Zhi-Liang Wu

Soluble starch functionalized graphene oxide as an efficient adsorbent for aqueous removal of Cd(II): The adsorption thermodynamic, kinetics and isotherms

Soluble starch-functionalized graphene oxide composite (GO-starch) was prepared by a facile esterification reaction. And the composite was used as a novel adsorbent for the removal of Cd(II) from aqueous solution. The chemical composition and morphology of the GO-starch was investigated by fourier transform infrared spectroscopy, scanning electron microscopy and Raman spectroscopy. To evaluate the effects of the adsorption of Cd(II) by GO-starch, batch adsorption studies were performed to optimize the major parameters such as contact time, pH, initial concentration and temperature. The maximum uptake capacity of Cd(II) was 43.20 mg/g under the optimal conditions. Furthermore, the adsorption kinetics, isotherms and thermodynamics of Cd(II) on GO-starch were also investigated. The experimental data indicated that the adsorption kinetics and adsorption isotherms of Cd(II) on GO-starch were well fitted by pseudo-second-order kinetic model and Langmuir isotherm model, respectively. The adsorption thermodynamic parameters were calculated as ΔG0 < 0, ΔH0 > 0 and ΔS0 > 0, respectively. The thermodynamic parameters indicated that the adsorption process was endothermic, feasible and spontaneous. Due to its high adsorption capacity for Cd(II), the GO-starch might have considerable potential for the aqueous removal of metal ions.Graphical AbstractSoluble starch-functionalized graphene oxide composite (GO-starch) was prepared and used as a novel adsorbent for the aqueous removal of Cd(II). The chemical composition and morphology of the GO-starch was characterized by fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and Raman spectroscopy. Batch adsorption experiments were performed to optimize the major parameters such as contact time, pH, initial concentration and temperature. The maximum uptake capacity of Cd(II) was 43.20 mg/g under the optimal conditions. The adsorption kinetics and adsorption isotherms were well fitted by pseudo-second-order kinetic model and Langmuir isotherm model, respectively. The adsorption thermodynamic parameters were ΔG0 < 0, ΔH0 > 0 and ΔS0 > 0, indicating that the Cd(II) adsorption process was spontaneous, endothermic and feasible.

Preconcentration and analysis of Rhodamine B in water and red wine samples by using magnesium hydroxide/carbon nanotube composites as a solid‐phase extractant

A convenient and accurate analysis approach that combined solid-phase extraction and high-performance liquid chromatography was developed to determine the amount of Rhodamine B in red wine and Xiang-jiang river water samples. A novel composite, magnesium hydroxide/carbon nanotube composites, was synthesized and used as the solid-phase extractant for the preconcentration/analysis of Rhodamine B. Magnesium hydroxide/carbon nanotube composites, which combined the merits of carbon nanotubes and magnesium hydroxide, exhibited acceptable adsorption and desorption efficiencies for Rhodamine B. The linear range of the proposed solid-phase extraction with high-performance liquid chromatography method for Rhodamine B was 0.05-20.0 mg/L, with a limit of detection of 3.6 μg/L. The precision and reproducibility of the developed solid-phase extraction with high-performance liquid chromatography method and the batch-to-batch reproducibility of the solid-phase extractant were also validated at spiking levels of 0.5 and 2.0 mg/L. The recovery of Rhodamine B was 94.33-106.7%, and the recovery relative standard deviations of the intra- and interday precisions were ≤ 3.83 and ≤ 6.01%, respectively. The relative standard deviation of the batch-to-batch reproducibility was ≤ 7.98%.

One-step separation of nine structural analogues from Poria cocos (Schw.) Wolf. via tandem high-speed counter-current chromatography

A novel one-step separation strategy-tandem high-speed counter-current chromatography (HSCCC) was developed with a six-port valve serving as the switch interface. Nine structural analogues including three isomers were successfully isolated from Poria cocos (Schw.) Wolf. by one step. Compared with conventional HSCCC, peak resolution of target compounds was effectively improved in tandem one. Purities of isolated compounds were all over 90% as determined by HPLC. Their structures were then identified via UV, MS and (1)H NMR, and eventually assigned as poricoic acid B (1), poricoic acid A (2), 3β,16α-dihydroxylanosta-7, 9(11), 24-trien-21-oic acid (3), dehydrotumulosic acid (4), polyporenic acid C (5), 3-epi-dehydrotumulosic acid (6), 3-o-acetyl-16α-hydroxydehydrotrametenolic acid (7), dehydropachymic acid (8) and dehydrotrametenolic acid (9) respectively. The results indicated that tandem HSCCC can effectively improve peak resolution of target compounds, and can be a good candidate for HSCCC separation of structural analogues.