Adsorption and catalytic performance of pipe growth rings from water distribution networks using 5-BSA as the target pollutant

In this study, we investigated the use of pipe growth rings from water distribution networks as a catalyst in heterogeneous Fenton-like oxidation processes. The major constituents of real pipe growth rings (α- and γ-FeOOH) were prepared and considered as a simulated growth ring (SGR). Its performance in removing 5-bromosalicylic acid (5-BSA), a novel phenolic halogenated disinfection byproduct, was examined. SGR exhibited strong catalytic ability and a certain degree of adsorption capacity. Under acidic conditions, the adsorption and oxidation efficiencies were 32.65% and 87.67%, respectively. Furthermore, 72.19% of 5-BSA could be oxidized even at pH₀ of 7. Kinetic characterizations at various temperatures revealed that both the adsorption and catalytic oxidation processes followed pseudo-second-order kinetic models and were surface-controlled with high activation energies (31.26 and 23.58 kJ mol⁻¹, respectively). Ecotoxicity analyses of the transformation products (TPs) showed that the SGR/H₂O₂ system could effectively reduce the toxicity of 5-BSA. Moreover, the number of iron ions leaching from SGR was below 0.1 mg L⁻¹ in all experiments. The results of this study support further investigation of using real pipe growth rings in off-line water treatment, as well water network contamination remediation.