-fiO-Ai65 946 EVALUATION OF SURFACTRNTS FOR PHVSICAL DECONTAMINATION 1/1IN SPRAY APPLICATIONS(U) NAVAL RESEARCH LAB WASHINGTONDC S G PANDE ET AL 17 MAR 86 URL-MR-5742

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MICROCOPY RESOLUTION TEST CHARTNATIONAI R1J9661J Of S!AN3ARDS 963 A

NRL Memorandum Report 5742

Ln Evaluation of Surfactants for Physical DecontaminationU in Spray Applications

S. G. PANDE* AND R. C. LrrrE

Combustion and Fuels BranchChemistry Division

*Geo-Centers, Inc.Newton Center, MA 021590~

DTICdLECT~MAR 25W

March 17, 1986

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NRL Memorandum Report 5742

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Evaluation of Surfactants for Physical Decontamination in Spray Applications

12. PERSONAL AUTHOR(S)Pande, S. G.* and Little, R. C.

13a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year, 40onth, Day) 5 PAGE COUNTInterim FROM 6/84 TO 6/85 1986 March 17 5016. SUPPLEMENTARY NOTATION ,*Geo-Centers, Inc., Newton Center, MA ' '

17, COSATI CODES . SUBJECT TERMS (Continue on reverse if necerWy and identify by blo-k oumber-

;IELD GROUP SUB-GROUP Surfactants - Detection methods, ,

Surfactant effectiveness Stainless steel, (Cotin)

19 ABSTRACT (Continue on reverse If necessary and identify by block number)

-7 Using a low pressure spray, the effectiveness of commercially available suifactants in removing a thickenedmustard simulant from a low and a high energy surface was determined in a series of laboratory bench scale tests.The objective of this investigation was to recommend suitable decontamination (decoy) candidates for larger scalefield tests. The test method involved a recycling flow system and a UV-VIS double-beam spectrophotometer whichmonitored the amount of simulant removed. The spectrophotometer was interfaced with a computer for datacollection. Because of light scattering problems, due to bubbles in the flow system, surfactant effectiveness datawere based on a visual method of detection.

The effectiveness of the decon test fluid appears to be specific for the type of substrate, the contaminant and theaqueous medium emW.ip L On a high energy surface (stainless steel), tap water and synthetic seawater were aseffective as an automatic dishwashing detergent in removing thickened methyl salicylate. However, on a low energy Lsurface (Teflon), surfactants that exhibited a combination of increased wettin~g, emulsification, and solubilization .. " "

(Continues)

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R. C. Little (202) 767-2332 I Code 6182DO FORM 1473,84 MAR 83 APR edition may be used until exhausted SECUPI-Y CLASSIFICATION OF -HIS PAGE V

All other editions are obsolete

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18. SUBJECT TERMS (Continued)

Teflon ,Thickened methyl salicylateMechanisms

* Redeposition.

19. ABSTRACT (Continued)

* j - properties removed the thickened simaulant more effectively than water. These include sodium dioctyl sulfosuccinate(1% in tap water), sodium dihel sulfosuccinate (1.6% in tap water), and Aqueous Film Forming Foam (AFFF -3%

F dilution in tap water and in synthetic seawater). Also, under the same test conditions, the removal times of these*surfactant 0-slutions"'were within 143 minutes, whereas that of water was > 15 minutes for complete removal of the

thickened simulant from the Teflon surface./(' /

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Ii

CONTENTS

INTRODUCTION ...................................................... 1

EXPERIMENTAL ...................................................... 2

Materials ........................................................... 2Apparatus .......................................................... 4Procedure .......................................................... 6Detection Methods .................................................... 6

UV Spectrophotometry .............................................. 6Visual Detection Method ............................................ 9Choice of Detection Method .......................................... 9

Systems Examined .................................................... 9

RESULTS AND DISCUSSION ............................................ 10

General Screening .................................................... 10Effect of Substrate .................................................... 11

Stainless Steel ...................................................... 11Evaluation ...................................................... 11Mechanism ...................................................... 11

Teflon ............................................................ 14

Evaluation ...................................................... 14Promising Decon Candidates ........................................ 14M echanism ...................................................... 18

Good Correlation with Surfactant Properties .......................... 18Poor Correlation with Surfactant Properties .......................... 19Possible Explanation of the Anomalies .............................. 19Prevention of Redeposition: Possible Factors Involved .................. 20

Effect of Synthetic Seawater (Aqueous Medium) ............................ 20Effect of Pennzoil Grease (Contaminant) .................................. 21Effect of lonicity, Concentration and Spray Temperature of the Surfactant ........ 21

SUMMARY AND CONCLUSIONS .......................................... 2203

RECOMMENDATIONS AND FUTURE WORK ................................ 23 ...........

ACKNOWLEDGMENTS...............................................24

REFERENCES...................................................... 24R... Codes

uIPY I_.. Avail and/or "1 V8'"'7 r Special

FIGURES

Fig Page

1 Schematic diagram of the decon spray system .......... 5

2 Colored thickened methyl salicylate (MST-D)spotted (.- 2-3 mm diameter) on Teflon: Before

Spraying ........................... .. .. ... .. ..

3 colored thickened methyl salicylate (MST-D)spotted (- 2-3 mm diameter) on stainless steel:Before Spraying ........ ...... ... ..... .. .... .12

4 stainless steel substrate: Larger MST-D droplets formed after spraying with 3% AFFF/5 min ....... 13

