测试——聚乙烯亚胺改性磁性膨润土对Pb2+和Cu2+的吸附性能(测试稿件)

在磁性膨润土(MBent)表面接枝聚乙烯亚胺(PEI)制备了聚乙烯亚胺改性磁性膨润土(PEI/KH560/MBent),采用FTIR、VSM、XRD、TGA、EA、SEM和EDS对其进行了表征,考察了其对水溶液中Pb_²⁺和Cu_²⁺的吸附性能。结果表明,聚乙烯亚胺已成功接枝于磁性膨润土表面,并有效提高其对Pb_²⁺和Cu_²⁺吸附量；溶液初始pH对吸附量影响较大,随着pH的增大,吸附量增加。在pH=5,溶液初始质量浓度为300 mg/L,PEI/KH560/MBent对Pb_²⁺和Cu_²⁺吸附量分别为96.21和61.08 mg/g；吸附过程符合准二级动力学模型,吸附行为符合Langmuir吸附等温模型。热力学研究表明,吸附为自发吸热过程。经过5次循环利用后,其吸附容量仍保持初始的60%以上,表明PEI/KH560/MBent具有一定的重复利用性。     

Comparative CO2 Adsorption Analysis in Pure and Amine-Modified Composite Membranes

In this study, the CO₂ adsorption analysis in cellulose acetate–TiO₂- and cellulose acetate–3-aminopropyl-trimethoxysilane TiO₂-blended membranes was performed. The membranes were also characterized using scanning electron microscopy and Fourier transform infrared analysis techniques. The adsorption results indicated that 120 and 90°C were considered as optimized temperatures for regeneration of cellulose acetate–TiO₂ and cellulose acetate–3-aminopropyl-trimethoxysilane-modified TiO₂ membranes. The testing results revealed that adsorption capacity reached maximum at 3.0 bars. Validation of experimental results was performed by pseudo-first-order, second-order and intraparticle diffusion models. The correlation factor R² represented that the second-order model was fitted well with the experimental data. The intraparticle diffusion model represented that adsorption is not a single-step process.     

Synthesis and application of nanocomposite Fe3O4@SiO2@CTAB–SiO2 as a novel adsorbent for removal of cyclophosphamide from water samples

ABSTRACT

We present a way of synthesizing nanocomposite Fe₃O₄@SiO₂@CTAB–SiO₂ by employing simple sol–gel technique with selective etching for extreme selectivity adsorption of cyclophosphamide (CP). The transmission electron microscopy (TEM); scanning electron microscopy (SEM); X-ray diffraction (XRD); Fourier transform infrared (FT-IR); vibrating sample magnetometer (VSM); pH_PZC; and Brunauer, Emmett and Teller (BET) techniques were used for nanocomposite characterization. These nanoparticles have an S_BET of 157.8 m² g^?1 and a high saturation magnetization of 67.5 emu g^?1. First, the adsorption system was examined as a function of contact time under various initial CP contents, ionic strength, initial solution pH, adsorbent dose and temperature in batch test. The optimum dose, pH and contact time were obtained to be 0.01 g, 7.0 and 30 min, respectively. Ultimately, experimental isotherm and kinetics data of adsorption of CP onto nanocomposite Fe₃O₄@SiO₂@CTAB–SiO₂ were fitted to classical models. Additionally, it was found that the maximum adsorption process capacity of CP on adsorbent was 342.8 mg g^?1.     

