Deposit Formation from Deoxygenated Hydrocarbons. II.
`Effect of Trace Sulfur Compounds
`
`Willlam F. Taylor
`
`Exxon Research and Engineering Company, Government Research Laboratory, Linden, New Jersey 07036
`
`The effect of trace impurity sulfur compounds on the rate of deposit formation in deoxygenated jet fuel range
`hydrocarbons was investigated. The change in the deposit formation rate following the addition of 3000 ppm of
`S to a stable jet fuel using representative sulfur compounds from the classes including thiols, sulfides, con-
`densed thiophenes, disulfides, and polysulfides was determined at temperatures up to 54OoC and with the mo-
`lecular oxygen content reduced to below l ppm. Markedly higher deposit formation rates were observed with
`added sulfides, disulfides, polysulfides, and a thiol. In contrast, the addition of condensed thiophene compounds
`did not increase the rate of deposit formation. The results confirm that the ability of rigorous deoxygenation per
`se to suppress the deposit formation process depends on the type and level of the trace impurity sulfur com-
`pounds which are present in the fuel,
`
`Introduction
`The deposit formation tendencies of jet fuel range hy-
`drocarbons has been the subject of considerable interest, in
`order originally to investigate storage stability characteris-
`tics and subsequently to investigate the stability of such
`fuels at higher temperatures when used in high speed su-
`personic aircraft (Nixon, 1962; Churchill, 1966). The major-
`ity of such studies were carried out with fuels saturated
`with molecular oxygen via exposure to air. This laboratory
`completed an extended study of the variables which control
`the kinetics of the deposit formation process in air saturat-
`ed jet fuels at temperatures up to 25OOC at reduced pres-
`sures (Taylor and Wallace, 1967, 1968; Taylor, 1968a,b,
`1969a,b). We are now extending our study of the kinetics of
`deposit formation to deoxygenated jet fuel range hydrocar-
`bons (i.e., fuel in which the molecular oxygen content has
`been drastically reduced). We initially reported the effect
`of variables such as fuel type, temperature, pressure, and
`molecular oxygen content on the rate of deposit formation
`from jet fuel range hydrocarbons at temperatures up to
`649OC and pressures up to 69 atm (Taylor, 1974). With
`most fuels, removal of molecular oxygen markedly lowered
`the rate of deposit formation. However, the poorest quality
`fuel tested did not exhibit lower deposit formation rates
`with deoxygenation. This surprising result suggested the
`need for a detailed study of the effect of trace impurity
`compounds in a deoxygenated fuel. This paper discusses
`the effect of trace impurity sulfur compounds on the rate of
`deposit formation in a deoxygenated jet fuel. Subsequent
`work will discuss the effect of trace impurity organic nitro-
`gen and oxygen compounds on deposit formation in deoxy-
`genated fuels.
`Experimental Section
`Apparatus. A schematic of the Advanced Kinetic Unit
`used to measure the rate of deposit formation was shown
`previously (Taylor, 1974). The molecular oxygen content of
`the fuel to be tested is adjusted in a fuel treatment vessel
`by sparging the fuel at an atmospheric pressure using ei-
`ther helium or air. Following this, the treated fuel is passed
`through an oxygen sensor cell and delivered to a double
`piston fuel delivery cylinder. The oxygen sensor cell con-
`tains a polarographic sensor and the oxygen content of the
`total fuel is monitored. Oxygen analyses were also made on
`selected samples using a thermal conductivity gas chroma-
`tographic analyzer. The fuel is delivered to the unit by
`
`64
`
`Ind. Eng. Chem., Prod. Res. Dev., Vol. 15, No. 1, 1976
`
`means of high-pressure nitrogen. The treated fuel is sepa-
`rated from the nitrogen drive gas by use of two individual
`pistons, separated by a small water layer. The fuel then
`passes through a heated tubular reactor section consisting
`of a 0.25-in. o.d., 0.083-in. wall S.S. 304 tube which is con-
`tained inside of four individually controlled heaters. Each
`heater zone is approximately 12 in. in length and is con-
`trolled by a proportional temperature controller. Unit pres-
`sure is controlled by means of a MITY-MITE type of pres-
`sure controller releasing to vent.