5 Teflon substrate: Residual MST-D at the-origin of application after spraying with

~~~~~~water/15 min ..... •.... . . . . . . . . . . . . . . .1

6 Teflon substrate: Residual MST-D showingredeposition after spraying with Class B sur-factant, Zonyl FSN, for 15 min ...................... 16

7 Teflon Substrate: Residual MST-D at theorigin of application after spraying withClass C Surfactant, Silwet L-7607 for 15 min........ 17

.4v

• °%

TABLES

I - Some Physical Properties of Mustard and Its Siulant withSpecific Reference to Physical Decon in An Aqueous Medium

2 - Anionic Surfactants Evaluated: Sodium Dialkyl Sulfosucci-nates

3 - Nonionic Surfactants Evaluated: Alkyl Phenol Polyoxy-ethylene (POE) Ethers

4 - Nonionic Surfactants Evaluated: Aliphatic Alcohol Polyo-xyethylene Ethers

5 - Nonionic Surfactants Evaluated: Other types of Polyoxy-ethylene Compounds

6 - Decon of MST-D/Tef/RX-30 (2%)

7 - Decon of MST-D/Tef/AFFF 3% (Ansul)

8 - Experimental Design: 23 Factorial

9 - Stainless Steel Substrate: Effect of Surfactants vs Water

10 - Teflon Substrate: Class A Surfactants - Effected 100%Removal of MST-D from the Entire Test Surface

11 - Teflon Substrate: Class B Surfactants - Effected IncompleteRemoval of MST-D from the Entire Test Surface

12 - Teflon Substrate: Class C Surfactants - Nonionics thatEffected Little/No Removal of MST-D from the Origin ofApplication

13 - Decon of MST-D/Tef/TWN-20 (2%)

14 - Decon of MST-D/Tef/Tap water

15 - Effect of Synthetic Seawater on Surfactant Effectiveness:Removal of MST-D from a Teflon Substrate

16 - Effect of Contaminant on Surfactant Effectiveness: Removalof Pennzoil Grease from Teflon

17 - Teflon Substrate: Effect of IonicIty, Concentration, andSpray Temperature of Surfactant on Surfactant Effectiveness

EVALUATION OF SURFACTANTS FOR PHYSICAL DECONTAMINATION

IN SPRAY APPLICATIONS

INTRODUCTION

The use of chemical and biological warfare (CBW) agents inmilitary combat operations threatens the lives of the crew andthe accomplishment of the mission. Thus, a vital need existsfor effective decontamination of personnel, equipment andaffected areas.

Decontamination (decon) methods may be physical or chemicalin nature. Physical decon involves "removal only" of thesimulant/agent via aqueous and non aqueous systems. In contrast,chemical methods involve detoxification/neutralization reactions,i.e., chemical conversion of the simulant/agent to less toxic andpreferably non toxic compounds via hydrolysis, oxidation, etc.In this report, physical decon involving an aqueous medium wasinvestigated using various types of commercially availablesurfactants. A method was also developed to evaluate theeffectiveness of the surfactants in specific simulant/substratesystems.

Effective methode of physical decontamination, involving anaqueous medium, which have been reported are consistent with thefact that mechanical action is a key factor in a cleaning pro-cessla. The role of detergents, however, is considered to eitherreduce the work requirement, or increase the efficiency withwhich mechanical energy is utilized in the cleaning process2 .Thus, at very high spray or jet pressures (10003a to 30004 psi),water at ambient temperature is an effective decontaminant;whereas at lower pressures (110 psi) 5 , or much lower 6 (value notgiven), water or steam is inadequate. The study of surfactantsvia sprays 7 as well as drop spreading tests 8 has demonstrated thepotential of a fluorosurfactant and a betaine surfactant aseffective decontaminants.

In this report, surfactant effectiveness was evaluated usinga low pressure spray (-5 psi) via a series of bench tests. Thesebench scale spray applications serve as a practical method ofstudying decontamination and offer better control of the indepen-dent variables as compared with larger scale field tests. Theuse of a low pressure spray also minimizes the contribution ofmechanical energy in the decontamination process, therebyproviding more accurate evaluations of surfactant effectiveness.Moreover, challenging simulant/contaminant-substrate systems wereManuscript approved December 17, 1985.

1

selected e.g., a high density application (-12 times a likelythreat concentration) of methyl salicylate (a simulant formustard)3b, thickened to a viscosity of -5 times the standard forthickened CW agents, on a low energy surface (Teflon). Themethod used for evaluating decon candidates involved a recyclingflow system and a UV detector. However, the problem of bubblesin the flow system has limited the use of a flow cell in thedetector. Thus, a visual method of detection involving the useof an oil soluble dye (incorporated in the thickened methylsalicylate/contaminant formulation) was also employed.

This report focused on the removal of thickened methylsalicylate from a low energy surface (Teflon), since preliminarystudies indicated that a high energy surface (stainless steel)was not a challenging substrate: water was found to be aneffective decon fluid for the removal of the thickened simulantfrom a stainless steel substrate. Various types of commerciallyavailable surfactants were evaluated using tap water and inspecific cases, synthetic sea water as the references. surfac-tant systems were considered promising on the basis of shortremoval times (- 3 mins or less). In addition to evaluating thevarious surfactants, possible mechanisms that may be involved inthe removal process were also discussed.

EXPERIMENTAL

Materials

Simulan t/Con tamlinan t

Simulant: Colored thickened methyl salicylate (MST-D)Methyl salicylate (Fisher Scientific Co.) is a well-knownsimulant for mustard. The solubility and surface active proper-ties of mustard and methyl salicylate, shown in Table 1, indicatethat methyl salicyate is also a good mustard simulant forphysical decontamination studies involving an aqueous medium.

Thickener: K-125 (Rohm and Haas) is a co-polymer consistingof the following monomers viz., methyl methacrylate, ethylacrylate, and butyl acrylate.

Dye: Celanthrene Brilliant Red (E.I., duPont de Nemours andCo., Inc.) is oil soluble.

Preparation of Colored Thickened Methyl Salicylate

K-125 (-1.89 g) was added gradually to methyl salicylate (25g). The mixture was stirred and gently heated over a warm waterbath, both during and after the addition until the K-125 wascompletely dissolved.

2

The viscosity of the resultant clear thickened liquid (5038centistokes) was measured using a Cannon-Manning capillaryviscometer (400 A25, constant 1.197). The thickened methylsalicylate was colored wine red by adding a very small amount ofCelanthrene Brilliant Red dye.

Contaminant: Pennzoil 705 (Pennzoil Products Co.), a multi-purpose lubricant is a lithium soap grease. It was colored darkpink by adding a small amount of Celanthrene Brilliant Red dye.This grease was selected to represent a worse case contaminantbecause of its very high viscosity and relatively non polarcharacteristics.

Surfactants

Various types of commercially available surfactants werescreened. Mainly nonionic samples were supplied by surfactantmanufacturers, in response to a request for surfactants whichexhibit the following properties:

