Organic Compounds Produced by the Aqueous Free-Chlorine-Activated Carbon Reaction Vernon L. Snoeyink,*t Robert R. Clark,* John J. McCreary,*§ and William F. McHie* Department of Civil Engineering, University of Illinois, Urbana, Illinois 6 1801 ~~
Materials a n d Methods
Granular activated carbon reacted with an amount of free chlorine in excess of 2 g as Clz/g of carbon produces a brownblack colored product and volatile organic compounds. The brown-black color was isolated and found to be of predominantly high molecular weight (100 000) with many carbonyl and hydroxyl groups and to have no mutagenic response in several test systems. Degradation of the colored product provided little additional structural information. Large quantities of volatile organics produced in batch reaction at high free-chlorine dosages (several grams of chlorine per liter) were not produced in column experiments at low dosage (10-50 mg of chlorine/L). Some increases in chloroform were apparent in column runs only after a 2 g of chlorinelg of carbon ratio had been achieved. Solvent extraction of the column effluent and the carbon in the column yielded no additional chlorinated organics formed from the carbon-chlorine reaction. The extent of chlorination required to produce significant chlorinated organics makes it unlikely that the reaction of chlorine with virgin granular carbon will pose a problem in drinking water treatment facilities. Introduction Aqueous chlorine often comes into contact with activated carbon, for example, when it is added to disinfect drinking water in water purification plants using activated carbon. The chlorine may react with the activated carbon surface or with compounds adsorbed on it. The kinetics of the free-chlorine-activated carbon reaction have been studied extensively ( I , 2), and, although this reaction may affect the adsorption properties of the carbon if extensive amounts of chlorine react (3), it has been shown that the effects on the carbon's properties even after several regenerations are insignificant if only moderate amounts of chlorine are reacted ( 4 ) . The monochloramine-activated carbon reaction (5) and dichloramineactivated carbon reaction (6) have also been closely examined. The inorganic products of the free-chlorine-activated carbon reaction include acidic oxides on the carbon surface, H+ and C1- (7, B ) , and chlorate after extensive (-1 g/g of carbon) amounts of chlorine react (9). Considerably less is known about the organic products of the free-chlorine-activated carbon reaction. It has been observed that continued reaction of free chlorine with carbon to a level of 1-4 g of chlorinelg of carbon results in the production of a dark brown colored material that is difficult to adsorb on carbon ( I O ) , and that application of more chlorine will result in disintegration of the carbon. Boehm ( 1 1 ) and Olson and Binning (12)also found this product. I t had a more intense color a t high pH than at low pH, but the product at each pH appeared similar on the basis of UV and IR spectra (12).In this paper the colored product is further characterized. Products of the reaction of chlorine with adsorbed compounds will be examined in a later paper. + Department of Environmental Engineering. Department of EnvironmentalEngineering. 5 Current address: Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL. 188
Environmental Science & Technology
Materials. The carbons used in the batch experiments were F-400 (Calgon Corp., Philadelphia, PA) and Hydrodarco 3000 (IC1 America Inc., Wilmington, DE). The carbon was sieved, washed, dried, and, if necessary, baked at 175 "C for 1 week to remove volatile impurities (such as benzene, toluene, etc.). The presence of volatile impurities on the carbon was checked by purging 1g of carbon in 100 mL of distilled-deionized water in a purge-and-trap apparatus as described below. Chlorine solution was prepared by bubbling high-purity chlorine gas (Linde Specialty Gas, Union Carbide, New York, NY) into distilled, deionized, and purged water made alkaline with several grams of NaOH per liter. The titer of the chlorine was checked by using the DPD procedure (13). Colored Product. The colored