`The rate of deposit formation is measured after a 4-hr
`run. The reactor tube is cut into 16 sections, each 3 in. long
`(4 sections per reaction zone), and the tube sections are an-
`alyzed for carbonaceous deposits using a modified LECO
`low carbon analyzer system previously described (Taylor,
`1974). The analytical system was calibrated against known
`standards. The deposit formation rate is obtained by divid-
`ing the net carbon production per section by the corre-
`sponding inner surface area and expressed as micrograms
`of carbon per cm2 per 4-hr reaction time.
`Reagents. The jet fuel employed was a JP-5 (MIL-T-
`5624H) whose properties were previously reported (Fuel A
`in Table I; Taylor, 1974). The fuel contained 234 ppm of
`total sulfur and less than 1 ppm of thiol sulfur. The fuel
`was additive free and was obtained in 1971 from the Baton
`Rouge refinery of the then Humble Oil and Refining Com-
`pany (now Exxon Company, U.S.A.). The tubing employed
`in the reactor section of the Advanced Kinetic Unit was
`0.25-in. 0.d. X 0.083-in. wall stainless steel type 304. Prior
`to use, the tubing is cleaned inside and out with acetone
`and chloroform and blown dry with nitrogen. Pure sulfur
`compounds of the highest quality available were obtained
`and employed as received. Ditertiary dodecyl disulfide and
`ditertiary butyl disulfide were obtained from Phillips Pe-
`troleum Co., Bartlesville, Okla. Di-n-hexyl sulfide, phenyl-
`n-propyl sulfide, diphenyl sulfide, phenyl benzyl sulfide,
`and phenyl methyl sulfide were obtained from Wateree
`Chemical Co., Lugoff, S.C. Ditertiary nonyl polysulfide, di-
`benzyl disulfide, 1-decanethiol, benzo(b) thiophene and di-
`benzothiophene were obtained from Matheson Coleman
`and Bell, East Rutherford, N.J.
`
`Results
`The source of petroleum is believed to be the remains of
`marine animal and vegetable life deposited with sediment
`in coastal waters (Hodgson, 1971). Bacterial action evolves
`
`Downloaded by UNIV OF WINNIPEG on September 12, 2015 | http://pubs.acs.org
`
` Publication Date: March 1, 1976 | doi: 10.1021/i360057a012
`
`GE-1021.001
`
`

`
`Thiol
`Condensed
`Thiophene
`
`Class of
`added
`sulfur
`compound
`Polysulfide
`
`Disulfide
`
`Sulfide
`
`Table I. The Effect of Individual Sulfur Compounds on
`Total Deposit Formation in a Deoxygenated Jet Fuel
`Total
`carbonaceous
`oxy-
`.depositsa
`gen
`As
`con-
`tent,
`Micro- ppm
`grams based
`PPm
`on
`of
`of
`carbon
`fuel
`Added compound
`____
`______
`0,
`__
`________
`7 450 3.85
`0.4
`Ditertiary nonyl
`polysulfide
`7 295 3.76
`0.9
`Ditertiary dodecyl
`disulfide
`6 691 3.45
`Dibenzyl disulfide
`0.2
`Ditertiary butyl
`10 659 5.51
`0.2
`disulfide
`5 739 2.96
`0.3
`Di-n-hexyl sulfide
`3 020 1.56
`0.3
`Phenyl-n-propyl sulfide
`4 503 2.32
`0.3
`Diphenyl sulfide
`1 2 253 6.33
`Phenyl benzyl sulfide
`0.2
`2 190 1.14
`Phenyl methyl sulfide
`0.1
`0.2
`2 788 1.44
`Thiocyclohexane
`3 909 2.02
`1-Decanethiol
`0.3
`1 351 0.70
`Benzo (b) thiophene
`0.9
`981 0.51
`Dibenzothiophene
`0.7
`1 485 0.77
`0.4
`Base Fuel
`a Cumulative deposits produced in 4 hr in the Advanced
`Kinetic Unit. Conditions: 69 atm, zone 1, 371"C, zone 2,
`427" C, zone 3, 482" C, zone 4, 538" c.
