Fabrication of Polyaniline/Silver Nanocomposite Under Gamma-ray Irradiation

Polyaniline （PANI）/silver composite was one-step synthesized under γ-ray irradiation. The structure of the composite was characterized by Fourier transform infrared spectroscopy, UV-Visible, and X-ray diffraction, which indicated that PANI and face-centered-cubic silver were synthesized under γ-ray irradiation. The reaction mechanism were discussed, which revealed that the PANI was formed by the reaction of aniline cation radicals formed by the reaction of aniline cation and -OH, and Ag was formed by the reaction of Ag＋ and eaq. The morphology of the composite consisted of PANI nanofibers and Ag nanoparticles, and the mechanism of the morphology formation was discussed, which revealed that the rapid mixing like polymerization process might play an important role. It was revealed that the transport behavior of the composite well fitted with the variable-range-hopping model in 80-300 K and deviated from the model below 80 K.

Colorful Silver/Carbon Nitride Composites Obtained by Photoreduction

The Ag^+photoreduction by graphitic carbon nitride(g-CN)materials in a high concentration of Ag^+solution is reported,and a series of colorful Ag/g-CN composites is prepared and characterized.The chromatic change correlates to the carbon nitride materials synthesized at different heating temperatures(CNr,where T means heating temperature),takingadvantage of the different photocatalytic activities of different CNr.The mechanism beneath this phenomenon is attributed to two factors:the particle size of Ag NPs and the coordinate effect of Ag NPs on CNr sheets.Interestingly,the multi-colors of Ag/g-CN composites display only on the CNr materials synthesized from heating melamine-cyanuric acid pre-cursor,but not on the CNr from heating pure melamine.The color of the as-prepared Ag/g-CN composites can endure the corrosion of HNO;and ethanol,which shows a good chemical stability and may hint its application as chromophores.

A Preliminary Study on Silver Isotopic Composition in Polymetallic Ore Deposits in Eastern China

A preliminary survey of silver isotopic composition in four polymetallic ores in eastern China shows a larger variation inδ^(109)Ag from-0.014‰to+0.983‰,which is within the total ranges for the entire respective ore deposit types worldwide.The diversity of silver isotopic compositions in oredeposits reported here and previous studies seemed to preclude simple isotopic links to particular sources,but reflected the silver isotope fractionation in transport-and deposit-related processes instead.Theδ^(109)Ag values in supergene samples from the Qixiashan Pb-Zn-Ag polymetallic deposit are more positive,in consistent with the statistical δ^(109)Ag distribution from-0.4‰to+2.2‰in 36 pieces of supergene ore samples around the World,which reflects the diverse controls on silver isotope fractionation from the first-order thermodynamic effect,reduction-mediated reaction,remobilization of silver with surficial low-temperature weathering processes.The hypogene samples in Dazhuangzi orogenic Au-Ag ore deposit,have δ^(109)Ag values close to 0,which implies that equilibrium partitioning associated with metal sources at the high-temperature does not result in a resolvable difference in silver isotopic compositions.By contrast,the hypogene samples which are dominated by pyrite without visible silver minerals (i.e.,skarn iron ore deposit in Edongnan) have shown the largest variation range of δ^(109)Ag,followed by that from the porphyry copper ore in Zijinshan.It could be concluded that the surface adsorption and/or lattice substitution are important factors to control Ag isotope fractionation in oreforming processes,especially for skarn deposits with only pyrite.The perspective of silver isotope shows great potentials to understand the processes that lead to the concentrations of metals to economic levels and to constrain the physicochemical conditions during ore-mineralization in metallic ore-deposits.