a. Excellent wetting and emulsification properties for theremoval of a thickened polar oil type material from aTeflon surface

b. Soluble or fairly soluble in water

The surfactants evaluated included 5 anionics, 2 cationics,12 nonionicsand 4 blends of anionic and nonionic surfactants.The anionic and nonionic surfactants and their respectivemanufacturers are listed in Tables 2-S, according to theirionicity and class of compounds. Their solubility properties andmanufacturers' recommended applications are also included whereavailable. The cationics and blends of anionic and nonionicsurfactants are likewise described below:

Cationics (I.C.I. Americas Inc.)

N-substituted-N-ethyl morpholinium ethosulfate

G-263: N-cetyl-N-ethyl morpholinium ethosulfate - 35%aqueous solution; soluble in water and in xylene at 10% concen-tration.

G-271: N-soya-N-ethyl morpholinium ethosulfate - 35% aqueoussolution; soluble in water and in xylene at 10% concentration.

Blends of Nonionic and Anionic SLurfactants

AFFF (Aqueous Film Forming Foam) is a formulated productcontaining a mixture of fluorocarbon surfactants and hydrocarbonsurfactants. Further information on its formulation is proprie-tary. It is manufactured by 3 Companies viz. National FoamSystem Inc., The Ansul Co., and 3M Co.

3

AFFF is available both as a 3% and a 6% concentrate (v/v).According to the manufacturers, the 3% concentrate is twice theconcentration of the 6% concentrate. In these investigations,AFFF was used at a 3% dilution level (manufacturer's term for a3% dilution of a 3% concentrate). AFFF is soluble in water, andis recommended in firefighting systems because of its stable highfoam and its spreading characteristics.

Bio-Soft HD-1O0 (Stepan Co.)

Information on its formulation is proprietary. However,Stepan Co., describes this product as a "unique blend of nonionicand anionic surfactants that makes it an excellent startingpoint for the formulation of high quality liquid laundry syn-dets." It is water soluble.

Preparation of Surfactant 'Solutions' (% w/v in liter)

To prevent gelling of the surfactant, 'solutions' wereprepared by adding a known weight of the surfactant to waterwith stirring, until dissolution was complete.

Apparatus

A schematic diagram of the decon spray system is shown inFigure 1. The test material (actual test surface, -14 cm long- see Procedure) was suspended vertically inside the decon tankat a distance from the nozzle (- 13.5 cm) that would allow theeffluent washings to fall directly into the reservoir of surfac-tant test fluid. The decon tank (a glass fish tank: 50.5 cm longx 31 cm high x 26 cm wide) was elevated at a 300 angle (notshown) to facilitate mixing of the stirred surfactant test fluid(I liter).

The stirred test fluid was drawn from the tank by a stain-less steel vane pump (Eastern Industries model VW-1) which wasdriven by an electric motor (General Electric, 1/15 HP, 5000 rpm,115 V). The fluid flowed through the pump and was split into 2streams. The pressure of the flow to the nozzle (SprayingSystems: full cone tip, orifice diameter .030 inch) was monitoredby a pressure gauge. The rate of the flow diverted to thedetector was monitored with a flowmeter (Brooks Rotameter Co.,stainless steel float in tube 6-15-2). Both the pressure and flowrate could be varied via a by-pass valve or pump motor speed

A control (General Radio Co., Varlac) or both. The detector, aIUV-Visible double-beam spectrophotometer (Perkin Elmer Lambda3A) was interfaced with a computer. Thus, the simulant concen-tration (via its absorbance measurements), and the nozzlepressure could be monitored during the decontamination process.However, problems of light scattering due to bubbles in the flowsystem has limited the usefulness of this automated method ofmonitoring surfactant effectiveness (see Detection Methods).

4

_4N. .,~

CONTROL DETECTOR TRANSDUCER SUSPENDED

FLOW( RESURE TEST SURFACE

DECON TANK

_________- - -4 CANDIDATE

Figure 1 -schematic diagram of the decon spray system

5

L I . ..

Procedure

Colored thickened methyl salicylato (-5038 centistokes) -referred to as MST-D, was spotted (drop diameter -2-3 mm) on asmooth substrate with a density coverage of -50 Mg over 2 cm x 2cm area (Figure 2), at the site of the fluid spray impact.Removal of the applied thickened simulant/contaminant from thetest surface was examined using a low pressure spray (-5 psi) ofthe test fluid and a flow rate of -600 mL/min. To avoid crosscontamination between evaluations, the tank and the entire flowsystem were thoroughly cleaned by pumping water through thesystem before each evaluation. The tank was considered cleanwhen no foam was present.

The test surface included the origin of application (-2 cmlength) plus an additional 12 cm vertical length of test surfaceprior to the effluent washings falling into the decon tank.Effectiveness of the test fluid was determined via two detectionmethods viz., UV spectrophotometry and a visual method. Thesemethods are subsequently discussed.

Detection Methods

UV Spectrophotoie try

This method determines the concentration of methyl salicy-late present in the effluent washings via its absorbance measure-ments. Thus, using a quartz flow cell (Helma, 2 cm path length),in the sample beam, and a regular quartz cell containing thesurfactant solution in the reference beam, absorbance measure-ments were made at 304 nm i.e., the wavelength of maximumabsorbance for methyl salicylate. As shown in Table 6, theabsorbance of methyl salicylate increased with increasing time toa maximum at -9 min, after which it decreased. The time at whichmaximum absorbance occurred was used to measure surfactanteffectiveness. The decrease in absorbance with time was due to aloss of methyl salicylate via the spray mode. For example, after-10 min. spray period, -15% methyl salicylate is lost and -25%after -15 min. spray period. Consequently, the accuracy of theabsorbance measurements decreases for spray periods > -10 min.Nevertheless, within a -10 min. spray period, UV spectrophoto-metry offers the capability of determining the rate of methylsalicylate removal.

Limltatlons: Table 6 represents surfactant systems in whichlight scattering did not interfere significantly with theabsorbance measurements. However, for systems in which lightscattering did interfere, the following problems wereencountered:

6

'~. %

Figure 2 -Colored thickened methyl salicylate (MST-D) spotted(2-3 mm diameter) on Teflon: Before Spraying

7

i. In the determination of surfactant effectiveness, thetime at which maximum absorbance occurred was either not defini-tive (see Table 7) or was erroneous, or both, as compared with avisual detection method.

2. In quantification of the data, poor precision of themaximum absorbance values was obtained for the same MST-Dconcentration e.g., "594, *756 and 1-389 were the maximumabsorbance values for the same concentration of 50 mg MST-D in 1liter of Aerosol MA-80 (1.6%).

Liqht Scattering: Causes and Recommendations