`sulfur, oxygen, and nitrogen as volatile compounds. These,
`however, are never completely eliminated despite the ever-
`increasing pressure of sediment. The result of this is that
`crude oil is a mixture of hydrocarbons containing varying
`quantities of sulfur, nitrogen, and oxygen compounds. The
`total sulfur content of crude oil varies from practically zero
`to as much as 14%. Sulfur compound classes identified in
`crude oil include thiols, sulfides, and thiophenes. In a re-
`view of the Bureau of Mines-API Project 48 work, it was
`stated that no disulfide has been conclusively identified as
`present in virgin crude oil (Rall, 1962). Subsequent exten-
`sive work appears to have identified a single disulfide in
`crude oil (Coleman, 1970).
`Sweetening processes which may be employed to convert
`odorous thiols in a jet fuel fraction to nonodorous disul-
`fides generally leave the resultant disulfides in the fuel. In
`addition, sweetening processes which employ elemental
`sulfur (e.g., Doctor Sweetening) rather than molecular oxy-
`gen can inadvertently form polysulfides which would re-
`main in the jet fuel (Thompson, 1949; Walker, 1956). Thus,
`a jet fuel can contain sulfur compounds from the classes in-
`cluding thiols, sulfides, condensed thiophenes, disulfides,
`and polysulfides.
`The effect of various trace sulfur compounds was investi-
`gated directly by adding 3000 ppm of S to a highly stable
`JP-5 fuel and measuring the effect of this addition on the
`rate of deposit formation in a rigorously deoxygenated sys-
`tem (Le., less than 1 ppm of 0 2 ) . The base fuel contained
`234 ppm of S so that the total sulfur content of the fuel
`with the added sulfur was still below the MIL-T-5624H
`specification of 4000 ppm of S. Sulfur compounds repre-
`sentative of all of the major classes potentially present in
`jet fuel were employed. Since the added sulfur content was
`set on a fixed weight basis, the addition of sulfides, con-
`densed thiophenes, and thiol compounds resulted in a
`higher molar concentration than the addition of disulfides
`and polysulfides.
`The rate of deposit formation was measured in the Ad-
`vanced Kinetic Unit at 69 atm with the temperature zones
`at 371-54OOC and with the fuel's molecular oxygen content
`
`.\
`
`-
`100
`
`'t
`
`N O A D D E D SULFUR
`
`,
`
`-
`10
`
`5.0
`1.10
`
`1.20
`
`1.30
`
`1.40
`1000PK
`
`1.50
`
`1.60
`
`70
`
`Figure 1. Deoxygenated fuel (0.4 ppm of 02) with added ditertiary
`nonyl polysulfide at 69 atm.
`
`Y c
`e
`z
`p
`c
`B
`-
`Y c
`
`ffl
`0
`Y 0
`
`NO
`
`lo t
`
`1
`J
`
`1000/'K
`Figure 2. Deoxygenated fuel at 69 atm: 0 , with added dibenzyl di-
`sulfide 0.2 ppm of 0 2 ) ; A, with added ditertiary dodecyl disulfide
`(0.9 ppm of 0 2 ) ; H, with added ditertiary butyl disulfide (0.2 ppm
`of 0 2 ) .
`
`reduced to below 1 ppm. Results with the base JP-5 fuel on
`a deoxygenated basis were previously reported at 69 atm
`over the range of 150-649OC (Taylor, 1974). The individual
`sulfur compounds evaluated are shown in Table I, along
`with the total deposits formed in each run. Representative
`Arrhenius plots of the rate of deposit formation are shown
`in Figures 1 to 5. It can be seen that the effect of individual
`sulfur compounds in a deoxygenated fuel is complex. In
`general, the addition of the polysulfide, disulfides, sulfides,
`and thiol all resulted in an increase in the rate of deposit
`formation. As can be seen from the Arrhenius plots, how-
`ever, the magnitude of this increase at a given temperature
`varied considerably. In contrast, the condensed thiophene
`compounds evaluated did not increase the rate of deposit
`formation, and actually appeared to inhibit the deposit for-
`mation process to some extent.
