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.

Adsorption of precious metals in water by dendrimer modified magnetic nanoparticles.

Magnetic nanoparticles modified by third-generation dendrimers (MNP-G3) and MNP-G3 further modified by ethylenediaminetetraacetic acid (EDTA) (MNP-G3-EDTA) were conducted to investigate their ability for recovery of precious metals (Pd(IV), Au(III), Pd(II) and Ag(I)) in water. Experiments were carried out using batch reactors for the studies of adsorption kinetics, adsorption isotherms, competitive adsorption and regeneration. The pseudo second-order model is the best-fit model among others suggesting that the adsorption of precious metals by MNP-G3 in water is a chemisorption process. Three adsorption isotherms namely Langmuir, Freundlich and Dubinin-Radushkevich isotherm were examined and the results showed the similarities and consistency of both linear and nonlinear analyses. Pd(IV) and Au(III) with higher valence exhibited relatively better adsorption efficiency than Pd(II) and Ag(I) with lower valence suggesting that the adsorption of precious metals by MNP-G3 is a function of valence. In the presence of the competing ion Zn(II), the adsorption efficiency of MNP-G3 for all four precious metals was declined significantly. The use of MNP-G3-EDTA revealed an increase in the adsorption efficiency for all four precious metals. However, the low selectivity of MNP-G3 towards precious metals was not enhanced by the modification of EDTA onto the MNP-G3. The regeneration of metal-laden MNP-G3 can be readily performed by using 1.0% HCl solution as a desorbent solution.

Social capital and health-protective behavior intentions in an influenza pandemic.

Health-protective behaviors, such as receiving a vaccine, wearing a face mask, and washing hands frequently, can reduce the risk of contracting influenza. However, little is known about how social capital may influence health-protective behavior in the general population. This study examined whether each of the social capital dimensions (bonding, bridging, and linking) contributed to the intention to adopt any of the health-protective behaviors in an influenza pandemic. The data of this study were from the 2014 Taiwan Social Change Survey. A stratified, three-stage probability proportional-to-size sampling from across the nation, was conducted to select adults aged 20 years and older (N = 1,745). Bonding social capital was measured by the frequency of neighborly contact and support. Bridging social capital was measured based on association membership. Linking social capital was measured according to general government trust and trust in the government's capacity to counter an influenza pandemic. Binary logistic regressions were used to assess the multivariate associations between social capital and behavioral intention. The study results indicate that social capital may influence the response to influenza pandemic. Specifically, the intention to receive a vaccine and to wash hands more frequently were associated with the linking dimension and the bonding dimension of social capital, while the intention to wear a face mask was associated with all forms of social capital. The findings of this study suggest that government credibility and interpersonal networks may play a crucial role in health-protective behavior. This study provides new insights into how to improve the effectiveness of influenza prevention campaigns.