Bases leaching

In addition, it is possible to extend the analysis to include an ortho substituent and the associated steric effects [98-101]. Thus it is possible by this procedure to predict with some accuracy the pKa and pKb of organic acids and bases leached from COMs. 

Vernon, R. H. (1979). Formation of late sillimanite by H metasomatism (base leaching) in some high grade gneisses. Lithos 12 143-152. 

Leaching Pure Gold in Sodium Thiosulfate based Leach Solutions... 

Baron, J. Y., Mirza, J., Nicol, E. A., Smith, S. R., Leitch, J. J., Choi, Y., Lipkowski, J. (2013). SERS and electrochemical studies of the gold-electrolyte interface under thiosulfate based leaching conditions. 

Kirschner PA. Sweller J, Clark RE (2006) Why minimal guidance during instruction does not work An analysis of the failure of constructivist, discovery, problem-based, experiential and inquiry-based leaching. Educ Psychol. 41 75-86... 

To allow for better accessibility of zeolite Y crystals extensive acid and/or base leaching has been applied. The physical properties of the thus obtained HMVUSY are shown in Table 1 while electron tomography results are shown in Fig. 10. Clearly cylindrical mesopores predominate at the expense of the number of cavities in these crystals. 

ADVANTAGES OF SULPHURIC ACID BASED LEACHING PROCESSES... 

NO." cycling, can reduce base leaching from the TLW soil. Although the decrease 2-... 

Phosphoric Acid-Based Systems for Cellulosics. Semidurable flame-retardant treatments for cotton (qv) or wood (qv) can be attained by phosphorylation of cellulose, preferably in the presence of a nitrogenous compound. Commercial leach-resistant flame-retardant treatments for wood have been developed based on a reaction product of phosphoric acid with urea—formaldehyde and dicyandiamide resins (59,60). 

The attack of water is related to the leaching mechanism described for acids. Table 4 rates glasses based on their resistance to water attack. Low alkah, high alumina, or borosiUcate glasses generally have high water durabiUty. 

Fluridone is a weak base with low water solubiUty. Sorption of fluridone increases with decreasing pH (436). Leaching of fluridone was not significant in field study, and the persistence has been determined to be less than 365 days. The degradation of fluridone appears to be microbial in nature, and accelerated breakdown of the herbicide occurs upon repeated appHcations (437). Fluorochloridone is shown to degrade by hydrolysis at pH 7 and 9, but not at lower pH. The half-Hves for this reaction are 190 and 140 days for pH 7 and 9, respectively. Breakdown by photolysis occurs rapidly with a half-hfe of 4.3 days at pH 7 (438). An HA is available for acifluorfen. 

Uranium ores are leached with dilute sulfuric acid or an alkaline carbonate [3812-32-6] solution. Hexavalent uranium forms anionic complexes, such as uranyl sulfate [56959-61-6], U02(S0 3, which are more selectively adsorbed by strong base anion exchangers than are other anions in the leach Hquors. Sulfate complexes are eluted with an acidified NaCl or ammonium nitrate [6484-52-2], NH NO, solution. Carbonate complexes are eluted with a neutral brine solution. Uranium is precipitated from the eluent and shipped to other locations for enrichment. Columnar recovery systems were popular in South Africa and Canada. Continuous resin-in-pulp (RIP) systems gained popularity in the United States since they eliminated a difficult and cosdy ore particle/leach hquor separation step. 

Performance assessments are predictions of radioactivity releases, the rate of transfer of contaminants through various media, and the potential for hazard to the pubHc. These are based on a combination of experimental data obtained in the process called site characterization and detaded computations about radionuchdes and their effects. The progressive attack on the metal or ceramic waste container, the diffusion of water into the waste form, the leaching of the radioactive compounds, diffusion out, and washing away of radionuchdes are all considered. 

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