Causest Light scattering was caused by the presence ofbubbles in the flow system, as well as by surfactant solutionsthat were not completely soluble at the concentrations employed.Bubble formation was due to: a) the nature of the surfactante.g., high foam characteristics; b) stirring the effluentwashings -adequate stirring was necessary to facilitate mixingof MST-D in the surfactant; and c) the fast flow rate employed(-600 ml/min.) - this was necessary to improve the samplingaccuracy of methyl salicylate in the effluent at known timeperiods.

It is important to note that high foaming surfactants didnot always interfere with the absorbance measurements. Thus,light scattering appears to be due to a combination of thefactors mentioned above.

Recommendations:

1. Use of an integrating sphere in the UV-spectrophotometerwould minimize, if not eliminate, scattering due to hazy surfac-tant solutions.

2. Improve the shape of the reservoir to a round configu-ration or increase the depth of the reservoir fluid or both.This can be accomplished by the use of 2 blocks placed insidethe tank -one on each side. This improvement would facilitatebetter mixing at lower stirrer speeds and minimize the entrain-ment of air caused by vortexing. Use of a tachometer would alsohelp to ensure a constant stirrer speed.

3. Use of a flow cell in the reference beam may help tonullify scattering due to the presence of bubbles in the sampleflow cell.

4. Use of a de-bubbler device in the flow system should bere-examined even though a preliminary test was inconclusive.

8

Visual Detection Method

This method involves the use of an oil soluble dye (Celan-threne Brilliant Red), which was incorporated in the thickenedmethyl salicylate formulation/contaminant. The method thusdetermines the removal of MST-Dlcontaminant from the testsurface. Using a stop watch, surfactant effectiveness wasmeasured as the time (min.) taken for complete removal of thethickened simulant/contaminant from the entire test surface. Thismethod is a more rigorous test of surfactant effectiveness thanUV spectrophotometry, since the latter determines only theconcentration of methyl salicylate/simulant removed.

Advantages of the method are as follows:

a. It is independent of light scattering problems caused bybubbles in the flow system and/or hazy surfactantsolutions.

b. It enables problems of redeposition to be readilyvisualized.

c. It is accurate and dependable in cases of completeremoval.

Limitations; Unlike UV spectrophotometry, the rate ofremoval cannot be determined. This limitation is particularlysignificant in cases of incomplete MST-D/ contaminant removalfrom the test surface. Thus the amount removed at a known timeperiod cannot be evaluated.

Choice of Detection Method

Because of the limitations of both methods of detection, andbecause the two methods complement each other, surfactanteffectiveness should be evaluated using both methods simultan-eously. However, in order to be consistent in the determinationof surfactant effectiveness the surfactants were evaluated andcategorized using the visual detection method. When possible,supporting data on the amount of methyl salicylate removed wasdetermined via UV spectrophotometry.

Systems Examined

The following parameters were investigated:

Substrate: A high energy surface e.g. stainless steel anda low energy surface e.g. Teflon.

Simulant/Contaminant (See Materials); Mainly, coloredthickened methyl salicylate (MST-D) was examined. ColoredPennzoil grease was also investigated, and was selected torepresent a worse case contaminant.

9

Surfactants (See Materials): These included various typesof commercially available anionic, cationic, and nonionic surfac-tants as well as blends of anionics and nonionics. Unlessotherwise stated, the concentration (w/v) of the surfactantsevaluated was above their critical micelle concentration (cmc)level, thereby optimizing their wetting properties.

Aqueous Medium: The surfactant solutions were usuallyprepared in tap water. In a limited number of experimentshowever, synthetic sea water was also used. Thus, tap water orsynthetic sea water was employed as the reference, depending onthe aqueous medium used to prepare the surfactant solutions.

Spray Temperature: Unless otherwise stated, the spraytemperature employed was -210C.

Effect of fonicity, Concentration, and Spray Temperature ofthe Surfactant: Results of this investigation were presented9

recently. Nevertheless, these experiments are redescribed in thisreport for purposes of completeness. In this investigation, themost promising anionic surfactant (Aerosol GPG), and an effectivenonionic surfactant (Renex 678) were screened using a 23 fac-torial designI0 (see Table 8), in the removal of MST-D from aTeflon substrate. Renex 678 was selected in preference to Renex30 because of its higher cloud point. Tap water was used as thereference.

RESULTS AND DISCUSSION

General Screening

Surfactant effectiveness was evaluated with reference towater in the removal of a colored thickened simulant for mustard.The colored thickened methyl salicylate is referred to as MST-D.These evaluations were performed using a low pressure spray (-5psi) directed at the origin of the MST-D application. Theeffectiveness of the test fluid was measured as the time (min.)required for -100% removal of MST-D from the entire test surface,and was based on the visual method of detection (see Experimental- Choice of Detection Methods). Results of the various para-meters investigated are subsequently described, and possiblemechanisms are discussed.

10

-LO

Iffect of Substrate

Stall"ess Steel

Evaluation

As shown in Table 9, on a stainless steel substrate, waterwas more effective than most of the surfactants evaluated in theremoval of MST-D from the entire test surface. Furthermore, WhiteMagic, a formulated automatic dishwashing detergent was only -10-25% more effective than water. Thus, on a stainless steelsubstrate, fresh and seawater appear promising as decon candi-dates with a thickened mustard simulant. The relatively poorperformance of the surfactants versus water indicates that forthe removal of this specific simulant from a high energy surface(stainless steel), detergency mechanisms do not play a majorrole. For example, the surfactants that exhibit better wettingproperties (i.e. lower surface tension and lower interfacialtension) and better emulsification properties (lower interfacialtension and high hydrophile lipophile balance (HLB) values:-14-20) exhibited longer removal times than water.

Mechanism

Although the detergency mechanisms that are operative inlaundering are well established, the detergency mechanismsinvolving spray applications (e.g., automatic dishwashing) areonly poorly understoodlb. A possible explanation for the greatereffectiveness of water (i.e., versus the surfactants) on astainless steel substrate may be related to the high adhesionalproperties of a high energy surface. That is, the extent ofwetting/spreading of the thickened simulant/contaminant on a highenergy surface will be greater than on a low energy surface suchas Teflon. Thus, on impact of the water-spray, the MST-Ddroplets are flattened into thinner films, and the mechanicalenergy required for their removal is thus reduced.

