Xueyan Liu

Adsorbing Properties of Magnetic Nanoparticles Mn-Ferrites on Removal of Congo Red from Aqueous Solution

In this study, the removal of Congo red (CR) from aqueous solution was investigated using magnetic nanoparticles Mn-ferrites (MnFe2O4). The results indicated that the removal percentages of CR could reach up to 99% within 10.0 minutes under pH 4–9. The formation of hydrogen bond was the main adsorption mechanism. Sorption kinetics data was found to follow the pseudo-second-order model. The overall rate process was mainly controlled by external mass transfer. The sorption behavior could be well interpreted by the Langmuir model with the maximum adsorption capacity of 41.99 mg g−1 at 298 K. Thermodynamic data indicated a spontaneous and endothermic process. GRAPHICAL ABSTRACT

Green sample clean-up based on magnetic multiwalled carbon nanotubes for the determination of lamivudine by high performance liquid chromatography

A simple, green and efficient method for the determination of trace lamivudine (LMV) based on magnetic solid-phase extraction (MSPE) coupled with high performance liquid chromatography (HPLC) was developed. Magnetic multiwalled carbon nanotubes (MMWCNTs) were prepared by assembling Ni nanoparticles onto multiwall carbon nanotubes (Ni/MWCNTs). Due to their excellent adsorption capability, the Ni/MWCNTs were used as adsorbents for magnetic solid-phase extraction (MSPE). Various parameters affecting the extraction efficiency such as the amount of adsorbent, the pH, ionic strength and desorption conditions were optimized. The extracted LMV was desorbed using ionic liquid (IL) “Green solvents” as substitutes of volatile organic solvents. Under optimized conditions, a limit of detection (LOD) of 0.14 ng mL−1 and enrichment factor (EF) of 292 were obtained. The calibration curves showed good linearity (r2 = 0.9978–0.9993) over the concentration ranges of 0.5–500 ng mL−1. The proposed method was applied to the analysis of river water and human urine samples, and the recoveries of analytes obtained were in the range of 97.6–103.0 and 93.4–102.2%, respectively. The relative standard deviations (RSD) were less than 5.93% (n = 5). The high efficiency of the method ensures its successful application in extraction of trace LMV from large volumes of environmental water and biological fluid samples.

Selective solid-phase extraction of trace thallium with nano-Al2O3 from environmental samples

A novel sorbent, nano-Al2O3 was employed for the separation and preconcentration of thallium from aqueous solution in batch equilibrium experiments. It was found that the adsorption percentage of thallium ions was close to 100% at pH 4.5, and the desorption by 1.0 mL of 0.25 M HCl reached 99%. The adsorption equilibrium was well described by the Langmuir isotherm model with maximum adsorption capacity of 5.78 mg/g (20 ± 0.1°C). The enrichment factor values of Tl(III) was 25 for 25 mL sample. Detection limit of thallium (3σ, n = 11) equal to 0.8 μg/mL and relative standard deviation (2.4%) were obtained. The method has been successfully applied to the determination of trace thallium in some environmental samples and the certified reference material polymetallic nodule (GBW07296) with satisfactory results.

Magnetic nano-sized cadmium ferrite as an efficient catalyst for the degradation of Congo red in the presence of microwave irradiation

A highly active nano-sized CdFe2O4 catalyst was prepared by a hydrothermal process and characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), BET specific surface area method, and vibrating sample magnetometer (VSM) at room temperature. Application of the microwave-induced catalytic degradation method in the abatement of Congo red (CR) using the magnetic catalyst was studied. The degradation ratio of CR with CdFe2O4 reached 94.4% with 10 min microwave irradiation (MW), proving CdFe2O4 to be an excellent microwave catalyst. The intermediate products from CR degradation were investigated by UV-Vis, HPLC and ion chromatography. The reaction kinetics, effects of different ion species (SO42−, NO3−, HCO3−, and CH3COO−), pH of the solution, dye initial concentration, dosage of catalyst, as well as degradation mechanism were comprehensively studied. Radical trapping studies and the fluorescence technique revealed the holes (h+) and hydroxyl radicals (˙OH) were involved as the main active species in the reaction. The band structure of CdFe2O4 was analyzed by UV-Vis diffuse reflectance spectroscopy and Mott–Schottky measurements. The mechanism of the degradation was discussed in detail. This work can provide an effective technology for dye wastewater treatment.

Separation of trace amounts of Ga and Ge in aqueous solution using nano-particles micro-column.

A simple and rapid analytical method for the separation of trace amounts of gallium and germanium from aqueous solution by solid-phase extraction with nano-particles was developed. It was found that only Ga(III) could be quantitatively retained on nano-SiO(2) in the pH range of 3-4 and 8-12 while Ge(IV) was not adsorbed, but both Ga(III) and Ge(IV) ions could be adsorbed quantitatively on nano-TiO(2) within the pH range of 4-11. These two ions adsorbed by nano-particles could be desorbed quantitatively. Effects of acidity, concentration of elution solution and interfering ions on the recovery of the analytes were systematically investigated. The sorption data could be well interpreted by the Langmuir model. Based on the Langmuir model equation, the monolayer adsorption capacity of nano-SiO(2)/nano-TiO(2) was calculated to be 4.26 mg g(-1)/19.68 mg g(-1) for Ga(III)/Ge(IV). Moreover, thermodynamic functions, the change of free energy (ΔG(0)), enthalpy (ΔH(0)) and entropy (ΔS(0)) of the adsorption reaction were estimated for each metal ion. Experimental data were also evaluated in terms of kinetic characteristics of adsorption and the adsorption process for both metal ions followed well pseudo-second-order kinetics. Finally, the proposed method was applied to the determination of trace Ga(III) and Ge(IV) in some water samples using loaded nano-particles columns, and it is found that the recoveries of Ga(III) and Ge(IV) were obtained to be in the range of 96.4-105.0%. And the method was validated with certified reference material (GBW07311, GBW 07406) and the values obtained for Ga(III) and Ge(IV) were in good agreement with the certified values.

Highly enhanced selectivity for the separation of rhenium and molybdenum using amino-functionalized magnetic Cu-ferrites

An effective method based on magnetic solid-phase extraction for the selective recovery of rhenium and molybdenum has been developed using diethylamine-functionalized magnetic CuFe2O4 (NH2@CuFe2O4) as adsorbents. Various experimental parameters that could affect the extraction efficiency had been investigated in detail. NH2@CuFe2O4 exhibited high adsorption ability and selectivity to

Comparative Studies of Removal of Methyl Green and Basic Fuchsin from Wastewater by a Novel Magnetic Nanoparticles Mg-Ferrites

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Fabrication of 3D Hierarchical Byttneria Aspera-Like Ni@Graphitic Carbon Yolk-Shell Microspheres as Bifunctional Catalysts for Ultraefficient Oxidation/Reduction of Organic Contaminants

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