Modification and magnetization of MOF (HKUST-1) for the removal of Sr2+ from aqueous solutions. Equilibrium,kinetic and thermodynamic modeling studies

In this research, metal-organic framework MOF(HKUST-1) was synthesized, magnetized and modified by hexacyanoferrate in order to prepare an efficient adsorbent for the removal of Sr²⁺ from aqueous solutions. The synthesized adsorbent was characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy, thermal methods (TG-DTG[Themogravimetry- Derivative Theromogravimetry]), Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) surface area and scanning electron microscopy (SEM). The non-magnetized (MOF/KNiFC[potassium nickel hexacyanoferrate]) and magnetized (MOF/Fe₃O₄/KNiFC) adsorbents were then employed for the removal of Sr²⁺ from aqueous solutions. The adsorption capacity of 110 and 90 mg.g^?1 was obtained, respectively, for MOF/KNiFC and MOF/Fe₃O₄/KNiFC. The adsorption process was kinetically fast and the equilibration was established within 45 min. The magnetic capability of the adsorbent examined by the vibrating sample magnetometer (VSM) technique indicated that the used adsorbent was capable of separating from the solution by applying an external magnetic field. The adsorbent showed good selectivity toward Sr²⁺ in the presence of Cs⁺, Na⁺, Mg²⁺, Ca²⁺ and Ba²⁺. The regenerated adsorbent retained more than 90% of its initial capacity. Different isotherm models including Langmuir, Freundlich, Tempkin, Sips and Redlich–Peterson were employed to examine the applicability of the isotherms to the experimental data. It was concluded that the data was best fitted to the Langmuir isotherm model. The thermodynamic parameters showed that the process was endothermic.     

Extraction of Uranium and Thorium from Nitric Acid Solution by TODGA in Ionic Liquids

Extraction of uranium (UO₂²⁺) and thorium (Th⁴⁺) from a nitric acid solution into an imidazolium-type ionic liquids (ILs) of 1-alkyl-3-methylimidazolium hexafluorophosphate ([C_nmim][PF₆], n = 6 or 8) was carried out using N,N,N′,N′-tetraoctyl-3-oxapentanediamide (TODGA) as an extractant. It was found that the extraction efficiencies of UO₂²⁺ and Th⁴⁺ ions are higher in comparison with that done in n-dodecane. The extraction mechanism was deduced by the slope analysis and extraction experiment. Transfer of both ions is assumed to proceed predominantly through the neutral solvation mechanism from nitric acid solution into ILs. The UO₂²⁺ ion forms a 1:2 complex with TODGA in ILs at lower acidity, and a 1:1 complex in ILs and in n-dodecane at higher acidity. The Th⁴⁺ ion forms a 1:2 complex with TODGA in C₆mimPF₆ IL or a 1:1 complex in C₈mimPF₆ IL at lower acidity and a 1:1 complex in both ILs, and n-dodecane at higher acidity. Stripping studies were conducted using sodium salt of EDTA as a stripping ligand. The thermodynamics of extracting UO₂²⁺ ions and Th⁴⁺ ions from a 3 M HNO₃ solution was also studied. The results indicated that the extraction reactions are spontaneous and go through an exothermic process.     

Effects of Water and Ion-Exchanged Counterion on the FTIR Spectra of ZSM-5. II. (Cu+–CO)-ZSM-5: Coordination of Cu+–CO Complex by H2O and Changes in Skeletal T–O–T Vibrations

The 2157 cm^–1 (strong) and 2108 cm^–1 (very weak) (CO) IR bands due to Cu⁺–CO in ZSM-5 zeolite with ¹²C and ¹³C isotopes, respectively, are reversibly red-shifted by subsequent adsorption of H₂O at 293 K. On the contrary, the locally perturbed internal (T–O–T) asymmetric stretching framework vibration [ _as ^int (TOT)(Cu⁺–CO)=965 cm^–1] is reversibly blue-shifted. The courses of the band shifts revealed notable features. Charge transfers from water to Cu⁺ ions, changes in coordination spheres of Cu⁺(CO)(H₂O) _n aqua complexes and secondary (solvent-like) effects were considered to explain the results.     

Study of the Oxygen Diffusion on Three-Way Catalysts: A Kinetic Model

A computer model was developed to take into account all the phenomena that can occur in ¹⁸O/¹⁶O isotopic exchange over Pt/CeZrO _x materials: adsorption/desorption on the metal, surface and bulk O diffusion. Discriminating each step of the exchange process is no longer necessary: kinetic parameters and O diffusivity can be calculated in a single experiment.     