In contrast, the excellent wetting properties of thesurfactants facilitate displacement of the MST-D droplets intothicker films. Consequently, the mechanical energy required forMST-D removal is increased, thereby resulting in the decreasedperformance of the surfactants. Formation of thicker films whichredeposited was observed particularly with AFFF. (cf. Figs. 3 and4). Furthermore, the high foam characteristics of AFFF wouldalso lower the impact energy of the spray, thereby contributingto the increased removal time. For similar reasons, automaticdishwashing formulations employ low foaming or defoaming surfac-tantslc.

11

Figure 3 -colored thickened methyl salicylate (MST-D) spotted(2-3 mm diameter) on stainless steel: Before Spraying

12

.) es,: RF 'F 3%".,

17Jbs.p : 2o'C

Figure 4 - Stainless steel substrate: Larger MST-Ddroplets formed after spraying with 3% AFFF/5 min

13

2eflon

Evaluation

Since water appears to be an effective decon fluid for theremoval of a thickened mustard simulant on a high energy surface(stainless steel), a low energy surface (Teflon) was subsequentlyexamined. For a Teflon substrate, the evaluation of varioustypes of commercially available surfactants indicated threelevels of surfactant effectiveness relative to water. Based onthe level of surfactant effectiveness during a maximum sprayperiod of 15 minutes, the surfactants were categorized into thefollowing three classes.

Class A: Surfactants which performed better than water andwere effective in -100% removal of MST-D from the entire testsurface. These included anionics, cationics, nonionics, and ablend of anionics and nonionics (see Table 10).

Class B: Surfactants which performed better than water Inthe removal of MST-D from the origin of application (cf Fig. 5and Fig. 6). However, these surfactants were not effective inthe removal of MST-D from the entire test surface during the 15minute spray period. Removal from the origin was due to acombination of actual MST-D removal as well as a mere downwardsmovement of MST-D via elongation of MST-D droplets into threads.These surfactants exhibited varying removal times from the originof application as well as varying amounts of redeposition (seeFig. 6). This class of surfactants included: anionics,nonionics and a blend of nonionic and anionic surfactants (seeTable 11).

Class C: Surfactants which performed similar to or worsethan water in the removal of MST-D from the origin of applica-tion. These included various nonionics (see Table 12, also Fig.7). However, based on UV absorbance data, these surfactantsremoved comparable amounts of methyl salicylate relative to water(cf Table 13 with Table 14).

Promising Decon Candidates

The surfactants in Class A (Table 10) were considered to bepromising decon candidates with a thickened mustard simulant, onthe basis of short removal times i.e., -3 minutes or less.Consequently, only the anionics and blends of anionic andnonionic surfactants qualify as promising candidates. Of theanionic surfactants, the most promising was sodium dioctylsulfosuccinate i.e., Aerosol GPG and Triton GR-5M (removal time,1 min) at 1% concentration in tap water. However, Aerosol MA-80(1.6% in tap water) also appears to be very effective (removaltime, 1.5 min).

14

Figure 5 -Teflon substrate: Residual MST-D at theorigin of application after spraying with water/15 min

15

&~~~q.. d4 'z'..j4 . .

ikk2 , I&I

Figure 6 -Teflon substrate: Residual MST-D showingredeposition after spraying with Class B surfactant,

Zonyl FSN. for 15 min

16

4e,,

Figre TelonSubstrate: Residual I4ST-D at theorigin of application after spraying with

Class C Surfactant, Silwet L-7607 for 15 min

17

The AFFF blends although promising at the 3% dilution level(see Experimental - Materials), were - three times less effectivethan Aerosol GPG or Triton GR-SM in tap water. However, nosignificant differences in surfactant effectivenesb were observedamong the three brands of AFFF. Nevertheless, significantdifferences have been reported11 in the extent ofnonreactivity/compatibility among the various brands of AFFF inbuffered hypochlorite solutions i.e., Ansul > 3M >, National.

Mechanism

Good Correlation with Surfactant Properties:

On comparison of the surfactants in Class A, an apparentcorrelation of surfactant effectiveness with the listed surfac-tant properties was observed between certain anionics and certainnonionics (see Table 10). Thus, an approximate ninefold increasein surfactant effectiveness of the most effective anionicsurfactant (Aerosol GPG or Triton GR-5M) versus the most effec-tive nonionic surfactant (Renex 30, 2%), may well be related toa combination of: lower surface tension, lower interfacialtension, faster rate of wetting and higher HLB value of theanionic surfactants. However, an approximate threefold decreasein surfactant efficacy of AFFF vs Aerosol GPG or Triton GR-5M,despite AFFF's much lower surface tension may be related to thehigh foam characteristics of AFFF. As alluded to earlier(Stainless Steel, Mechanisms), high foaming lowers the impactenergy of the spray. Nevertheless, these results support adetergency mechanism 12-14 involving the following:

1. Progressive displacement of MST-D/contaminant moleculesby more strongly adsorbed surfactant molecules (rolling-up-process). This is accomplished by those surfactantsthat lower the work of adhesion between MST-D/ contami-nant and the Teflon substrate. Thus, as shown byDupre's equation for a low energy surfacel5a

WA = 7IFT (1 + cos 0)where WA is the work of adhesion,YIFT is the interfacial tension, ande is the contact angle.

the work of adhesion is lowered by surfactants thatexhibit excellent wetting properties i.e., low surfacetension and low interfacial tension. Since the rate oflowering of theselproperties (i.e., the rate of wetting)is also important ba , this factor would be particularlyrelevant in dynamic modes such as spray applications.

2. Emulsification of the MST-D contaminant: Emulsificationdisperses the contaminant (non polar) as globules whichare easily dislodged from the substrate after therolling-up processl2a. Furthermore, dispersion of the

18

0Z

globules as a fairly stable emulsion would prevent

problems of redepositionl 2b. Ease of emulsification isfacilitated b surfactants that exhibit low interfacialtensionsl5blib, and HLB values within the range -8 _1 8 .

16c However, stability of the dispersed dropletsare not necessarily related to low interfacial tensionsand high HLB values (see also, "Prevention of Redeposi-tion: Possible Factors Involved" which are discussedlater).

Poor Correlation with Surfactant Properties

Poor correlation of surfactant effectiveness with thesurfactant properties listed was observed among the nonionicsurfactants in Class A, and more so on comparison of thenonionics in Class A versus those in Class C. Although, incom-plete surfactant properties data of the surfactants in Class Chave limited the extent of the analyses, some examples of theanomalies are as follows:

