in natural gas combustion because the moisture level is lower. Anything that reduces the moisture level, such as lowering the stoichiometric ratio or predrying the coal, will help to increase fuel rich sulfur capture, especially at lower sulfur levels. Increasing temperature will increase fuel rich sulfur capture only if the sulfur level is significantly above the thermodynamic limit (which increases with temperature).These results suggest that the rate-limiting step under fuel rich conditions is distinctly different than under fuel lean conditions. Theoretical calculations using a distributed pore model (19) have suggested that the relative insensitivity of calcium utilization to SOz concentration under fuel lean conditions is a result of pore closure effeds, as the SOz concentration is increased, the kinetic and diffusion rates increase but this further aggravates the problem of pore closure and results in essentially no overall increase in sulfur capture. The increased calcium utilization measured with increasing sulfur species concentrations under fuel rich conditions may be the direct result of enhanced product layer diffusion; pore closure would not be expected to limit calcium utilization under fuel rich conditions because the molar volume of calcium sulfide is less than either parent sorbent.Size fractionation method has been used for the speciation of trace elements in river waters. Both filtration and ultrafiltration techniques were applied to fractionate the trace elements into various sizes and/or molecular weight ranges. The size distribution was determined for 39 elements by means of neutron activation analysis to estimate their physicochemical forms. Alkali and alkaline earth elements, heavy rare earth elements (REEs), As, Co, Mn, Ni, Sb, Se, V, W, and Zn were mainly present in the dissolved phase, while Ag, Al, Fe, Sc, and light REEs were predominantly associated with the suspended particles. The dominant dissolved species for alkali and alkaline earth elements, Al, V, Mn, Sb, and Au were regarded as simple ions, while heavy REEs, Sc, Co, Ni, and Zn were apt to form soluble complexes with organic ligands. Light REEs, Fe, and Ag were mainly associated with colloidal materials.

No abstract

The radiolysis of solutions of polychlorinated biphenyls (PCB’s) and potassium hydroxide in simple aliphatic alcohols was studied. The major products in alkaline 2-propanol solutions were potassium chloride, acetone, lower chlorinated biphenyls, and biphenyl. Their yields increased and the concentration of the hydroxide ions decreased with the dose. Acetone and potassium chloride were formed in high yields, and their concentrations were almost equal to the diminution in the hydroxide ions. The dechlorination yield was determined as a function of the dose, the dose rate, and the concentrations of PCB’s, potassium hydroxide, and organic solutes. The chain-dechlorination reaction proceeded in the alkaline 2-propanol solution, but not in alkaline methanol, ethanol, 1-propanol, and butanols. The 2-propoxide radical anion, which is formed by the electron transfer from the hydroxide ion to the 2-propanol radical, is the chain carrier for the dechlorination reaction of PCB’s in alkaline 2-propanol solutions. The mechanism is discussed in detail.

No abstract

Chlorinated benzenes dissolved in deoxygenated alkaline 2-propanol were dechlorinated by irradiating with 6°C o r-rays to produce the lower chlorinated benzenes and chloride ion. The yield of dechlorination was found to depend on the number of chlorine atoms on the benzene ring, the G(CI-)-values being, for instance, 6,500, 480 and 2.0 for 0.07 M pentachlorobenzene, I, 2, 4-trichlorobenzene, and monochlorobenzene, respectively, in 0.2 M KOH-2-propanol solution. In contrast, the values of G(CI-) differed little between the isomers of trichlorobenzene. The large difference in G(CI-) according to the number of chlorine atoms can be explained by considering the redox potential of the chlorinated benzenes and the ketyl radical ion. Trichlorobenzene is dechlorinated to dichlorobenzene and then to monochlorobenzene while producing potassium chloride and acetone, and consuming hydroxide ion. In the experiment, some chlorinated benzene derivatives were observed to be generated in the course of this process-probably dichlorophenyl-2-propanol and monochlorophenyl-2-propanol, judging from observation by gaschromatograph-mass spectrometer and from the pathway of formation. The observation also indicated the presence of dichlorophenyl-2-propanol in predominant amounts in 1, 3, 5-trichlorobenzene solution, but only in a small fraction in 1, 2, 3-trichlorobenzene.