Synthesis of High Surface Area MgAl2O4 Nanopowder as Adsorbent for Leather Dye Removal

Abstract

MgAl₂O₄ nanopowder has been prepared by alkoxides hydrolysis with further calcination at temperature of 700°C. The adsorption of a leather dye, Direct Black 38, onto this material was investigated. The sample was characterized by X-ray-diffraction (XRD), N₂ adsorption–desorption isotherm and Fourier transform infrared spectroscopy. The results showed that sample present a pure phase, and the average nanocrystal size of 8 nm, the BET surface area is about 206.5 m² · g^?1 and total pore volume is about 1.44 cm³ · g^?1. Adsorption kinetics data were modeled by film and pore diffusion model. The experimental isotherm was described by the Langmuir model. MgAl₂O₄ nanopowder presented a great removal efficiency of leather dye by adsorption process, with a maximum adsorption capacity of 833 mg of dye per gram of adsorbent.     

Evaluating Cu(II) Removal From Aqueous Solutions with Response Surface Methodology by Using Novel Synthesized CaCO3 Nanoparticles Prepared in a Colloidal Gas Aphron System

Removal of heavy metals from water and wastewaters has recently gained a great deal of attention due to their serious environmental problems. In this study, novel synthesized calcium carbonate nanoparticles, prepared in a colloidal gas aphron (CGA) system, were used as adsorbents for the removal of Cu²⁺ ions from aqueous solutions under different conditions. A developed pseudo-second-order (PSO) model well described the adsorption kinetics of the process. Langmuir and Freundlich adsorption isotherms have been examined and the maximum adsorption capacity from the Langmuir isotherm equation was found to be 666.67?mg Cu/g adsorbent. The effects of temperature, Cu²⁺ initial concentration, and CaCO₃ dosage on the removal capacity were also investigated using the three-level Box–Behnken experimental design method. The response surface modeling results demonstrated that under certain experimental conditions (i.e., T?=?26°C, [Cu²⁺]?=?200?mg/L, and [CaCO₃]?=?0.5?g/L), maximum removal capacity value (393.52?mg/g) was achieved.     

The promotional effect of Cr on catalytic activity of Pt/ZSM-35 for H2-SCR in excess oxygen

Selective catalytic reduction of NO by hydrogen was studied over Cr modified Pt/ZSM-35 catalysts. The preparation process greatly influenced catalytic activity and sample prepared by co-impregnation method exhibits the best activity. In situ DRIFT studies revealed that on Pt–Cr/ZSM-35, (1) new Pt-NO^δ+ and NO species adsorbed on Pt were detected upon NO + O₂ adsorption; (2) much more ammonia species were formed under reaction condition. Cr addition not only enhanced the adsorption of NO_x but also promoted the formation of surface NH₄⁺ species, which should be the origin of promotional effect of Cr on Pt/ZSM-35 for H₂-SCR reaction.     

Adsorption of Cu2+ Cations from Aqueous Solution by S-doped TiO2

S-doped TiO₂ as a novel adsorbent for Cu²⁺ cations removal from aqueous solutions was synthesized by simple sol-gel process. Removal of Cu²⁺ cations from aqueous solutions was investigated with particular reference to the effects of initial Cu²⁺ cations concentration, pH-value, adsorbent dosage, and temperature on adsorption. It was found that the maximum adsorption capacity was 96.35 mg g^?1 at 328 K. The adsorption equilibrium isotherms and the kinetic data were well described by the Langmuir and pseudo-second-order kinetic models, respectively. The high uptake capability of S-doped TiO₂ makes it a potentially attractive adsorbent for the removal of heavy metal pollutants from aqueous solution.     