1. Among the nonionics in Class A (Table 10), the surfac-tant effectiveness of Poly-Tergent SL-62 was notimproved relative to Renex 678, in spite of the lowersurface tension, lower interfacial tension, and fasterrate of wetting of SL-62.

2. Little or no removal of MST-D from the origin ofapplication was exhibited by Silwet L-7607 (Class C,Table 12) despite its excellent wetting propertiesand high HLB value. This anomaly was further emphasizedon its comparison with the anionic and nonionic surfac-tants in Class A.

Possible Explanation of the Anomalies

In the cases cited, the poor correlation of surfactanteffectiveness with wetting and emulsification properties indi-cates other factors may be involved. Possible factors includethe role of solubilization17 ,18 . This involves the spontaneoustake-up of water-insoluble substances, such as oils, within themicelles of the surfactant. In this way1 7 ,1 8 , non polar typematerials are removed from the substrate. The possibilities of asolubilization mechanism being operative in the systems studiedare described in the following analogies:

1. Solubilization occurs to a higher extent with oils thatcontain polar constituentsl9 a such as fatty acids, esters, etc.,(cf. methyl salicylate which, like the chemical agents, can bedescribed as a polar oil 20 ).

2. Solubilization is facilitated by the use of a surfactantconcentration that is greater than its critical micelle concentra-tion (cmc)1 5 c. Thus, the greater surfactant effectiveness of

19

Renex 678 (nonionic in Class A). versus Aerosol AY-65 and AerosolAY-100 (anionics in Class B) may be related to Renex 678 beingevaluated at a concentration level (2%) which was far greaterthan its cmc (.0077%); Aerosol AY-65 and Aerosol AY-100 wereevaluated at concentration levels 1.3% and 2% respectively whichwere not much above their cmc values (.9 to 1.2%). This assump-tion can be examined in future studies.

3. Surfactants which exhibit high HLB values within therange 15-18 are classified as solubilizersl 6C. Thus, a solu-bilization mechanism may also contribute to the effectiveness ofTriton GR-5M and Aerosol GPG (HLB, 14-20); likewise, to theefficacy of Aerosol MA-80, since it is described as a solubiliz-ing agent (see Table 2). Furthermore, the ineffectiveness of theClass B nonionic surfactants may be due to their lower HLB values(12.7-13.6).

Prevention of Redeposition: Possible Factors Involved

* Redepositon, which was exhibited by the Class B surfactants,is a complex phenomenon. As alluded to earlier, it is notnecessarily related to the interfacial tension and HLB values.In the prevention of redeposition, the effect of the surfactanton the contaminant and the substrate may involve the following:

1. Development of a stable interfacial layer structurebetween the contaminant droplet and the aqueous phase. Thus,coalescence with other drops on nearby surfaces is inhibited. Apossible mechanism involves the formation of liquid crystals.21

2. Adsorption of the surfactant on the substrate: Factorswhich may be involved include electrical forces of repul-sion.lc ,1 6d,22, the energy barrierl9 b,23 , and the hydrationbarrierl 6d,19c, between the contaminant and the substrate.

Effect of Synthetic Seawater (Aqueous Medium)

The most promising anionic and blend of anionic and nonionicsurfactants. as well as an effective nonionic (Class A, Table 10)were subsequently re-evaluated using synthetic seawater as theaqueous medium. The nonionic surfactant, Renex 678, was selectedin preference to Renex 30 because of its higher cloud point(99.40C versus 840C for Renex 30) - hence greater solubility inhigh salt concentrations such as seawater. The results shown inTable 15, indicate the following order of surfactant effective-ness AFFF (3%) >> Renex 678 (2%) > Aerosol GPG (1%) > syntheticseawater.

Based on removal time, AFFF appears promising (3 min. at 3%)as a decon candidate with a thickened mustard stimulant in seawater applications. Although the surfactant effectiveness ofAFFF and Renex 678 were unaffected in a synthetic seawater

20

medium versus tap water, the effectiveness of Aerosol GPGdecreased eighteenfold in synthetic seawater. This decrease maybe related to its poor solubility in water: Aerosol GPG exhibits1.6% solubility in distilled water at 30"C and only 540 ppmcalcium tolerance at .5% concentration. In future studies,Aerosol MA-80 (1.6% or above) should also be evaluated in a seawater medium because of its greater solubility in water.

Effect of Pennzoil Grease (Contaminant)

The most promising anionic and blend of anionic and nonionicsurfactants as well as the most effective nonionic were alsoevaluated in the removal of a worse case contaminant e.g.,Pennzoil grease (see Experimental-Materials). The results shownin Table 16, indicate only Aerosol GPG (1% in tap water) to beeffective (surfactant effectiveness, 25 min.). Since neitherAFFF nor Renex 30 were effective even after 45 min spray period,the results indicate that in addition to its excellent wettingand emulsification properties, Aerosol GPG may also exhibitbetter solubilization properties than AFFF or Renex 30. This isconsistent with its solubility in non polar organic solvents (seeTable 2).

Effect of lonicity, Concentration and Spray Temperature

of the Surfactant

Avaluation

The effect of these variables on surfactant effectivenesswas examined using a 23 factorial design (for details, seeExperimental, Systems Examined). As shown in Table 17, at 200C,surfactant effectiveness increased with an increase in ionicityand concentration. However, at 40"C and high surfactant concen-tration, a negative temperature effect was observed with thenonionic surfactant i.e., its surfactant effectiveness decreasedwith increase in temperature. Under similar conditions, theanionic surfactant exhibited no change. Thus, in the systemsstudied, surfactant effectiveness did not increase with increasein temperature.

$fechanlam

The increase in surfactant effectiveness with increase inconcentration is consistent with a detergency mechanism. Thus,at the critical micelle concentration, wetting properties areoptimi2ed. Also, above the critical micelle concentration,removal via solubilization Is facilitated as was discussedearlier (see Possible Explanation of the Anomalies).

The approximate tenfold increase in surfactant efficacy ofthe anionic versus the nonionic surfactant - is more likely dueto the superior wetting, emulsification~and solubilization

21

properties of Aerosol GPG than to its ionicity. However, therole of ionicity would be better evaluated by comparing sur-factants with similar surface active properties, but differingonly in ionicity.

The effect of temperature on soil removal is not defini-tive 24 . However, the negative temperature effect of Renex 678 atthe high concentration level, may be due to decreased surfactantadsorption with increase in temperaturel2c.

SUMMARY AND CONCLUSIONS

