Preparation, characterization and evaluation of a styrene-based molecularly imprinted polymer for capturing pyridine and pyrrole from crude oil

Abstract

The rapid increase in global energy demand met with fossil fuel exploration and use as an energy source has not been achieved without its impacts on human and environmental health. Consequently, the imposition of stricter measures on key pollution sources in the effort to reduce the emission of contaminants into the environment became necessary. In this work, a new molecularly imprinted polymer (MIP) targeting pyridine (pyd) and pyrrole (pyr) was synthesized using styrene as a functional monomer. MIP and the non-imprinted polymer (NIP) were characterized by infrared spectroscopy, x-ray spectroscopy, and scanning electron microscopy. The polymer had spongy surfaces and porous network structures. The effects of several factors, such as initial analyte concentration, contact time, and adsorbent dose on pyd and pyr removal efficiencies from crude oil were evaluated. Quantitative analyses indicated that the removal of pyd and pyr occurred at fast kinetics, with a removal efficiency of 15.12 and 15.33, respectively, after 10 min of adsorption time. Optimum adsorption for both analytes was however not reached until 420 min, indicating slow kinetics. The uptake of the analytes increased with a rise in concentration. The highest removal percentages were recorded at 99.9% and 99.7% for pyd and pyr respectively, at 0.06 mol dm−3 adsorbate concentration of the modeling organic media. Two adsorption isotherm models were applied to analyze the equilibrium data, obtaining the best description by the Freundlich isotherm model. The accuracy of the MIP materials was validated using Bonny crude oil from Nigeria. The results showed that the MIP was effective for the adsorption of pyd and pyr in both modeling organic media and real crude oil.