Accelerators organic, commercial types

Accelerants are used to increase coating weight and shorten coating time. Many different accelerants can be used including a variety of organic and transition metal compounds [60, 91], The predominant accelerant in commercial formulations is ferricyanide, Fe(CN)6 , which is added to acid chromate-fluoride formulations in concentrations ranging from 2 to 5 mM [92, 93]. The two primary theories for the action of Fe(CN)6 are (1) formation of mixed metal cyanide compounds [91, 94, 95] and (2) acceleration of the film-forming Cr(VI) to Cr(III) reduction reaction by Fe(CN)6 /" redox mediation [96]. These types of CCCs are discussed in more detail below. 

Zinc oxide is commercially the most important compound of zinc and it is used to a considerable extent in the rubber, ceramic and paint industries. It is utilized to activate the organic accelerator of the vulcanization process for natural rubber and for most synthetic rubbers. Also zinc oxide serves as the accelerator for some types of elastomers. Further, it provides reinforcement to the rubber, it improves its heat conduetivity, it limits the degradation by UV radiation and it improves adherence. Typically, rubber eontains 2 % zinc oxide. A very broad range of other compounds are of extensive interest in chemistry, biology and physics and they make great practical contributions to the chemical, ceramic, fertilizer, paint, plastics, textile and electronics industries. 

The kinetics of the extraction of metals, especially copper(II), by ort/io-hydroxyoximes (HA) has been widely studied in recent years.146 Of particular interest is the observation that the rate of extraction can be considerably increased by the incorporation of small amounts of aliphatic a-hydroxyoximes (H2B) into the organic phase.168 An even more marked effect has been noted with a-dioximes.169 170 Accelerator compounds of the former type are used in Henkel s commercial extractant LIX 64N, whereas those of the latter type are used in the Shell reagent SME 530. 

Highly dealuminated Y zeolite, commercially labeled as DAY (dealuminated Y), with an FAU framework type is an excellent adsorbent for the removal of organic compounds in wastewaters, as a consequence of the hydrophobic surface properties of this zeolite, owing to the low concentration of A1 (see Section 2.5.1). As an example of adsorption in a zeolite, in Figure 6.9, the N2 adsorption isotherm at 77 K of the DAY zeolite, DAY-20 F (Si/Al = 20), provided by Degussa AG, Dusseldorf, Germany, is shown. The N2 adsorption isotherms were measured with an Accelerated Surface Area and Porosimetry System (Autosorb-1) from Quantachrome, Boynton Beach, FL, USA [21] which is a volumetric automatic equipment similar to that reported in Figure 6.8. 

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