A method involving a recycling flow system was developed toevaluate candidate decon fluids for spray applications. Themethod offers the capability of evaluating various simulant/substrate/surfactant systems, and uses two detectors. In theremoval of a thickened simulant for mustard, UV spectrophotometryoffers the potential for monitoring both the amount of methylsalicylate removed, and the rate of removal, within a 10 min.spray period. However, problems of light scattering due to thepresence of bubbles in the flow system and/or hazy surfactantsolutions have limited the usefulness of this detection method.Nevertheless, because of the automated aspect of this detectionsystem (i.e., the UV-VIS spectrophotometer is interfaced with acomputer), resolving these light scattering problems wouldgreatly enhance the usefulness of the method.

The visual detection method offers a more rigorous test ofsurfactant efficacy than UV spectrophotometry since it monitorstotal removal of the thickened methyl salicylate (i.e., via theuse of a dye incorporated in the formulation, MST-D). However,the visual detection method cannot be used to measure the rate ofremoval. Nevertheless, in cases of incomplete removal, it isuseful in visualizing problems of redeposition. The two detec-tion methods therefore complement each other. In order to beconsistent in the determination of surfactant effectiveness thesurfactants were evaluated using the visual detection method. UVabsorbance measurements were also used as supporting data whenpossible.

Consistent with a detergency system, effectiveness of thedecon test fluid was found to be specific for the type of

*i substrate, the contaminant, and the aqueous medium employed.Thus, on a high energy surface such as stainless steel, tapwater, which was used as the reference, and synthetic seawaterappear to be promising decon candidates with a thickened mustardsimulant (removal time, - 1 min). On the low energy surface,Teflon, promising decon candidates with a thickened mustard

' simulant include: sodium dioctyl sulfosuccinate i.e. AerosolGPG, and Triton GR-5M (1%) in tap water but not in synthetic seawater; sodium dihexyl sulfosuccinate i.e., Aerosol MA-80 (1.6% intap water) and AFFF (3% dilution) in both synthetic seawater and

22

in tap water. The removal times of these surfactant solutionswere within 1 - 3 mins. In tap water, the order of effectivenesswas: sodium dioctyl sulfosuccinate > sodium dihexyl sulfosucci-nate > AFFF. Moreover, with a worse case contaminant such asPennzoil grease on a Teflon substrate, only sodium dioctylsulfosuccinate (1% in tap water) was effective.

On a Teflon substrate, surfactant effectiveness increasedwith surfactants that exhibited a combination of increasedwetting, emulsification, and solubilization properties (e.g.,sodium dioctyl sulfosuccinate). In a seawater medium, sur-factants must also exhibit a high cloud point and high toleranceto calcium. Alternatively, sequestering agents can be added tothe detergent formulation. Furthermore, in the removal of athickened mustard simulant from a Teflon surface, surfactanteffectiveness did not increase with increase in temperature. Theoverall results indicate various detergency mechanisms to beoperative on a Teflon substrate but not on stainless steel.

In conclusion, the results are promising. However, theirspecificity, as described, indicates further work is necessary.(See Recommendations and Future Work).

RECONERDATIONS AND FUTURE WORK

1. The decon candidates which were found to be promising with athickened mustard simulant on a Teflon substrate, should bere-evaluated on other challenging substrates and surfaces, andwith other contaminants. Examples of such substrates/surfacesinclude other low and high energy surfaces such as: Lucite,

" samples of materials used on ships' deck surfaces - before andafter wear, as well as various forms of surfaces viz., painted,dry, wet, rough, smooth, porous etc.

2. In conlunction, the search for superior physical deconcandidates should continue, especially so, should the presentcandidates prove ineffective in the challenging systems proposedabove. Some suqqestions for improving the efficacy of thesurfactants are based on the properties of those surfactantswhich were found to be promising. Thus, obtain commercially, orprepare win house", detergent formulations that exhibit acombination of the following properties:

Low surface tension: < 20 dynes/cm at 25QC

Low interfacial tension : < 2 dynes/cm at 25uC

Fast rate of wetting: Almost instant at (0.5%surfactant concentration

23

Low critical micelle concentration: <0.01%

High hydrophile lipophile balance : -20 (or experiment)

High Cloud Point: > 600C

High calcium tolerance

Soluble in water, polar and non polar organic solvents.

Consequently, formulated detergents should contain the following:

Wetting agents

Emulsifiers

Sequestering agents for hard/sea water

Anti-redeposition agents or suspending aids to preventredeposition of the removed contaminant.

Corrosion inhibitors

3. Investigate other physical decon systems such as micro-emulsions.

4. Select decon candidates that are compatible with hypochloriteand/or other detoxifiers.

ACKNOULEDGMRETS

The authors wish to thank Mr. James B. Romans for buildingthe decon spray apparatus and the various manufacturers forsamples of their surfactants. This work was sponsored by theNaval Sea Systems Command.

REFERCES

1. Mizuno, William G., In *Detergency: Theory and Test Methods,Part III", Surfactant Science Series, Vol 5, Cutler, W.G.and Davis, R.C., Ed.; Marcel Dekker Inc.: New York, 1981;Chapter 21, (a) p. 828; (b) p. 826; (c) p. 831.

2. Loeb, L. and Shuck, R.O., J. Am. Oil Chem. Soc. 46, 299(1969).

3. Carpenter, Ben H., Cleland, J.C., Ranade, M.B., Summers, D.A.,"Liquid Spray/Jet Decontamination: Mechanisms of SurfaceInteractions", Chemical Research and Development Center,CRDC-CR-84046, Aberdeen Proving Ground, MD, 21010-5423,September 1984, (a) p. 70; (b) p. 29. ADB086532L

24

4. Bless, S.J., Akers, C.A., Summers, D.A., Zakin, J.L.,Mackay, R.A., "Decontamination by Liquid Blasting", ChemicalSystems Laboratory Special Publication ARCSL-SP-81012, June1981 Symposium on Toxic Substance Control: Decontamination,Columbus, Ohio, April 22-24, 1980. ADA102107

5. Cox, Robert M., "CW Decontamination of Ship Decks", NavalWeapons Center, NWC Technical Memo 3304, China Lake, CA,January 1979.

6. Cante, Charles J., Dellicolli, H.T., Eachus, Alan C.,Stuempfle, Arthur K., "Chemical Additives for ImprovedSurface Decontamination by Steam or Hot Water", ChemicalSystems Laboratory Technical Report ARCSL-TR-81028,Aberdeen Proving Ground, MD 21010, July 1981. ADB059456L

7. Meyer, A.E., Akers, C.K., Baier, R.E., "Surface-ActiveDisplacement Solutions", Chemical Systems Laboratory SpecialPublication, ARCSL-SP-81012, June 1981 Symposium on ToxicSubstance Control: Decontamination, Columbus, Ohio, April22-24, 1980. ADA102107

8. Meyer, A. E., Akers, C. K., and Baier, R. E., "Surface-ActiveDisplacement Solutions for Removing Chemical Warfare Agentsfrom Contamination Surfaces," Calspan Final Report preparedfor ARRADCOM, Chemical Systems Laboratory, February 1979.

9. Pande, Seetar G., and Little, R.C., "A Novel Method for theEvaluation of Candidate Decon Fluids for Spray Applica-tions", presented at the Scientific Conference on ChemicalDefense Research, Aberdeen Proving Ground, Md., November13-16, 1984.