product was generated from Hydrodarco carbon by applying distilled water containing -500 mg/L aqueous chlorine as Clz with a 0.001 M phosphate buffer a t p H 7 to a 1 X 10-cm column containing 2.2 g of carbon. The flow rate was -3 mL/min or -1 gal/(min ft2).Colored product first appeared in the effluent after -1.5 days. Precipitation at pH 1-2 and filtration (0.45-km Nucleopore, Nucleopore Corp., Pleasanton, CA) were used to concentrate the colored product, and it was then dissolved in 0.1 N NaOH. The alkaline filtrate was dialyzed (molecular-weight cutoff: 12 000-14 000, Spectrapore, Los Angeles, CA) against distilled water for 3 days during which time the water was changed every day. The colored solution was then freeze-dried; scanning electron microscope photos of the product did not show fine carbon particles. The infrared spectrum was run on a Beckman IR-4260 dual-beam spectrophotometer, and the visible and ultraviolet spectra were run on a Beckman Acta I11 spectrophotometer (Beckman Instruments, Inc., Fullerton, CA). The elemental analysis was run by the School of Chemistry's analytical services laboratory a t the University of Illinois. Carbon, hydrogen, and nitrogen were determined by using a Perkin-Elmer Model 240 CHN analyzer (Perkin-Elmer, Norwalk, CN); sulfur was determined by barium titration, and chloride was determined by mercury titration, both after reduction. Amicon Ultrafilters (Amicon, Lexington, MA) with molecular-weight cutoffs of 300 000,100 000,50 000 and 10 000 (SM300, SM100, SM50, PM10) were used in a 400-mL ultrafiltration cell (Model 402) to determine molecular size. (An initial attempt to use Sephadex (Pharmacia Fine Chemicals, Inc., Piscataway, NJ) was not successful because the colored product adsorbed to it.) The amount of colored product in the filtrate and retentate was determined both by absorbance at 400 nm and by total organic carbon (TOC) (Model 915, Beckman Instruments, Inc., Fullerton, CA). The colored product was examined for mutagenic activity with several Salmonella typhimurium (TA 1975, TA 1535, TA 100, TA 1978, TA 1538, TA 98, and TA 1537) and Escherichia coli (WP-2, WP-2uvrA-, WP-2/100, CM 561, CM 571, CM 611, CM 871, and CM 971) strains. S. typhimurium strains were tested for histidine-dependent reverse mutations while the E. coli strains were tested for tryptophan-dependent reverse mutations. The tests were conducted with the assistance of Dr. J. Johnston, University of Illinois, using the DNA-repair assay developed by him which can detect muta-
0013-936X/81/0915-0188$01.00/0 @ 1981 American Chemical
Society
tion and/or fatal DNA damage (toxicity) over a wide range of concentrations on a single plate. The repair assay was performed with and without S-9 activation. The bacterial induction assay developed by Elespuru and Yarmolinsky ( I 4 ) using E. coli strain BR 513 was also used. If the DNA is mutated or damaged, this strain produces /3-glactosidase, which is then assayed. The colored product was assayed with and without S-9 activation. Fragmentation of the colored product was done so that it could be studied by gas chromatography-mass spectrometry (GC-MS). Two techniques developed by Christman et al. (15, 16) for humic acid degradation were used; humic acid extracted from peat and purified (ether washed, dialyzed) was used as a control to assure that the techniques were properly applied. (1) Humic acid or colored product (0.5 g) was dissolved in 200 mL of distilled water with 8 g of KMn04 and refluxed. After 48 h the excess KMn04 was destroyed with methanol, the pH was adjusted to pH 1,and the MnOz(s) was removed by centrifugation, The supernatant was extracted with ethyl acetate (3X with 60 mL), and the ethyl acetate was dried over NazS04 and evaporated to dryness. The sample was taken up with 2 mL of methanol and methylated with Diazald (Aldrich Chemical Co., Milwaukee, WI). (2) Humic acid or colored product (0.5 g) was dissolved in 200 ml of 5 N NaOH in distilled water. After reflux for 20 h, acidification to pH 1,and centrifugation, the supernatant was extracted as in part 1.The samples were analyzed on a Hewlett Packard GC/MS Model 5985.4 (Avondale, PA). A 2-pL injection was made