Renjian Deng

Three-dimensional electro-Fenton oxidation of N-heterocyclic compounds with a novel catalytic particle electrode: high activity, wide pH range and catalytic mechanism

A novel three-dimensional (3D) heterogeneous electro-Fenton (EF) system with sludge deserved activated carbon from sewage and iron sludge (SAC-Fe) as catalytic particle electrodes (CPEs) was constructed in this study. Its application in degrading nitrogen-heterocyclic compounds (NHCs) exhibited high catalytic efficiency over a wide applicable pH range from 3.0 to 9.0. SAC-Fe worked as both CPEs and a heterogeneous catalyst in this 3D EF system, enhancing oxidation activity. Degradation pathways of the NHCs (indole, quinoline and pyridine) and reasonable reaction mechanisms involved in this 3D EF were proposed. At pH 3.0, hydroxyl radicals were the dominant participant oxidants, following a Haber–Weiss mechanism. The FeII sites catalyzed the decomposition of electro-generated H2O2 to yield ˙OH. At pH 9.0, the oxidants generated from the decomposition of H2O2 were mainly ˙O2−/HO2˙ and to lesser extent were ˙OH. The formation and decomposition of H2O2 complex with catalytic sites (FeII and FeIII) as well as the catalytic decomposition of H2O2 were involved in the catalytic reactions to generate ˙O2−/HO2˙ and ˙OH. A quantitative structure–activity relationship analysis (QSAR) model was developed to describe the relationship between degradation properties of NHCs and their structures by involving quantum descriptors.

Research on the Characteristics and Mechanism of the Cumulative Release of Antimony from an Antimony Smelting Slag Stacking Area under Rainfall Leaching

We aimed to study the characteristics and the mechanism of the cumulative release of antimony at an antimony smelting slag stacking area in southern China. A series of dynamic and static leaching experiments to simulate the effects of rainfall were carried out. The results showed that the release of antimony from smelting slag increased with a decrease in the solid-liquid ratio, and the maximum accumulated release was found to be 42.13 mg Sb/kg waste and 34.26 mg Sb/kg waste with a solid/liquid ratio of 1 : 20; the maximum amount of antimony was released within 149–420 μm size fraction with 7.09 mg/L of the cumulative leaching. Also, the antimony release was the greatest and most rapid at pH 7.0 with the minimum release found at pH 4.0. With an increase in rainfall duration, the antimony release increased. The influence of variation in rainfall intensity on the release of antimony from smelting slag was small.

Facile preparation of a novel catalytic particle electrode from sewage sludge and its electrocatalytic performance in three-dimensional heterogeneous electro-Fenton

A novel type of catalytic particle electrode (SAC-Fe) was developed from sewage sludge and iron sludge via a facile method. The catalytic particle electrodes (CPEs) were also supposed to be heterogeneous catalyst for electro-Fenton (EF). The CPEs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). SAC-Fe showed superior porous structure and higher adsorption capacity and catalytic activity than Fe3O4 magnetic nanoparticles. Catechol and total organic carbon (TOC) removal efficiency can reach 96.7% and 88.3% after three-dimensional (3D) EF with SAC-Fe as CPEs. A possible mechanism was deduced based on adsorption tests and radicals detection. Meanwhile, the stability and reusability of the CPEs were evaluated.