Comparison of polyelectrolytes applied in drinking water treatment

The applicability of an inorganic, polyaluminium-type flocculent was tested comparing to polyacrylamides — an organic-type flocculent — used in the drinking water treatment process. The efficiency of this inorganic flocculent in the removal of suspended solids and also in minimizing the residual concentrations of the dissolved organic and inorganic micro-pollutants was checked in the case of purifying filter backwash water. Experimental data showed the advantage of the inorganic flocculent applying procedure as a part of recent water treatment technology. The applied polyaluminium-salt was economically competitive, improved the process stability and also ensured good water quality parameters.     

Preparation of magnetic separable CoFe2O4/PAC composite and the adsorption of bisphenol A from aqueous solution

CoFe₂O₄/PAC composite adsorbent has been prepared via an immersing-calcination process, using ethylene diamine tetraacetic acid (EDTA) and citric acid (CIT) ligands containing sol as the CoFe₂O₄ precursor. The microstructure characterization and magnetic property of as-prepared sample were performed by means of XRD and VSM measurements. The adsorption kinetics, isotherms and thermodynamic process toward Bisphenol A molecules (BPA, which is considered as one of the typical endocrine disrupting chemicals) occurred on as-prepared magnetic adsorbent which were investigated by the pseudo-second order kinetic/intraparticle models, the Langmuir/Freundlich adsorption isothermal models and basic chemical thermodynamics principles, respectively.     

PAC experiments for a short range study of the Zr(10%Pr)O2 solid solution

A Zr(10 mol % Pr)O₂ powder obtained by high-energy ball milling has been investigated at nanoscopic scale using primarily the Perturbed Angular Correlations technique. The aim has been to determine the nanoconfigurations around Zr⁴⁺ cations present in the solid solution and their thermal evolution with the intention of providing knowledge on the stability of the system. Results indicate that the milled product is a substitutional cubic solid solution described by two hyperfine interactions: a highly disordered interaction due to oxygen vacancies located very close to Zr⁴⁺ and an ordered interaction probably depicting a charge distribution including Pr³⁺ as nearest neighbor to Zr⁴⁺ probes. On cooling from high temperatures, monoclinic zirconia appears mostly at the expense of the oxygen defective cubic form. A gradual cooling indicates that destabilization of the solid solution takes place around 500°C. Thermal cycling leads to increasing amounts of the monoclinic phase.     

Mössbauer Study of Lanthanum–Strontium Ferromanganite Oxides

TDPAC has been employed to study the local structure of implanted palladium in silicon utilizing 87–75 keV γ–γ cascade of probe nucleus ¹⁰⁰Pd. The observed hyperfine parameters revealed the presence of Pd–V defect pair only in highly doped n-type silicon. A dumbbell structure with substitutional palladium and silicon vacancy as nearest neigbor is suggested for this defect.     

The Formation of Lithiated Ti-Doped α-Fe2O3 Nanocrystalline Particles by Mechanical Milling of Ti-Doped Lithium Spinel Ferrite

Perturbed Angular Correlation method has been used to study the hyperfine magnetic field in the Heusler alloy Pd₂MnSb(Sn). Ion implantation of the recoil ¹¹¹In nuclei following heavy ion nuclear reactions ¹⁰⁸Pd(⁷Li, 4n)¹¹¹In and ¹⁰⁸Pd(⁶Li, 3n)¹¹¹In has been used to great advantage in the present case resulting in large implantation efficiency. Only a few hours of irradiation time with moderate beam current of the order of 400–500 nA resulted in sufficient implanted ¹¹¹In activity on the sample for good quality measurements. The hyperfine field was measured at ¹¹¹Cd probe nuclei substituting Mn and Sb(Sn) sites as a function of temperature. The fraction of ¹¹¹Cd nuclei occupying Mn atom sites was found to increases with the annealing of sample at higher temperatures.     

