Abstract

The degradation of nonylphenol polyethoxylates (NPEOs) was investigated by persulphate (PS) activated using naturally pyrite semi-conductor mineral (NP-SCM) in aqueous solutions. The effects of various factors including solution pH, NP-SCM dosage, NPEOs and PS concentration were examined through response surface methodology (RSM) and Box-Behnken design (BBD) technique. The properties of NP-SCM were characterised by FESEM, BET, XRD and EDX analyses. The results showed that the RSM model had a well correlation (R2 > 0.99) between the predicted data and the experimental findings of NPEOs degradation. In addition, under the optimum conditions (PS = 5.85 mM, pH = 3.0, NP-SCM = 0.85 g/L and NPEOs = 10 µM), the removal efficiency of NPEOs reached more than 99. The maximum removal efficiency of COD and TOC was obtained 87 and 80 at 90 min reaction time, respectively. The negative effect of various competing ions on the removal of NPEOs was as phosphate>bicarbonate>copper>nitrate>calcium>ammonium. After five successive catalyst cycles reuse, the degradation efficiency was insignificantly decreased from 99.6 to 90.5, which indicated the excellent potential reusability of NP-SCM catalyst. It can be concluded that NP-SCM along with PS, due to the generation of highly reactive oxidising species (SO4●-), its simplicity and easy separation of the catalyst, has a great potential for the degradation of NPEOs from aqueous solutions. © 2020 Informa UK Limited, trading as Taylor & Francis Group.