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Xia L.-Q.,Xian Institute of Geology and Mineral Resources
Earth-Science Reviews | Year: 2014

Contamination by continental crust or lithosphere can impart subduction-like signatures and lead to the misidentification of contaminated continental intraplate basaltic rocks as arc related ones. Uncontaminated plume-derived continental basaltic rocks are normally characterized by high Nb/La ratios of higher than or near one, low 87Sr/86Sr(t) ratios, high εNd(t) values and "hump-shaped" OIB-like mantle-normalized multi-element patterns without negative Nb, Ta and Ti anomalies. As the uncontaminated plume-derived basaltic rocks have been found in the studied volcanic successions, the possibility can be basically excluded that they belong to island-arc or active continental margin volcanic rocks. The contaminated continental basaltic lavas have higher 87Sr/86Sr, concentrations of incompatible trace elements and lower εNd relative to the arc related ones. For the basaltic lavas with subduction-like signatures, we can judge whether they are really island-arc or active continental margin basalts by utilizing the geochemical diagrams which do not use Nb, Ta or Ti as discriminating factors. The contaminated continental basalts can be distinguished from continental margin by two factors: 1) the overall level of the incompatible elements, including Nb is higher for the contaminated continental basalts, and 2) on trace element diagrams that do not involve Nb, Ta and Ti, even the contaminated basalts exhibit within plate character. © 2014 Elsevier B.V.

Huang R.,Northwest University, China | Yang B.,Xian Institute of Geology and Mineral Resources | Liu Q.,Northwest University, China
Journal of Applied Polymer Science | Year: 2013

This articles provided information on Cr(VI) adsorption onto protonated crosslinked chitosan particles (PCPs) as an adsorbent. Batch experiments were performed to investigate the effects of the adsorbent dosage, pH, contact time, initial Cr(VI) concentration, and coexisting ions on the adsorption capacity and the regeneration ability of the adsorbent. The equilibrium data fit well with the Freundlich and Redlich-Peterson isotherm models. The presence of other anions weakened Cr(VI) adsorption, especially high-valence anion such as sulfate. PCP could be regenerated well by a 0.1N sodium hydroxide solution. Electrostatic attraction was the main driving force for Cr(VI) adsorption. Copyright © 2013 Wiley Periodicals, Inc.

Huang R.,Northwest University, China | Yang B.,Xian Institute of Geology and Mineral Resources | Liu Q.,Northwest University, China | Ding K.,Northwest University, China
Journal of Fluorine Chemistry | Year: 2012

Protonated cross-linked chitosan particles (PCP) were used to remove fluoride from aqueous solution. PCP were characterized using FTIR, XRD and SEM. Adsorption isotherms, the effects of adsorbent dosage, pH, contact time and co-existing anions on adsorption process, and the regeneration ability of PCP were investigated. The optimum pH value was achieved at 7. The equilibrium was attained in 40 min. The presence of co-existing anions weakened fluoride adsorption on PCP, especially the high valence anions such as sulfate. The equilibrium data fitted well with Langmuir and Freundlich isotherm models, and the maximum monolayer adsorption capacity was 8.10 mg g -1 at room temperature. 0.1 M HCl was identified as the best eluent. Electrostatic attraction was the main driving force for fluoride adsorption. © 2012 Elsevier B.V. All rights reserved.

Diwu C.,Northwest University, China | Sun Y.,Northwest University, China | Guo A.,Northwest University, China | Wang H.,Xian Institute of Geology and Mineral Resources | Liu X.,Northwest University, China
Gondwana Research | Year: 2011

The Dengfeng complex is located on the southern margin of the North China Craton (NCC) and belongs to the southern portion of the Trans-North China Orogen. This terrane is important to understand the formation and evolution of NCC during late Neoarchean (~2.5Ga). The Dengfeng complex is well exposed in the Junzhao region and comprises two distinct lithologic units: supracrustal assemblage and plutonic rocks. LA-ICPMS magmatic zircon U-Pb age data shows that the rocks formed within the range of 2547-2504Ma. The available Hf isotope data indicate that the majority of ca. 2.5Ga zircons from the Dengfeng complex have high εHf(t) values close to the initial Hf isotope ratios of the contemporaneous depleted mantle. These data indicate that the rocks in the Dengfeng represent juvenile crust. The TTG gneisses in the Dengfeng complex display low Mg# (41-48), MgO (<2wt.%), Cr (6-14ppm), Ni (9-22ppm) contents and low Nb/Ta ratio (6-12), which are interpreted to have been produced by the partial melting of a flatly subducted slab. The metadiorites of the Dengfeng complex are typically characterized by high Mg# (59-69), MgO (3.5-6.6wt.%), Ni (82-130ppm) and Cr (148-237ppm) abundances, elevated Sr (1759-1927ppm) and Ba (1742-2289ppm) concentrations, and high LREE (LaN=38-487). Such geochemical features are similar to Archean sanukitoids. A two-stage model is applied here to explain the genesis of metadiorites of Dengfeng complex: (1) firstly, the mantle is metasomatized either by melts or by aqueous fluids from a subducted slab; (2) subsequently, sanukitoid magmas were produced by partial melting of the hybridized mantle. Furthermore, the amphibolites of supracrustal rocks have a mixture of MORB- and arc-like geochemical affinities, suggesting the development of a back-arc in the southern NCC at ca. 2.5Ga. The contemporary late Neoarchean TTGs, sanukitoids and MORB-back arc association may represent a late Neoarchean tectonic mélange, implying a Neoarchean subduction-accretion process which would suggest that modern-style plate tectonics processes was probably initiated in the southern NCC by 2.5Ga. © 2011 International Association for Gondwana Research.

Liu Q.,Northwest University, China | Zhang L.,Northwest University, China | Yang B.,Xian Institute of Geology and Mineral Resources | Huang R.,Northwest University, China
International Journal of Biological Macromolecules | Year: 2015

In the present paper, zirconium immobilized cross-linked chitosan (Zr-CCS) was reported for the adsorption of fluoride. Zr-CCS was synthesized by methods of membrane-forming and subsequent cross-linking reaction. Zr-CCS was characterized by FTIR, XRD, and SEM technologies. Batch adsorption experiments were performed to evaluate the adsorption capacity of Zr-CCS toward fluoride. The adsorption of fluoride onto the Zr-CCS favored at low pH values, and reduced in the presence of other co-anions. The adsorption equilibrium data had a good agreement with the Langmuir isotherm model, and the maximum adsorption capacity was calculated as 48.26. mg/g for fluoride at 303. K and natural pH (6.0). Thermodynamic parameters indicate that the nature of fluoride adsorption was spontaneous and endothermic. The adsorption mechanism of fluoride onto the Zr-CCS was controlled by chemical ion-exchange and electrostatic attraction between Zr-CCS and fluoride. © 2015 Elsevier B.V.

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