`The effect of sulfur compound concentration in a deoxy-
`genated fuel was investigated using both a sulfide (phenyl
`
`Ind. Eng. Chem., Prod. Res. Dev., Vol. 15, No. 1, 1976 65
`
`Downloaded by UNIV OF WINNIPEG on September 12, 2015 | http://pubs.acs.org
`
` Publication Date: March 1, 1976 | doi: 10.1021/i360057a012
`
`GE-1021.002
`
`

`
`4
`
`1
`
`TkG- ih4--A7G
`
`q
`:
`
`1 J L t
`
`'1
`
`8
`
`c
`
`1000 O K
`Figure 3. Deoxygenated fuel at 69 atm: 0 , with added diphenyl
`sulfide (0.3 ppm of 0 2 ) , A, with added phenyl benzyl sulfide (0.2
`ppm of 02).
`
`i
`
`4
`4
`
`I
`
`'1 10
`
`1 2 0
`
`1 3 0
`
`1 4 0
`"
`
`1 5 0
`
`1 6 0
`
`l
`1 7 0
`
`Figure 4. Deoxygenated fuel (0.3 ppm of 0 2 ) with added l-dec-
`anethiol at 65 atm.
`
`1000/'K
`
`_I.----
`
`Compound
`added
`Phenyl benzyl
`sulfide
`
`_
`
`.
`
`-
`
`~
`
`
`
`markedly increase the rate of deposit formation of a fuel
`Table 11. Effect of Sulfur Compound Concentration on
`even when it is rigorously deoxygenated.
`Deposit Formation in a Deoxygenated Jet Fuel
`_ _ _ _ _ ~
`Of the five major classes of sulfur compounds potentially
`Concn of Oxygen
`present in jet fuel, only condensed thiophene compounds
`added sulfur content, Relative total
`did not increase the rate of deposit formation in a deoxy-
`compound, ppm of
`carbonaceous
`genated system.
`deposits0
`ppmof S
`0,
`The formation of deposits from jet fuel range hydrocar-
`bons involves complex chemical and physical processes,
`whose exact nature have not been elucidated. In air-satu-
`rated systems at temperatures below the pyrolysis range, it
`is clear that deposits form as the end result of free radical
`chain reactions involving molecular oxygen. Deposit char-
`acterization studies indicate that typically such deposits
`contain high concentrations of oxygen and lesser but signif-
`icant amounts of sulfur and nitrogen in a relatively low mo-
`lecular weight species which collects into microspherical
`particles of an approximate 1000 A diameter. This suggests
`that in liquid phase autoxidative deposit formation it is the
`change in solvent character resulting from the incorpora-
`tion of oxygen, nitrogen, and sulfur into the deposit species
`which is important rather than an increase in molecular
`weight per se. As reported previously, in general, deoxyge-
`nation greatly reduced low-temperature, liquid phase de-
`posit formation rates, and significant rates of deposit for-
`mation did not occur until higher temperatures were
`reached.
`At higher temperatures new hydrocarbon reactions begin
`to assume importance. Jet fuel range hydrocarbons start to
`exhibit measurable rates of pyrolysis at temperatures
`above approximately 35OoC (Fabuss et al., 1965). The pre-
`dominate products from pyrolysis reactions have molecular
`weights equivalent to or less than the parent hydrocarbons,
`although higher molecular species have been reported (Fa-
`buss et al., 1965). The catalytic effect of surfaces would also
`be expected to increase in importance with increasing tem-
`perature. Surfaces are known to exert catalytic effects in
`so-called "homogeneous" pyrolysis reactions. In addition,
`at higher temperatures where a vapor phase rather than a
`liquid phase would be present it would be expected that
`changes in the molecular weight of deposit precursors
`would be more important than their liquid phase solvent
`properties. As previously reported (Taylor, 1974), the anal-
`ysis of deposits formed from a deoxygenated fuel indicated
`that its composition is different from deposits formed in a
`
`3 000
`300
`0
`
`Ditertiary dodecyl
`disulfide
`
`8.22
`0.2
`3.56
`0.3
`1 .00 (base)
`0.4
`4.88
`0.9
`3 000
`2.36
`0.2
`300
`1.00 (base)
`0.4
`0
`a Relative cumulative deposits produced in 4 hr in the
`Advanced Kinetic Unit. Conditions: 69 atm, zone 1, 371" C,
`zone 2, 427"C, zone 3, 482'C, zone 4, 538°C.
