Heterogeneous activation of permonosulfate by biochar supporting CuCoFe layered double hydroxide for rapid degradation of phenanthrene

In this study, a ternary layered double hydroxide (CuCoFe-LDH) coated on corn straw-based biochar (BC@LDH) was synthesized and characterized using various approaches. Application in heterogeneous activation of permonosulfate (PMS) for the degradation of phenanthrene (PHE) suggested that the higher Co content in the material, the higher the catalytic activity, maximum of which was 96.5% reached at catalytic dosage of 0.2 g/L, PMS concentration of 2.0 mmol/L, pH 7 and temperature of 45 ℃ within 15 min in BC1 @LDH1 (BC to mass ratio of 1:1)/PMS system. Improved PHE degradation and wide pH application range supported that BC not only acted as CuCoFe-LDH carrier, but also probably participated in the activation of PMS due to abundant functional groups, like hydroxyl as FT-IR revealed. Co-existing ions (NO3-, CO32-) and humic acid (HA), but not Cl-, significantly inhibited PHE degradation. Moreover,the removal of PHE was mainly attributed to SO4·- and ·OH, while O2·− and 1O2 contributed less. It was proposed that Cu (I), Co (II) and Fe (II) were responsible for the PMS activation and produced Co (III) can be reduced by HSO5- and Fe (II) to achieve Cu (I)/Co (III) cycle, thereby maintaining high catalytic activity and structural stability of BC1 @LDH1. Remarkably, Consecutive runs (>80.0% PHE removal after 4 cycles) and low level of leaching metal concentration (0.053 mg/L of Co and 0.077 mg/L of Cu at pH 7) all implied that BC1 @LDH1 possesses much greater potential in activating PMS for practical application.