Selective adsorption of 2,4-dinitrophenol on molecularly imprinted nanocomposites of mesoporous silica SBA-15/polyaniline

Abstract

Surface imprinting and adoption of a nano-sized physical form are two effective approaches to overcome the template transfer difficulty within molecularly imprinted polymers (MIPs). This work is an attempt to conquer the problem of template transfer difficulty within MIPs by using a nano-reactor as a substrate for the reaction between the monomer and the template. Negatively charged hexagonal nano-channels of SBA-15 can act as a support for attachment of positively charged aniline monomers and the 2,4-dinitrophenol (2,4-DNP) template. The imprinted and non-imprinted SBA-15/polyaniline nanocomposites were characterized by Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and nitrogen adsorption–desorption isotherms. The results showed that the synthesized polymer possessed a highly ordered mesoporous structure. The distribution coefficient values of 2,4-DNP, K_{d (2,4-DNP)}, were estimated as 301.4 ± 2.3 and 101.2 ± 1.0 mL g⁻¹ for imprinted and non-imprinted polymers (NIP), respectively. The MIP–solid-phase extraction (SPE) process was optimized by evaluating the type of washing solvent and the composition and volume of the eluting solvent. The prepared MIP was used as a selective sorbent for SPE of 2,4-DNP in the presence of phenolic compounds in tap and sea water. The experimental results indicated that the MIP-SPE and NIP-SPE column yielded recoveries higher than 96% and 38%, respectively. The R.S.D. values were also lower than 3.2% and 4.6% for MIP-SPE and NIP-SPE, respectively.