Effect of γ-Irradiation on Electrical Conductivity of Metal-Chloride-Treated Polyacrylamide

The electrical conductivity of polyacrylamide (PAAm) before and after treatment with low concentrations of ZnCl₂, NiCl₂, and CoCl₂ was determined at different temperatures. The effects of γ-irradiation on the electrical conductivity and activation energy of the original and the metal-chloride-treated specimens were investigated. The experimentally obtained data revealed that the conduction in PAAm is ionic in nature. The treatment of the polymer with 2% or 4% (w/w) of ZnCl₂, NiCl₂, or CoCl₂, as determined from its weight, either increases or decreases its conductivity according to the nature of the metal ions, concentration of metal chloride, ratio of KOH/metal chloride, and temperature and cycle of measurement. The exposure of PAAm to 2 to 10 Mrad of γ-radiation produces no significant changes in its conductivity. On the other hand, the exposure of the PAAm pretreated with a metal chloride produces considerable changes in its conductivity. Also, the γ-irradiation of PAAm increases its activation energy. The extent of the γ-induced changes in activation energy was influenced by the pretreatment of PAAm with metal chlorides.     

Infrared spectroscopy and electrical properties of ternary poly(acrylic acid)–metal–poly(acrylamide) complexes

Fourier transform infrared spectroscopy (FTIR) and electrical measurements were used for the characterization of the interpolymer complexation between poly(acrylic acid) (PAA) and poly(acrylamide) (PAAm) and also the ternary PAA–metal–PAAm complexes. The interpolymer complexes were prepared by adjusting the pH value of the mixture solutions at different PAA weight fractions (W_PAA). The ternary complexes were prepared by mixing metal chloride solutions (such as ErCl₃ and LaCl₃) with different concentrations to PAA–PAAm mixtures and adjusting the pH value for different W_PAA. It was found that the IR spectra of the interpolymer complexes showed absorption bands at shifted positions and of intensities different from those of the parent polymers. Also, the examination of the spectra of the ternary metal–polymer complexes revealed that they depend on the nature, lency, ionic radius, and concentration of the added metal chlorides. Analysis of the electrical results showed that the electrical conductivity of the interpolymer complexes are always lower than those of PAA and PAAm, which was attributed to the decrease in the mobility of the polymer chains as a result of the complexation. Also, the conductivity of the ternary metal complexes showed a dependence on the properties of the additives and were found to decrease with increasing their concentrations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2699–2705, 2002     

Shielding Behavior of Gamma-Irradiated MoO<Subscript>3</Subscript> or WO<Subscript>3</Subscript>-Doped Lead Phosphate Glasses Assessed by Optical and FT Infrared Absorption Spectral Measurements

Undoped and MoO₃- or WO₃- doped lead phosphate glasses were prepared by the melting-annealing technique. The glasses were characterized through UV-visible and infrared measurements which were repeated after gamma irradiation. Optical spectrum of binary lead phosphate glass shows distinct ultraviolet bands correlated with unavoidable trace iron impurities within the chemicals used for the preparation of the glasses. UV-visible absorption spectra of MoO₃- or WO₃- doped glasses exhibit additional UV-visible bands which are related to the presence of four oxidation states of the two transition metal (molybdenum or tungsten) ions (Mo³⁺, Mo⁴⁺, Mo⁵⁺, Mo⁶⁺, W³⁺, W⁴⁺, W⁵⁺, W⁶⁺). The extra UV band is related to hexavalent (5d⁰) state while the rest of the visible bands are related to (350–440 nm - trivalent state), (450, 550, 650 nm - tetravalent state) while the broad band centered at about 770 nm (pentavalent state). The intensities of the absorption bands are observed to change with the transition metal content and their valencies. Infrared absorption spectra reveal distinct vibrational bands which are assigned to phosphate groups with sharing of Pb-O vibrations within both the range 460–620 cm^-1 and the range 900–1100 cm^-1 revealing a compact network structure. Gamma irradiation causes a minor increase in intensity of one of the UV band due to suggested photo-oxidation of some trace ferrous ions to additional ferric ions but the remaining spectral curve remains unaffected which is obviously related to some shielding effects of heavy atomic weight of PbO. This heavy metal oxide (PbO) is assumed to retard or prohibit the free passage of free electrons or positive holes generated during the irradiation process.     

