-
[show abstract]
[hide abstract]
ABSTRACT: A simple and highly sensitive method for the electrochemical determination of olaquindox (OLA) was developed, which was carried out on the multi-walled carbon nanotubes (MWCNT) modified glassy carbon electrode (MWCNT/GCE) using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results showed that MWCNT remarkably enhanced the reduction of OLA, which improved the cathodic peak current of OLA significantly. Under the optimum condition, the linear range for the calibration curve was 0.3-18.0μgmL(-1) with a detection limit of 0.26μgmL(-1). The MWCNT/GCE showed a well reproducibility and the relative standard deviation (R.S.D.) was 3.5% (n=9). And a great anti-interference ability of the MWCNT/GCE was also observed. Finally, the MWCNT/GCE was satisfactorily employed to analyze some synthetic and real water samples.
Talanta 05/2013; 109:185-90. · 3.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The removal of bisphenol AP (BPAP) by multi-walled carbon nanotube (MWCNT) was investigated. BPAP, representing typical scenarios for the BPAP-MWCNT interactions, was employed as probe molecule. It was found that BPAP exhibited a great adsorptive affinity to MWCNT, and the adsorption kinetics equilibrium was arrived within 4.0 min following the pseudo-second-order model. The overall rate process was mainly controlled by the external mass transfer. The hydrogen bonds, hydrophobic and π-π stacking interactions were dominant factors to for the strong adsorption of BPAP instead of the pH ionic strength and other ionic species in contaminated water. The MWCNT have higher stability within eight removal-regeneration recycles and up to 95% of recovery could be obtained by eluting the adsorbed BPAP on MWCNT adsorbent using ethanol/sodium hydrate solution. The results of the experiment on real samples verified the effectiveness for the recovery and removal of BPAP from wastewater samples.
Langmuir 02/2013; · 4.19 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Nano-TiO2 was employed for the adsorption of gallium from aqueous solution in batch equilibrium experiments to investigate its adsorption
properties. It was found that the adsorption efficiency of Ga(III) was more than 96% at pH 3.0. The adsorption capacities
and rates of Ga(III) onto nano-TiO2 were evaluated as a function of solution concentration and temperature. The results were analyzed using the Langmuir adsorption
isotherms. Adsorption isothermal data could be well interpreted by the Langmuir model. The mean energy of adsorption, 15.81
kJ·mol−1, was calculated from the D-R adsorption isotherm. The kinetic experimental data properly correlate with the pseudo-second-order
kinetic model. The thermodynamic parameters for the process of adsorption have been estimated. The ΔH
Ɵ and ΔG
Ɵ values of gallium(III) adsorption on nano-TiO2 showed an endothermic and spontaneous nature of adsorption.
Rare Metals 04/2012; 29(1):16-20. · 0.59 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The interaction between olaquindox (OLA) and bovine serum albumin (BSA) was investigated using fluorescence, UV-vis absorption and circular dichroism (CD) spectroscopy. The results showed that the fluorescence quenching of BSA by OLA was a static quenching process induced by the formation of OLA-BSA complex. The binding constant of OLA-BSA complex was calculated to be 1.299 × 10(4)L mol(-1) (293K). The negative values of ΔH(0) and ΔS(0) indicated that hydrogen bond and van der Waals interactions played major roles in stabilizing the complex. Site probe competition experiments and number of binding sites (n) revealed that OLA could bind to site I in subdomain IIA of BSA, and the binding distance (r) was evaluated to be 3.643 nm according to Förster's non-radiative energy transfer theory. The results of CD and three-dimensional fluorescence spectra suggested some conformational changes of BSA after OLA binding.
Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association 04/2012; 50(7):2540-6. · 2.99 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Multi-walled carbon nanotubes (MWCNT) were employed for the sorption of olaquindox (OLA) from aqueous solution. A detailed study of the adsorption process was performed by varying pH, ionic strength, sorbent amount, sorption time and temperature. The adsorption mechanism is probably the non-electrostatic π-π dispersion interaction and hydrophobic interaction between OLA and MWCNT. The adsorption efficiency could reach 99.7%, suggesting that MWCNT is excellent adsorbents for effective OLA removal from water. OLA adsorption kinetics were found to be very fast and equilibrium was reached within 2.0 min following the pseudo-second-order model with observed rate constants (k) of 0.169-1.048 g mg(-1)min(-1) (at varied temperatures). The overall rate process appeared to be influenced by both external mass transfer and intraparticle diffusion, but mainly governed by intraparticle diffusion. A rapid initial adsorption behavior occurred within a short period of time in this adsorption system. The sorption data could be well interpreted by the Langmuir model with the maximum adsorption capacity of 133.156 mg g(-1) (293 K) of OLA on MWCNT. The mean energy of adsorption was calculated to be 0.124 kJ mol(-1) (293 K) from the Dubinin-Radushkevich adsorption isotherm. Moreover, the thermodynamic parameters showed the spontaneous, exothermic and physical nature of the adsorption process.
Journal of hazardous materials 12/2011; 197:389-96. · 4.14 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: 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.