`
`benzyl sulfide) and a disulfide (ditertiary dodecyl disul-
`fide). Results are summarized in Table TI. In both cases
`higher levels of added sulfur compounds resulted in higher
`levels of deposit formation. The deposit formation level,
`however, did not increase linearly with added sulfur com-
`pound level. In both cases, increasing the added sulfur level
`by a factor of 10 (Le., from 300 to 3000 ppm) approximatrely
`doubled the level of total deposits.
`
`Discussion
`The most striking feature of the results of our initial
`study of the deposit formation tendencies of deoxygenated
`jet fuel range hydrocarbons was that not all fuels exhibited
`lower deposit formation rates with rigorous deoxygenation.
`Numerous studies had shown that deposits in air-saturated
`hydrocarbons form as the end result of complex free radi-
`cal, chain reactions involving molecular oxygen (Nixon,
`1962, Boss and Hazlett, 1969). Thus, a priori, it would be
`expected that the rigorous exclusion of molecular oxygen
`would suppress autoxidative reactions and result in a re-
`duction in deposit formation. At the time of the initial
`study, it was postulated that the anomalous behavior of the
`fuel which failed to respond to deoxygenation was caused
`by the presence of disulfides. The present study has clearly
`demonstrated that the presence of trace levels of not only
`disulfides, but sulfides and a polysulfide and a thiol can
`
`66
`
`Ind. Eng. Chem., Prod. Res. Dev., Vol. 15, No. 1, 1976
`
`Downloaded by UNIV OF WINNIPEG on September 12, 2015 | http://pubs.acs.org
`
` Publication Date: March 1, 1976 | doi: 10.1021/i360057a012
`
`GE-1021.003
`
`

`
`Table 111. Relative Effect of Sulfides in a Deoxygenated vs.
`an Air Saturated System
`
`Rate of deposit forma-
`tion relative to that of
`base fuel
`De-
`Air-
`saturated0 oxygenatedb
`20.0
`1 . 9
`
`Sulfur compound
`added to base fuel
`Methyl phenyl sulfide
`..,-Sa -
`n-Propyl phenyl sulfide
`-
`C,H.-S-(-J
`Benzyl phenyl sulfide
`(-+-sa
`1.0 (base)
`1.0 (base)
`Base fuel with no added sulfur
`a Sulfur compound added to base fuel (P&W 523) to the
`1000 ppm of S level. Rates measured at 177" C and 0.2 atm
`(Taylor and Wallace, 1968). b Sulfur compound added to
`base fuel ( J P - 5 ) to the 3000 ppm of S level. Rates measured
`at 427°C and 69 atm.
`
`8.9
`
`1.3
`
`2.9
`
`15.3
`
`typical air-saturated fuel. This suggests that deposits are
`formed as a result of different chemical and physical pro-
`cesses in a deoxygenated environment than in an air-satu-
`rated environment.
`In a previous study of the effect of sulfur compounds on
`the deposit formation rate in an air-saturated system, it
`was observed that the addition of equal quantities of differ-
`ent sulfides to a stable fuel resulted in markedly different
`changes in the rate of deposit formation (Taylor and Wal-
`lace, 1968). In the present study in a deoxygenated system
`marked differences among the effect of various sulfide
`compounds were also observed. In Table I11 is shown a
`comparison of the effect of the addition of the same sulfide
`compounds on the deposit formation rate in a deoxygenat-
`ed versus air saturated system. The rates are compared on
`a relative basis since the base fuels and conditions em-
`ployed vary between the two studies. It can be seen that
`the relative effects of the addition of the same sulfide com-
`pound differed greatly between the low-temperature air-
`saturated environment and the higher temperature deoxy-
`genated environment, again suggesting that different de-
`posit formation processes are involved.