A Novel Gd<Superscript>3+</Superscript>–Pb<Superscript>2+</Superscript> Doped LiSrPO<Subscript>4</Subscript> Phosphor for Phototherapy Lamp Applications

The phosphors LiSrPO₄:Gd³⁺ and LiSrPO₄:Gd³⁺, Pb²⁺ with different concentration of Gd³⁺ and Pb²⁺ were synthesized by combination of re-crystallization and modified solid state diffusion method. The synthesized phosphors were characterized using XRD, SEM and PL spectroscopies. The PL excitation spectra of LiSrPO₄:Gd³⁺ phosphor exhibit peak at 275 nm due to the ⁸S_7/2 →⁴I_J transition of Gd³⁺ ions and gave narrow UVB emission at 312 nm. The effect of Pb²⁺ ions on the PL properties of LiSrPO₄:Gd³⁺have also been investigated. Upon the addition of Pb²⁺ ions, the excitation of phosphors shows broad peak with maximum at 247 nm, overlapping the Hg 253.7 nm line. This addition of Pb²⁺ ions improved the emission intensity of narrow band UVB i.e. 312 nm under the excitation of 247 nm. The phosphor could be good candidate as phototherapy lamp phosphor material.     

Application of Fourier transform infrared spectroscopy to study the interactions of poly(acrylic acid) and mixtures of poly(acrylic acid) and polyacrylamide with bone powders and hydroxyapatites

Fourier transform infrared (FTIR) spectroscopy was used to study the interactions of aqueous solutions of poly(acrylic acid) (PAA) and mixtures of aqueous solutions of PAA and polyacrylamide (PAAm) with chemically and thermally treated bone powders (BPs) and two commercial hydroxyapatites (HAs). An analysis of the spectra of the precipitates that resulted from the mixtures of PAA and the chemically treated samples of BP revealed that the spectra exhibited three new bands at 1544, 1552, and 1661 cm^?1. The first band was attributed to the formation of calcium–polycarboxylate resulting from the interaction between the carboxylic acid groups of PAA and the calcium ions of BP. The appearance of the other two bands, in addition to the disappearance of the band corresponding to the absorption of the acid groups of PAA, provided strong evidence for the existence of other interactions between the carboxylic acid groups and the amide groups of the organic matrix of BP. On the other hand, the FTIR spectra of the samples that resulted from the mixture of PAA and thermally treated BP and the two commercial HAs showed only a new absorption band at 1544 cm^?1. The interactions of mixtures of the aqueous solutions of PAA and PAAm, adjusted at low or high pH values, with the different BPs and HAs were examined. The mixtures of the aqueous solutions of PAA and PAAm interacted with the different BPs and two HAs, resulting in the formation of ternary PAA–BP–PAAm and PAA–HA–PAAm complexes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Size‐controlled gold nanoparticles inside polyacrylamide microgels

Gold nanoparticles (AuNPs) of different sizes were synthesized into a crosslinked network of polyacrylamide (PAAm) microgels. PAAm was prepared by means of semicontinuous inverse heterophase polymerization under monomer‐starving conditions with a z‐average particle size of 384 ± 18 nm. AuNPs with controlled size were obtained by a reduction reaction of Au⁺³ to Au⁰ from a gold(III) chloride trihydrate (HAuCl₄) solution inside microgel the crosslinked network (AuNP‐PAAm). The reduction reaction was verified for 2 h by ultraviolet–visible spectroscopy (UV–vis). AuNP–PAAm exhibited a particle size between 288 ± 12 and 230 ± 15 nm at HAuCl₄ concentrations of 0.4 and 1.3 mM, respectively. The AuNP–PAAms were observed by transmission electron microscopy, and their sizes were determined to be 19 ± 2 nm (1.3 mM) and 17 ± 2 nm (1.1 mM). With UV–vis spectroscopy, we detected the formation of AuNPs at a wavelength of 552 nm, and with X‐ray diffraction analysis, we proved that the crystal arrangement was face‐centered cubic. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43560.     

