it, thus accelerating transformation kinetics. Hydrogen also increases the relative stability of the ordered structures compared with that of the σ phase without affecting the shape of the phase diagram. The hydrogen-induced formation of the ordered structures is expressed by a reversible decrease of the electrical resistivity with increasing hydrogen pressure. Such behavior has not been reported before in thin H absorbing films. Formation of the ordered structures is further substantiated by the kinetics of the resistivity changes upon variation of the hydrogen pressure, where two stages are distinguished: a fast initial stage and a much slower subsequent process in which the resistivity changes direction, associated with hydrogen dissolution and phase transformation, respectively.

Equilibrium, kinetic, and thermodynamic biosorption of Pb(II), Cr(III), and Cd(II) ions by dead anaerobic biomass from synthetic wastewater

Heavy metals are toxic pollutants released into the environment as a result of different industrial activities. Biosorption of heavy metals from aqueous solutions is a new technology for the treatment of industrial wastewater. The aim of the present research is to highlight the basic biosorption theory to heavy metal removal. Heterogeneous cultures mostly dried anaerobic bacteria, yeast (fungi), and protozoa were used as low-cost material to remove metallic cations Pb(II), Cr(III), and Cd(II) from synthetic wastewater. Competitive biosorption of these metals was studied. The main biosorption mechanisms were complexation and physical adsorption onto natural active functional groups. It is observed that biosorption of these metals was a surface process. The main functional groups involved in these processes were hydroxyl (-OH) and carboxylic groups (C=O) with 37, 52, and 31 and 21, 14, and 34 % removal of Pb(II), Cr(III), and Cd(II), respectively. Langmuir was the best model for a single system. While extended Langmuir was the best model for binary and ternary metal systems. The maximum uptake capacities were 54.92, 34.78, and 29.99 mg/g and pore diffusion coefficients were 7.23, 3.15, and 2.76 × 10(-11) m(2)/s for Pb(II), Cr(III), and Cd(II), respectively. Optimum pH was found to be 4. Pseudo-second-order was the best model to predict the kinetic process. Biosorption process was exothermic and physical in nature. Pb(II) offers the strongest component that is able to displace Cr(III) and Cd(II) from their sites, while Cd(II) ions are the weakest adsorbed component.

Anisotropy of Wetting and Spreading in Binary Cu-Pb Metallic System: Experimental Facts and MD Modeling

Contact angle for millimeter-size drops of lead on {100} and {110} surfaces of monocrystalline copper and on polycrystalline copper was determined by means of dispensed drop technique at 450 °C under He-H2 atmosphere. It was demonstrated that the wetting anisotropy (a difference between contact angles on differently oriented substrates) is not exceed a few degrees. Spreading kinetics was found to be different for the first and second drops deposited on each substrate. This result was interpreted as an effect of a lead precursor film formation on the substrate surface. Molecular dynamics simulations of the lead drop spreading over {111}, {100}, and {110} surfaces of monocrystalline copper confirm the weak anisotropy of equilibrium contact angle and a formation of lead precursor film on copper surface in front of wetting line.

Removal of Ni (II) and Cu (II) from their Solutions and Waste Water by Nonliving Biomass of Pseudomonas oleovorans

The nonliving biomass of Pseudomonas oleovorans was used for the removal of Nickel and Copper from their single and binary solutions. The optimum conditions such as pH, initial metal ion concentration, contact time and biomass dose were determined experimentally. q max and ‘b’ values for Ni(II) were 95.6 mg/g and 0.010 and for Cu(II) 137.5 mg/g and 0.008 respectively. The removal of the metals was studied in binary metal systems also. The developed method was applied for the removal of the metals from the wastewater samples. The investigations on the speciation of the metals revealed that both Ni and Cu exist as hydrated Ni (II) and Cu (II) ions and precipitates of Ni(OH) 2 and Cu(OH) 2 at different pH ranges.

Biosorption of cadmium and zinc by activated sludge from single and binary solutions: Mechanism, equilibrium and experimental design study

Dried activated sludge (DAS) has been used for obtaining quantitative data of the cadmium and zinc biosorption from single and binary aqueous CdCl2 and ZnCl2 solutions in batch experiments using radiotracer technique. It was shown that the metal removal is a rapid process significantly influenced by solution pH. The mechanisms of biosorption of Cd and Zn by DAS were examined by FTIR, SEM–EDX analysis and chemical blocking of functional groups. Results revealed the dominant role of the carboxyl group in Cd and Zn ion-binding by DAS and participation of the ion-exchange mechanism in metal ion biosorption. The maximum uptake capacity Qmax at pH 6.0 calculated from Langmuir isotherm was 540±16μmol/g for Zn2+ and 510±17μmol/g for Cd2+ ions. The response surface methodology was used for investigation of interactions and competitive effects in binary metal system Cd2+–Zn2+. Interaction plots revealed strong interactions between the initial concentration of co-ion, solution pH and sorption capacity of the primary ion. Maximum sorption capacities of DAS in the binary system Cd2+–Zn2+ were 321μmol Cd2+/g and 312μmol Zn2+/g, indicating a higher affinity for Cd2+ compared with Zn2+ ions.

