Separation and Recovery of 4-Hydroxybenzoic Acid Using Molecular Imprinting Technique from Dilute Solution

Abstract

Fruits and vegetable waste (FVW) have been reported to have micronutrient and bioactive compound like polyphenol albeit in very small quantity (μg g⁻¹). The challenge of selective separation and recovery of one of the polyphenols from dilute solution is addressed in the present work using molecular imprinting technique, which uses molecularly imprinted polymers (MIPs). This study focuses on the extraction of a high value bioactive compound [P-Hydroxybenzoic acid (PHBA)] which is present in FVW. Chitosan-based PHBA imprinted polymer was synthesized using PHBA as template and TEOS as cross-linker to achieve the above goal. MIP was characterized using SEM, EDAX and FTIR. Batch adsorption studies were conducted to optimize the adsorbent dose, initial concentration, and contact time. Two-parameter isotherm models namely Langmuir, Freundlich, Temkin and Dubinin–Radushkevich and three-parameter isotherm model Sips was used to analyze the experimental data. The equilibrium data fitted best into Langmuir isotherms model with capacity of 74.56 mg g ⁻¹ and followed pseudo-second-order kinetic model. The reusability confirmed that MIP retained its adsorption capacity up to 6 cycles.