INDUSTRIAL AND ENGINEERING CHEMISTRY
1212
general, a 2 per cent solution of sodium carbonate would be most practical. One of the most striking characteristics of this resin, in contrast with exchange material in general, is its extremely high capacity for adsorption and the high chemical efficiency of regeneration. As might be expected, the rinse water requirements of Amberlite IR-4 are dependent upon the rate of flow used, the high rates of flow being rather inefficient. In general, at a flow rate of 1 gallon per square foot per minute, the equivalent of 60 gallons of water per cubic foot of resin was required. Philadelphia tap water was used for rinsing downflow. Complete removal of sodium salts from the resin bed after regeneration by sodium carbonate solution is necessary; otherwise these neutral salts will appear in the effluent during the beginning of the next run. Figure 27 is a photograph of a commercial installation for water treatment in the powerhouse of a large chemical manufacturing plant. The two units are 7 X 4 foot rubber-line tanks with stainless steel fittings. At present both units are filled with 30-inch beds of cation exchangers, one with Amberlite and the other with a carbonaceous cation exchanger for comparison. Both are operating in the sodium cycle t o give completely softened water from a raw water whose average hardness is 3.0 grains (51 p. p , m.) of calcium carbonate. The Amberlite IR-1 unit has operated successfully at rates of 1t o 9 gallons per square foot per minute, the head loss (downflow operation) of the unit being substantively 1 pound per
Vol. 33, No. 9
square inch a t these rates. The raw water pressure is 60 t o 70 pounds per square inch. The performance of the two units is still under study and will be reported in detail in a later paper. T o date, the resin exchanger has given excellent performance.
Literature Cited Adams, B. A., and Holmes, E. L., J . SOC.Chem. I d . , 54, 1-6T (1935); Brit. Patents 450,308-9 (June 13, 1936), 474,361 (Nov. 25, 1937) ; French Patents 796,796-7 (April 15, 1936) ; U. S. Patents 2,104,501 (Jan. 4, 1938). 2,151,883 (March 28, 1938). 2,191,853 (Feb. 27, 1940).
Am. Water Softener Co., unpublished data. Babbit and Doland, “Water Supply Engineering”,p. 593 (1939). Collins, L. F., J . Am. Water Works Aasoc., 29, 1472 (1937). Davis, D. E., Ibid., .29, 1517 (1937). Griessbaoh. R., “fiber die Herstellung und Anwendung neuer Austauschadsorbienten, inbesondere auf Harzbasis”, Berlin, Verlag Chemie, 1939; Angew. Chem., 52,215 (1939); Melliand Temtilber., 20, 577 (1939).
Myers, R. J., Eastes, J. mi., and Myers, F. J., IND.ENQ.CHEIM., 33, 697 (1941).
Myers, R. J., Eastes, J. W., and Urquhart, D. J., Ibid., to be aublished. 018on, H. M., Ohio Conf. Water PurZfication, 18th Ann. Rept., 1938, 98-101.
Richter, A., Angew. Chem., 52, 679 (1939) : Melliand Textitber., 29, 579 (1939). Seyb, E., Chem. Fabrik,1940, 30.
PRUSENTUD before the Division of Water, Sewage, and Sanitation Chemistry at the l O l s t hleeting of the American Chemical Sooiety, St. Louis, Mo.
CORRESPONDENCE Effect of Sodium Sulfate on Alkali Resistance of Portland Cement TDA mixture in cement was shown by Kenned a t o promote better dispersion with consequent improved griniability, increased strength, and better setting qualities. Siliceous materials have been shown to increase the resistance of concrete to alkali and the cement can be changed to the double sulfoaluminate. In sea water attack, although such mixtures usually set slowly. this way the expansion, which accompanies the double salt forOn the other hand numerous admixtures advocated to inmation, will occur before the cement has hardened, and specicrease the strength of cement or to impart special properties, mens made from such a mix might be sound under certain condias alkali resistance, waterproofness, or workability, have such tions in contact with sulfate solutions. been tested and found to be worthless for the purpose claimed Unfortunately, however, the sulfoaluminate forms crystals or to decrease strength t o such a degree as to nullify any advantwhich continue to grow in certain orientations with changes in age gained in other respects. temperature and moisture content. Such growth is very apt to Although sodium sulfate is among the materials cause disintegration of conc.rete.1 The sodium hydroxide set regarded as objectionable in concrete mixes, the r e s u ? t t g % free by interaction with the lime from the hydrated cement may show that addition of sodium sulfate markedly improved alkali react in many unfortunate ways, including painful attack upon resistance and that tensile strength was also increased especially the epidermis of the applicators. at early ages. All cement contains some alkali and ’is more or It is hoped that these facts will suggest the desirability of makless caustic, and only trial will show whether the mixture is “hot”. ing adequate tests before investing much money in portland Even then the workmen can be protected. cement-sodium sulfate mixes. The references cited by Anderegg do not show the effect of usF. 0. ANDEREGG ing sodium sulfate, as he apparently used calcium sulfate. In Newark, Ohio our experiments only sodium sulfate improved either strength or alkali resistance. The mechanism of stabilization advanced * * . e by Anderegg does not explain why other soluble sulfates, which would likewise react with the aluminate, do not stabilize the ceSIR: Anderegg emphasizes the general attitude toward the ment. It seems doubtful, therefore, that a simple reaction of sulpresence of sodium sulfate in cement and concrete. Effloresfate with the calcium aluminate suffices t o explain the results. cence, “hotness” or causticity, and weakened concrete are some of The authors entirely agree that further investigation should be the evil effects often described as caused by sodium sulfate. Usumade before investment of much money. ally alkali resistance is secured by controlling the cement comAn error in the caption of our Figure 1 (page 692) has been position and limiting the alumina content. noted; 10 per cent was the strength of the sodium sulfate soluMany attempts have been.made t o improve the quality of tion instead of 4 per cent as printed. concrete by admixture of various compounds to the cement or PHILIP H. DELANO concrete mix, and some of these have proved beneficial for specific purposes. For example, the use of small amounts of 12061/$ Riverside Drive
SIR: By the addition of sodium sulfate to portland cement,
as proposed by Delano and Weber [IND. ENG.CHEM.,33, 692 (1941)] it is true that most of the tricalcium aluminate found in
1 Anderegg, F. O., Proc. Am. Concrete Fab. 28. 1931.
I n a t . , 23, 332 (1929); Rock Producta,
Tusoaloosa, Ala. 1
IND. ENQ.CHEX., 28, 963 (1936).