Application of FTIR spectroscopy for structural characterization of ternary poly(acrylic acid)–metal–poly(vinyl pyrrolidone) complexes

The FTIR spectroscopic technique was used in the study of ternary polymer–metal complexes containing two polyelectrolytes of opposite charge and metal ions. The structure of the ternary (PAA‐Fe³⁺‐PVP) complexes was examined by following the changes in their infrared spectra. It was found that the shapes of the absorption bands of the resultant compounds are influenced by the presence of Fe³⁺. According to this result it was suggested that two types of structure which differ in the composition are formed, one of which results from the coordination of Fe³⁺ with PAA‐PVP complex and the other is due to the formation of Fe³⁺ polycarboxylate. Comparison between the spectrum of PAA‐PVP complex and those of the compounds resulted from the reaction between the two opposite charged electrolytes, PAA and PVP and each of the divalent metal chlorides NiCl₂, CoCl₂, CuCl₂, and ZnCl₂) led to the conclusion that a reaction took place between the divalent transition metal chlorides and the extent of reaction depends on the nature of metal ions and PAA‐PVP complex. The FTIR spectra of the precipitate resulted from the mixtures of PAA‐PVP and Ni(NO₃)₂ or Sr(NO₃)₂ were investigated. It was noted that the addition of Ni(NO₃)₂ or Sr(NO₃)₂ to the mixture of the electrolytes of PAA and PVP provoked appreciable changes in the characteristic spectral features of the complex resulting from the interaction of the metal ions with the polymer–polymer complex. The FTIR spectra of the precipitate resulted from the reaction between CeCl₃, ErCl₃, and LaCl₃ were also investigated. It was concluded that a reaction took place between the rare earth metals and the PPC. This means that ternary polymer–metal–polymer complexes were formed. The extent of changes in the spectral features differs from metal to metal according to the nature of metal ions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Nanostructured PZT synthesized from metal–polyvinyl alcohol gel: Studies on metal–polymer interaction

PbZr_0.53Ti_0.47O₃ (PZT) nanoparticles of size distribution ～1–6 nm were synthesized by single‐step autoignition of metal–polyvinyl alcohol (PVA) gel. The physical and chemical bonding between the metals ions and PVA in gel was analyzed from the results of the characterization by FTIR, SEM, and XRD techniques. The appearance of a doublet band between 3500 and 3200 cm^?1 and the shifting of stretching frequency of O? H band in the FTIR spectra of gel indicated strong electrostatic interaction between the metal ions and the polar OH groups of the polymer. The electrostatic interaction decreased the extent of hydrogen bonding drastically due to engagement of polar OH groups in complex formation with the metal ions. Microstructural study of the dried gel by SEM coupled with its FTIR analyses indicated crosslinking in the metal–polymer gel. The loss of crystallinity of PVA in gel detected by XRD also indicated the drastic degradation of hydrogen bonding in PVA due to the formation of coordination complex with the metal ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of Laser Fluence on the Structural,Morphological and Optical Properties of 2H-PbI<Subscript>2</Subscript> Nanoparticles Prepared by Laser Ablation in Ethanol

The effect of laser fluence on the optical, structural and morphological properties of PbI₂ nanoparticles NPs synthesized by pulsed laser ablation in ethanol was studied. The direct optical energy gap of PbI₂ NPs prepared at various laser fluences was in the range of (3–3.3 eV) at room temperature. Three absorption peaks related to surface plasmon resonance at 337, 435 and 507 nm are observed. XRD results show that all the grown PbI₂ NPs are polycrystalline in nature and the formation of hexagonal structure 2H-polytype was observed at laser fluence of 3.6 J/cm². The surface morphology of PbI₂ NPs investigated by SEM revealed formation of hexagonal, platelet-like and spherical NPs morphologies. TEM images showed formation of spherical particles with size varied from 10 to 75 nm depending on the laser fluence. PL measurement shows emission of broad peak centered at 350 nm and increasing the laser fluence results in red shift. The Raman spectra of PbI₂ NPs revealed existence of five vibration modes situated at 74, 96,106, 169 and 213 per cm. FT-IR investigation showed a broad band at 3383 per cm indexed to symmetric stretching vibration of Pb–I clusters and band at 725 per cm related to bending mode of O–H.     

Solid state metathesis synthesis of BaTiO3, PbTiO3, K0.5Bi0.5TiO3 and Na0.5Bi0.5TiO3

A solid state metathesis approach has been applied to synthesize perovskite oxides such as BaTiO₃, PbTiO₃, K_0.5Bi_0.5TiO₃ and Na_0.5Bi_0.5TiO₃, these were characterized by powder XRD, IR and energy dispersive spectra (EDS). Potassium titanium oxalate and metal chlorides are used as the starting materials. X-ray analysis shows the formation of a single phase with tetragonal structure for BaTiO₃, PbTiO₃, K_0.5Bi_0.5TiO₃ and a monoclinic structure for Na_0.5Bi_0.5TiO₃. The Infrared spectra of these compounds show the characteristic band due to Ti–O octahedron for all the compounds. The EDS spectra show the relative ratio of the metal ions. The morphology of synthesized compounds was obtained from SEM measurements.     

