Na2S2O3 facilitating the Fenton reaction for the degradation of Polyacrylamide

Abstract In the field of oilfield wastewater treatment, polyacrylamide (PAM) is identified as a major pollutant, which has prompted extensive research endeavors aimed at exploring efficient and cost-effective degradation methods for its removal. In this study, sodium thiosulfate (Na 2 S 2 O 3 ) was introduced into the Fenton system as an inorganic co-catalyst with the explicit aim of rectifying the limitations of the traditional Fenton reaction pathway. By employing the variation in system viscosity as a metric to gauge degradation efficacy, a meticulous investigation was conducted into the impacts of co-catalyst dosage, temperature, and pH on PAM degradation. Concurrently, the underlying reaction mechanism was dissected. The experimental results show that optimal PAM degradation occurs at a molar ratio of n(Fe 2+ ): n(S 2 O 3 2- ) of 1:2, a pH of 6.0, and a temperature of 40 °C, reducing the viscosity from 3.29 mm 2 /s to 1.48 mm 2 /s within 30 min. Remarkably, even under neutral conditions, the degradation rate of PAM could still reach up to 52%. In summary, the newly developed catalytic system effectively enhances the regeneration of Fe(II) and markedly extends the pH range within which the Fenton reaction can be efficiently conducted.