The influence of different alkaline earth oxides on the structural and optical properties of undoped,Ce-doped,Sm-doped,and Sm/Ce co-doped lithium alumino-phosphate glasses

Undoped, singly Sm doped, Ce doped, and Sm/Ce co-doped lithium alumino-phosphate glasses with different alkaline earth modifiers were prepared by melt quenching. The structure of the prepared glasses was investigated by FT-IR and Raman, as well as by optical spectroscopy. The effect of the optical basicity of the host glass matrix on the added active dopants was studied, as was the effect doping had on the phosphate structural units. The optical edge shifts toward higher wavelengths with an increase in the optical basicity due to the increased polarizability of the glass matrix, but also with increasing CeO₂ concentration as a result of Ce³⁺/Ce⁴⁺ inter valence charge transfer (IV-CT) absorption. The optical band gap for direct and indirect allowed transitions was calculated for the undoped glasses. The glass sample containing Mg²⁺ modifier ions is found to have the highest value (4.16 eV) for the optical band gap while Ba²⁺ has the lowest value (3.61 eV). The change in the optical band gap arises from the structural changes and the overall polarizability (optical basicity). Refractive index, molar refractivity R_m and molar polarizability α_m values increase with increasing optical basicity of the glasses. The characteristic absorption peaks of Sm³⁺ were also investigated. For Sm/Ce co-doped glasses, especially at high concentration of CeO₂, the absorption of Ce³⁺ hinders the high energy absorption of Sm³⁺ and this effect becomes more obvious with increasing optical basicity.     

Interactions of gamma rays with tungsten-doped lead phosphate glasses

Undoped lead phosphate glass of the composition PbO 50 mol%, P₂O₅ 50 mol% together with samples of the same ratio doped with various WO₃ contents were prepared. UV–Visible spectroscopic studies were measured out in the range 200–1100 nm before and after successive gamma irradiation. Infrared and Raman spectroscopic measurements were carried out for the undoped and WO₃-doped samples. All the prepared samples are observed to absorb strongly in the UV region due to the combined contributions of absorption from trace iron impurities and sharing of lead Pb²⁺ ions. The bluish WO₃-doped lead phosphate samples reveal visible absorption bands which are attributed to the existence of pentavalent W⁵⁺ ions. ESR measurements support this assumption. Infrared and Raman spectra indicate the presence of metaphosphate chains as the structural main building units and the possible presence of appreciable pentavalent (W⁵⁺O₃) of W⁵⁺ units together with hexavalent WO₄ units. Gamma irradiation reveal the shielding behaviour of the studied tungsten-doped lead phosphate glasses due to the combined presence of heavy Pb²⁺ ions and tungsten ions.     

Comparative and competitive adsorption of cadmium, copper, nickel, and lead ions by Iranian natural zeolite

The competitive adsorption behavior of cadmium (Cd²⁺), copper (Cu²⁺), nickel (Ni²⁺), and lead (Pb²⁺) ions using Iranian natural zeolite has been studied in order to determine its applicability in treating industrial wastewater. Tests to determine both the rate of adsorption and the uptake at equilibrium were performed under batch conditions from single- and multi-component solutions. The optimum conditions for the treatment process were investigated by observing the influence of pH levels, the presence of competing ions, varying the mass of zeolite and different contact time. Adsorption kinetics of the zeolite followed first-order kinetics, showing about 100 % of Pb²⁺ removal within 40 min and reaching an equilibrium state within 24 h for Cd²⁺, Cu²⁺, and Ni²⁺. The results indicated that removal of metals from single- and multi-component solutions is best described by a Freundlich isotherm, in which the distribution coefficient was in the following order: Pb²⁺ > Cu²⁺ > Cd²⁺ > Ni²⁺. In the multi-component solutions, metals exhibit competitive adsorption on the zeolite. The adsorption is reduced to 90, 53, 30, and 22 % of single component of Cu²⁺, Ni²⁺, Cd²⁺, and Pb²⁺, respectively. However, the total adsorption was higher than single component. Finally, soil solution saturation indices and speciation of metals was assessed using Visual MINTEQ 2.6 software, and probability of precipitation of minerals supported by scanning electron microscopy. The research indicates that Cd²⁺ and Ni²⁺ retention by zeolite can be viewed as the result of ion exchange reaction, but Pb²⁺ and Cu²⁺ retention is both due to ion exchange and precipitation. These results show that Iranian natural zeolite particularly effective in removing cationic heavy metal species from industrial wastewater.     