Investigation of Hyperfine Interactions in GdNiIn Compound

Perturbed gamma–gamma angular correlation technique was used to measure the hyperfine interactions in the compound GdNiIn using the ¹¹¹InCd → and ¹⁴⁰La¹⁴⁰Ce probe nuclei at the In and Gd sites, respectively. A unique quadrupole frequency with asymmetry parameter η = 0.78 was observed for ¹¹¹Cd probe at In sites for the measurements above Curie temperature. Below T _C , the spectra for ¹¹¹Cd show combined magnetic dipole and electric quadrupole interaction. Below 85 K, a unique magnetic interaction is observed at ¹⁴⁰Ce. A linear relationship between the saturated magnetic hyperfine field and the magnetic transition temperature was observed for both probes, indicating that the main contribution to the mhf comes from the conduction electron polarization.     

Temperature Dependence of the Magnetic Hyperfine Field at 140Ce on Gd Sites in GdAg Compound

Perturbed gamma–gamma angular correlation technique was used to measure the magnetic hyperfine field at Gd sites in the intermetallic compound GdAg using the ¹⁴⁰La→¹⁴⁰Ce nuclear probe. A major and well-defined magnetic interaction is observed at ¹⁴⁰Ce substituting Gd sites in GdAg below 130 K, corresponding to a ferromagnetic ordering of Gd moments. The temperature dependence of magnetic hyperfine field, however, shows a sharp deviation from an expected Brillouin-like behavior for temperatures below 75 K. This additional magnetic interaction is believed to result from the polarization of Ce spin moments induced by the magnetic field from Gd atoms.     

Comparative Studies Using EXAFS and PAC of Lattice Damage in Semiconductors

We have used the perturbed angular correlation (PAC) method and extended X-ray absorption fine structure spectroscopy (EXAFS), along with microscopic methods to investigate the implantation induced disorder and characterize the ion-induced amorphisation of elemental and compound semiconductors.     

Anomalous Temperature Dependence of the EFG in AlN Measured with the PAC-Probes 181Hf and 111In

¹⁸¹Hf and ¹¹¹In ions were implanted into AlN-layers in order to investigate their immediate lattice site environment and its temperature dependence by means of the Perturbed Angular Correlation (PAC) technique. After rapid thermal annealing at 1273 K up to 50% of the probe atoms were incorporated on undisturbed lattice sites defined by an electric field gradient (EFG) of 33 MHz for In and 572 MHz for Hf for measurement at room temperature. PAC-spectra taken at temperatures between 25 and 1200 K show that the EFG measured at the site of the undisturbed probes changes with temperature. While for Hf it decreases by 3%, for In it increases by 25% within the measured temperature range. Thus, the change cannot be due only to the thermal lattice expansion. In the case of In the fraction of probe atoms on substitutional sites increases with temperature until it reaches nearly 100% at 973 K. These effects are fully reversible. For the Hf probe, an additional EFG was detected at temperatures above 300 K.     

高浓度高Al13含量聚合氯化铝溶液的制备

通过快速加碱在82 ℃下合成0.2 mol·L^-1、Al_b为60%～70%的低浓度高Al_b聚合氯化铝(L-PAC)，在热侧温度为50～95 ℃，冷侧温度约9～12 ℃的条件下进行膜蒸馏浓缩，制备出总铝浓度在2 mol·L^-1以上，Al_b含量大于90%，Al₁₃含量约为70%的高浓度高Al_b含量的聚合氯化铝溶液。对膜蒸馏浓缩过程中热侧温度、PAC的碱化度和初始pH值等因素对最终聚合氯化铝溶液产品中聚铝形态分布、总铝浓度的影响进行了初步研究，发现在热侧温度低于70 ℃、碱化度为2.47、初始pH值为5.0 ± 0.2的条件下，可以得到高浓度、高Al_b含量的聚合氯化铝溶液，纳米Al₁₃形态在较高的浓度下可以存在；低温贮存条件下，高浓度PAC中Al_b相当稳定。