Sodium form saturation capacities

The temperature programmed desorption (t.p.d) of n-hexane from the sodium and hydrogen forms of ZSM-5. ZSM-11 and THETA-1 have been studied. The t.p.d profiles have been analysed by a newly developed method. From these analyses peak temperatures, peak widths, maximum rates of desorption and activation energies of desorption as a function of coverage have been obtained. The saturation capacities of these high silica zeolites for n-hexane have also been determined. The effect of change of cation on all of these quantities is demonstrated. 

Cation-exchange capacities (CEC) of clay samples were determined based on the amount of Ca which was replaced by Na. Each clay sample (0.3 g) was diluted with quartz sand and packed in a Pyrex column (18 mm diameter). Aqueous Ca(CH COO) (0.5 M) was added and the clay was saturated with Ca ion. The clay was washed with a 90% EtOH solution and again exchanged to the sodium form with 1.71 M aqueous solution of NaCl. The Ca ions leached out were determined by chelatometric titration. 

Dihydroxybenzaldehyde 5 9 0 A reaction flask (500-ml capacity) is fitted with an efficient stirrer, a reflux condenser, and a wide gas-inlet tube the end of the condenser is connected to, successively, a wash-bottle containing sulfuric acid, an empty safety flask, and a tube that passes over the surface of a sodium hydroxide solution. Resorcinol (20 g) and anhydrous ether (150-200 ml) are placed in the reaction flask, and anhydrous zinc cyanide (1.5 equivalents) is added. Then a rapid stream of dry gaseous hydrogen chloride is passed in. The zinc cyanide disappears as a milky mixture is formed and as the hydrogen chloride dissolves, the imide hydrochloride condensation product separates as a thick oil which solidifies in 10-30 min. The ether is usually saturated in 1.5 h, after which hydrogen chloride is passed in slowly for a further 0.5 h. Then the ether is decanted, water (100 ml) is added to the imide hydrochloride, and the solution is heated to the boiling point, filtered and allowed to cool. About half the aldehyde separates. After this has been collected the remainder of the aldehyde crystallizes in 10-15 h. The total yield is about 95 %, and the m.p. is 135-136° after recrystallization with charcoal from water. 

Inorganic arsenic, MMA, and DMA were found to be the only metabolic forms of As in urine of volunteers who ingested 125, 250, 500, or 1000//g sodium As daily for 5 days (Buchet et al. 1981a). The amounts of iAs, MMA, and DMA excreted in urine on day 5 (taken separately or together) correlated significantly with daily ingested dose. As noted above, this study provided equivocal evidence that the capacity for methylation of As could be saturated at high levels of iAs intake. 

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