`Sulfur compounds are known to pyrolyze via a homoge-
`neous free-radical process; e.g., phenyl methyl sulfide was
`shown to decompose to phenyl thiyl and methyl radicals
`(Back and Sehon, 1960), benzyl methyl sulfide decomposed
`to benzyl and methyl thiyl radicals (Braye et al., 1955), and
`various thiols decomposed via rupture of the C-S bond to
`alkyl and hydrosulfide radicals (Sehon and Darwent, 1954).
`The weakest bond in disulfides and polysulfides is usually
`the S-S bond, and disulfides have been used to initiate free
`radical, chain reactions in the same manner that peroxides
`are employed (Pryor, 1962).
`The heterogeneous decomposition of thiols occurs readi-
`ly and usually yields olefins, sulfides, and hydrogen sulfide
`(Reid, 1958). Sulfides and disulfides both (Reid, 1960a,b)
`undergo a complex heterogeneous decomposition at tem-
`peratures above 200OC. Rudenko and Gromova (1951)
`passed a series of sulfur compounds over iron and reported
`the minimum temperature at which decomposition became
`significant as evidenced by evolution of hydrogen sulfide.
`Thiols, disulfides, and dialkyl sulfides readily decomposed
`at temperatures above 15OOC. Diary1 sulfides decomposed
`at 449OC, but thiophene was stable at 5OOOC. Fabuss et al.
`(1965) have shown that ti-ace quantities of sulfur com-
`
`1 0 0 0
`
`i)
`0 i
`
`YI ir
`3 0
`
`9
`<
`u
`8 1 0 0
`
`0.
`Y r
`a
`c
`z
`-
`0
`r
`a
`a
`D! 0 L
`-
`r
`s 0
`
`Y 0
`
`IC
`
`1
`
`\
`
`NO ADDED SULFUR
`
`5.c
`
`0
`
`1.20
`
`1.30
`
`1.40
`1 0 0 0 P K
`Figure 5. Deoxygenated fuel at 69 atm: 0 , with added benzo-
`(b)thiophene (0.9 ppm of 0 2 ) ; B, with added dibenzothiophene
`(0.7 ppm of 0 2 ) .
`
`1.50
`
`1 . 6 0
`
`1.70
`
`pounds can either increase or decrease the rate of thermal
`pyrolysis of various hydrocarbons.
`In the present study condensed thiophene compounds
`were found not to increase the rate of deposit formation in
`a deoxygenated system. This presumedly reflects the rela-
`tive strength of the aryl C-S bond in these compounds. A
`similar effect was previously observed in an air saturated
`environment (Taylor and Wallace, 1968). The other delete-
`rious sulfur compounds contain weaker s-S bonds and
`alkyl C-S bonds which presumedly undergo pyrolysis and/
`or surface catalyzed decomposition reactions at milder con-
`ditions than the bonds present in pure hydrocarbons and
`whose products ultimately lead to the acceleration of the
`deposit formation processes. The various deleterious sulfur
`compounds evaluated in the present study often produced
`maximum increased deposit formation rates at different
`temperatures. This presumably reflects the effect of the
`variation in bond strength between S-S bonds and the var-
`ious alkyl C-S bonds (Pryor, 1962), which would cause
`these compounds to exhibit scission of these bonds at dif-
`ferent temperatures. In the present study added sulfur
`compounds in a deoxygenated system exhibited a less than
`linear effect on the increase in the level of deposits formed.
`A similar effect was found previously in a study of the ef-
`fect of added sulfur compounds in an air-saturated system
`(Taylor, 1974).
`
`Acknowledgments
`Helpful discussions with C. J. Nowack, L. Maggitti, Jr.,
`and J. R. Pitchtelberger are gratefully acknowledged.
`
`Literature Cited
`Back, M. H.. Sehon, A. H., CanJ. Chem., 38, 1076 (1960).
`Boss, 5. D., Hazlett, R. N., Can. J. Chem.. 47, 4175 (1969).
`Braye, E. H., Sehon, A. H., Darwent, B. de B., J. Am. Chem. SOC., 7, 5282
`(1955).
