Base Hydrolysis of HMX and HMX-Based Plastic-Bonded Explosives

2254

Ind. Eng. Chem. Res. 1999, 38, 2254-2259

Base Hydrolysis of HMX and HMX-Based Plastic-Bonded Explosives with Sodium Hydroxide between 100 and 155 °C Robert L. Bishop, Raymond L. Flesner, Philip C. Dell’Orco, Terry Spontarelli, and Sheldon A. Larson Los Alamos National Laboratory, P.O. Box 1663, MS C920, Los Alamos, New Mexico 87545

David A. Bell* Department of Petroleum and Chemical Engineering, University of Wyoming, Laramie, Wyoming 82071-3295

The degradation of HMX-based high explosives (HMX, PBX 9404, and PBX 9501) with sodium hydroxide solutions is described. To obtain practicable reaction rates, the reaction was carried out in a pressurized reactor at temperatures up to about 155 °C. Above about 70 °C, mass transfer rates significantly affect the observed reaction rate. Therefore, a solid-liquid mass transfer model, based on gas-liquid film theory, was developed to describe the reaction rate. This model successfully predicted the experimentally observed degradation of explosives. Similar work with sodium carbonate solutions was reported previously.11 Faster reaction rates were observed with sodium hydroxide, a stronger base. Sodium hydroxide is preferred when the explosive contains a base-resistant binder, such as the binder used in PBX 9501, or when large, pressed pieces of explosives are used. Sodium carbonate hydrolysis and sodium hydroxide hydrolysis yielded the same degradation products. Introduction The HMX-based (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane) explosives PBX 9404 and PBX 9501 are U.S. Department of Energy (DOE) explosives that were developed at Los Alamos National Laboratory primarily for nuclear ordnance. Because of both stockpile stewardship and the decommissioning of nuclear weapons, a large amount of surplus explosives needs to be destroyed. One method for destroying these explosives is base hydrolysis. Base hydrolysis with 1.5 M NaOH at atmospheric pressures,1-16 or by reaction with 1.5 M Na2CO3 in a pressurized reactor at temperatures of around 150 °C,11 has been previously reported in the literature. Both 1.5 M NaOH at atmospheric pressures and 1.5 M Na2CO3 at 150 °C give short processing times for HMX powder and PBX 9404 molding powder; however, large consolidated pieces of plastic-bonded explosives (PBXs) could take up to several hours.1 Furthermore, PBXs with base-resistant binders, such as the Estane (B.F. Goodrich) in PBX 9501, do not react at practicable rates with either NaOH below 100 °C or Na2CO3 at 150 °C. To obtain reasonable reaction rates for consolidated PBXs and for formulations containing base-resistant binders, base hydrolysis using 1.5-6 M NaOH at temperatures approaching 150 °C is necessary. To determine the reaction rate of PBX 9404, PBX 9501, and HMX powder with NaOH, kinetic studies were performed. In these studies, the time-temperature profile and final conversion of the explosives were used to develop a rate model. The aqueous reaction products were NO2-, HCOO-, NO3-, and CH3COO- ions. The gaseous products were N2, N2O, and NH3. The reaction was found to be mass-transfer-limited, and a mass* To whom correspondence should be addressed. Telephone: (307) 766-5769. Fax: (307) 766-6777. E-mail: [email protected].