into a 20-m SP-2100 glass capillary column at 20 O C . The column was programmed from 20 "C with a 5-min hold to 240 OC at 2 OC/min. Chlorine-ActivatedCarbon Reaction. Batch tests (125 mL of chlorine solution plus activated carbon in headspacefree, aluminum-coveredbottles sealed with Teflon) were used to determine volatile and extractable compounds. After 4-7 days on an inversion shaker, remaining chlorine was reduced with excess sodium sulfite, and the bottles were recrimped and refrigerated at 4 "C until analyzed. Samples were warmed to 20 OC before purge-and-trap analysis using high-purity nitrogen (200 mL/min, 20 min) and a 0.5-g Tenax trap. A 12-ft 0.2% Carbowax 1500 on Carbopack C column programmed from 40 to 170 OC at 8 "C/min, with FID, was used for GC analysis. Several of the samples were extracted with 2 mL of pentane (Burdick and Jackson, distilled in glass, Muskegon, MI). The extracts were combined and then concentrated to 10 pL by using a Kuderna-Danish evaporator with Snyder column (Kontes, Vineland, NJ) followed by passage of a stream of high-purity helium over the extract. A 2-pL split (141) injection of the extract and methylated extract (Diazald, Aldrich Chemical Co., Milwaukee, WI) was made into a 60-m SP-2100 capillary column, 135 OC, in a 5736 Hewlett Packard GC (Avondale,PA) with EC detection. GC/MS identification of volatile organics was done with a Hewlett Packard 5985A system (Avondale, PA), and duplicates were analyzed by California Analytical Laboratories, Sacramento, CA, for confirmation. The compounds were identified by using computerized data systems and published spectra (17). Column tests using carbon secured between baked Pyrex wool in glass columns (0.5 g of carbon in 3-mm i.d. tube; 50 g of carbon in 3-cm i.d. tubes) were also used. Chlorine solution was applied with a metering pump, and samples were periodically analyzed by purge-and-trap and a pentane extraction procedure described by Grob (18).The large columns were constructed with three sections, each with ground-glass fittings, so carbon samples could easily be taken at the one-third points. At the conclusion of the run, 1-2-g samples of carbon were taken, several milliliters of CH30H were added, and the samples were Soxhlet extracted for 24 h with CH2C12. The
extracts were concentrated, derivatized, and injected splitless into a 20-m capillary column as described for the coloredproduct degradation products. The effluent from the columns was analyzed for aqueous TOX as described by Dressman et al. (19).
Results and Discussion Colored-Product Characterization.Colored product (-1 g) was obtained from each 2.2 g of carbon. Each column was run for 5 days at which time 75% of the carbon had been converted to soluble organic matter or fines. Chloroform from the carbon-chlorine reaction and residual chlorine appeared in the column effluent before colored-product production started. Ca. 60% of the effluent TOC and 95% of the product which adsorbed light at 400 nm were recovered by the precipitation-filtration technique. The pH 1filtrate was a pale yellow. Only the colored product which could be recovered by precipitation-filtration was examined. The infrared spectrum of the colored product (Figure 1) shows only a few peaks. The large, broad band at 3400 cm-l could be due to HO-C bonds or water in the sample. The band at 1600 cm-l could be due to aromatics. The band at 1400 cm-l could be due to hydroxyl groups, and the small band at 1750 cm-l to C=O bonds. These assignments agree with those of Olson and Binning (12); however, we did not observe peaks at 2900 and 2830 (alkanes), 1130 (esters), and 690 and 620 cm-l (C-C1 bond), which they observed. Their product may have contained salts and other low molecular weight organic compounds which complicated their spectrum because they did not use a purification step such as precipitation or dialysis. The ultraviolet and visible spectra showed only an increased absorption at shorter wavelengths. This is different from the results of Olson and Binning (IZ),who found three peaks. Again the reason may be the differences in the isolation technique and the presence of lower molecular weight compounds. Table I shows