Effect of Tm3+ Ions on the White Light Emission of Dy3+–Tm3+ Codoped SrMg2La2W2O12 Phosphors

Dy³⁺–Tm³⁺ ions codoped SrMg₂La₂W₂O₁₂ (strontium magnesium lanthanum tungstate) phosphors were synthesized by conventional high‐temperature solid‐state reaction method. X‐ray analysis of the end products revealed the well‐crystallized phases with orthorhombic structure. The functional groups present in the phosphors were studied by the Fourier transform infrared measurements. To know the potential applicability of these phosphors for white light emission, the excitation and emission spectra were recorded. The excitation spectra exhibited an intense broad band at 313 nm, pertaining to the O → W ligand‐to‐metal charge‐transfer state (LMCT) of the host. With the excitation of LMCT band (313 nm), the decay curves of singly doped SrMg₂La₂W₂O₁₂:Dy phosphors exhibited single exponential, where as the codoped SrMg₂La₂W₂O₁₂:DyTm phosphors exhibited double exponential nature. The luminescence colors of these phosphors were estimated from Commission Internationale de L'Eclairage (CIE) coordinates using the photoluminescence data. The color of singly doped SrMg₂La₂W₂O₁₂:Dy phosphor has been tuned by codoping with Tm³⁺ ions. It has been noticed that the CIE chromaticity coordinates (x,y) determined from the luminescence spectrum of singly Dy³⁺ doped SrMg₂La₂W₂O₁₂ phosphor shifted toward the white light region, when codoped with Tm³⁺ ions. The increase in correlated color temperatures (T_cct) has been noticed with the increase of Tm³⁺ ions concentration in SrMg₂La₂W₂O₁₂:DyTm phosphors.     

Enhancement of fluorescence and magnetic properties of CeF3:RE3+ (Tb,Gd) nanoparticles via multi-band UV excitation and Li doping regulation

In this study, hydrothermal synthesis of CeF₃: Tb, Gd nanoparticles doped with Li⁺ alkali metal ions were demonstrated using introduction of Li⁺ ions through LiNO₃ nitrate. These nanoparticles have dual properties of magnetic fluorescence. X-ray diffraction, Fourier transform infrared spectrometer, XPS and photoluminescence spectra, and vibrating sample magnetometry were used to characterize structural properties, surface functional groups, fluorescence, and magnetic properties of these particles. Results show that CeF₃: Tb, Gd nanoparticles exhibit bright green light emission under excitation at 258 nm and 378 nm ultraviolet band. Through the modification of Li⁺ ions, luminous intensity of green light is further improved. Energy transfer between rare earth ions was investigated via photoluminescence spectroscopy. This work demonstrates potential applications of Li doped CeF₃: Tb, Gd nanoparticles as photomagnetic dual-functional materials in fields of biological imaging, solid state lighting, and magnetic biological separation.     

FT-IR SPECTROSCOPY OF NITRIC ACID IN TBP/OCTANE SOLUTION*

Infrared studies for the HNO₃/0.73 M TBP n-octane system are reported. Two extracted species, TBP · HNO₃ and TBP · 2HNO₃, were identified in the organic phase. The concentration of the individual species was determined by the analysis of the vibrational band at ～1650 cm^?1. The band at 1648 cm^?1 was assigned to the monosolvate TBP · HNO₃ and the band at 1672 cm^?1 to the hemisolvate TBP · 2HNO₃. The infrared spectra revealed that with respect to the P═O bond, as well to each other, the HNO₃ molecules in the hemisolvate are spectrally non-equivalent. The predominant structure of TBP · 2HNO₃ involves the chain HNO₃ dimer. Some ionic NO₃ ^? and hydronium ions were identified in this system but only during formation of the monosolvate. The analyses performed in this system can serve for the characterization of HNO₃ in related systems in the presence of metal species.

