Environ. Scl. Technol. 1092,26, 1847-1847
Literature Cited (1) Diyamandoglu, V.; Marifias, B. J.; Selleck, R. E. Enuiron. Sci. Technol. 1990,24, 1711-1716. ( 2 ) Lister, M. W.; Rosenblum, P. Can. J. Chem. 1961, 39, 1645-1651. (3) Weil, I.; Morris, J. C. J.Am. Chem. SOC.1949,71,1664-1671. (4) Hoign6, J.; Bader, H.; Haag, W. R.; Stlihelin, J. Water Res. 1985,19, 993-1004.
Werner R. Haag
Purus, Inc. 2713 North First Street San Jose, Callfornia 95134
S I R The correspondence by Dr.Haag (1)regarding the findings of our kinetic analysis on the reaction of nitrite with free chlorine contains serious errors. The stoichiometric analysis of our experimental results indicated that the reaction between nitrite and free chlorine can be represented by dA/dt = -KAC (1) where A and C represent nitrite and free chlorine concentrations and K represents the overall rate constant. The paper analyzes two possible reaction mechanisms (pH > 9): (a) Reaction between nitrite and hypochlorous acid. In this analysis the overall rate constant K becomes K = k[H+]/K, (2) where k represents the true rate constant. Equation 2 depicts the dependency of K on [H+]. (b) Reaction between nitrous acid and hypochlorous acid. In this analysis the true rate constant kl is (pH > 9) kl = ~ K N / [ H + ] (3) Combining eq 2 and eq 3 kl = kK,/[H+] = KKAKN/[H']' and rearranging
K = k,[H+I2/K~K~
0013-936X192/0926-1847$03.00/0
which depicts the second-order dependency of K on [H+I2. Eguations 1-3 correspond to eqs 2 , 9 , and 16 of the original paper (2). The overall rate constant K was determined from the experimental data using eq 11 of the original paper. Rate constants k and kl were then calculated using eq 2 and eq 3. Dr. Haag (1) points out that the equation postulated by Lister and Rosenblum (3) WLLSperceived by these authors to contain no pH dependency. This is incorrect. The pH dependency is the same as the one shown in eq 2. Dr. Haag also states that if the reaction were to occur as described in case b, one would expect a second-order dependence on [H+]for the rate constant, contrary to what the authors observed. This statement is also incorrect as depicted in Figure 5 and numerically shown in eq 12 of the original paper. Rate constants k and K are dependent on [H+]and ["I2, respectively. The most significant support to the suggestion that the reaction proceeds as described in case b is the comparison of experimental data with analytical results, examples of which are shown in Figures 8 and 9 in ref 2. Finally, the pH dependency described herein has also been independently observed by Dr. S. Leung during his graduate studies at the University of Iowa (4). We suggest that the editor invite Dr. Leung or his thesis adviser Prof. Richard L. Valentine to prepare a commentary comparing the results of our study with those of Dr. Leung. Registry No. Chlorine, 7782-50-5; nitrous acid, 7782-77-6; hypochlorous acid, 7790-92-3.
Literature Cited (1) Haag, W. R., preceding letter in this issue. (2) Diyamandoglu, V.; Marinas, B. J.; Selleck, R. E. Enuiron. Sci. Technol. 1990,24, 1711-1716. (3) Lister, M. W.; Rosenblum, P. Can. J . Chem. 1961, 39, 1645-1651. (4) Leung, S. Ph.D. Dissertation, University of Iowa, Iowa City, IA, 1989.
Vas11 Diyamandoglu,* Benlto J. Marlfias Civil Engineering Department The City College of The City university of New York Convent Avenue at 138th Street New York, New York 10031
0 1992 American Chemical Society
Environ. Sci. Technol., Vol. 26, No. 9, 1992
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