Waste calcite sludge as an adsorbent for the removal of cadmium, copper, lead, and zinc from aqueous solutions

Sludge residues, an industrial waste material for the removal of cadmium (Cd²⁺), copper (Cu²⁺), lead (Pb²⁺), and zinc (Zn²⁺) from aqueous solutions were investigated using batch method. Batch mode experiments were carried out as a function of solution pH, adsorbent dosage, initial concentration, and contact time. The results indicated that the adsorbent showed good sorption potential and maximum metal removal was observed at pH ≥?3. Within 120?min of operation, about 63.7, 95.2, 99.9, and 88.2% of Cd²⁺, Cu²⁺, Pb²⁺, and Zn²⁺ ions were removed from the solutions, respectively. Sorption curves were well fitted to the Langmuir and Freundlich models. The adsorption capacities for Cd²⁺, Cu²⁺, Pb²⁺, and Zn²⁺ ions at optimum conditions were 121.2, 1067.8, 566.4, and 534.2?mg?g^?1, respectively. The kinetics of Cd²⁺, Cu²⁺, Pb²⁺, and Zn²⁺ adsorption from aqueous solutions was analyzed by fitting the experimental data to pseudo-first- and pseudo-second-order kinetic models. However, the pseudo-first-order kinetics model provided much better R ² values and the rate constant was found to be 0.001?min^?1 for Cd²⁺, Cu²⁺, Pb²⁺, and Zn²⁺ ions. The results revealed that sludge residues can adsorb considerable amount of Cd²⁺, Cu²⁺, Pb²⁺, and Zn²⁺ ions and it could be an economical method for the removal of these ions from aqueous systems.     

Comparative study of room temperature ferromagnetism in undoped and Ni-doped TiO2 nanowires synthesized by solvothermal method

We report a comparative study of room temperature ferromagnetism (RTFM) in undoped and Ni-doped TiO₂ nanowires synthesized by solvothermal method. Both undoped and Ni-doped TiO₂ nanowire samples showed the RTFM with coercive field of ~125 Oe due to intrinsic effect. Interestingly, compared to the doped TiO₂ nanowires, the undoped nanowires exhibited the higher saturation magnetization value, indicating surface defects such as Ti³⁺ and oxygen vacancy play more important role in realizing RTFM than Ni doping. The origin of RTFM in the undoped nanowires can be attributed to the ferromagnetic coupling between Ti³⁺ ions via F⁺ center resulting from oxygen vacancy on the nanowire surface. Furthermore, saturation magnetization value of the doped nanowires is increased with increasing the doping concentration due to the enhanced ferromagnetic coupling between Ni²⁺ ions via F⁺ center.     

改性木质素磺酸盐制备及吸附重金属离子研究

工业废水中的铅离子和镉离子对人类健康构成重大威胁。为开发一种高效绿色的吸附剂,本文运用自由基聚合法合成了改性木质素磺酸盐复合材料(LC),同时将改性木质素磺酸盐复合材料应用于处理Pb^{2+和Cd2+。采用傅里叶红外光谱仪、扫描电镜以及热分析仪对改性木质素磺酸盐复合材料进行表征,研究了pH、吸附剂用量、时间、质量浓度4种因素对改性木质素磺酸盐复合材料吸附性能的影响,并在此基础上探究了改性木质素磺酸盐复合材料的吸附动力学和等温线模型。研究表明,改性木质素磺酸盐复合材料具有多孔的结构,且热稳定性高。当pH=5时,改性木质素磺酸盐复合材料对Pb2+}的吸附容量为345 mg/g,对Cd²⁺的吸附容量为278 mg/g。针对动力学和等温线模型的研究表明,改性木质素磺酸盐复合材料对Pb^{2+和Cd2+的吸附主要由静电吸引和化学螯合主导。此外,经过5次吸附-解吸实验后,改性木质素磺酸盐复合材料对Pb2+和Cd2+的吸附效率仍可达84%以上。改性木质素磺酸盐复合材料具有高效、绿色的吸附性能,能够有效地处理Pb2+和Cd2+}。     

