Effect of organic carbon structures on the degradation of nonylphenol by hydrogen peroxide in sediment-water system.

Abstract

A laboratory experiment is conducted to investigate the effects of organic carbon (OC) from riverine and marine sediments on the degradation of ring-14 C-labeled nonylphenol (14 C-NP) by hydrogen peroxide (H2 O2 ). Researchers have isolated demineralized OC (DM) before and after oxidation, namely, DM and resistant OC (ROC) fractions, respectively. The structures of DM and ROC are characterized using solid-state 13 C nuclear magnetic resonance. Unstable structures (O-alkyl, OCH3 /NCH, and COO/NC=O) show a significant and positive correlation with the degradation of 14 C-NP (R2 >0.73, p<0.05), thus suggesting that the NP absorbed in the unstable structures is easily degraded because of the decomposition of unstable components. The stable structures (alkyl C and non-protonated aromatic C [Arom C─C]) exhibit a significant and negative correlation with the degradation of 14 C-NP (R2 >0.69, p<0.05), thus suggesting that the NP absorbed and protected in these resistant structures is minimally degraded. The significant correlations among the degradation kinetic parameters (Frap and Fslow ), OC structures (Falip and Farom ), and microporosity further illustrate the important protective roles of OC structures and micropores in the degradation of 14 C-NP by H2 O2 (R2 >0.69, p<0.05). The parent NP fraction that desorbed into the aqueous solution or extracted is completely degraded, indicating preferential degradation of the easily desorbed NP. This study provides important insights into the NP degradation mechanism in sediment-water systems, particularly regarding sediment OC structures and microporosity.