Photo-swing extraction system for lanthanide separation by a thermosensitive polymer gel combined with carbon nanotubes

A novel photo-swing extraction system for lanthanide separation was developed using an acid phosphoxy ethyl methacrylate (Phosmer-M) copolymerized thermosensitive polymer gel and N-isopropylacrylamide (NIPAM) combined with single-walled carbon nanotubes (CNTs) as the extracting material. The swelling and shrinking phase transition of the Phosmer-M/NIPAM/CNT gel was successfully induced by photo-irradiation with a halogen lamp because of the heat generation by the CNTs, which occurred upon visible light absorption. The extraction ability of Eu(III) increased upon photo-irradiation because of changes in the volume and hydrophobicity of the composite gel. The ratio of the distribution coefficient with and without photo-irradiation ( K dphoto/ K d25) increased with an increase in the pH. The composite gel possessed sufficient loading and release capacities for Eu(III), La(III) and Lu(III) in repeated processes after photo-irradiation. The selectivity for Eu(III) over La(III) in binary metal systems increased due to photo-irradiation because the observed improvement in the extraction of Eu(III) was greater than that of La(III) during the phase transition of the gel.

The conversion of phase diagrams of solid solution type into electrochemical synthesis diagrams for binary metallic systems on inert cathodes

A method has been developed to convert equilibrium phase diagrams into equilibrium electrochemical synthesis diagrams (EESDs) using the same Calphad (Calculation of the Phase Diagrams) type of information behind them. The method is developed for binary ( A–B) metallic systems electrodeposited from an electrolyte containing cations A + n and B + m on inert cathodes in a galvanostatic regime at very low cathodic current densities, i.e. close to equilibrium. The EESD shows the equilibrium composition of different phases in the equilibrium cathodic product at fixed values of temperature and pressure as a function of parameter Δ E B , being the deposition potential of one of the components ( B) relative to another ( A). The key to construct the EESD is a new equation derived for the synthesis potential of the alloy as a function of Δ E B , the charges the ions n and m in the electrolyte and the Gibbs energy of the cathodic product (alloy) as a function of its composition, temperature and pressure. The general method of phase diagram construction (i.e. the Gibbs energy minimization) is converted during the construction of the EESDs into the method of synthesis potential maximization. The given EESD is generally valid for the corresponding binary metallic A–B system, independent of the electrolyte (for the given values of n and m). The EESD can be used to design electrochemical synthesis of alloys if parameter Δ E B is known as a function of the composition of the given type of electrolyte (ionic liquid, aqueous solution, molten salt, etc.) at given temperature and pressure. In the present paper the method is developed to construct EESDs for phase diagrams of solid solution type.

Effects of pH and low molecular weight organic acids on competitive adsorption and desorption of cadmium and lead in paddy soils

The bioavailability and ultimate fate of heavy metals in the environment are controlled by adsorption-desorption process. Batch equilibrium experiments were performed to assess the effects of pH and low molecular weight organic acids (LMWOAs) on competitive adsorption and desorption of cadmium and lead in paddy soils from China. The results indicated that both soils exhibited greater sorption capacity for lead (Pb) (1.37-1.61-fold) than cadmium (Cd) as estimated by the maximum sorption parameter (Q) from the Langmuir equation. The Langmuir bonding energy coefficient (b) and distribution coefficient (K (d)) were greater for Pb than for Cd, furthermore, b (binary) and K (d) (single) were greater than b (single) and K (d binary), indicating that competition for sorption sites promote the retention of both metals on more specific sorption sites. Both Cd and Pb desorption as a function of solution pH was characteristic of "S" pattern. The presence of LMWOAs inhibited Cd or Pb desorption at the low concentrations (≤0.1 mmol L(-1)) but promoted Cd and Pb desorption at higher concentrations (≥0.5 mmol L(-1) for citric acid and ≥1 mmol L(-1) for malic and oxalic acid). The two paddy soils had a greater d (Cd) than d (Pb) in the presence of LMWOAs, indicating that Cd desorption was more affected by the presence of LMWOAs in binary metal system.