Development of tetraethylene pentamine functionalized multi-wall carbon nanotubes as a new adsorbent in a syringe system for removal of bisphenol A by using multivariate optimization techniques

A simple portable solid phase microextraction (P-SPME) has been developed for Bisphenol A in a syringe system for different environmental water samples by using UV–Vis spectrophotometric determination. In this work, tetra ethylene pentamine functionalized was immobilized on the surface of multi-wall carbon nanotubes. Their surface morphology has been characterized by Fourier-transform infrared spectroscopy and Scanning electron microscope techniques. In order to study the sorption behavior for Bisphenol A, the Langmuir, and Freundlich isotherm models were studied in the batch and proposed method. The monolayer adsorption capacity of the tetra ethylene pentamine functionalized was immobilized on the surface of multi-wall carbon nanotubes for bisphenol A was determined to be 45.5 mg/g at pH 6.5, 30 °C and 40 min. The R ² and R _L values show that the reaction follows pseudo-second-order kinetic is naturally favorable. The K _f and 1/n values indicate that the adsorbent of bisphenol A on their surface is chemically. The positive value of ∆H° indicates that reaction was endothermic, whereas value of ∆S°, showing an increase in randomness at the solid solution interface during the BPA adsorption. The centroid simplex mixture design was used to optimized the elution solvent (methanol, acetone and acetonitrile) and central composite design was applied for optimize the process variables (pH, final amount of multi-wall carbon nanotubes and adsorption/desorption cycle) after mixture optimization. The proposed method provides a linear response for Bisphenol A over the concentration range 10–100 μg L ⁻¹ with correlation coefficients (r) ≥ 0.9986 and their limit of detection is 0.45 μg L ⁻¹ . The precision of the method was obtained to be 4.5%. Validity of the method was verified by spiking addition method. The optimized method was successfully applied to different water samples.