β-FeOOH-loaded Juncus effusus as a heterogeneous persulfate activator for rhodamine B degradation

Abstract

Root ion film widely existed on hydrophyte rhizosphere, being potential to enhance pollutant removal. In the present study, β-FeOOH-loaded Juncus effusus composite (β-FeOOH-JE) was synthesized by rapidly introducing Fe²⁺ into the three-dimensional structure of JE and then underwent a in-situ slow oxidation. The obtained β-FeOOH-JE had a macro-size and three-dimensional open-cell structure, and the ion film covering on the surface of JE fibers consisted of amorphous akaganeite. Meanwhile, the characteristic adsorption peaks of β-FeOOH were clearly observed in the FTIR sepectrum of β-FeOOH-JE. Compared with the PDS (39.62%), JE/PDS (43.36%) and β-FeOOH-JE/PDS (28.38%) systems, the β-FeOOH-JE/PDS system achieved a higher removal rate (98.53%) of Rhodamine B (Rh B) at 60 min. Acidic conditions favoured for the Rh B degradation. The process conformed to the pseudo-second-order kinetic model (R² > 0.99), implying a heterogeneous chemical reaction. Compared with NO₃⁻ and SO₄²⁻, the coexisting Cl⁻ showed a stronger negative impact. Active radical species including ·SO₄⁻ and ·OH were determined in the developed system, and the ·OH was dominant. The activation of PDS was involved in a heterogeneous reaction, and no new benzene compounds were generated during the phenol degradation. More importantly, the toxicity of Rh B showed a significant decrease after the treatment with the β-FeOOH-JE/PDS system. In view of the efficient, economical and environment-friendly advantages, the prepared β-FeOOH-JE has the potential to activate PDS for the treatment of organic wastewater.