`Coleman, H. J.. Hopkins, R. L.. Thompson C. J., Am. Chem. SOC. Div. Pet.
`Chem. frepr., 15, (3), A17 (1970).
`Churchill, A. V., Hager, J. A., Zengel, A. E., S.A.E. Trans.. 74, 641 (1966).
`Fabuss, E. M., Duncan, D. A.. Smith, F. O., Satterfield, C. N., Ind. Eng.
`Chem., Process Des. Dev., 4, 1 17 (1 965).
`Hodgson, G. W., Adv. Chem. Ser., No. 103 (1971).
`Nixon. A. C., in "Autoxidation and Antioxidants," Vol. 11, W. 0. Lundberg, Ed.,
`Interscience, New York, N.Y., 1962.
`Pryor. W. A,, "Mechanisms of Sulfur Reactions," McGraw-Hill, New York.
`N.Y.. 1962.
`
`Ind. Eng. Chem., Prod. Res. Dev., Vol. 15, No. 1, 1976 67
`
`Downloaded by UNIV OF WINNIPEG on September 12, 2015 | http://pubs.acs.org
`
` Publication Date: March 1, 1976 | doi: 10.1021/i360057a012
`
`GE-1021.004
`
`

`
`Rall, H. T., Thompson, C. J., Coleman, H. J., Hopkins, R. L.. Roc. Am. Pet.
`lnst., 42, Sect. VIII, 19 (1962).
`Reid, E. M.. "Organic Chemistry of Bivalent Sulfur," Vol. I, p 1 IO, Chemical
`Publishing Co., New York, N.Y.. 1958.
`Reid, E. M., "Organic Chemistry of Bivalent Sulfur," Vol. 11, p 60, Chemical
`Publishing Co., New York, N.Y., 1960a.
`Reid, E. M., "Organic Chemistry of Bivalent Sulfur," Vol. Ill, p 369, Chemical
`Publishing Co., New York, N.Y. 1960b.
`Rudenko, M. G., Gromova, V. N., Dokl. Akad. Nauk, SSSR, 81, 297 (1951).
`Sehon, A. H., Darwent, B. de B., J. Am. Chem. SOC., 78, 4806 (1954).
`Taylor, W. F., J. AppI. Chem., 18, 251 (1968a).
`Taylor, W. F., SA€ Trans., 78, 281 1 (1968b).
`Taylor, W. F., J. Appl. Chem., 19, 222 (1969a).
`Taylor, W. F., Ind. Eng. Chem., Prod. Res. Dev., 8, 375 (1969b).
`
`Taylor, W. F., Ind. Eng. Chem., Prod. Res. Dev., 13, 133 (1974).
`Taylor, W. F., Wallace, T. J., lnd. Eng. Chem., Prod. Res. Dev., 6, 258 (1967).
`Taylor, W. F., Wallace, T. J.. Ind. Eng. Chem.. Prod. Res. Dev.. 7, 198 (1968).
`Thompson, R. B., Druge, L. W., Chenicek, J. A,, lnd. fng. Chem., 41, 2715
`( 1949).
`Walker, H. E., Kenney, E. B., Pet. Process., 11, 58 (1956).
`
`Received for review June 5, 1975
`Accepted August 14,1975
`
`This work was sponsored by the Department of the Navy under
`Contracts N00019-71-C-0463 and N00140-72-C-6892.
`
`Analyzing Cetyldimethylbenzylammonium Chloride
`by Using Ultraviolet Absorbance
`
`Lawrence K. Wang,' Donald B. Aulenbach, and David F. Langley
`
`Department of Chemical and Environmental Engineering, Rensselaer Polytechnic Institute, Troy, New York 72 78 7
`
`The engineering significance of cetyldimethylbenzylammonium chloride is described. The compound in distilled
`water in the range of 1.0 to 5.0 mg/l. can be rapidly measured by a uv method at 210 nm with less than 8 %
`relative standard deviation and relative error.
