Real-Time Observation of Pyoverdine Dissolving Ferric Hydroxide

Pyoverdine is one of the siderphores excreted by Pseudomonas aeruginosa that can help microbe to uptake iron in vitro. To determine the effect of pyoverdine chelating with iron, we purified the free pyoverdine and applied the dynamic laser light scattering （DLS） to detect the interaction between the pyoverdine and ferric hydroxide. The real-time DLS data analysis indicated that pyoverdine can directly combine with Fe（OH）3 to form complexes and these substances are gradually degraded by themselves then completely disappeared. In our experiment, we have demonstrated that pyoverdine may not only chelate ferric ion but also availably dissolve ferric hydroxide which assists bacteria to survive in iron-deficient environments.

A novel Fe(OH)3/TiO2 nanoparticles and its high photocatalytic activity

A very simple and controllable approach was proposed to synthesize novel Fe（OH）3/TiO2 nanoparticles. Compared with neat TiO2, the Fe（OH）3/TiO2 increased the rate of the photocatalytic degradation of methyl orange at pH 6.0 by more than five times, showing photocatalytic activity as excellent as P25. This enhancing effect is mainly attributed to the ferric hydroxide deposits as the electron scavenger and the enriched surface hydroxyl groups.

Micaceous iron oxide prepared from pyrite cinders by hydrothermal method

Micaceous iron oxide （MIO） with a hexagonal flaky shape was prepared by hydrothermal method. The ferric hydroxide used as precursor was obtained by an acidic leaching solution of pyrite cinders reacting with ammonia solution. The optimal experimental conditions for preparing micaceous iron oxide were investigated by orthogonal experiments. Micaceous iron oxide can be successfully prepared when optimal parameters of total iron concentration of 2.0 mol/L, pH value of 8, n（Fe2＋）/n（Fe3＋） of 0.1, mass of seed crystal of 1 g, reaction temperature of 260 ℃ and reaction time of 30 min are applied. X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and selected area electron diffractometry （SAEM） were adopted to characterize the hydrothermal products prepared under optimal conditions. The results indicate that highly crystallized α-Fe2O3 hexagonal flakes, about 1.0-1.5 μm in diameter and 0.1 μm in thickness, are prepared. Furthermore, the quality of micaceous iron oxide prepared can meet the required characteristics of micaceous iron oxide pigments for paints （ISO 10601--2007）.

Bacterial reduction and release of adsorbed arsenate on Fe(III)-, Al- and coprecipitated Fe(III)/Al-hydroxides

Mobilization of arsenic under anaerobic conditions is of great concern in arsenic contaminated soils and sediments. Bacterial reduction of As（V） and Fe（III） influences the cycling and partitioning of arsenic between solid and aqueous phase. We investigated the impact of bacterially mediated reductions of Fe（III）/Al hydroxides-bound arsenic（V） and iron（III） oxides on arsenic release. Our results suggested that As（V） reduction occurred prior to Fe（III） reduction, and Fe（III） reduction did not enhance the release of arsenic. Instead, Fe（III） hydroxides retained their dissolved concentrations during the experimental process, even though the new iron mineral-magnetite formed. In contrast, the release of reduced As（III） was promoted greatly when aluminum hydroxides was incorporated. Thus, the substitution of aluminum hydroxides may be responsible for the release of arsenic in the contaminated soils and sediments, since aluminum substitution of Fe（III） hydroxides universally occurs under natural conditions.

Comparing the adsorption behaviors of Cd, Cu and Pb from water onto Fe-Mn binary oxide, MnO2 and FeOOH

The adsorption potential of FMBO, FeOOH, MnO2 for the removal of Cd^2＋, Cu^2＋ and Pb^2＋ in aqueous systems was investigated in this study. Comparing to FMBO and FeOOH, MnO2 offered a much higher removal capacity towards the three metal ions. The maximal adsorption capacity of MnO2 for Cd^2＋, Cu^2＋ and Pb^2＋ were 1.23, 2.25 and 2.60 mmol· g^-1, respectively. And that for FMBO were 0.37, 1.13, and 1.18mmol·g^-1 and for FeOOH were 0.11, 0.86 and 0.48 mmol·g^-1, respectively. The adsorption behaviors of the three metal ions on the three adsorbents were all significantly affected by pH values and heavy metal removal efficiency increased with pH increased. The Langmuir and Freundlieh adsorption models were used to describe the adsorption equilibrium of the three metal ions onto the three adsorbents. Results showed that the adsorption equilibrium data fitted well to Langmuir isotherm and this indicated that adsorption of metal ions occurred on the three metal oxides adsorbents limited to the formation of a monolayer. More negative charged of MnOa surface than that of FMBO and FeOOH could be ascribed by lower pHiep of MnO2 than that of FMBO and FeOOH and this could contribute to more binding sites on MnO2 surface than that of FMBO and FeOOH. The higher metal ions uptake by MnO2 than FMBO and FeOOH could be well explained by the surface charge mechanism.

A comprehensive study of treatment of arsenic in water combining oxidation,coagulation,and filtration

Arsenic is one of the most common inorganic contaminants in groundwater worldwide,mainly due to the release of naturally occurring arsenic from aquifer sediments（Amini et al.,2008;Li and Cai,2015;Rahman et al.,2015）.Naturally occurring arsenic exists predominantly in arsenate and arsenite species in groundwater.