Adsorption of Textile Dye on Zinc Stannate Oxide: Equilibrium,Kinetic and Thermodynamics Studies

Zn₂SnO₄ powder was prepared by hydrothermal process at 200°C for 12 h. The material was characterized by X-ray-diffraction and surface area. The synthesized sample presented a pure phase and a surface area of 48.8 m² · g^?1. It was used as adsorbent to remove the Reactive Red 141 that is a azo textile dye. The adsorption kinetics of the textile dye on Zn₂SnO₄ followed the pseudo-second-order model. The adsorption process was found to be controlled by both external mass transfer and intraparticle diffusion. The equilibrium data were in good agreement with both Langmuir and Freundlich isotherms. Thermodynamic parameters were calculated, and the results revealed that the adsorption process is endothermic in nature, with weak forces of the Van der Walls acting.     

CO2 adsorption performance of polyethyleneimine-modified ion-exchange resin

A series of solid amine adsorbents were prepared by the template method with ion-exchange resin (D001) as the carrier and polyethyleneimine (PEI) as the modifier. The absorbents were characterized by energy disperse spectroscopy (EDS), scanning electron microscope (SEM), N₂ adsorption–desorption, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) techniques. The effects of PEI loading, adsorption temperature and influent velocities on CO₂ adsorption capacity in a fixed-bed reactor were investigated. The results show that the solid amine adsorbent prepared by the template method had a better PEI dispersion, stability and CO₂ adsorption capacity. The maximum CO₂ adsorption capacity was 3.98 mmol·g^?1 when PEI loading was 30%, the adsorption temperature was 65°C and the influent velocity was 40 mL·min^?1. The CO₂ adsorption capacity decreased only by 9.50% after 10 cycles of adsorption–desorption tests. The study of kinetics indicates that both chemical adsorption and physical adsorption occurred in the CO₂ adsorption process. The CO₂ adsorption process included fast breakthrough adsorption and gradually approaching equilibrium stage. The particle internal diffusion process was the control step for CO₂ adsorption.     

Removal of SO2 at low temperature using dead Bacillus licheniformis

In this paper we studied the adsorption and desorption behavior of SO₂ by the dead Bacillus licheniformis R08 biomass. The effects of water vapor, temperature and O₂ on the removal of SO₂ by the biomass were studied. FTIR and XPS were used to characterize the mechanism of the SO₂ adsorption on the biomass. The experimental results showed that water vapor and temperature deeply influenced the adsorption of SO₂ by the biomass. However, O₂ cannot oxidize SO₂ to SO₃ on the biomass. FTIR and XPS results showed that oxygenous and nitrogenous functional groups on the cell walls of biomass may be related to the SO₂ adsorption and three sulfur species were formed on the biomass in adsorption process. In the desorption process, weakly adsorbed SO₂ could be desorbed by increasing temperature and the biomass can be reused for 10 cycles.     

Photoluminescence properties of Eu3+-doped stalk-like Al2O3 via a hydrothermal route followed by heat treatment

ABSTRACT

Uniform Al₂O₃:Eu³⁺ samples were successfully fabricated via a hydrothermal method and subsequent thermal decomposition of Eu³⁺-doped precursors. The sample characterisations were carried out by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence spectra. XRD results revealed Eu³⁺-doped samples were a pure γ-Al₂O₃ phase after being calcined at 1173?K. SEM results showed that these Eu³⁺-doped Al₂O₃ samples were stalk-like, with an average length of 1.5?μm. Upon excitation at 394?nm, the orange–red emission bands, having wavelengths longer than 580?nm, were to be from ⁵D₀→⁷F_J (J?=?1, 2) transitions. The asymmetry ratio of (⁵D₀→⁷F₂)/(⁵D₀→⁷F₁) intensity is about 0.54, 2.76, 3.29, 2.86, 3.36, 3.13 for Eu³⁺ concentrations of 0.1, 0.4, 0.7, 1.0, 1.5 and 2.0?mol-%, respectively. The optimal doping concentration of Eu³⁺ ions in Al₂O₃ is 1.5?mol-%. According to Dexter's theory, the critical distance between Eu³⁺ ions for energy transfer was determined to be 14?Å.     

