Static adsorption properties of Ni（Ⅱ）by IDA resin and U-shaped continuous countercurrent desorption

研究了亚胺基二乙酸型螯合树脂R604对模拟含镍废水中镍离子静态交换吸附性能的主要影响因素,包括废水浓度、pH值、温度等,还研究了吸附平衡态、吸附过程的动力学、热力学,并给出了相应的模型,这些模型均与实验结果有很好的符合度。最后研究了独创的U形解吸柱系统对吸附饱和树脂的解吸性能,探讨了树脂停留时间、解吸液树脂流量比对解吸率和金属浓缩液浓度在柱体内分布的影响。研究表明,亚胺基二乙酸型树脂在废水金属离子镍的去除中有着高效、独特的性能,连续逆流U形解吸系统能提高重金属浓缩液浓度,并大幅度节省解吸液用量,减少解吸时间。     

Impedance characterization of Cr3+, Y3+ and Zr4+ activated forsterite nanoceramics synthesized by sol–gel method

The synthesis of forsterite-based ceramic nanopowders using sol–gel method assisted by further thermal treatment has been performed. X-ray diffraction and SEM analysis of the obtained nanopowders are presented. Detailed impedance spectroscopy study of the forsterite nanoceramics doped with Cr³⁺, Y³⁺ and Zr⁴⁺ ions has been carried out. Impedance spectra are interpreted in terms of equivalent circuits. Peculiarities of the electrical properties for each of the materials under study are discussed.     

Study of the degradation of hybrid sol–gel coatings in aqueous medium

The design and development of suitable multilayered functional coatings for delaying corrosion advance in metals and become controlled-release vehicles requires that the properties of the coatings are known. Coatings prepared by the sol–gel method provide a good approach as protective layers on metallic surfaces. This kind of coating can be prepared from pure chemical reagents at room temperature and atmospheric pressure, with compositions in a very wide range of environmentally non-aggressive precursors. Sol–gel coatings based on siloxane bonded units were prepared, starting with an organic–inorganic hybrid system. Synthesis procedures included acid-catalysed hydrolysis, sol preparation, and the subsequent gelation and drying. The alkoxide precursors used were methyl-triethoxysilane (MTMOS) and tetraethyl-orthosilicate (TEOS) in molar ratios of 10:0, 9:1, 8:2 and 7:3. After determination of the optimal synthesis parameters, the materials were characterised by solid ²⁹Si nuclear magnetic resonance (²⁹Si NMR), Fourier transform infrared spectroscopy (FTIR), contact angle measurement and electrochemical impedance spectroscopy (EIS) test. Finally, the materials were assayed by controlling their weight in contact with water, to determine their ability to degrade by hydrolysis. Electrochemical analysis reveals the formation of pores and water uptake during the degradation. The quantity of TEOS is one of the principal parameters that determine the kinetics of degradation. There is a correlation between the degradation process obtained for long periods and the electrochemical parameters obtained by EIS in short times. The study tries to incorporate knowledge that can be used for designing the degradation process of the functional coatings and to control their properties in short times.     

The effects of La2O3 on the structural properties of La2O3–Al2O3 prepared by the sol–gel method and on the catalytic performance of Pt/La2O3–Al2O3 towards steam reforming and partial oxidation of methane

The effect of La₂O₃ content on the structural properties and catalytic behavior of Pt/xLa₂O₃–Al₂O₃ catalysts in steam reforming of methane and partial oxidation of methane was investigated. There was a decrease in the density of Pt sites with the increase of La₂O₃ loadings according to Fourier transform infrared spectroscopy of adsorbed CO and to dehydrogenation of cyclohexane results. However, transmission electron microscopy data indicates an opposite trend. This apparent disagreement could be due to the partial coverage of Pt sites by LaO_x species. CH₄ turnover rates and specific rates of steam reforming of methane increased for higher La₂O₃ loadings. The Pt/Al₂O₃ catalyst was strongly deactivated during partial oxidation of methane, while La₂O₃-containing catalysts exhibited higher stability. The increase of activity observed during the reactions was ascribed to the ability of the [LaPt_xO]Pt⁰-like species to promote the gasification of coke. This cleaning mechanism led to higher accessibility of the active sites to CH₄.     

