5. Chemical Bonding in Sulfide Minerals

2006 ◽  
pp. 231-264 ◽  
Author(s):  
David J. Vaughan ◽  
Kevin M. Rosso
Author(s):  
M. L. Knotek

Modern surface analysis is based largely upon the use of ionizing radiation to probe the electronic and atomic structure of the surfaces physical and chemical makeup. In many of these studies the ionizing radiation used as the primary probe is found to induce changes in the structure and makeup of the surface, especially when electrons are employed. A number of techniques employ the phenomenon of radiation induced desorption as a means of probing the nature of the surface bond. These include Electron- and Photon-Stimulated Desorption (ESD and PSD) which measure desorbed ionic and neutral species as they leave the surface after the surface has been excited by some incident ionizing particle. There has recently been a great deal of activity in determining the relationship between the nature of chemical bonding and its susceptibility to radiation damage.


Author(s):  
El'vira Kolmachikhina ◽  
◽  
Ekaterina Ryzhkova ◽  
Dar'ya Dmitrieva ◽  
◽  
...  

1996 ◽  
Vol 34 (10) ◽  
pp. 25-33 ◽  
Author(s):  
Cheng Jiayang ◽  
Makram T. Suidan ◽  
Albert D. Venosa

Abiotic reduction of 2,4-dinitrotoluene (DNT) in the presence of sulfide minerals has been investigated under anoxic conditions at 35°C. 2,4-DNT was abiotically reduced to 4-amino-2-nitrotoluene (4-A-2-NT) and 2-amino-4-nitrotoluene (2-A-4-NT) in the presence of high concentration of sulfide (0.84 mM). No abiotic reduction of 2,4-DNT was observed in the presence of low sulfide concentration (0.42 mM). The rate and the extent of the abiotic reduction of 2,4-DNT were increased with an increase in sulfide concentration. Sulfide served as an electron donor for the reduction of 2,4-DNT. The 2-nitro group was preferentially reduced, making the 2-A-4-NT:4-A-2-NT ratio in the final products 2:1. The addition of iron, nickel, and cobalt minerals significantly enhanced the abiotic reduction. The FeS, NiS, and CoS solids formed in the serum bottles catalyzed the reduction of 2,4-DNT preferentially to 4-A-2-NT. MnS and CuS solids also catalyzed the reduction of 2,4-DNT to 4-A-2-NT, but did not change the overall reduction of 2,4-DNT. However, the presence of calcium, zinc, and magnesium minerals impeded 2,4-DNT reduction. The calcium, zinc, and magnesium ions have a high affinity to sulfide, inactivating sulfide as an electron donor for the chemical reduction of 2,4-DNT.


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