Enhanced copper removal from aqueous solution by hydrous TiO2/zeolite composite

ABSTRACT

Hydrous titanium dioxide was impregnated on the surface of zeolite to obtain a kind of hydrous TiO₂/zeolite (HTiO₂/ZFA) adsorbent using the hydrothermal method. HTiO₂/ZFA was characterised by scanning electron microscopy combined with energy-dispersive spectrometer, X-ray diffraction, Fourier transform infrared, particle size distribution; and the pH of zero point charge measurement and its performance for Cu(II) adsorption were investigated. It was shown that Ti was not inserted into the skeleton of ZFA and hydrous TiO₂ loaded on the surface was amorphous. The pHzpc of HTiO₂/ZFA decreased to pH 5.5 from pH 6.5 of ZFA. Cu(II) adsorption was favoured in a pH range of 3.0–6.0, and 90% copper could be removed in first 30?min for 60?mg?L^–1 Cu(II) solution. The Langmuir isotherm model could well describe the adsorption isotherm data and the maximal Cu(II) adsorption capacity reached 251.9?mg?g^–1. Moreover, the HTiO₂/ZFA could be desorbed by HCl solution for further use, which implied an effective application in wastewater treatment.     

Preparation and characterization of SO42-/TiO2 and S2O82-/TiO2 catalysts

Nanosized solid superacids SO₄ ²⁻/TiO₂ and S₂O₈ ²⁻/TiO₂, as well as MCM-41-supported SO₄ ²⁻/ZrO₂, were prepared. Their structures, acidities, and catalytic activities were investigated and compared using XRD, N₂ adsorption-desorption, and in situ FTIR-pyridine adsorption, as well as an evaluation reaction with pseudoionone cyclization. The results showed that SO₄ ²⁻/TiO₂ and S₂O₈ ²⁻/TiO₂ possess not only nanosized particles with diameters < 7.0 nm, a BET surface greater than 140 cm²/g and relatively regular mesostructures with pores around 4.0 nm, but also a pure anatase phase and strong acidity. Different from the Lewis acid nature of SO₄ ²⁻/ZrO₂/MCM-41, SO₄ ²⁻/TiO₂ and S₂O₈ ²⁻/TiO₂ exhibit mainly Bronsted acidities. The strongest Bronsted acid sites were produced on SO₄ ²⁻/TiO₂ promoted with H₂SO₄, while Lewis acid sites on S₂O₈ ²⁻/TiO₂ even stronger than those on SO₄ ²⁻/ZrO₂/MCM-41 were generated when persulfate solution was used as sulfating agent. Because of their distinct acid natures, SO₄ ²⁻/TiO₂ and S₂O₈ ²⁻/TiO₂ exhibited catalytic activities for the cyclization of pseudoionone that were much higher than that of SO₄ ²⁻/ZrO₂/MCM-41. It can be concluded that the existence of more Br?nsted acid sites was favorable for proton participation in the cyclization reaction. Translated from Journal of Chemical Engineering of Chinese Universities, 2006, 20(2): 239–244 [译自: 高校化学工程学报]     

Cerium dioxide nanoparticles decorated on CuFe2O4 nanofibers as an effective adsorbent for removal of estrogenic contaminants (bisphenol A and 17-α ethinylestradiol) from water

CeO₂/CuFe₂O₄ nanofibers with high adsorption selectivity for bisphenol A (BPA) and 17-α ethinylestradiol (EE2) were synthesized by support of CeO₂ on the CuFe₂O₄ nanofibers. The characteristics of nanocomposite were investigated via using XRD analysis, FT-IR, SEM, pH_pzc, and Brunauer, Emmett, and Teller methods. The results showed that the maximum adsorption capacities of adsorbent for BPA and EE2 were 226.9 and 179 mg g^?1, respectively. Moreover, the regeneration experiments illustrated that synthesized adsorbent could be recovered, and it showed good recycling ability after being used for six cycles. The isotherm analysis indicated that the equilibrium data could be represented by the Langmuir–Freundlich model. The thermodynamic study showed that the adsorption processes were spontaneous and endothermic under studied conditions.     