10. Strategy of Experimentation Course, E.I. DuPont De Nemoursand Co., Applied Technology Division, Revised Edition,October 1975, p. 18.

11. Taylor, R.G., Little, R.C., and Utz, J.L., "Aircraft CarrierDecontamination Study Hypochlorite/AFFF Compatibility TestI", Naval Research Laboratory, NRL Memorandum Report 5103,Washington, D.C., June 8, 1983. ADB073832L

12. Adam, N.K., and Stevenson, D. G., "Detergent Action",Endeavour, January 1953, (a) p. 25; (b) p. 26; (c) p. 32:ibid, Endeavour, 1953 12, 45.

13. Adam, N.K., J. Soc. Dy. Col. 1937, 53, 121.

14. Palmer, R.C., J. Soc. Chem. Ind., Lond., 1941, 60, 56.

15. Osipow, Lloyd I., "Surface Chemistry Theory and IndustrialApplications"; Rheinhold Publishing Corporation: New York,1962; (a) p. 237; (b) p. 296; (c) p. 165.

25

16. Davies, J.T., and Rideal, E.K., "Interfacial Phenomena";Academic Press: New York, 1961; (a) p. 419; (b) p. 360; (c)p. 373; (d) p. 420.

17. McBain, J.W., In "Advances in Colloid Science", Kraemer,E.O., Ed.; Wiley Interscience: New York, 1942; Vol. 1, pp.99-142.

18. McBain, M.E.L., and Hutchinson, E., "Solubilization andRelated Phenomena", Academic Press: New York, 1955.

19. Lange, H. In "Solvent Properties of Surfactant Solutions",Surfactant Science Series, Vol. 2, Shinoda Kozo, Ed., MarcelDekker, Inc.: New York, 1967, Chapter 4, (a) p. 163; (b) p.136; (c) p. 151.

20. Cante, Charles J., Dellicolli, Humbert T., Wright, RobertJ., "A Program to Study the Effect of Additives in Water-Wash Sprays", Defense Technical Information Center,Alexandria, VA; Report No. ARCSL-SP-80005, May 1980.ADB048312L

21. Friberg, S. and Wilton, I., American Perfumes andCosmetics, 1970, 85 p. 27.

22. Stillo, H.S., and Kolat., R.S., Text. Res. J., 1954, 24,881.

23. Harris, Jay C., "Forces in Detergency", Soap and ChemicalSpecialities, 1961, 68, 68.

24. Niven, W.W. Jr., "Fundamentals of Detergency"; Rheinhold:New york, 1950; p. 229.

2

| .",26

TABLE 1

Some Physical Properties of Mustard and Its Simulantwith Specific Reference to Physical Decon

in an Aqueous Medium

PROPERTY* METHYL SALICYLATE MUSTARD (HD)

Molecular weight 152.14 159

Melting point (9C) -8.6 11

Boiling point (OC) 220-224 217

Solubility in water (. .067 .09 (220C)

Surf Tension at 25-C 37.5 42.1(dynes/cm)

Contact Angle on Dry Surface:

(deg)

Teflon 46 63

White gloss polyurethane paint <4 17

* *From Reference 3b with some corrections.

V 27

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28

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31

%**~a*** *~, *N

M TABLE 6

[I~EC":..N o--vF H T-D/TE*F/RX, 30 2%

TI M I N.RS PRESS8 .015 .765

I (3.9 .e241.5 .@!-4 .8?42 .0 93 .8432.5 .123 .74b3 .185 .7453.5 .25,5 .7f.4 .-4 .7844.5 .4?4 .804

5.5 .641 .8446 ./1 .8146.5 .7k-4

5?.S .R44..

8 .8:564 .848.5 .8 .(4

.8X .8144

1..• 88 . R. 44115 .53 R .8

11.5 .872 E ;le2!12 .849 .74512.5 .333 7t:.'%13 .983.3 ',513.5 .926 .78414 .. 8 .414.5 .826 .80415 .L8 .

RUN *1 ON 2-7-85

SI1ULANT a THICKENED METHYL SALICYVLTE (UISC 538 CS) WITH CIELA WHENBRILLIANT DYE SPOTTED AT NOZZLE IMPACT C51.8 M8) OVER 4 S CM WMR,IECON IS RENEX 39 (2%) IN TAP WATER WIT4 SPRAY TEMP 21 DEG C

NOZZLE FULL CONE ABOUT 5 PSI MITH FLOW4 RATE ABOUT ABOUT 609 HMIN

32

TABLE 7

UECON OF NST-OTEF/AFFF 3% (ANSUL)

TIME(IN) ABS PRESSa .869 .863.5 .154 .902I , .417 .8631.5 .602 .863, .664 .8822.5 .772 . 863• 3 .741 .8823.5 .779 .8.24 .803 .9024.5 .772 .9025 .81 .9025.5 .818 .90b .864 . W26.5 .857 .90.d" .895 .9027.5 .i.0:"8 . 72 •.982

8.5 .6.9214 .863

9.5 .942 .8821o . S57 .88218.5 814.2

11.849 .88211.5 .926 .90212 . k1? .88212.5 .934 .88213 .9.3 .88213.5 .949 .912

*14 .926 .90214.5 .918 .!jIe15 .849 .882

RUN *35 LPN 3-5-85

SIMULI4TN = THICKENED METHYL SALICYLATE (UISC 5038 CS) WITH CELANTHRENEBRILLIANT DYE SPOTTED AT NOZZLE IMPACT (50 MG) OUER 4 SO CM AREA

OECON IS :FFF 3% EX 3;. CONCENTRATE (ANSUL) IN TAP HATER WITH SPRAY TEMP 25 DE

'CC

NUZZLE FULL GU;NE ABO6UT 5 PSI WITH FLOW RATE ABOUAT 91BOUT 69W8 ML/MIN

33

v P . , .

TABLE 8

Experimental Design: 23 Factoriala,

Independent Variables LevelsZero-Low High

Ionicity Nonionicb Aflionicc

Concentration ()0.05 1-2

Spray Temperature (OC) 20 40

a Refers to 3 independent variables studied at 2 levels.

b Renex 678: polyoxyethylene (15) alkyl aryl ether

C Aerosol GPG: dioctyl sodium sulfosuccinate

34

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35

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38

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444 4 45 h 0.0

TABLE 13

OECON OF lMST-O/TEF/TNN-2d (20%)

TIME(HIN) ABS PRESS( .15 .941.5 .839 . 88.'1 .062 .8431.5 .093 .863e .1 .843t. 5 .131 bies .162 .9823.5 .193 .%024 .;eel .9224.5 .224 .9415 .24? .9415.5 .27 .9bl6 .278 .9816.5 .301/ .309 .4417.5 .332 .9418 .341 .418.5 .417 .9Sb

.386 .l419.5 .417 .961la .409 .96118.5 .432! .96111 .448 .922I1.5 .455 .92212 .4/1 .98212.5 .471 .92213 .494 .92213.5 .569 .Wie14 .509 .94114.5 .525 ,92d15 .517 .941

F4N 04'4 LIN 3- 7-t;

sIIJLiwNT = rHICKENED METHYL SOLICYLIgrE (UISC 5038 CS) WITH CELAiNTHNEBRILIANT DYE SPOTTED AT NOZZLE IMPACT (50 Mb) OUER 4 SO CM ARE1

IECON IS l.C.I. AMERICAS INC TWEEN 20 (2%) IN TAP WATER WITH SPRAY TEMP 23 DEL

"3ULL t;ULL CUNE .BOUT 5 PSI WITH FLOW RATE ABOUT AMOUT 6V MLMWIN

40

TABLE 14

DJEC ON OF ttST-O'TEF/TAP HATER

TIM1E(MIN) FBS PRESS0 .023 .922.5 .085 .941

-. 1 .1162 .9611.5~ .208 .9814 .239 .961

25.255 .981.3 .27 1.023.5 ie8b 1.0344 ..3811.54.5 .3?4 1.0985 .332 1. 11e5.5 .347 1.059

6.355 1.0796.5 .3861.7

7.386 1.0797.5 .4031 1. 11168 .4131 .9228.5 .4.24 92

.44 t1229.5 .44e..12183 .463 .88210.5 .459211 .463 .811I. -* .4Kb*,.*.b12 .478 .86312.5 .494 .8k!413 .471 .86313.5 .478 .84314 .502 .8t-314.5 .509 .p;15 .517 .882

RUN 048 LIN 3-14-85

SIIIULHNT = THICKENED METHY'L SALICVLATE (VISC 5938 CS) WITH CELANTHRENEBRILLIANT DYE SPOTTED AT NOZZLE IMIPACT (56 MG6) OV~ER 4 SQ CMI AREA

* CDECON IS TAP HATER AS CONTROL IN TAP HATER WITH SPRAY TEMP 21 11G C

NOIZZLE FULL CONE ABOUT 5 PSI WITH FLOW RATE ABOUT ABOUT 668 MLeI

41

*** .'& -. - .* '~-~. . -' q %~~\.~bW ~ W~b?. .01f '.''

F--T

TABLE 15

Effect of Synthetic Seawater on Surfactant

Effectiveness: Removal of MST-D from a Teflon

Substrate at 5 psi Spray Pressure and -21°C

Surfactants Removal Time(concn in synthetic seawater) (min)

National AFFF (3%) 3

Aerosol GPG (1%,) 18

Renex 678 (2%) 10

Reference: Synthetic Seawater >15

TABLE 16

Effect of Contaminant on Surfactant Effectiveness

Removal of Pennzoil Grease from Teflont

5 psi Spray Pressure and ~216C.

Surfactants Removal Time(concn in tap water) min

Aerosol GPG (1%) 25

National AFFF (3%) >45

Renex 30 (1.5%) >45

Reference: Water >45

As

42

TABLE 17

Teflon Substrate: Effect of Ionicity, Concentration andSpray Temperature of Surfactant on Surfactant Effectiveness

Surfactant Concentration Temperature Removal Time(Ionicity) % UC (min)

Aerosol GPG .035 20 >15(Anionic) .035 40 >15

1 20 11 40 1

Renex 678 .05 20 >15(Nonionic) .05 40 >15

2 20 102 40 >15

Reference: Water 0 20 >150 40 >15

43

9

_____I