the elemental analysis of virgin activated carbon and the colored product. The colored product has a significantly higher chlorine and oxygen content. Puri et al. (20) noted that the chlorine must be bonded to the activated carbon. Since the colored product was dialyzed against distilled water, no chloride should be present. The increase in oxygen is due to the oxidation of the carbon by the chlorine. The nitrogen and sulfur contents are consistent with the colored product being an oxidized portion of the carbon surface. Table I1 shows the molecular-size data. The effluent from the 300 000-M, filter was passed through the 100 000-M, filter and so on. The amount of colored product passing through and that being retained by each filter was then determined by measuring absorbance at 400 nm and TOC. From the concentration of colored product and the volume passed or retained, the mass of material passed or retained was determined. Absorbance proved to be a much more sensitive 100
1 i
=I-
cm-'
Flgure 1. IR spectrum of colored product. Volume 15, Number 2, February 1981
189
technique than TOC. The colored-product species are very large, with 84 (TOC) to 90%being larger than 100 000 M,. The mutagenicity tests showed that the colored product was inactive in all of the test systems. Since the three tests are widely different and complementary, it is safe to assume that the colored product is not genotoxic. The two degradation procedures did not break down large portions of the colored product, although the NaOH procedure was somewhat more effective (15,16). Except for vanillin and several fatty acid methyl esters which indicate the presence of carboxyl groups, there was little similarity between the colored-product fragments and the humic acid fragments identified by Christman et al. (15,16).Few other compounds were identified. Batch Experiments. Several batch experiments were conducted by using 400 mg/L Hydrodarco carbon (60 X 80 mesh) and a very high free-chlorine concentration of 1g/L at p H 7 (initial). The chlorine was depleted in 4 days; purgeand-trap chromatograms (see Figure 2 for typical results) of the samples showed increased quantities of several compounds as well as new compounds when compared to the chromatogram of the blank solution which was chlorinated without carbon. Analysis of a blank sample containing only water and carbon showed that the compounds were not contaminants on the carbon. GC/MS analyses of duplicate samples at two laboratories gave the results shown in Table 111. The increases in concentration as compared to the chlorinated blank were from 300 pg/L to -1.6 mg/L for CHC13, from 8 to 34 pg/L for CCl4, from 0.8 to 6.7 pg/L for benzene, and from 0.3 to -1.8 pg/L for toluene. Several compounds were found only in the chlorine-carbon solution; among these were bromodichloromethane, dichloropropene, and several chlorinated aromatics. The purge-and-trap procedure with FID was very sensitive to aromatic hydrocarbons, and the increase of benzene and toluene a t the low pg/L range was consistent Table 1. Colored-Product Elemental Analysis percent of dry weight activated carbon colored product
carbon hydrogen nitrogen
70.80 0.30
43.09
0.46
0.16
0.94 0.22
0.38
sulfur chlorine oxygen
0.97
1.55
-108
-546
a By difference, assuming carbon has 16.7% ash as measured by using a separate sample. By difference, assuming colored product has < 1'YOash as measured by using a separate sample.
Table 11. Molecular-Weight Distribution of Colored Product Determined by Ultrafiltration percent by absorbance (400 nm)
Mr
300 000 retained passed 100 000 retained passed
50 000 retained passed
10 000 retained passed
65.3 35.5 26.28
5.7 4.1
0.9 0.9
0
TOC
61.2 39.5 22.8a ND (16.7 by difference) 5.7 ND (1 1.O by difference)
ND ND
a The solution passing the 300 000 M, filter was further processedby using the 100 000-M, filter, etc. Thus 84-91 % was larger than 100 000 M,. ND = not detectable.
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I1
I7
Flgure 2. Typical purge-and-trap chromatogram for a sample which contained 1 g/L chlorine and 400 mg/L activated carbon at pH 7. The numbered peaks correspond to the identified compounds in Table 111.
