Environmental applications sulfur compounds

Environmental Pollution Control. The importance of chemical oxidation of reduced sulfur compounds lies in its application to treatment of wastes-treams from municipal sewage systems, acid mine drainage and industrial plants such as tanneries, paper and pulp mills, oil refineries and textile mills. 

The first section contains overview and introductory material, some historical background, summaries of the present state of knowledge, and other general topics applicable to all fossil fuel These include environmental consequences of fossil fuel combustion, polysulfide chemistry, microbial metabolism of sulfur compounds, and a review of methods for isolating sulfur compounds from petroleum. 

Sulfur oxides (S02 and S03) present in flue gases from upstream combustion operations adsorb onto the catalyst surface and in many cases form inactive metal sulfates. It is the presence of sulfur compounds in petroleum-based fuels that prevent the super-sensitive base metal catalysts (i.e., Cu, Ni, Co, etc.) from being used as the primary catalytic components for many environmental applications. Precious metals are inhibited by sulfur and lose some activity but usually reach a lower but steady state activity. Furthermore the precious metals are reversibly poisoned by sulfur compounds and can be regenerated simply by removing the poison from the gas stream. Heavy metals such as Pb, Hg, As, etc. alloy with precious metals and permanently deactivate them. Basic compounds such as NH3 can deactivate an acidic catalyst such as a zeolite by adsorbing and neutralizing the acid sites. 

Customized catalysts are also available for more specialized environmental uses. For instance, Pt/mordenite catalysts are used for the treatment of air pollutants in spray painting and coating workshops, and also to control emission in benzoic anhydride manufacturing industries. Pt-V205-S04 /mordenite is sometimes employed to purify flue gases containing sulfur compounds. Metal-based catalysts are ideal for such applications, because they work at low reactant concentrations (4-6 g/m ), high space velocities... 

SPME has been used to analyze volatile, semivolatile, and several nonvolatile organic sulfur compounds. Only a few specific applications have been published for the extraction of sulfur compounds in environmental compartments, such as wastewater and air. ° ... 

See alsa Atomic Absorption Spectrometry Electrothermal. Atomic Emission Spectrometry Flame Photometry. Cadmium. Carbon. Chemiiuminescence Overview. Fluorescence Environmental Applications. Gas Chromatography Environmental Applications. Laser-Based Techniques. Lead. Nitrogen. Ozone. Polycyclic Aromatic Hydrocarbons Environmental Applications. Remote Gas Sensing Overview. Spectrophotometry Inorganic Compounds. Sulfur. X-Ray Fluorescence and Emission X-Ray Fluorescence Theory. 

Sulfur scavenging processes are typically batch operations. They make use of materials that capture and retain sulfur compounds, but have a finite effective capacity. When this capacity is reached, the spent sorbent (liquid or solid) must be removed and replaced with fresh material. The spent sorbent is normally disposed of as waste, and the production of an environmentally acceptable waste has become a key factor in the selection of. scavenging proces.ses for specific applications. Other important considerations are operating safety and reliability (unattended operation is often required) and, of course, capital and operating costs. 

Whitehurst, Isoda, and Mochida write about catalytic hydrodesulfurization of fossil fuels, one of the important applications of catalysis for environmental protection. They focus on the relatively unreactive substituted di-benzothiophenes, the most difficult to convert organosulfur compounds, which now must be removed if fuels are to meet the stringent emerging standards for sulfur content. On the basis of an in-depth examination of the reaction networks, kinetics, and mechanisms of hydrodesulfurization of these compounds, the authors draw conclusions that are important for catalyst and process design. 

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