Use of ultraviolet spectroscopy for studying interdiffusion reactions of PbO on vitreous surfaces

Previous studies of the UV spectra of glasses doped with Pb²⁺ have revealed that the frequency of the ¹S₀ → ³P₁ band can be correlated with the “optical basicity” and hence the chemical composition of the site occupied by Pb²⁺. The present work reports how this method of approach can be successfully extended for studying the interaction between thin PbO films (also Bi₂O₃ films) and vitreous surfaces. The previously studied reactions between PbO films and silica substrates were re-examined, and it was found that the initially broad UV absorption envelope (due to the PbO film) is changed by thermal treatment, and eventually the absorption pattern usually observed for Pb²⁺ in a glass is obtained. The frequency indicates that the Pb²⁺ ions are in sites where the SiO₄ units correspond to the metasilicate composition, slightly diluted with silica, in agreement with results obtained from refractive index and electron microscopy measurements.     

Structural, optical and electrical measurements on boron-doped CdO thin films

Several boron-doped CdO with different boron composition thin films have been prepared on glass substrate by a vacuum evaporation technique. The effects of boron doping on the structural, electrical and optical properties of the host CdO films were systematically studied. The X-ray diffraction study shows that some of B³⁺ ions occupied locations in interstitial positions and/or Cd²⁺-ion vacancies of CdO lattice. The band gap of B-doped CdO suffers narrowing by 30–38% compare to undoped CdO. Such band gap narrowing (BGN) was studied in the framework of the available models. Furthermore, a phenomenological evaluation of the dependence of band gap on the carrier concentration in the film samples is discussed. The electrical behaviours show that all the prepared B-doped CdO films are degenerate semiconductors. However, the boron doping influences all the optoelectrical properties of CdO. Their dc-conductivity, carrier concentration and mobility increase compare to undoped CdO film. The largest mobility of 45–47 cm²/V s was measured for 6–8% boron-doped CdO film. From near infrared transparent-conducting oxide (NIR-TCO) point of view, boron is effective for CdO donor doping.     

Nanoscale zero-valent iron modified with carboxymethyl cellulose in an impinging stream-rotating packed bed for the removal of lead(II)

A novel impinging stream-rotating packed bed (IS-RPB) was proposed to continuous, macro and industrialized prepare nanoscale zero-valent iron (nZVI) with simultaneously modified with carboxymethyl cellulose (CMC) for the removal of Pb²⁺. The obtained CMC-nZVI particles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The components on the surface of CMC-nZVI after react with Pb²⁺ were also analyzed by X-ray photoelectron spectroscopy (XPS). The IS-RPB makes it possible for the continuous, macro and industrialized preparing of CMC-nZVI particles, and CMC can significantly improve the dispersion and reduce aggregation of nZVI particles. The effects of solution pH, initial Pb²⁺ concentration and reaction time on the removal efficiency of Pb²⁺ by nZVI and CMC-nZVI particles were also investigated. The results show that CMC-nZVI particles outperform nZVI particles in removing Pb²⁺, and the removal efficacy reaches a maximum of 838.84 mg·g⁻¹ for nZVI particles and 1237.32 mg·g⁻¹ for CMC-nZVI particles at pH = 6.0. The adsorption of Pb²⁺ by nZVI and CMC-nZVI particles can be described by the Langmuir isotherm adsorption model with a R² of 0.999, and the calculated maximum adsorption capacity is 900.90 and 1376.07 mg·g⁻¹ for nZVI and CMC-nZVI particles. The adsorption of Pb²⁺ follows the pseudo second-order kinetics with a linear correlation coefficient R² of 0.999. In addition, the effect of co-existing cations such as Na⁺, Cu²⁺, Ni²⁺ and Cd²⁺ on Pb²⁺ removal efficiency was also investigated. The results showed that Na⁺ had no effect on Pb²⁺ removal efficiency and Cu²⁺ and Ni²⁺ had inhibited Pb²⁺ removal efficiency. Cd²⁺ had an inhibitory effect on Pb²⁺ removal efficiency when the concentration was 50 mg·L⁻¹ and 100 mg·L⁻¹, Cd²⁺ enhanced Pb²⁺ removal efficiency while the concentration of Cd²⁺ was 200 mg·L⁻¹.     

