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The ultrasonic nebulization extraction (UNE) was developed and applied to extract anthraquinones (emodin, aloe-emodin and rhein) from Rheum palmatum L. Several parameters of UNE, including type of extraction solvent, concentration of extraction solvent, volume of extraction solvent, extraction time and ultrasonic power, were studied and the optimized parameters were selected. The operation conditions of micellar electrokinetic capillary chromatography (MEKC) were also studied. Under the selected conditions, contents of emodin, aloe-emodin and rhein obtained from different cultivated areas of R. palmatum L. were 1.08-2.04 mg/g, 0.65-1.16 mg/g and 0.70-2.90 mg/g, respectively. The relative standard deviations (RSDs) for emodin, aloe-emodin and rhein were 1.3-2.4%, 1.9-4.7% and 1.3-3.9%, respectively. Compared with maceration extraction (ME), reflux extraction (RE), stirring extraction (SE) and ultrasonic extraction (UE), the proposed method was more efficient, faster and easier to be operated and lower equipment costs and lower extraction temperature were required. The results indicated that UNE was a good alternative method for extracting anthraquinones from R. palmatum L. Compared with traditional extractions, the proposed extraction has a potential in on-line sampling, especially when the gas is used as the carrier of sample.

Graphene oxide (GO) was prepared and characterized by Fourier transform infrared spectrometry (FT-IR) and scanning electron micrographs (SEM). Batch adsorption studies were carried out to investigate the adsorption data, including the effects of pH, initial concentration, contact time, and temperature. The adsorption of Au(III), Pd(II), and Pt(IV) was optimum at pH 6.0. The adsorption isotherms all obeyed the Langmuir equation in the case of Au(III), Pd(II), and Pt(IV), and the maximum adsorption capacities were 108.342 mg•g −1 , 80.775 mg•g −1 , and 71.378 mg•g −1 , respectively. The adsorption kinetics of Au(III), Pd(II), and Pt(IV) onto GO followed a pseudosecond-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. Thermodynamic parameters such as Gibbs energy (ΔG o ), enthalpy (ΔH o ), and entropy (ΔS o ) were calculated, indicating that the adsorption were spontaneous, endothermic, and feasible. The desorption studies showed that the best desorption reagents were 0.5 mol•dm −3 thiourea−0.5 mol•dm −3 HCl for Au(III) and 1.0 mol•dm −3 thiourea−0.5 mol•dm −3 HCl for both Pd(II) and Pt(IV).

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3′-Nitro-4-amino azobenzene modified chitosan has been prepared and characterized by FT-IR. The adsorption data have been investigated including the effects of pH, initial concentration, and contact time by batch method. The adsorption of Pd(II) and Pt(IV) was best in the pH range of 4.0–6.0 for Pd(II) and at pH 3.0 for Pt(IV), where the maximum mass adsorption were (29.33 and 43.10) mg·g–1, respectively. The adsorption isotherms obeyed the Langmuir equation for the adsorption of Pd(II) and Pt(IV). The adsorption kinetic data were fitted with a pseudosecond-order model and an intraparticle diffusion model. The results indicated that the adsorption of Pd(II) and Pt(IV) followed a pseudosecond-order model. The adsorbent shows high affinity for Pd(II) and Pt(IV) in binary systems containing each noble metal ion and other base metal ions. The optimal desorption reagent was 0.20 mol·L–1 thiourea + 0.50 mol·L–1 HCl solution for both Pd(II) and Pt(IV). The method was successfully applied for the determination and separation of Pd(II) and Pt(IV) in ore samples.