LAUSR

Abstract A novel synthesized N-methyl pyrrolidinium-based Polymeric Ionic Liquid (PIL) was examined as adsorbent for the removal of the widely used in industries anionic dyes, Orange G (OG), Orange II (OII) and Sunset Yellow FCF (SY), from wastewater. The synthesis of the adsorbent was performed in 3 steps involving a free radical polymerization, an N-quaternization reaction and an ion exchange reaction. The final PIL and the precursor copolymers were characterized through 1HNMR, 19FNMR, TGA analysis and their molecular weights were determined by GPC chromatography. The adsorbent was characterized by Attenuated total reflection Fourier transform infrared (ATR-FTIR), N2 Adsorption, SEM, and XRD in order to explore the adsorption mechanisms. The ATR-FTIR spectroscopy acted as a key-role player for the chemical characterization of the adsorbent, but most importantly for investigating the nature of the adsorbent/dye interactions; interesting aspects concerning the adsorption mechanism for each dye were extracted. The effect of several experimental parameters such as pH, adsorbent dose, contact time and initial dye concentration were examined. The ranking of adsorption capacity concerning the three dyes was SY > OII > OG, over the whole concentration range (Cdye = 10–100 mg/L). The adsorption in all cases (OG, OII, SY) could be described smoothly by both Freundlich and Langmuir isotherms with the first being more effective for OG and the latter for OII and SY. The maximum monolayer adsorption capacities were equal to 198.4, 279.3 and 316.5 mg/g for OG, OII and SY, respectively. The adsorption kinetics were better described using a pseudo-second-order model indicating that the prevailing adsorption mechanism was chemisorption.