Efficient synthesis of Eu(III)-containing nanoporous silicas

Europium (III) (Eu³⁺)-containing nanoporous silicas were successfully synthesized by two different loading methods (adsorption or doping), and the states of the Eu³⁺ in the structure were investigated. The Eu³⁺-adsorption indicated that the Eu³⁺ interacts with hydroxyl groups on the pore surface and H₂O molecules to enhance the quenching, whereas the Eu³⁺-doping indicated that the Eu³⁺ was located inside the structure framework that produced the efficient luminescence. The interaction between the Eu³⁺ and silica structure depended on the loading method.     

A non-water-soluble modified β-cyclodextrin for sensitive electrode

Partially benzylated β-cyclodextrins (β-CDs) are deposited with no coupling agent on the silica surface of a wafer which was used as an electrolyte–insulator–semiconductor (EIS) heterostructure to detect cations in aqueous solution. The sensitivity of the EIS devices has been tested for Ca²⁺, Cu²⁺, K⁺ and heavy metal cations Pb²⁺ and Cd²⁺. The results showed a Nernstian response towards Pb²⁺ as found with β-cyclodextrins incorporated in gel membrane, with good selectivity. The benzylation of the β-cyclodextrins did not affect the complexation properties of the molecule. However, a considerable capacitive effect should be taken into account. The results were compared to a previous work where the β-CD molecules were fixed onto silica insulator surfaces obtained by means of either one of these two ways: chemically grafted to polymethyl-hydrosiloxanes (PMHS) chains, or physically entrapped in plasticized poly(vinyl chloride) (PVC).     

Manifestation of Nd ions on the structure,Raman and IR spectra of (TeO<Subscript>2</Subscript>-MoO-Nd<Subscript>2</Subscript>O<Subscript>3</Subscript>) glasses

The structure of [80TeO₂ + (20–x)MoO + xNd₂O₃] glasses, with x = 0, 4, 6, 10 and 12 mol%, is studied in this work. Raman scattering in the spectral range (−2000 to 3500 cm⁻¹) and IR absorption spectra have been measured for crystalline TeO₂ and glasses, and their assignments were discussed and compared. Many vibrational modes were found active in both Raman and IR and their assignments for crystalline TeO₂ and for the glasses were discussed in relation to the tetragonal structure of crystalline α -TeO₂. Nd₂O₃ was found to completely eliminate diffuse scattering and enhance the Raman scattering intensity. Anti-stokes Raman bands in the range −1460 cm^{− 1} to −1975 cm^{− 1} were observed for both (30Li₂O + 70B₂O₃+ xNd₂O₃) glasses and [80TeO₂ + (20−x)MoO + xNd₂O₃] glasses and were attributed to some emission processes due to the doping of the glasses with Nd₂O₃.     

Organic/inorganic hybrid nanospheres based on hyperbranched poly(ethylene imine) encapsulated into silica for the sorption of toxic metal ions and polycyclic aromatic hydrocarbons from water

Organic–inorganic hybrid silica nanospheres were prepared through a biomimetic silicification process in water at ambient conditions by the interaction of low cost poly(ethylene imine) hyperbranched polymer with silicic acid. The characterization of these nanoparticles by FTIR spectroscopy, scanning electron microscopy (SEM), zeta-potential and dynamic light scattering (DLS) experiments confirmed that the dendritic polymer was incorporated into the silica network. Preliminary experiments show that these hybrid nanoparticles can be employed for the removal of toxic water contaminants. Hybrid nanospheres’ sorption of two completely different categories of pollutants, i.e. metal ions such as Pb²⁺, Cd²⁺, Hg²⁺, Cr₂O₇²⁻, and polycyclic aromatic hydrocarbons such as pyrene and phenanthrene, was largely enhanced in comparison with the corresponding polymer-free silica nanospheres. This was attributed to the to the formation of conventional metal-ligand and charge-transfer complexes proving that although integrated into the silica network poly(ethylene imine) retains its chemical properties.     