among several samples. Results are only semiquantitative since the carbon was not removed from the sample prior t o , purging, and adsorbed compounds were not easily stripped. Several of the solutions were decanted from the carbon and extracted with pentane. No compounds were found in the derivatized and nonderivatized extracts that were not in the blank. Volatile compounds identified by using the purgeand-trap procedure were not found because these would have coeluted with the pentane during GC analysis. Several solutions containing 1136 mg/L chlorine and 400 mglL Hydrodarco carbon were reacted for 1 week a t acidic (pH 1.7), neutral (pH 7.8, comparable to the pH 7 data in Table 111),and basic (pH 11.5) initial pH values. Water at the same pH and chlorine concentration was the control. The results of the purge-and-trap GC/MS analyses as compared to the blank are given in Table IV. The neutral and basic chlorine-carbon solutions were black in color after the reaction period, and these samples contained large increases of hexane, benzene, and toluene. The acidic reaction was only slightly colored and did not have increased levels of the hydrocarbons. The chlorinated volatile compounds also increased with increasing pH of reaction, with the exception of carbon tetrachloride and dichloropropene, which were not detected in the basic sample. The observed increases in concentration were quite large; for example, the basic reaction had a chloroform concentration of -2.7 mg/L, 60 times the blank concentration of 45 pg/L. Column Studies. The observation that many organic compounds are produced from the chlorine-carbon reaction at high chlorine dose and large amounts of chlorine reacted per gram of carbon make it necessary to determine whether such compounds are produced under conditions that may be encountered in practice. Concentrations of 10-50 mg/L free chlorine, values which are on the high end of the range of concentrations expected in drinking water treatment plants, were applied to carbon columns in these experiments. In the first experiment, a 0.5-g 50 X 60 mesh F-400 carbon bed received a chlorine dose of 40 mg/L at 4.2 mL/min at a pH of 8 0. After -16 L of solution had passed through the column (1.3of chlorine reacted/g of carbon), the effluent was yellowish in color; and after 40 L had passed (3.2 g of chlorine/g of carbon), a brownish color was observed. The influent and effluent were extracted at various times by using the Grob procedure (18),but the chromatograms showed no differences, indicating either that no new compounds were produced or that, if they were produced, they were adsorbed on the carbon. An extract of 4 L of effluent showed similar results. Purgeable compounds were not analyzed. The sensitivity of the extraction was
Table 111. Volatile Compounds in the Carbon-High Chlorine Dose Solutions no.
compd
1
methylene dichloride
2
1,l-dichloroethylene
3 4
diethyl ether chloroform 1,2-dichIoroethane
5 6 7 8
chlorine blank
+ + + + +
l,l,l-trichloroethane carbon tetrachloride cycloalkane bromodichlorornethane
9 10
dichloropropene
11
trichloroethylene
12 13
benzene 111,2-trichloroethane
14
hexane
-
15
1,1,1,2-tetrachloroethane
16 17
tetrachloroethylene
18 19
chlorobenzene
+ + + + + + + +
toluene
20
hexachloroethane chloroalkylbenzene
21 22
dichlorobenzene
chlorotoluene
*
carbon-chlorlne
+ + + + trace + + + + + + + + + + + + + + + +
area ratlo b
2.3
trace
5.6 2.4 3.7
0.32 5.9 11.4 1.3 1.8 0.86 5.8 1.7
+
indicatesthat the compound was present in the solution. The area ratio is the peak area for the chlorine-carbon solution divided by the area for the chlorinated blank (no carbon).
checked by using a solution of mono-, di- and trichlorophenok 4 pg/L monochlorophenol was at the limit of detection for this procedure, but 4 pg/L each of the di- and trichlorophenol were well within the limit. Another 0.5-g column of F-400 carbon received a 10 mg/L free-chlorine solution at pH 7-8 at 3 mL/min. Ca. 75 L of solution (1.5 g of chlorine/g of carbon) was applied before chlorine residual appeared in the effluent; after 81 L (1.6 g of chlorine/g of carbon) some brown color was eluted and the chloroform concentration increased to 9 pg/L above the influent concentration. The color disappeared and the chloroform concentration decreasedwith additional influent, however. After 100 L had passed the bed (2 g of chlorine/g of carbon), no volatile peaks were consistently being produced as a result of the chlorine-carbon reaction.
Table IV. Volatile Compounds in the Carbon-High Chlorine Dose Solutions at Different pH a compd
methylene dichloride
pH 1.7
chloroform
+ (4.3)
carbon tetrachloride dichloropropene
+ (5) + (76)
trichloroethylene benzene hexane tetrachloroethylene toluene
pH 7.8
pH 11.5
+ (4)
-
+ (8.5) +
4- (4.2)
+ (40)
+ (18) + (15)
+ (103) + (3) + (31)
+ (60)
-
+ (73) + (71) + (46)
+ (4.4)
+ (25) *Compounds with larger peaks than in the blank solution are noted with a +; the number in parentheses is the peak area ratio of the chlorine-carbon solution to the chlorine blank solution.