     

‘Optical and FT Infrared Absorption Spectra of Soda Lime Silicate Glasses Containing nano Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> and Effects of Gamma Irradiation

The optical absorption spectra of undoped soda lime silicate glass together with two glasses doped with either (1 % nano Fe₂O₃ ) or with both (1 % Nano Fe₂O₃ + 5 % cement dust) have been measured from 200 to 2400 nm before and after gamma irradiation with a dose of 8 Mrad. The undoped glass reveals strong UV absorption with two distinct peaks which are attributed trace ferric iron ions present as impurity. Upon gamma irradiation , this base glass exhibits three peaks at 240,310 and 340 nm and the resolution of an induced broad visible band centered at 530 nm. The two doped glasses show an additional small visible band at about 440 nm and followed by a very broad band centered at 1050 nm. Upon gamma irradiation, the two doped samples reveal the decrease of the intensities of the spectrum. The two additional bands are related to ferric (Fe⁺³) ions to the band at (440 nm) while and the broad band at 1050 nm is due to ferrous iron (Fe⁺²) ions. The decrease of the intensities of the UV-visible spectrum upon irradiation can be related to of capturing freed electrons during irradiation . Infrared spectra of the glasses reveal repetitive characteristic absorption bands of silicate groups including bending modes of Si–O–Si or O–Si–O, symmetric stretching , antisymmetric stretching and some other peaks due to carbonate , molecular water , SiOH vibrations . Upon gamma irradiation, the IR spectra reveal a small change in the base spectrum while the IR spectra of the two doped glasses remain unchanged. The change of the IR spectrum of the base glass is related to suggested changes in the bond angles or bond lengths of the mid band structural units. The doped glasses show resistance to gamma irradiation because the nano Fe₂O₃ can capture released electrons and positive holes.     

Chemical Synthesis and Characterization of ZnO–TiO<Subscript>2</Subscript> Semiconductor Nanocomposites: Tentative Mechanism of Particle Formation

The compounds of ZnO–TiO₂ can combine the characteristics of the individual oxides which has allowed them to be used as photocatalysts in general, photodegradants in the degradation of dyes, photocatalytic oxidation of NO_x, antimicrobial, among other applications. In this study, ZnO–TiO₂ semiconductor nanocomposites were synthesized in a controlled way at low temperature. These samples of ZnO–TiO₂ were characterized using thermal analysis (TDA/TGA), IR and UV–Vis absorption spectroscopies, X-ray diffraction, and scanning electron microscopy. The primary particles showed a nanometric size (<?100 nm) and spheroidal morphology. All samples presented zincite as the main crystalline phase. When Ti⁴⁺ was added, the peaks of the diffractograms shifted slightly with respect to pure ZnO. This indicates the formation of a solid solution. Zn₂TiO₄ was observed in doped ZnO samples treated at 700 °C. The UV–Vis absorption spectra showed a band in the range between 350 and 425 nm, with a maximum around 375 nm (3.31 eV). With the addition of Ti⁴⁺, the nanocomposites showed a better absorbance in the visible range. Considering the nature of the synthesis process used, a mechanism was proposed to explanation of the formation of Nanocomposites.     

First-principles calculation on the electronic structure and optical properties of Eu2+ doped γ-AlON phosphor

The crystal structure, electronic structure, and optical properties of Eu-doped γ-AlON at various Eu concentrations were obtained from density functional theory. Based on the calculated results, the luminescence properties and mechanism of Eu-doped γ-AlON are discussed. The calculated results demonstrate that AlON:Eu²⁺ phosphor exhibits a direct band gap, which is advantageous for luminescence. The absorption spectrum of AlON:Eu²⁺ phosphor has a single intense broad absorption band from 275 to 425 nm with a peak at 355 nm, which is consistent with corresponding experimental excitation spectra. The existence of Eu?N bonds enhanced the local covalence of Eu²⁺, hence the optical stability of AlON:Eu²⁺ phosphor.     

Photo Catalytic Degradation of Imidachloprid Under Solar Light Using Metal Ion Doped TiO2 Nano Particles: Influence of Oxidation State and Electronic Configuration of Dopants

Anatase TiO₂ was doped with metal ions like Th⁴⁺, V⁵⁺ and Mo⁶⁺ and tested for the degradation of imidachloprid under solar light. X-ray diffraction results inferred that all the dopants stabilized the anatase phase irrespective of their nature, oxidation state and ionic size. The undoped and transition metal ion doped TiO₂ were completely transformed to rutile phase at 700 °C while rare earth Th⁴⁺ doped sample completely transformed to rutile phase at 1,000 °C. The rare earth dopant stabilized the anatase phase by hindering the growth of crystallite size. Among the photo catalysts used, Th⁴⁺ (0.06%)-TiO₂ showed highest activity and its efficiency was 2.8 times higher than that of Degussa P-25. The Th⁴⁺ ion lowered the band gap of TiO₂ to 2.6 and 2.5 eV facilitating solar light absorption. Detrapping of the trapped charge carriers depends on electronic configuration and the oxidation state of the dopants.     

