Synthesis and characterization of a bulk-polymerized molecularly imprinted polymer for selective bitch adsorption of acid yellow 76 dye from real water samples

Abstract In this study, a molecularly imprinted polymer (MIP) for the adsorption of Acid Yellow 76 dye (AY76) from wastewater was synthesized using methacrylic acid as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, and AIBN as the initiator via bulk polymerization, with methanol as the porogenic solvent. Non-imprinted polymer (NIP) was also prepared for comparison. MIP was characterized using FT-IR, SEM, and surface area analysis. Adsorption parameters such as time, pH, dye concentration, and MIP/NIP doses were optimized, with maximum adsorption at pH 3 (94 % for MIP, 30 % for NIP). Adsorption followed pseudo-second-order kinetics with k2 values of 0.00538, 0.00523, and 0.00832 mg/g min at 283 K, 298 K, and 313 K, respectively. Langmuir isotherms showed Qm values of 175.439, 185.185, and 204.081 mg/g at the same temperatures, which is significantly greater than Qm of similar dye Acid Yellow 119 adsorption on activated carbon made from lemon wood and Zinc oxide (ZnO) nanoparticles activated with carbon (85.51 and 116.29 respectively). The distribution coefficient (Kd) and imprinting factor (IF) are 1.24 L/g and 2.968, which are slightly greater than for the MIP of Acid Violet 19 (0.116 L/g and 2.89 respectively). Thermodynamic studies indicated the adsorption was endothermic and spontaneous, with recoveries of 85–96 %. MIP showed excellent selectivity for AY76 with selectivity factors of 3.24, 4.48 and 11.19 against the Acid Yellow 17, Acid black 234 and Safranin respectively, and maximum adsorption capacity of 204.08 mg/g at 313 K for AY76.