Application of 50 mg/L free chlorine at 3 mL/min to a 0.5-g, 50 X 60 mesh F-400 column at a pH of 7-8 resulted in the appearance of residual chlorine and color after 18-L throughput (1.8 g of chlorine/g of carbon). Purge-and-trap analysis of the influent and the effluent showed 2.5 times as much total chloroform in the effluent than was in the influent for a total volume applied of 45 L (4.5 g of chlorine/g of carbon). The effluent concentration was never greater than 50 yg/L and was not greater than the influent concentration until 2 g of chlorinelg of carbon had been achieved. Benzene was the only other volatile contaminant a t higher concentration in the effluent than in the influent; however, the influent concentration of benzene varied, creating uncertainty in these results. A large column containing 52.5 g of 16 X 20 mesh WV-G carbon (Westvaco, Covington, WV) received 14.2 mL/min of solution, pH 5.6 with 10 mg/L free chlorine. This carbon is similar in composition to F-400. Purge-and-trap analyses of the influent and effluent were done periodically. After 530 L of solution (0.11 g of chlorine reacted/g of carbon) had passed through the column, all volatile organics in the effluent were still a t lower concentration than in the influent. No chlorine residual or black color was present in the effluent. A second column with 52.5 g of F-400 carbon (30 X 40 U S . Standard mesh, Calgon Corp., Philadelphia, PA) received 14.2 mL/min of solution, pH 6.0 with 10 mg/L free chlorine. Purge-and-trap analyses indicated again that no volatile organics were being produced and released into the effluent from the column. After 525 L of influent (0.1 g of chlorine/g of carbon), the column was dismantled and the carbon was Soxhlet extracted. The carbon a t the inlet contained the greatest number and highest concentration of organic compounds. As many compounds as possible were identified and compared to the compounds in an extract of carbon from a control column that received the same influent after an excess of sulfite was added to dechlorinate it. Compounds produced Volume 15, Number 2, February 1981
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from the chlorine-carbon reaction were toluene, benzaldehyde, benzoic acid, 2-methoxyfluorene, and benzalacetophenone. These compounds were not observed in the carbon-column effluents, however, and no halogenated compounds were observed in the extracts that were not also present in the influent to the bed. No chlorine residual or color was present in the effluent a t the conclusion of the run. Additional evidence that no halogenated species were being released into the effluent was provided by the aqueous TOX test. Throughout all column runs the effluent TOX was found to be less than 2 pg/L, which was the limit of detection for this procedure. The level of 0.1 g of chlorine reacted/g of carbon is that expected for a carbon column in a typical water treatment plant if the column receives 1-2 mg/L free chlorine for 1-6 months.
Conclusions At large amounts of free chlorine reacted with activated carbon (1gas Clp/g of carbon or more) a brown-black colored product is produced with an intensity that increases with pH. The product is highly oxidized, water soluble (precipitates at pH l),and of very high molecular weight. It is not mutagenic to several Salmonella and E. coli test systems, and thus the possibility that some of it may be formed under certain conditions during water treatment does not appear to be a serious concern. The extent of reaction to produce black color is large and is not generally expected in water treatment plants. Further, it should be noted that its presence in water treatment plants has never been reported. Batch reactions at a very high dosage of free chlorine, 2.5 g as Clz/g of carbon, resulted in the production of several chlorinated organics, including chloroform, trichloroethane, and several chlorinated aromatics. Nonchlorinated aromatics such as benzene and toluene also were produced. The production of chlorinated organics was mostly favored at high pH, and benzene and toluene were produced in neutral and basic solutions that had black color. The increases in concentrations of various organics were quite marked; for example, chloroform was present a t 2.7 mg/L in a pH 11.5 batch reaction. For all column runs a t lower (50 mg/L or less) chlorine dosage, no volatile organics were observed in the effluent before 2 g as Clp/g of carbon had been achieved. After this ratio, chloroform levels in the effluent were as large as 50 pg/L. Pentane extraction and GC analysis did not show evidence of additional compounds. Soxhlet extraction of the carbon from a column receiving 10 mg/L chlorine until 0.11 g of Clz/g of carbon had reacted indicated several nonchlorinated aromatics that were not present in the influent. Halogenated compounds were not produced and desorbed since the TOX of the effluent remained below a measurable concentration throughout the column run.
