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Preparation of voltammetric biosensor for tryptophan using multi-walled carbon nanotubes
Majid Kia,Akbar Islamnezhad,Shahab Shariati,Pouria Biparva 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.10
Multi-walled carbon nanotubes (MWCNTs) were grown by chemical vapor deposition. The effect of the composition of carbon paste electrode on its voltammograms was evaluated in basic solution with 5.0×10^(−5) M tryptophan (Trp). It was found that addition of MWCNTs to the carbon paste would generate the peak current of Trp because of its catalytic effect on the redox process. The pH strongly affects the peak potential of Trp. The best analytical response was obtained at pH 13.0. The anodic peak currents were proportional to Trp concentrations in the range of 1.0×10−9-1.0×10^(-4) M under the optimized experimental conditions. The detection limit was 2.2×10^(−10 ) M. The effect of potential scan rate on the peak potential and peak current of tryptophan was investigated. The correlation of the peak currents against v^(1/2) (v is the scan rate) is linear, which is very similar to a diffusion-controlled process. The proposed biosensor was applied to the determination of Trp in pharmaceuticals formulations successfully.
Mona Ehyaee,Fariba Safa,Shahab Shariati 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.4
Magnetic nanocomposite of multi-walled carbon nanotube (m-MWCNT) was synthesized for adsorptive removal of methyl violet (MV) from aqueous solutions. The experiments were conducted using a central composite design (CCD) with the variables of adsorbent dosage (0.4-1.2 g/L), solution pH (3-9), contact time (10-42 min) and ionic strength (0.02-0.1mol L−1). Regression analysis showed good fit of the experimental data to a quadratic response surface model whose statistical significance was verified by analysis of variance. By applying the desirability functions, optimum conditions of the process were predicted as adsorbent dosage of 0.99g/L, pH=4.92, contact time of 40.98 minutes and ionic strength of 0.04 mol L−1 to achieve MV removal percentage of 101.19. Experimental removal efficiency of 99.51% indicated that CCD along with the desirability functions can be effectively applied for optimizing MV removal by m-MWCNT. Based on the study, the adsorption process followed Langmuir isotherm model and pseudo-second-order kinetic model could realistically describe the dye adsorption onto m-MWCNT.