Development of polystyrene coated persulfate slow-release beads for the oxidation of targeted PAHs: Effects of sulfate and chloride ions

Abstract

In this study, we synthesized polystyrene coated persulfate polyacrylonitrile beads (PC-PSPANBs) to control persulfate (PS) release for targeted PAHs' degradation in a batch reactor. Initially, the persulfate release rate (k_sr = 20.553 h^-1) from PSPANBs was fast, but coating the PSPANBs with polystyrene controlled PS release rate (k_sr= 2.841 h^-1), nearly ten times slower than without coating. When Fe(II) activated PC-PSPANBs applied for 12 h degradation of acenaphthene (ACE), 2-methlynaphthalene (2-MN) and dibenzofuran (DBF), the optimum percent removal efficiencies (% R.Es) were as ACE (82.12%) > DBF (68.57%) > 2-MN (58.80%) and the optimum degradation rate constants (k_obs) were found as ACE (11.348 h^-1) > 2-MN (3.441 h^-1) > DBF (1.101 h^-1). The effect of SO₄^2- and Cl^- on ACE degradation showed that % R.E and k_obs were enhanced with increasing anionic concentrations. The maximum % R.E was achieved for SO₄^2- (76.24%) > Cl^- (65.51%), but the highest k_obs was in case of Cl^- (1.536 h^-1) > SO₄^2- (0.510 h^-1). The effectiveness of PS release longevity was also found because net degradations of ACE and DBF after first spiking were 12 mg L^-1 and 16 mg L^-1, while after second spiking were 18 mg L^-1 and 10 mg L^-1, respectively.

Keywords: Chloride ion; Ferrous; PAHs; Persulfate slow-release beads; Sulfate ion.