Environmental consideration alkali

Recent years have seen considerable research into the modification of cellulose and reactive dyes, specifically to overcome some of the drawbacks of this dye-fibre system, including the limited degree of fixation in full depths, the need for alkali and relatively high concentrations of electrolyte. This research, which is driven by environmental considerations, was discussed in sections 7.10 and 10.9.1. Thus it need not be considered further here. 

ENVIRONMENTAL CONSIDERATIONS AFFECTING THE GROWTH OF THE CHLOR-ALKALI INDUSTRY... 

Recently, there has been considerable interest in developing molten salts that are less air and moisture sensitive. Melts such as l-methyl-3-butylimidazolium hexa-fluorophosphate [211], l-ethyl-3-methylimidazolium trifluoromethanesulfonate [212], and l-ethyl-3-methylimidazolium tetrafluoroborate [213] are reported to be hydro-phobic and stable under environmental conditions. In some cases, metal deposition from these electrolytes has been explored [214]. They possess a wide potential window and sufficient ionic conductivity to be considered for many electrochemical applications. Of course if one wishes to take advantage of their potential air stability, one loses the opportunity to work with the alkali and reactive metals. Further, since these ionic liquids are neutral and lack the adjustable Lewis acidity common to the chloroaluminates, the solubility of transition metal salts into these electrolytes may be limited. On a positive note, these electrolytes are significantly different from the chloroaluminates in that the supporting electrolyte is not intended to be electroactive. 

These uncertainties and differences in interpretation would be less important were it not for the environmental and economic aspects of the issue described in preceding sections of this chapter. If the Recommendation were honoured to the letter and all OSPAR area chlor-alkali plants were to be forced to close or convert by 2010, we would see no environmental gain but considerable economic and social damage. EU lawyers might also like to consider the situation for major producer countries like France and Spain where some of their plants are within the OSPAR catchment area and others - with drainage to the Mediterranean basin -are not ... 

It is necessary to bleed about 25% of the filtrate from the carbonate precipitation to maintain material balances. This large bleed is due to the sulfate added in the sulfuric acid leach and because the waste material contains considerable amounts of alkali (KOH) and water. The bleed needs special treatment to recover ammonia and to produce an environmentally acceptable effluent. 

The hydrochloric acid formed should then be neutralized with an alkali agent such as aqueous ammonia, sodium hydroxide, lime slurry, etc., and should be added as an aqueous solution with agitation to the acidic medium. Consideration must be given to the additional heat that will be produced by the neutralization. Silicon-containing solids should be washed to remove residual acid. Discard any product, residue, disposable container, or liner in an environmentally acceptable manner, in full compliance with federal, state, provincial, and local regulations. 

Numerous types of basic heterogeneous catalysts, such as alkahne earth metal oxide, anion exchange resins and alkali metal compounds supported on alumina or zeolite can catalyze various chemical reactions such as isomerization, aldol, Michael, and Knoevenagel condensation, oxidation and transesterification [1], Today considerable attention is devoted to the production of biodiesel (FAMEs) as an alternative for petroleum-derived diesel fuel. Biodiesel is synthesized by direct transesterification of vegetable oil or animal fat with a short-chain alcohol, viz. methanol, ethanol, and isopropanol in presence of an acid, base or enzymatic catalyst [2], Considering the advantages of solid base catalysts, for easy separation and recovery, reduced corrosion and environmental acceptance [1], many studies have been conducted on basic heterogeneous catalysts development for biodiesel production [3-13],... 

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