Preparation and characterization of multicomponent porous materials prepared by the sol-gel process

An experimental strategy was developed to obtain transparent Si-Al-Ti-Ni-Mo and Si-Zr-Ti-Ni-Mo sols via the sol-gel process. The sol was prepared from Si(OEt)₄ (TEOS), Al(OBu^s)₃ (OBu^s: C₂H₅CH(CH₃)O), Ti(OEt)₄ (OEt: OCH₂CH₃), Zr(OPrⁿ)₄ (OPrⁿ: OCH₂CH₂CH₃). In both cases nickel nitrate hexahydrate (Ni(NO₃)₂ · 6H₂O) and ammonium heptamolybdate tetrahydrate ((NH₄)₆Mo₇O₂₄ · 4H₂O) were the Ni and Mo sources, respectively. The sols were characterized by Fourier Transform Infrared Spectroscopy (FTIR). Assignments of the simultaneous formation of the Si-O-Al, Si-O-Ti, Si-O-Ni, and Si-O-Zr bonds were done. The sols were polymerized at room temperature (293 K) to obtain gels, and these were dried at 423 K and calcined at 573, 853 and 893 K in air. The characterization techniques used were small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and ²⁹Si and ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR). The density of the solids was measured following ASTM method D-4892 and the porosity and surface area were determined by N₂ adsorption/desorption isotherms. The corresponding average pore diameters were evaluated using the BJH, HK, and DA methods.     

Luminescent properties of a novel afterglow phosphor Sr3Al2O5Cl2:Eu,Ce

A series of Eu²⁺ and Ce³⁺ doped/co-doped Sr₃Al₂O₅Cl₂ afterglow phosphors that presented various bright colors were successfully synthesized via high temperature solid state reaction. The structure and luminescence properties of the obtained samples were characterized by X-ray powder diffraction (XRD), photoluminescence (PL) spectra and decay curves as well as the thermoluminescence (TL) glow curves. The XRD results showed that all the phase could be indexed to the orthorhombic structure with the space group P2₁2₁2₁. After being exposed to a 254 nm or 365 nm mercury lamp, blue/yellow-orange afterglow emissions with broad bands peaking around 620 nm/435 nm, which were ascribed to the characteristic 4f⁶5d–4f⁷/5d¹–4f¹ transitions of Eu²⁺/Ce³⁺, could be observed in phosphors of Sr₃Al₂O₅Cl₂:Eu²⁺/Sr₃Al₂O₅Cl₂:Ce³⁺, respectively. Because of the overlap spectral range between the Sr₃Al₂O₅Cl₂:Eu²⁺ and Sr₃Al₂O₅Cl₂:Ce³⁺ phosphors, the energy transfer (ET) from Ce³⁺ to Eu²⁺ occurred. The related ET process was discussed in detail. Moreover, the incorporation of Ce³⁺ could significantly prolong the afterglow duration of Sr₃Al₂O₅Cl₂:Eu²⁺ phosphor, which was due to the increase of trap concentration. Consequently, 6 h of the afterglow duration could be observed in Sr₃Al₂O₅Cl₂:1.0%Eu²⁺, 0.5%Ce³⁺ sample, exhibiting much longer than that of Sr₃Al₂O₅Cl₂: 1.0%Eu²⁺ (3 h). From the afterglow decay curves and the fitting results, the optimal concentration of Ce³⁺ for the enhanced afterglow property was experimentally determined to be 0.5%.