Structural properties of lead vanadate glasses containing La3+ or Fe3+ ions

Structural properties of lead vanadate glasses containing La³⁺ or Fe³⁺ ions were investigated using X-ray diffraction, Fourier transform infrared spectroscopy and laser Raman spectroscopy. Crystalline Pb₂V₂O₇ was formed for the molar composition 66.7PbO-33.3V₂O₅. Incorporation of greater quantities of La³⁺ into lead metavanadate glass caused the crystallization of Pb₂V₂O₇. Fourier transform infrared and laser Raman spectra also suggested the presence of LaVO₄. Incorporation of Fe³⁺ ions into lead metavanadate glass, up to 20 wt% Fe₂O₃, did not cause crystallization inside the glass matrix. Changes in the vibrational spectra are discussed.     

Synthesis and structural study of mixed lithium and cadmium phosphate glasses

A large glass-forming region at 1000°C has been identified in the ternary diagram Li₂O-CdO-P₂O₅. The thermal stability of the glasses seems to be enhanced by the introduction of Cd²⁺ cations. Raman scattering has allowed the study of the structural transformations created by the addition of Li₂O and CdO. The increase of the number of non-bridging oxygens due to the stoichiometric deviation from pure P₂O₅ has been followed, inside the vitreous domain, by Raman spectroscopy.     

Highly selective ion-imprinted particles for solid-phase extraction of Pb ions

The Pb²⁺-imprinted (PHEMAC-Pb²⁺) particles were prepared by bulk polymerization as a solid-phase extraction (SPE) adsorbent. N-methacryloyl-(l)-cysteine (MAC) was used as functional monomer to have a well-shaped molecular geometry between MAC monomer and Pb²⁺ ions that provide molecular recognition based on well fitted cavities for Pb²⁺ ions after removal of template ions. The PHEMAC-Pb²⁺ particles were characterized and the applicability of these particles was investigated for the solid-phase extraction of Pb²⁺ ions from aqueous solutions and environmental samples. The PHEMAC-Pb²⁺ particles with a size range of 50–200 µm have a rough surface and macropores in bulk structure. The adsorption capacity of the PHEMAC-Pb²⁺ particles is relatively low (2.01 mg/g). However, the high selectivity towards competitive ions (Cd²⁺, Ni²⁺ and Cu²⁺) promises the PHEMAC-Pb²⁺ particles an alternative SPE adsorbent in literature. The relative selectivity coefficients of PHEMAC-Pb²⁺ particles for Pb²⁺/Ni²⁺, Pb²⁺/Cd²⁺ and Pb²⁺/Cu²⁺ were almost 71, 117 and 192 times greater than that of non-imprinted (PHEMAC) particles, respectively. Moreover, the reusability of the PHEMAC-Pb²⁺ particles was tested for several times and no significant loss in adsorption capacity was observed. The accuracy of the proposed procedure was also verified by the determination of Pb²⁺ ions in the certified reference material, LGC 6137 Estuarine sediment.     

Preparation method and thermal properties of samarium and europium-doped alumino-phosphate glasses