transfer model was developed. Gas-liquid film theory2-4 was used, with the liquid mass-transfer coefficients determined using Kolmolgoroff’s theory of isotropic turbulence5-7 coupled with a mass-transfer coefficient correlation developed by Kawase and Moo-Young.5 The model predicted within an average of 10% the final percent conversion of HMX, PBX 9501, or PBX 9404. Experimental Methods Three energetic materials were hydrolyzed in this study: one pure explosive, coarse HMX crystals, and two HMX-based explosive formulations, PBX 9404 and PBX 9501. The HMX crystals were manufactured by Holsten Defense Corp., had a mean diameter of 234 µm,8 and resembled table salt or sugar. PBX 9404 consists of HMX (94 wt %) bonded with nitrocellulose (NC; 3 wt %) and tris(β-chloroethyl) phosphate (CEF; 3 wt %) as the plasticizer. Diphenylamine (DPA; 0.1 wt %) is added to stabilize NC. The HMX in PBX 9404 is a 3:1, by weight, bimodial blend of the coarse HMX and fine HMX with a mean diameter of 5 µm.8 PBX 9501 consists of the identical bimodial distribution of HMX (95 wt %) bonded with a polyurethane elastomer, Estane 5703 (2.5 wt %), and the low melting point eutectic mixture of bis(2,2-dinitropropyl)acetal and bis(2,2-dinitropropyl)formal (BDNPA/BDNPF) (2.5 wt %) as the plasticizer. Irganox 1010 (Ciba-Geigy; tetrakis[methyelene 3-(3,5di-tert-butyl-4-hydroxyphenol)propionate]methane; 0.1 wt %) is added to stabilize Estane. Both PBX 9404 and PBX 9501 were produced at Los Alamos National Laboratory (LANL) as a molding powder by distillation of a slurry using water and an immiscible solvent.9,10 The molding powder agglomerates can then be pressed into consolidated pieces with specific geometries. This study included hydrolysis of molding powder and pressed pieces. Kinetic experiments were carried out in two previously described reactors.11 Most experiments were car-

10.1021/ie980522b CCC: $18.00 © 1999 American Chemical Society Published on Web 04/27/1999

Ind. Eng. Chem. Res., Vol. 38, No. 6, 1999 2255 Table 1. Experimental Parameters for the HMX Powder, PBX 9404, and PBX 9501 Kinetic Study parameter temperature (°C) base concentration (M) solid loading (g of explosive/ g of liquid) stirrer speed (rpm) stirrer size (cm) reactor volume (mL) reactor diameter (cm)

HMX experiments

PBX 9404/9501 experiments

105-155 1.5 or 3 0.08-0.1

100-155 1.5, 3, or 6 0.08-0.11

160-600 2.3-8.9 30-400 5 or 10

300-700 2.3-8.9 30-400 5 or 10 Figure 1. C-13 nuclear magnetic resonance results for the base hydrolysis of HMX powder using sodium hydroxide. Experiments were performed using the 100 mL Hastelloy C reactor with 50 mL of solution and a 2.54 cm stirring bar rotating at 400 rpm. Experimental conditions: 150 °C, 1.5 M base solutions, and a solid loading of 0.1 g of HMX/mL of base solution.

ried out in a 100 mL Hastelloy C reactor, with some being carried out in a 2 L stainless steel reactor. Gaseous and aqueous samples were taken after each run and analyzed for total carbon, ion content, and gas concentration. First scrubbing the off-gas with 0.1 M HCl and then using an ammonia probe determined the gaseous ammonia concentration.

of hydrolysis products, such as formaldehyde. Figure 1, a carbon-13 NMR spectrum, suggests the presence of a large number of formaldehyde breakdown products. The stoichiometric ratio of HMX to NaOH for base hydrolysis was determined to be 4.4 mol of NaOH/mol of HMX.18 One hydroxide ion (OH-) is needed for each of the four nitro (NO2) groups on the molecule.19 The other 0.4 mol of NaOH is consumed by subsequent hydrolysis of the hydrolysate products. The pressure in the reactor due to the accumulation of gaseous products increased as high as 21 bar in the 100 mL reactor and 5 bar in the 2 L reactor. The volume of gas produced by HMX is ∼150 standard cm3/g. The reaction rate did not change when the pressure was reduced by venting or by using a larger headspace volume (2 L vs 100 mL reactor). Reaction Rate Modeling. A model was developed to predict the hydrolysis rate as a function of NaOH concentration, temperature, explosive loading, and mixing conditions (agitation, reactor size, impeller size, and liquid volume). The base hydrolysis of HMX, PBX 9404, and PBX 9501 with NaOH is mass-transfer-limited at temperatures above 70 °C.1 Gas-liquid film theory was successfully used to model the base hydrolysis of HMX and PBX 9404 in Na2CO3.11 The same theory is applied in this study. In gas-liquid film theory, mass-transfer resistances are modeled as if there is a stagnant liquid film around each bubble. Outside of the film, the liquid is perfectly mixed. When applied to solid-liquid reactions, the film

