Behavior and Impact of Zirconium in the Soil–Plant System: Plant Uptake and Phytotoxicity

Because of the large number of sites they pollute, toxic metals that contaminate terrestrial ecosystems are increasingly of environmental and sanitary concern (Uzu et al. 2010, 2011; Shahid et al. 2011a, b, 2012a). Among such metals is zirconium (Zr), which has the atomic number 40 and is a transition metal that resembles titanium in physical and chemical properties (Zaccone et al. 2008). Zr is widely used in many chemical industry processes and in nuclear reactors (Sandoval et al. 2011; Kamal et al. 2011), owing to its useful properties like hardness, corrosion-resistance and permeable to neutrons (Mushtaq 2012). Hence, the recent increased use of Zr by industry, and the occurrence of the Chernobyl and Fukashima catastrophe have enhanced environmental levels in soil and waters (Yirchenko and Agapkina 1993; Mosulishvili et al. 1994 ; Kruglov et al. 1996)

Prediction of the edaphic factors influence upon the copper and cobalt accumulation in two metallophytes using copper and cobalt speciation in soils.

Background and aims: Among the unique flora on copper and cobalt rich soils, some species are able to hyperaccumulate the Cu and Co in their shoots, however, the unexplained high variations of Cu and Co concentrations in shoots have been highlighted. A good comprehension of the Cu and Co accumulation variations would go through a characterization of the Cu and Co speciation in soils. We examined the covariations of Cu and Co speciation in soils and Cu and Co concentrations in plants. Methods: Plant samples of two species and soil samples (n = 146) were collected in seven pedogeochemically contrasted sites. Cu and Co speciation in soils was modeled by WHAM 6.0. Results: Variation in copper accumulation in plant shoots were mostly influenced by Cu adsorbed by the Mn and Fe oxides fractions, whereas Co accumulation variations were strongly influenced by Co free and Co adsorbed by the OM and Fe fractions. Conclusions: Availability of Cu and Co seems to be species-specific and is not explained only by the free Cu and Co content in the soil solution, but also strongly by the part linked to colloidal fractions. Availability of Cu and Co is a complex mechanism, closely related to all the biogeochemical processes which occur in the rhizosphere. Future work should perform experiments in controlled conditions to examine the soil parameters that influence the Cu and Co availability. © 2014 Springer International Publishing Switzerland.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

La0.1Ca0.9MnO3/Co3O4 for oxygen reduction and evolution reactions (ORER) in alkaline electrolyte

Non-precious metal bifunctional catalysts are of great interest for metal–air batteries, electrolysis, and regenerative fuel cell systems due to their performance and cost benefits compared to the Pt group metals (PGM). In this work, metal oxides of La0.1Ca0.9MnO3 and nano Co3O47 catalyst as bifunctional catalysts were used in oxygen reduction and evolution reactions (ORER). The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption isotherms. The electrocatalytic activity of the perovskite-type La0.1Ca0.9MnO3 and Co3O4 catalysts both as single and mixtures of both were assessed in alkaline solutions at room temperature. Electrocatalyst activity, stability, and electrode kinetics were studied using cyclic voltammetry (CV) and rotating disk electrode (RDE). This study shows that the bifunctional performance of the mixed La0.1Ca0.9MnO3 and nano Co3O4 was superior in comparison to either La0.1Ca0.9MnO3 or nano Co3O4 alone for ORER. The improved activity is due to the synergistic effect between the La0.1Ca0.9MnO3 and nano Co3O4 structural and surface properties. This work illustrates that hybridization between these two metal oxides results in the excellent bifunctional oxygen redox activity, stability, and cyclability, leading to a cost-effective application in energy conversion and storage, albeit to the cost of higher catalyst loadings.QC 20180212</p