Reversible adsorption and desorption of water in nanoporous copper(II) metal–organic nanocapsules

Nanocapsule of [Cu₂(bda)₂(bpy)₂]·4H₂O (1) with nanoparticle morphology (bda^2? = 2,2?-biphenyl dicarboxylate and bpy?=?2,2?-bipyridine), was synthesized by sonochemical process. Guest water molecules can be removed from the nanopores of 1 by thermal treatment at 200?°C. The color of this compound changed from blue to deep green during this process. This process is reversible and compound [Cu₂(bda)₂(bpy)₂] (2) with the pore size of 4.3?×?5.5 Å can absorb water again. Thus nanoparticles of compound 2 with 1.53% weight absorption of water/compound 2 at room temperature could be used as water adsorption material like silica gel. Adsorption and desorption of water in these copper(II) metal–organic nanocapsules were studied by IR spectroscopy, thermo gravimetric analyses (TGA), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM).     

Study on the Effect between Dynamics of MgO Grain Growth and Additive of Y2O3

1IntroductionAdditive agent plays a great role in changingphysical and chemical properties and microstructure ofmaterials,especially in CaO-riched MgO-CaO refracto-ry system.Rare earth elements[1~6]have high electronlevel and special electronic structure …     

Characterization of Copper–Cobalt Ores and Quantification of Cu2+, Co2+, Co3+, and Fe3+ in Aqueous Leachates Using UV/Visible Spectrophotometry

Ultraviolet/visible (UV/vis) spectroscopy was used to determine qualitatively and quantitatively Cu²⁺, Co²⁺, Co³⁺, and Fe³⁺ in oxidized Cu–Co ore leachates. The mineralogical and chemical characteristics of the three oxidized Cu–Co ore samples considered were determined using Fourier transform infrared spectroscopy (FTIR), X-ray powder diffractometry (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and X-ray fluorescence spectrometry (XRF). The results showed that Cu and Co in the samples were in the form of carrollite (Co₂CuS₄), malachite (Cu₂CO₃(OH)₂, and heterogenite (CoO(OH)). The samples contained (2.73% Cu and 0.19% Co), (2.82% Cu and 0.07% Co), and (0.03% Cu and 0.05% Co), respectively. Gangues were mainly constituted of quartz, goethite, and hematite. The ultraviolet/visible (UV/vis) results indicated that the wavelengths of absorbance of the metal ions in dilute ethylenediaminetetraacetic acid aqueous solution (pH ≈ 3.5) were Fe³⁺ (293 nm), Cu²⁺ (821 nm), Co³⁺ (344 nm), and Co²⁺ (512 nm). The molar concentrations of the metal ions obtained using the UV/vis method compared well with the results obtained using the atomic absorption spectroscopy (AAS) method. UV/vis spectroscopy was also used to monitor the conversion of Co³⁺ into Co²⁺ using different reducing agents. The results showed that the molar concentration of Co²⁺ in the aqueous solutions increased with the addition of reducing agents, of about 80.95% (copper foil), 61.22% (ferrous sulfate), and 20.35% (sodium sulfite), respectively.     

Effect of La3+ substitution on the structural and thermoelectric properties of Ca3-xLaxCo4O9+δ

The thermoelectric properties of Ca₃Co₄O₉ were optimized by the substitution of La³⁺ for Ca²⁺ in Ca₃Co₄O₉. The La³⁺ substitution significantly enhanced the thermoelectric power factor and reduced the lattice thermal conductivity. The lattice thermal conductivities at 800 °C for x = 0 and 0.3 samples were 1.80 and 1.34 Wm⁻¹ K⁻¹, respectively. The reduced thermal conductivity was mainly attributed to mass and strain field fluctuations in the crystal lattice. Ca_2.7La_0.3Co₄O_9+δ showed the largest dimensionless figure-of-merit (0.282 at 800 °C) by combining high power factor and the lowest lattice thermal conductivity. This work demonstrates that the La³⁺ substitution is a highly effective approach for improving high-temperature thermoelectric properties.     

