November, 1931
INDUSTRIAL A N D ENGINEERING CHEMTSTR Y
formation of the phosphoric acid to the available form. The favorable temperature for the transformation is about 65’ C., and a steady state or equilibrium is attained when about twothirds of the phosphoric acid has become available. On increasing the temperature, the amount of transformation falls off, there is much decomposition of the sulfur dioxide, and much more sulfur dioxide is apparently absorbed than corresponds t o the available phosphates produced. Free sulfur, sulfates, sulfides, and sulfites are formed. Probably a t moderate temperatures thiosulfates are formed. When tricalcium phosphate or finely ground phosphate rock is heated in a current of sulfur dioxide, the maximum transformation of the phosphoric acid t o an available form is attained at about 450’ C. Probably it is due t o a maximum formation of sulfur trioxide a t this temperature, the reaction being between the phosphates and the trioxides rather than the dioxide of sulfur. T h e highest possible transformation seems t o be about two-thirds of the total phosphoric acid present in the phosphate. Large amounts of sulfates, sulfides, and elemental sulfur, but no sulfites or thiosulfates, are formed a t high temperatures. Protective coatings form on the reaction mass which can be removed mechanically. With increase in temperature the available phosphate in the reaction product decreases rapidly to a vanishing amount at 1100” C. and 2.5 atmospheres.
(9) (10) (11) (12) (13) (14) (15) (16) (17) (18) (19)
Literature Cited
(31) (32) (33) (34) (35) (36)
(1) (2) (3) (4) (5) (6) (7) (8)
Aufsalzteil, Z . angew. Chem., 34, 272-5 (1921). Bailey, J. Chem. Soc., 121, 1813 (1922). BaumC and Tykociner, J . chim. phys., 12, 270 (1914). Bergstrom, J . Phys. Chem., 26, 358 (1922); Bull. s c i . a t a d . roy. Belg.. 6, 529 (1919). Bichowsky, J . A m . Chem. Soc., 46, 2225 (1924). Birnbaum, Ber., 13, 651 (1880). Briner, J . chim. phys., 4, 476 (1906). Briner and Wronynski, Z . anorg. Chem., 63, 49 (1909).
(20) (21) (22) (23) (24) (25) (26) (27) (28) (29) (30)
(37) (38)
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Burrell and Robertson, J. Am. Chem. Soc., 37, 2691 (1915). Campbell, Pulp Paper Mag. Can., International No. 128 (Feb., 1928) Carter and Butler, J . Chcm. Soc., 123, 2370 (1923). Defries, British Patent 17,384 (1915). Designolles, U. S. Patent 196,881 (1877). Faber, British Patent 302,290 (1927). Farnell, J. SOC.Chem. I n d . , 44, 530-2T (1925). Forester and Kubel, Z. anorg. allgem. Chcm., 139, 261 (1924). Freeze, Wochbl. Papierfabr., 61, 861 (1920). Gerland, J. prakt. Chem., [2] 4, 97 (1871). Griffin, ”Technical Methods of Analysis,” 2nd ed., p. 763, McGrawHill, 1921. Hammick, J . Chem. Soc., 111, 379 (1917). Henning, Ann. Physik, 22, 609 (1907). Henning and Stock, Z . Physik, 4, 226 (1921). Hodgman and Lange, “Handbook of Chemistry and Physics,” Chemtcal Rubber Publishing Co., Cleveland, Ohio. Hofbauer, Z . physik. Chem., S4, 764 (1914). Holborn and Baumann, Ann. Physik, 31, 945 (1911). Linden, J. SOC. Chem. I n d . , 36, 96 (1917). Lorah, Tartar, and Wood, J. .4m. Chem. Soc., 61, 1097 (1927). Mebane, Dobbins, and Cameron, J. Phys. Chem., 33, 961 (1929). Mieg, Res. sci., 67, 202 (1919). Roozeboom, Rec. traw. chim., 3, 29 (1884); 4, 65 (1885); Z. physik. Chem., 2, 425 (1888). Rotondi, Ann. chim., 74, 128 (1882). Scheel and Heuse, Ann. Physik, 29, 723 (1909); 31, 715 (1910). Schott, Dinglers poljtech. J . , I , 202, 52 (1871). Sestini, J . SOL.Chem. Ind., 31, 293 (1912); Ind. Chim., 11, 49-53 (1912). Thilo, Z . physik. Chem., Abt. A, 148, 361 (1930). Tirelli, Rass. min. met. chim., 26, 101-3, 118-20 (1907); Rev. prod. chim., 22, 5-7 (1919). Veley, J . Chem. S O L , 63, 82 (1893). Waggaman and Easterwood, “Phosphoric Acid, Phosphates, and Phosphatic Fertilizers,” American Chemical Society Monograph 34, Chemical Catalog, 1927.