`
`Introduction
`Quaternary ammonium compounds are widely used for:
`(a) fabric antistatics and softening (cationic quaternary
`ammonium compounds can eliminate the normal buildup
`of static electrical charges of plastics and synthetic fibers
`when dried in a mechanical drier, and the quaternary am-
`monium compounds with two long alkyl chains also have
`excellent softening properties when used in conjunction
`with common synthetic detergents for cleaning fabrics and
`clothes); (b) corrosion inhibition in flue gas scrubbers, acid
`pickling baths, and petroleum pipelines; (c) emulsion com-
`pounding (they have the special property of being substan-
`tive, that is, causing the oil phase of an emulsion to plate
`out on such surfaces as textile fabrics, metals, glass, plastic,
`wood, and foliage); (d) pigment treatment; and (e) ore flo-
`tation (separation of certain minerals from low grade ores
`can best be accomplished using quaternaries). For water
`pollution control, the release of such cationic surfactants to
`water resource systems should be monitored and con-
`trolled.
`Recently environmental engineers have been researching
`the use of quaternary ammonium compounds for water
`treatment (Grieves and Schwartz, 1966; Grieves and Cong-
`er, 1969; Grieves et al., 1970; Wilson, 1969; Wang, 1972;
`Wang and Peery, 1975), wastewater treatment (Wang et al.,
`1974a; 1974b; Wang, 1973a, 1973b), and sludge treatment.
`Therefore, the development of effective analytical tech-
`niques for determining the initial and residual concentra-
`tions of quaternary ammonium compounds is necessary.
`For general analysis of quaternary ammonium com-
`pounds in aqueous solution, the presently accepted method
`is the two-phase titration method (Wang, 1973c; Wang et
`al., 1974b), which can measure the concentrations of qua-
`ternaries at a range of l to 30 mg/l. More recently, Wang
`and Langley (1975) developed a methyl orange method for
`more accurate determination of cationic surfactants (in-
`
`68
`
`Ind. Eng. Chem., Prod. Res. Dev., Vol. 15, No. 1, 1976
`
`cluding quaternaries) at the concentration range of 0.1 to
`4.5 mg/l. Either the two-phase titration method (Wang
`1973c; Wang et al., 1974b) or the methyl orange method
`(Wang and Langley, 1975) is applicable to the quantitative
`measurement of a single type of cationic surfactant in
`water. Neither method can differentiate between two qua-
`ternary ammonium compounds, between two amines, or
`between a quaternary ammonium compound and an amine
`compound. Nevertheless, the two methods are effective for
`chemical engineering processes control in which the specif-
`ic cationic surfactant used is known, and for environmental
`water quality control in which only the residual concentra-
`tion of a group of contaminants, such as cationic surfac-
`tants, is of particular concern.
`The objective of this paper is to introduce an ultraviolet
`spectrophotometric method for rapid analysis of a specific
`cationic surfactant (quaternary ammonium compound),
`cetyldimethylbenzylammonium chloride (CDBAC). Its mo-
`lecular structure is shown in Figure l. Since CDBAC is an
`approved germicide (U.S.D.A. Regulation No. 1457-16), it
`may be used in throat lozenges, provided the individual
`lozenge contains not more than 5 mg of CDBAC and that
`the directions for use do not provide for consumption of
`more than 8 lozenges in 1 day. CDBAC is also generally
`used in mouth washes in a concentration of 1:4000. In the
`field of environmental engineering, CDBAC is a highly ef-
`fective sanitizer (Ehlers and Steel, 1958; Fine Organics Inc.,
`1970), flotation agent (Wilson, 1969; Grieves and Conger,
`1969; Grieves et al., 1970; Wang, 1972), and disinfectant
`(Wang and Peery, 1975). Many research projects are pres-
`ently being conducted for the exploration of other applica-
`tions and recovery techniques. The proposed uv method
`provides direct measurement (30 solvent extraction is in-
`volved), thereby significantly reducing the time for analysis
`and eliminating possible health hazards from toxic solvent
`vapors, such as chloroform.
`
`Downloaded by UNIV OF WINNIPEG on September 12, 2015 | http://pubs.acs.org
`
` Publication Date: March 1, 1976 | doi: 10.1021/i360057a012
`
`GE-1021.005