1.A hydrometallurgical process for recovering total metal values from waste monolithic ceramic capacitors.
Prabaharan G1, Barik SP2, Kumar B1. Waste Manag. 2016 Apr 12. pii: S0956-053X(16)30173-8. doi: 10.1016/j.wasman.2016.04.010. [Epub ahead of print]
A hydrometallurgical process for recovering the total metal values from waste monolithic ceramic capacitors was investigated. The process parameters such as time, temperature, acid concentration, hydrogen peroxide concentration and other reagents (amount of zinc dust and sodium formate) were optimized. Base metals such as Ba, Ti, Sn, Cu and Ni are leached out in two stages using HCl in stage 1 and HCl with H2O2 in stage 2. More than 99% of leaching efficiency for base metals (Cu, Ni, Ba, Ti and Sn) was achieved. Precious metals such as Au and Pd are leached out using aquaregia and nitric acid was used for the leaching of Ag. Base metals (Ba, Ti, Sn, Cu and Ni) are recovered by selective precipitation using H2SO4 and NaOH solution. In case of precious metals, Au and Pd from the leach solution were precipitated out using sodium metabisulphite and sodium formate, respectively. Sodium chloride was used for the precipitation of Ag from leach solution.
2.Mucosal acidification increases hydrogen sulfide release through up-regulating gene and protein expressions of cystathionine gamma-lyase in the rat gastric mucosa.
Mard SA1, Veisi A2, Ahangarpour A2, Gharib-Naseri MK2. Iran J Basic Med Sci. 2016 Feb;19(2):172-7.
OBJECTIVES: This study was performed to investigate the effects of mucosal acidification on mRNA expression and protein synthesis of cystathionine gamma lyase (CSE), cystathionine beta synthase (CBS), and mucosal release of H2S in gastric mucosa in rats.
3.Development of a gas phase source for perfluoroalkyl acids to examine atmospheric sampling methods.
MacInnis JJ1, VandenBoer TC2, Young CJ1. Analyst. 2016 Apr 18. [Epub ahead of print]
An inability to produce environmentally relevant gaseous mixing ratios of perfluoroalkyl acids (PFAAs), ubiquitous global contaminants, limits the analytical reliability of atmospheric chemists to make accurate gas and particulate measurements that are demonstrably free of interferences due to sampling artefacts. A gas phase source for PFAAs based on the acid displacement mechanism using perfluoropropionate (PFPrA), perfluorobutanoate (PFBA), perfluorohexanoate (PFHxA), and perfluorooctanoate (PFOA) has been constructed. The displacement efficiency of gas phase perfluorocarboxylic acids (PFCAs) is inversely related to chain length. Decreasing displacement efficiencies for PFPrA, PFBA, PFHxA, and PFOA were 90% ± 20%, 40% ± 10%, 40% ± 10%, 9% ± 4%, respectively. Generating detectable amounts of gas phase perfluorosulfonic acids (PFSAs) was not possible. It is likely that lower vapour pressure and much higher acidity play a role in this lack of emission.
4.DFT and experimental study on the mechanism of elemental mercury capture in the presence of HCl on α-Fe2O3 (001).
Liu T, Xue L, Guo X, Huang Y, Zheng C. Environ Sci Technol. 2016 Apr 15. [Epub ahead of print]
To investigate the mechanism of Hg0 adsorption on α-Fe2O3 (001) surface in the presence of HCl, which was considered to be beneficial for Hg0 removal, theoretical calculations based on density functional theory as well as corresponding experiments were carried out. HCl adsorption was firstly performed on α-Fe2O3(001) surface, and the Hg0 adsorption on HCl-adsorbed α-Fe2O3(001) surface was subsequently researched, demonstrating that HCl dissociates on the surface of α-Fe2O3, improving the Hg0 adsorption reactivity. With further chlorination of α-Fe2O3(001) surface, the FeCl3 could be achieved and the adsorption energy of Hg0 on FeCl3 surface reaches -104.2 kJ/mol, belonging to strong chemisorption. Meanwhile, a group of designed experiments, including the Hg0 adsorption on HCl pre-adsorbed α-Fe2O3 as well as the co-adsorption of both gaseous components, were respectively performed to explore the pathways of Hg0 transformation. Combining computational and experimental results together, the Eley-Rideal mechanism with HCl pre-adsorption can be determined.