Influence of La3+ additions on the phase behaviour and antibacterial properties of ZrO2–SiO2 binary oxides

The present study reports the influence of lanthanum (La³⁺) content on the phase stability and antibacterial activity of ZrO₂–SiO₂ binary oxides. Four different concentrations of La³⁺ additions in ZrO₂–SiO₂ binary oxides were synthesized using a sol–gel technique. Heat treatment of the synthesized powders resulted in the formation of t-ZrO₂ phase at 1000 °C. Heat treatment beyond 1000 °C resulted in the phase degradation of t-ZrO₂ to yield m-ZrO₂ and ZrSiO₄. Results from antibacterial tests confirmed the potential activity of La³⁺ doped ZrO₂–SiO₂ binary oxides in countering the microbial invasion.     

Studies on solvent extraction of La(III) using [A336][NO3–] and modeling by statistical analysis and neural network

Solvent extraction of La(III) from acidic nitrate medium has been studied with [A336][NO₃^–] in kerosene. The factors affecting the extraction of La(III) like equilibration time, nitrate ion, extractant and La(III) concentrations, aqueous acidity, O/A ratio variation, nature of diluent, and temperature have been investigated. McCabe-Thiele diagram has been plotted to find out the actual number of theoretical stages needed for complete extraction of lanthanum. The solvent has been successfully regenerated for further use after stripping of the metal. IR studies of [A336][NO₃^–] and La(III) loaded [A336][NO₃^–] have been carried out. Modeling of extraction data has been done using Multiple linear regression analysis and Artificial Neural Network, and the performances have been compared. Error in each case was evaluated in terms of R² and Root mean squared error (RMSE). Maximum extraction of La(III) was 82% when 0.6 M [A336][NO₃^–] was used for extraction. About 98% of the metal has been recovered using 0.2 M HNO₃ as stripping agent. Extractive separation of La(III) and Sm(III) was maximum (β = 65.2) using 0.1 M [A336][NO₃^–]. IR studies revealed formation of lanthanum complex in the extraction process. Artificial Neural Network proved to be better over Multiple linear regression in data prediction.     

Hydrophobic interaction-mediated reversible adsorption–desorption of nanoparticles in the honeycomb-patterned thermoresponsive poly(N-isopropylamide) hydrogel surface

Hydrophobic interaction-mediated reversible adsorption–desorption of Ag nanoparticles in water solutions was studied in surface-tailored poly(N-isopropylacrylamide) (PNIPAAm) hydrogel film. Surface-tailoring of PNIPAAm hydrogel was performed by the preparation of the hydrogel as a honeycomb-patterned film using a honeycomb-patterned PS film as a template. The surface morphology and hydrophobic interaction of the patterned hydrogel surface were significantly altered by temperature change of the aqueous solution that came in contact with the gel. The surface of the hydrogel became hydrophobic for adsorption at a higher temperature than the lower critical solution temperature of 32 °C, but became hydrophilic with decreased adsorptivity at lower temperature condition. Adsorptivity was obtained through measuring the concentration of the silver nanoparticles using UV–vis spectroscopy in an aqueous solution. A reversible adsorption–desorption of nanoparticles dependent on the temperature in the hydrogel surface obtained in this study clearly suggested that the hydrophobic interaction was reversibly changed in the patterned temperature-responsive hydrogel surface, similar to various biological systems in nature.     

Impact of hybrid self-assembled nanophase particle-based sol–gel coatings on the localized corrosion behavior of modified 9Cr–1Mo steel in chloride medium

Corrosion protection coatings were developed based on a hybrid self-assembled nanophase particle process (HSNAP) for the localized corrosion resistance of modified 9Cr–1Mo steel in 0.05 M NaCl solution. The coating sol was prepared using silane-zirconia precursors and a polymeric crosslinking agent. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to study the morphology and composition of the coated specimens, respectively. The thickness of the coatings was determined by a thickness gauge meter and Raman imaging analysis. The corrosion resistance of coated specimens was analyzed using electrochemical impedance spectroscopy, and it was observed that HSNAP-coated specimens showed superior resistance to localized corrosion than the as-received specimens in chloride medium.     

