Selective extraction of nitroaromatic compounds: Uni- vs multi-templated molecularly imprinted polymers

Nitroaromatic compounds (NACs) such as 2-nitrotoluene (2-NT) and 2,6-dinitrotoluene (2,6-DNT), are significant environmental pollutants requiring efficient and selective extraction methods for monitoring and remediation. This study details the synthesis and characterization of multi-template molecularly imprinted polymer (MIP) for the simultaneous removal of 2-NT and 2,6-DNT. FTIR analysis confirmed the successful polymerization and verified the incorporation of the templates within the polymer matrix, as well as their subsequent removal after washing. BET analysis revealed a mesoporous structure for the polymers, evidenced by a Type IV isotherm. Crucially, the washed multi-template MIP demonstrated a superior surface area of 43.5 m² g^-1, significantly higher than both the uni-template MIP (31.3 m² g^-1) and the non-imprinted polymer (NIP) control (17.0 m² g^-1). The performance of the MIPs was optimized through batch adsorption experiments. Optimal conditions were determined to be sample pH of 3, which maximized binding interactions, and an adsorbent mass of 15 mg, which yielded the highest imprinting factor of 2.14. Kinetic studies identified an optimal contact time of 30 min, offering an excellent balance of rapid uptake and efficiency by achieving over 91% of the total equilibrium adsorption capacity. Furthermore, adsorption isotherm experiments confirmed that the maximum adsorption capacity (up to 292 μg g^-1) was achieved at an initial concentration of 2 mg L^-1. These results demonstrate the highly efficient and practical applicability of the synthesized multi-template MIP.