Synthesis and characterization of L-tryptophan containing microbeads for removal of dimethyl phthalate from aqueous phase

Abstract

Poly(ethylene glycol dimethacrylate-N-methacryloyl-L-tryptophan methyl ester) [poly(EGDMA-MATrp)] beads (average diameter = 106-300 mu m) were synthesized by copolymerizing of N-methacryloyk-L-typtophan methyl ester (MATrp) with ethylene glycol dimethacrylate (EGDMA). The usability of newly synthesized material for the removal of dimethyl phthalate (DMP) from aqueous phase was investigated. The poly (EGDMA-MATrp) beads were characterized by N-2 adsorption/desorption isotherms (BET), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and swelling studies. Initial concentration, pH, contact time and temperature effects on the adsorption of DMP from aqueous solutions were analyzed. An optimum adsorption capacity of 237.3 mg g(-1), for DMP was obtained at 25 degrees C. The present adsorption process obeyed pseudo-second-order kinetic model. All the isotherm data can be fitted with both the Langmuir, and the Dubinin-Radushkevich isotherm models with high correlation coefficients. Thermodynamic parameters Delta N = 2.398 kJ mol(-1), Delta S = 65.76 J K-1 mol(-1), and Delta G = 17.20 kJ mol(-1) to -18.57 kJ mol(-1) with the rise in temperature from 25 degrees C to 45 degrees C indicated the adsorption process was endothermic and spontaneous. The DMP adsorption capacity did not change after 10 batch successive reactions, demonstrating the usefulness of the beads in applications.