Electrochemical techniques are the most reliable techniques for determination of neurotransmitters and selective determination is their most challenging issue. Herein we have optimized the condition for oxidation of adrenaline and noradrenaline, as the most similar neurotransmitters, to find a simple and fast technique for their selective determination. Under mild acidic condition, oxidation of adrenaline is followed by a cyclization reaction and oxidation of the product (ECE mechanism) whereas noradrenaline undergoes just oxidation (E mechanism). The redox potential of the product of ECE mechanism has 350 mV difference with the product of E mechanism. This different in reactivity and redox potential yields two baseline separated reduction peaks for the oxidation products of adrenaline and noradrenaline, which used for their selective determination.
a b s t r ac tIn this study, the application of synthesized Fe 3 O 4 magnetic nanoparticles and 1-butyl-3-methylimidazolium tetrachloroferrate (bmim [FeCl 4 ]), as a magnetic ionic liquid, for removal of Acid Red 88 (AR88) from aqueous solution was investigated. At first, Fe 3 O 4 magnetic nanoparticles (MNPs) were synthesized via a chemical co-precipitation method with drop-wise addition of sodium hydroxide to an ideal mole ratio mixture of Fe 2+ and Fe 3+ solutions (Fe 2+ /Fe 3+ ), about 0.5, as well as under argon gas protection. X-ray diffraction and transmission electron microscopy were used to characterize the synthesized nanoparticles. The effect of important experimental parameters on the removal of Acid Red 88 such as pH of solution, contact time, temperature, ionic liquid and sorbent dosages was investigated. Also, Langmuir and Freundlich isotherm models were used for evaluation of the equilibrium adsorption. Acid dye adsorption equilibrium data were fitted well to the Langmuir isotherm and the maximum monolayer capacity q max was calculated from it as 909.1 mg g -1 . Thermodynamic studies indicated that the adsorption process was exothermic and spontaneous, and the adsorption mechanism was physisorption. On the other hand, a rapid sorption dynamics and quantitative removal of dye (≈95%) were observed under optimal conditions: 50 mL of 50 ppm dye solution at pH 3, 5 mg of ionic liquid, 10 mg of magnetic nanoparticles (MNPs), 2 min contact time at 10°C. Finally, this method was used for the removal of AR88 from real water samples of Chalus River. The obtained results indicated that Fe 3 O 4 MNP and magnetic ionic liquid (bmim [FeCl 4 ]) could be used as an efficient sorbent material for very simple and fast removal of acid dyes from aqueous solutions.
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