Inactivation of Escherichia coli by dual-functional zerovalent Fe/Al composites in water.

A bimetallic Fe/Al disinfection system was developed to examine the feasibility of inactivation of water borne microorganisms. In this study, the effectiveness and mechanisms of the bimetallic Fe/Al system on the inactivation of model bacteria, Escherichia coli (E. coli), were investigated. Results revealed that the Fe/Al system effectively inactivated E. coli to reach nearly 2 logs (99%) removal within 20 min and 4 logs (99.99%) at 24 h, indicating that the Fe/Al composite was able to sustain a long-term disinfection capacity. The inactivation ability resulted from hydroxyl radicals produced by a Fenton reaction through in-situ self-generated Fe2+ and H2O2 species in the Fe/Al system. In addition to the attack by the radicals, some of E. coli were adsorbed onto the Fe/Al composite (zeta potential of 30-50 mV) as a result of Coulomb interaction. Scanning electron microscope (SEM) images showed that the adsorbed bacteria had damaged pores at the two ends of their rod-like cells. This phenomenon suggested that a micro-electric field between the Fe/Al galvanic couple induced electroporation of the adsorbed E. coli and thus further advanced additional inactivation ability for the bacteria disinfection.

Controlled pyrolysis of MIL-88A to prepare iron/carbon composites for synergistic persulfate oxidation of phenol: Catalytic performance and mechanism.

In this study, based on the extensive discussion of the phase transformation process of metal-organic frameworks (MOFs)--MIL-88A(Fe) under thermal treatment, the catalytic performance of MIL-88A-derived iron/carbon (FexC) composites on persulfate (PS) activation for phenol degradation was investigated. FexC-600 (γ-Fe2O3/C) exhibited a superior catalytic activity on PS activation for phenol degradation due to higher carbon content, more sp2-hybridized structure, carbonyl group and defective sites in composites, in which 98.23% of phenol (20 mg/L) was degraded after 60 min with 0.3 g/L catalyst and 0.3 g/L PS at ambient pH (6.1). The phenol degradation experiments and mechanism studies revealed that there was a catalytic synergism between iron oxides and carbon component in FexC 400-600 composites. Moreover, sulfate radicals (SO4-), hydroxyl radical (•OH), singlet oxygen (1O2) and interfacial electron transfer process all involved in the degradation of phenol by FexC 400-600 composites, but the 1O2-mediated non-radical oxidation was the dominant pathway rather than reactive radicals. Finally, the possible mechanism of PS activation on FexC 400-600 composites was proposed. This work discusses the synergistic catalytic mechanism of FexC composites on PS activation, and favors to provide a better understanding of the metal species and carbon component interaction in iron/carbon-based materials.