Cumulative effect of hydrophobic PLMA and surface epoxide groups in composite polymer particles on adsorption behavior of congo red and direct red-75

Abstract

Industrial application of hydrophobic materials is numerous particularly as adsorption beads to remove organic pollutants. In this research combined effect of hydrophobicity and reactive epoxide group on the adsorption behavior of dye molecules by composite polymer particles was investigated. Lauryl methacrylate (LMA) a poor water soluble long chain vinyl monomer is commercially available. Polystyrene/poly(LMA-divinyl benzene) or PS/P(LMA-DVB) composite seed particles were first prepared by slightly modified activated swelling of micron-sized PS seed particles utilizing either water or water-ethanol dispersion medium. The influence of poly(vinyl alcohol) (PVA) as steric stabilizer on the size and size distribution was evaluated. The poor solubility of LMA in the continuous phase hindered the homogeneous swelling of PS particles even in the presence of ethanol (5% w/w) and resulted in fairly polydispersed PS/P(LMA-DVB) composite seed particles. The composite seed particles were then functionalized with epoxide group by seeded polymerization of glycidyl methacrylate (GMA) to produce PS/P(LMA-DVB)/PGMA composite polymer particles. The epoxide functionalized PS/P(LMA-DVB)/PGMA composite polymer particles were used to adsorb two kinds of azo dyes, congo red (CR) and direct red-75 (DR-75). The effects of initial dye concentration at 303 and 323K on adsorption behavior were investigated and the adsorption was explained by adsorption isotherms. Temperature dependent adsorption measurements were also carried out at identical initial dye concentration. The adsorption results showed that inclusion of reactive epoxide group on/near the surface of hydrophobic PS/P(LMA-DVB) composite seed particles improved the adsorption capacity of dye molecules.