Sorption of Water Vapor b y Paper-Making Materials I--Eff ect of Beating’ C. 0.Seborg a n d A. J . Stamm FORESTPRODUCTS LABORATORY,% FORESTSERVICE, U. S. DEPARTMENT OF AGRICULTURE, MADISON,WIs.
M e a s u r e m e n t s were m a d e of the m o i s t u r e contentrelative h u m i d i t y a n d m o i s t u r e content-electrical conductivity relationships of p u l p a n d stuffs. An a p p a r a t u s was designed for m e a s u r i n g t h e relative h u m i d i t y relationship of materials a t a t m o s p h e r i c pressure, using a m e t h o d in which air, humidified by passi n g t h r o u g h various s a t u r a t e d s a l t solutions t o give the desired relative humidities, was circulated a b o u t the adsorbent m a t e r i a l suspended from a sensitive q u a r t z helix balance. The extensions of this balance were
measured w i t h a cathetometer. T h e hydration (hygroscopicity) of the pulp, which t h e regularity of t h e curves showed to be physical r a t h e r than chemical, was not affected by beating. Electrical conductivity-moisture c o n t e n t relations likewise showed n o differences between beaten a n d u n b e a t e n Pulp. The so-called h y d r a t i o n of t h e paper i n d u s t r y is n o t a t r u e hydration. It is probably a p h e n o m e n o n of fiberfiber bonding r a t h e r than of fiber-water bonding.
. . .. .. . . .. .. .. HE objectives in this series of studies are to determine the hygroscopicity of pulps, stuffs, and the various components of wood under normal atmospheric conditions; to determine the relationship of the sorption hydration (hygroscopicity) to the so-called hydration of the paper industry, that is, the change in properties of fibers produced by beating which in the past has been assumed to result from a change in their ability to retain water; to determine the extent to which this sorption hydration affects the fiberbonding properties; and t o critically study the desorptionadsorption hysteresis. The various materials to be studied are sulfite, kraft,
T
1 Received July 8, 1931. Presented before the Division of Cellulose Chemistry a t the 82nd Meeting of the American Chemical Society, Buffalo, N. Y.,August 31 t o September 4, 1931. Maintained at Madison, Wis., in cooperation with the University of Wisconsin.
soda, and semi-chemical pulps; bleached pulps; beaten pulps; isolated wood components, such as lignin, Cross and Bevan cellulose, and alpha cellulose from both pulp and Cross and Bevan cellulose; and furnishing materials, such as coatings, sizings, and fillers. This paper deals only with the effect of beating on the sorptive hydration of a sulfite pulp. The word “sorption” is the same as used by McBain (8) to include both adsorption and absorption phenomena. Previous Sorption Studies
A number of investigators have published papers on subjects pertaining to the hysteresis of the adsorption and desorption of water vapor by various materials, which ranged from silica gel to textiles and paper ( 1 , W, 6, 7 , 11, 12, 13, 15, 16, 17, 18, 19).
-411 of these investigators, with the exception of Patrick (11)
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and his co-workers, have obtained definite hysteresis effects. The hysteresis effect in non-elastic gels, such as silica gel, has been attributed by Zsigmondy (19) to a difference under adsorption and desorption conditions in the curvatures of the menisci of the liquid filling the capillary spaces. These differences in curvature are supposedly due to differences in the wetting of the capillary walls, which are less readily wetted after drying. A somewhat different explanation, by Urquhart and Williams ( l 7 ) , is more applicable to elastic gels, such as cellulose, in which the swelling follows adsorption from the start. These investigators attribute the effect to the free
b
Figure 1-Sorption a-Inlet b-Humidifying c-Spray trap d-Manifold
chambers
Apparatus e-Stopcocks