The present work investigates alumino-phosphate glasses from Li₂O–BaO–Al₂O₃–La₂O₃–P₂O₅ system containing Sm³⁺ and Eu³⁺ ions, prepared by two different ways: a wet raw materials mixing route followed by evaporation and melt-quenching, and by remelting of shards. The linear thermal expansion coefficient measured by dilatometry is identical for both rare-earth-doped phosphate glasses. Comparatively to undoped phosphate glass the linear thermal expansion coefficient increases with 2 × 10⁻⁷ K⁻¹ when dopants are added. The characteristic temperatures very slowly decrease but can be considered constant with atomic weight, atomic number and f electrons number of the doping ions in the case of T_g (vitreous transition temperature) and T_sr (high annealing temperature) but slowly increase in the case of T_ir (low annealing temperature–strain point) and very slowly increase, being practically constant in the case of T_D (dilatometric softening temperature). Comparatively to undoped phosphate glass the characteristic temperatures of Sm and Eu-doped glasses present lower values. The higher values of electrical conductance for both doped glasses, comparatively to usual soda-lime-silicate glass, indicate a slightly reduced stability against water. The viscosity measurements, showed a quasi-linear variation with temperature the mean square deviation (R²) being ranged between 0.872% and 0.996%. The viscosity of doped glasses comparatively to the undoped one is lower at the same temperature. Thermogravimetric analysis did not show notable mass change for any of doped samples. DSC curves for both rare-earth-doped phosphate glasses, as bulk and powdered samples, showed T_g values in the range 435–450 °C. Bulk samples exhibited a very weak exothermic peak at about 685 °C, while powdered samples showed two weak exothermic peaks at about 555 °C and 685 °C due to devitrification of the glasses. Using designed melting and annealing programs, the doped glasses were improved regarding bubbles and cords content and strain elimination.     

In-situ stabilization of Pb, Zn, Cu, Cd and Ni in the multi-contaminated sediments with ferrihydrite and apatite composite additives

Three additives were evaluated for their effectiveness in the attenuation of Pb²⁺, Zn²⁺, Cu²⁺, Cd²⁺, Ni²⁺ in contaminated sediments. Apatite, ferrihydrite and their composite were applied to the sediments. For the remediation, BCR, SEM/AVS and TCLP were adopted as the evaluating method and comparison of their results were used for the first time to test in-situ stabilization effect. The results showed that after 5 months composite treatment, more than 70% Pb²⁺, 40% Zn²⁺, 90% Cu²⁺, 50% Cd²⁺ and 80% Ni²⁺ was immobilized in oxidizable and residual phases, respectively. Compared to untreated sediment, Pb²⁺, Zn²⁺, Cu²⁺, Cd²⁺ in residual fraction increased 20%, 10%, 10%, 10% with composite treatment after 5 months, respectively. ΣSEM/AVS ratio declined from 12.6 to 9.3, in addition, composite treatments reduced the leaching of Pb²⁺ and Zn²⁺ from 10.6 mg L⁻¹and 42.5 mg L⁻¹to 5.4 mg L⁻¹ and 24.1 mg L⁻¹ in the sediment by TCLP evaluation. Meanwhile, apatite and ferrihydrite composite additives lowered the bioavailability and toxicity of sediments as well. Ferrihydrite had a positive effect in controlling the bioavailability and toxicity of heavy metals because it effectively retarded the oxidation of AVS in sediment.     

Effects of the co-addition of Zn and sodium dodecylbenzenesulfonate on photocatalytic activity and wetting performance of anatase TiO2 nanoparticle films

In this paper, doped and undoped anatase TiO₂ nanoparticle films on indium tin oxide glasses have been fabricated by spin coating sols containing Zn²⁺ or Zn²⁺ and sodium dodecylbenzenesulfonate (DBS), respectively. The effects of the co-addition of Zn²⁺ and DBS on the photocatalysis performance and wetting properties of the resulting TiO₂ nanoparticle films were investigated. The results showed that the addition of Zn²⁺ improved both the photocatalytic activity and the hydrophilicity, which was attributed to surface oxygen vacancies. The co-addition of Zn²⁺ and DBS resulted in an important increase of the surface roughness, resulting in films showing a superhydrophilic behavior. However, the photocatalytic activity was slightly decreased by co-adding Zn²⁺ and DBS. The DBS addition resulted in changes in the surface microstructure of the TiO₂ films, changing the photocatalytic activity and wetting performance.     

Pb2+ release by lead-ceramic glazes related to the chromophorous ion Cu2+

A quantitative relationship between lead release and the chemical composition of different lead-ceramic glazes doped by Cu²⁺, having similar ceramic properties and the same Pb²⁺ release from undoped samples, was established by means of EPR evaluation of the number of C_2h (or lower) symmetry sites occupied by Cu²⁺ ions. A parameter was also defined which is a function of the ionic radii and of the ionic molar content of glazes. This parameter is linearly correlated with Pb²⁺ release by acid attack.