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Although compounds have been shown to be produced in the free’-chlorine-activated carbon reaction, the extent of reaction at which significant production is observed is outside the range which would be encountered in normal drinking water treatment practice. This study has only examined the chlorination of virgin GAC, however, and the reaction between chlorine and adsorbed organics is discussed in a later paper.
Literature Cited (1) Suidan, M. T.; Snoeyink, V. L.; Schmitz, R. A. Enuiron. Sci. Technol. 1977.11. 785. (2) Suidan,M. T:; Snoeyink,V. L.; Schmitz, R. A. Proc. Enuiron. Eng. Diu., ASCE 1977,103,677. EE4. PaDer 13138. (3) Snoeyink, V. L.; Lai, H. T.; Johnson, J. H.; Young, J. F. In
“Chemistry of Water Supply, Treatment, and Distribution”; Rubin, A. J., Ed.; Ann Arbor Science: Ann Arbor, MI, 1974; pp 233-52. (4) Weber, W. J., Jr.; Sherrill, L. D.; Pirbazari, M. “The Effects of Chlorine on the Properties and Performance of Activated Carbon”; paper presented at the 34th Purdue Industrial Waste Conference, Lafayette, IN, 1978. (5) Kim, B. R.; Snoeyink, V. L. In “Activated Carbon Adsorption of Organics from the Aqueous Phase”; Suffet, I. H., McGuire, M. J., Eds.; Ann Arbor Science: Ann Arbor, MI, 1980; Chapter 22. (6) Kim, B. R.; Snoeyink, V. L.; Schmitz, R. A. J . Water Pollut.
Control Fed. 1978,50, 122. (7) Magee, V. Proc. SOC.Water Treat. Exam. 1956,5, 17. (8) Puri, B. R. In “Chemistry and Physics of Carbon”; Walker, P. L., Ed.; Marcel Dekker: New York, 1970; p 191. (9) Puri, B. R.; Mahajan, 0. P.; Singh, D. D. J . Indian Chem. SOC. 1960,37, 171. (10) Snoeyink, V. L.; Suidan, M. T. In “Disinfection-Water and Wastewater”: Johnson. J. D.. Ed.: Ann Arbor Science: Ann Arbor. MI, 1972;‘pp339-58. (11) Boehm. M. P. Adu. Catal.. 16. 179-222 (1964). (12) Olson, L. L.; Binning, C. D. In “Chemistry of Water Supply, I
I
,
Treatment, and Distribution”; Rubin, A. J., Ed.; Ann Arbor Science: Ann Arbor, MI, 1974; pp 253-95. (13) “Standard Methods for the Examination of Water and Wastewater”, 14th ed.; American Public Health Association; Washington, D.C., 1975. (14) Elespuru, R. K.; Yarmolinsky, M. B. Enuiron. Mutagens 1979, I, 65. (15) Christman, R. F.; Johnson, J. D.; Hass, J. R.; Pfaender, F. K.; Liao, W. T. ;Norwood, D. L.; Alexander, H. L. In “Water Chlorination: Environmental Impact Health Effects”; Vol. 2; Jolley, R. L.; Gorchev, H.; Hamilton, D. H.; Eds.; Ann Arbor Science: Ann Arbor, MI, 1978; pp 15-28. (16) Christman, R. F. Department of Environmental Engineering Sciences, University of North Carolina, personal communication, 1978. (17) “Eight Peak Index of Mass Spectra”; Mass SpectrometryData Center, AWRE, Reading, U.K., 1974. (18) Grob, K.; Grob, K., Jr.; Grob, G. J. Chromatogr. 1975, 106, 299. (19) Dressman, R. C.; McFarren, E. F.; Symons,J. M. Proc.-AWWA Water Qual. Technol. Conf. 1977 1978, Paper 3A-5. (20) Puri, B. R.; Dhingra, A. K.; Sehgal, K. L. Indian J. Chem. 1969, 7, 174. Received for review February 11,2980. Accepted September 24,1980. This research was supported by the USEPA Grant No. R805293.