Talanta 10/2011; 85(5):2463-9. · 3.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Florisil was employed for the sorption of antimony ions from aqueous solutions. A detailed study of the process was performed by varying the sorption time, pH, and temperature. The sorption was found to be fast, equilibrium was reached within 15 min. Moreover, a maximum sorption has been achieved from solution when the pH ranges between 1-10. From kinetic experiments it follows that the process correlate with the second-order kinetic model. The overall rate process appears to be influenced by both boundary layer diffusion and intra-particle diffusion. The Langmuir and Dubinin-Radushkevich (D-R) type sorption isotherms can be applied to fit and interpret the sorption data. The mean energy of adsorption (9.73 kJ mol(-1)) was calculated from the Dubinin-Radushkevich (D-R) adsorption isotherm at room temperature. Furthermore, the thermodynamic parameters for the sorption were also determined, and the deltaH0 and deltaG0 values indicate a spontaneous endothermic behavior.
Water Science & Technology 01/2011; 63(10):2114-22. · 1.12 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Titanium dioxide nanoparticles (nano-TiO(2)) were employed for the sorption of Te(IV) ions from aqueous solution. A detailed study of the process was performed by varying the sorption time, pH, and temperature. The sorption was found to be fast, equilibrium was reached within 8 min. When the concentration of Te(IV) was below 40 mg L(-1), at least 97% of tellurium was adsorbed by nano-TiO(2) in the pH range of 1-2 and 8-9. The sorbed Te(IV) ions were desorbed with 2.0 mL of 0.5 mol L(-1) NaOH. The sorption data could be well interpreted by the Langmuir model with the maximum adsorption capacity of 32.75 mg g(-1) (20 ± 0.1 °C) of Te(IV) on nano-TiO(2). The kinetics and thermodynamics of the sorption of Te(IV) onto nano-TiO(2) were also studied. The kinetic experimental data properly correlated with the second-order kinetic model (k(2)=0.0368 g mg(-1)min(-1), 293 K). The overall rate process appeared to be influenced by both boundary layer diffusion and intra-particle diffusion. The mean energy of adsorption was calculated to be 17.41 kJ mol(-1) from the Dubinin-Radushkevich (D-R) adsorption isotherm at room temperature. Moreover, the thermodynamic parameters for the sorption were estimated, and the ΔH(0) and ΔG(0) values indicated the exothermic and spontaneous nature of the sorption process, respectively. Finally, Nano-TiO(2) as sorbent was successfully applied to the separation of Te(IV) from the environmental samples with satisfactory results (recoveries >95%, relative standard deviations was 2.0%).
Talanta 12/2010; 83(2):344-50. · 3.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Titanium dioxide nanoparticles were employed for the sorption of selenium ions from aqueous solution. The process was studied in detail by varying the sorption time, pH, and temperature. The sorption was found to be fast, and to reach equilibrium basically within 5.0 min. The sorption has been optimized with respect to the pH, maximum sorption has been achieved from solution of pH 2-6. Sorbed Se(IV) and Se(VI) were desorbed with 2.0 mL 0.1 mol L(-1) NaOH. The kinetics and thermodynamics of the sorption of Se(IV) onto nano-TiO2 have been studied. The kinetic experimental data properly correlate with the second-order kinetic model (k(2)=0.69 g mg(-1) min(-1), 293 K). The overall rate process appears to be influenced by both boundary layer diffusion and intraparticle diffusion. The sorption data could be well interpreted by the Langmuir sorption isotherm. The mean energy of adsorption (14.46 kJ mol(-1)) was calculated from the Dubinin-Radushkevich (D-R) adsorption isotherm at room temperature. The thermodynamic parameters for the sorption were also determined, and the DeltaH(0) and DeltaG(0) values indicate exothermic behavior.
Journal of hazardous materials 06/2009; 170(2-3):1197-203. · 4.14 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Titanium dioxide nanoparticles (NPs) were employed for the sorption of Tl(III) ions from aqueous solution. The process was
studied in detail by varying the sorption time, pH, Tl(III) concentration, temperature, and amount of sorbent. The sorption
was found to be fast and to reach equilibrium within 2min, to be less efficient at low pH values, and to increase with pH
and temperature. The sorption fits the Langmuir equation and follows a pseudo second order model. The mean energy of the sorption
is approximately 15kJ mol−1 as calculated from the Dubinin–Radushkevich isotherm. The thermodynamic parameters for the sorption were also determined,
and the ΔH
0 and ΔG
0 values indicate endothermic behavior.
Microchimica Acta 01/2009; 165(1):73-78. · 3.03 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A novel sorbent, nano-Al(2)O(3) was employed for the removal of thallium from aqueous solution in batch equilibrium experiments, in order to investigate its adsorption properties. The removal percentage of thallium by the sorbent increased with increasing pH from 1 to 5. The adsorption capacities and removal percentage of Tl(III) onto nano-Al(2)O(3) were evaluated as a function of the solution concentration and temperature. Results have been analyzed by the Langmuir, Freundlich adsorption isotherms. Adsorption isothermal data could be well interpreted by the Langmuir model. The mean energy of adsorption 9.32 kJ mol(-1) was calculated from the Dubinin-Radushkevich (D-R) adsorption isotherm. The kinetic experimental data properly correlated with the second-order kinetic model. The thermodynamic parameters for the process of adsorption have been estimated. The DeltaH(0) and DeltaG(0) values of thallium(III) adsorption on nano-Al(2)O(3) showed endothermic adsorption.
Journal of Hazardous Materials 10/2008; 157(2-3):352-7. · 4.17 Impact Factor