Fe3+-substituted aluminium oxide nano-flakes: Structural,morphological, optical,and gas sensing properties

Mixed metal oxides with chemical formula Fe_xAl_2-xO₃ (where x = 0.2–1.0) (FANF) was synthesized via sol-gel auto combustion process. X-ray diffraction, field emission scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy were employed to characterize produced oxide materials. The final product FANF was sintered for 5 h at 1100 °C. The TG-DTA validated the mixed metal oxides phase evolution and steady-state temperature. The replacement of aluminium ions results in orthorhombohedral structure in mixed metal oxides (MMO). The bandgap decreased from 3.72 eV to 3.21 eV and the crystallite size decreased from 28 nm to 14 nm as the iron content increased in the sample Fe_xAl_2-xO₃ (where x = 0.2–1.0). The FT-IR confirmed no impurity peaks and the single phase with iron oxide band is near 432 cm^?1, while the aluminium oxide band is 565–600 cm^?1. Microstructural investigation shows flake-like growth, and EDS confirmed a stoichiometric ratio of MMO. Iron-substituted aluminate gas sensors detected CO, H₂S, and NO₂ at temperature ranging from 25 to 300 °C. Fe_0.6Al_1.4O₄ (F₃ANF) sensor responded 46.69% towards 100 ppm H₂S at 200 °C. Overall, the results showed that a flake-like FANF sensor can be used effectively as a H₂S gas sensor.     

Synthesis of a novolac‐based 3‐aminopropylsiloxane resin and its application for the removal of Cu2+, Cr3+, and Ni2+ from electroplating wastewater

Novolac resin was modified with 3‐aminopropyltrimthoxysilane to obtain phenol‐formaldehyde‐aminopropylsiloxane resin (PF‐APS). Fourier transformation infra‐red spectra, thermogravimetric analysis, elemental analysis, and pH‐metric titration were used to characterize PF‐APS. Its chemical formula was suggested to be C₁₄H_12.49N_0.1O₂Si_0.1. The resin shows high experimental metal ions uptake capacity within short time of equilibration. The metal capacity was determined by atomic absorption spectrometry to be 0.787 mEq Cu/g. Maximum separation efficiencies of Cu²⁺, Cr³⁺, and Ni²⁺ from aqueous solutions on PF‐APS were at pH 8.0 and time of stirring 60 min; 94.0%, 90.8%, 83.2%, respectively. No significant interference from the background ions Na⁺, Cl^?, and was observed on the separation process. The heavy metal ions were eluted using 0.01 mol L^?1 EDTA at 65°C releasing >94% of the separated metal ions. The method of separation was applied successfully to remove the heavy metal ions Cu²⁺, Cr³⁺, and Ni²⁺ from electroplating wastewater from Dekirnis, Dakahlia Governorate, Egypt. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40993.     

Influence of copper (II) on biomineralization of CaCO3 and preparation of micron pearl-like biomimetic CaCO3

In all the waters where mollusks can grow, a variety of metal ions abounds. Attention has focused, however, on the effects of K⁺, Na⁺ and Mg²⁺ on the biomineralization of nacre, and those of other metal ions have been relatively neglected. This paper investigated the effects of representative copper (II) on the biomineralization of CaCO₃ using egg white as the organic matrix. The effects of copper ion concentration, aging time and the combined actions of a high concentration of both egg white and Cu²⁺ on the morphology and crystal type of CaCO₃ were studied, and the action mechanism was analyzed. The results show that copper (II) can induce the formation of vaterite, promote the spheroidization of mineralized particles, distort and deform the lamellar structure, and affect the surface roughness. Mechanism analysis shows that the bending and twisting of the protein molecule chain caused by the biuret reaction of Cu²⁺ with egg-white protein is the primary reason for the effects of copper (II) on the morphology and crystal type of CaCO₃. On this basis, a micron pearl-like CaCO₃ with a spherical structure consisting of uniform lamellae about 350 nm thick was obtained by exploiting the combined actions of high concentrations of egg white and Cu²⁺.