Parameters optimization of recombinant hepatitis B antigen adsorption–desorption in purification process on three different kinds of diatomaceous earth matrix

The purpose of this study was to compare adsorptive capacity of three kinds of celite for r-HBsAg. The experimental design methodology was used to optimize the parameters which affect adsorption efficiency. The examined parameters were the adsorption/desorption temperature, pH, time, agitation speed and antigen concentration.     

Impact of the A-site rare-earth ions (Ln3+ – Sm3+, Eu3+, Gd3+) on structure and electrical properties of the high entropy LnCr0.2Mn0.2Fe0.2Co0.2Ni0.2O3 perovskites

High entropy perovskites LnCr_0.2Mn_0.2Fe_0.2Co_0.2Ni_0.2O₃ ceramics were produced by solid-state reactions from oxides. The B-site chemical composition was fixed (Cr_0.2Mn_0.2Fe_0.2Co_0.2Ni_0.2) and A-site composition was varied by the rare-earth ions (Ln = Sm³⁺, Eu³⁺ and Gd³⁺). The entropy of B-sublattice mixing was 1.609R J/(mol*K). The dependences of the lattice parameters, microstructure features, and electrical properties were discussed as function of the A-site rare-earth ions. The correlation of the lattice parameters with the nature of the A-site rare earth ions was demonstrated. Impact of the rare-earth ions in A-site on microstructural parameters was observed. Charge conduction mechanisms were discussed in details for a wide range of temperatures.     

Effective and simple recovery of 1,3-propanediol from a fermented medium by liquid–liquid extraction system with ethanol and K_3PO_4

1,3-Propanediol,traditionally obtained from fossils,has numerous industrial applications,including use in the production of high performance polymers.The microbial production of 1,3-propanediol presents several opportunities,and the final purity grade determines its price and commercial viability.The development of novel separation technology could improve the economic viability of the bioproduction of 1,3-propanediol.Thus,we investigated salting-out extraction as a novel process for 1,3-propanediol recovery from fermentation broth.Initially,a screening for the best salt/solvent combination was conducted and then optimized using the response surface methodology.The solvents studied were methanol,ethanol,isopropanol and acetone,and the salts examined were K_2HPO_4,Na_2CO_3,K_2CO_3,(NH_4)_2SO_4,NaHPO_4,K_3PO_4 and C_6H_5NaO_7.The optimal extraction system consisted of 34 wt%K_3PO_4,28 wt% ethanol,and 38 wt% fermentation broth containing 23.0 g·L~(-1)1,3-propanediol,which gave the highest partition coefficient of 33 and recovery yield of 97%.The results demonstrated that salting-out extraction was a promising method for 1,3-propanediol recovery from fermentation broth.     

Overcoming the quality–quantity tradeoff in dispersion and printing of carbon nanotubes by a repetitive dispersion–extraction process

Dispersion-printing processes are essential for the fabrication of various devices using carbon nanotubes (CNTs). Insufficient dispersion results in CNT aggregates, while excessive dispersion results in the shortening of individual CNTs. To overcome this tradeoff, we propose here a repetitive dispersion–extraction process for CNTs. Long-duration ultrasonication (for 100 min) produced an aqueous dispersion of CNTs with sodium dodecylbenzene sulfonate with a high yield of 64%, but with short CNT lengths (a few μm), and poor conductivity in the printed films (∼450 S cm⁻¹). Short-duration ultrasonication (for 3 min) yielded a CNT dispersion with a very small yield of 2.4%, but with long CNTs (up to 20–40 μm), and improved conductivity in the printed films (2200 S cm⁻¹). The remaining sediment was used for the next cycle after the addition of the surfactant solution. 90% of the CNT aggregates were converted into conductive CNT films within 13 cycles (i.e., within 39 min), demonstrating the improved conductivity and reduced energy/time requirements for ultrasonication. CNT lines with conductivities of 1400–2300 S cm⁻¹ without doping and sub-100 μm width, and uniform CNT films with 80% optical transmittance and 50 Ω/sq sheet resistance with nitric acid doping were obtained on polyethylene terephthalate films.