Results Base Hydrolysis Experiments. Over 50 experiments were carried out with varying reactor temperature, initial NaOH concentration, explosives, explosive loading, and agitation. The extent over which these parameters were varied is shown in Table 1. Reaction products measured after complete destruction of the explosives are listed in Table 2. The primary products shown in Table 2 were previously detected after HMX and PBX 9404 hydrolysis using Na2CO3.11,12 These compounds were also reported as products of RDX hydrolysis,13,14 which was expected because Croce and Okamoto15 proposed that RDX and HMX hydrolysis follow the same fundamental mechanism. Formaldehyde, although reported as a product in earlier RDX hydrolysis studies by Hoffsommer et al.16 and Heilmann et al.,14 was not detected in this study. In strong alkaline solutions (such as those used in this study), formaldehyde reacts via the Cannizzaro17 reaction to formate and its absence is thus not surprising. The nitrogen material balance for the hydrolysis of HMX, PBX 9404, and PBX 9501 was achieved. Two earlier studies of RDX hydrolysis reported 80%16 and 90%14 closure on the nitrogen balance. The carbon material balances shown in Table 2 are about 100%, but only 65-78% of the carbon can be attributed to identified product compounds. The unidentified compounds are suspected to be the products of secondary reactions

Table 2. Product Analysis for Sodium Hydroxide Base Hydrolysis of HMX Powder, PBX 9404, and PBX 9501a % total carbon or nitrogen in explosive processed HMX carbon in solution inorganic carbon organic carbon carbon bearing species formate (aqueous) acetate (aqueous) carbon dioxide (gaseous) carbon monoxide (gaseous) carbon (not detected by IC or GC) nitrogen bearing species nitrite (aqueous) nitrate (aqueous) nitrogen (gaseous) nitrous oxide (gaseous) ammonia (gaseous + aqueous) nitrogen sum (average) a

0.5-1.5 ∼99

PBX 9404 0.5-1.5 ∼99

44 ( 8 21 ( 7 0.9 ( 0.2 0.7 ( 0.1 33 ( 11

40 ( 5 22 ( 3 0.82 ( 0.3 0.7 ( 0.1 36 ( 6

20 ( 4 0.1 ( 0.1 4.3 ( 0.7 43 ( 4 25 ( 6 93 ( 12

19 ( 2 0.23 ( 0.01 4.3 ( 0.7 53 ( 11 29 ( 6 106 ( 13

Quantities are expressed as percent of carbon or nitrogen initially present in the explosive.

PBX 9501 0.5-1.5 ∼99 54 ( 2 23 ( 2 0.8 ( 0.2 0.65 ( 0.02 22 ( 3 21 ( 1 0.1 ( 0.1 3.1 ( 0.9 45 ( 13 29 ( 4 98 ( 14

2256 Ind. Eng. Chem. Res., Vol. 38, No. 6, 1999

surrounds a solid particle rather than a bubble. The observed reaction rate is modeled as a mass-transfer process modified by an enhancement factor:

dHMX ) -kLa[HMX]aqE dt

(1)

The overall reaction rate can be subdivided into several regimes, according to the relative effect of kinetic or mass-transfer rates on the overall reaction rate. In the prior work with sodium carbonate solutions,1 a fast pseudo-first-order model was used.

Efpf )

x

DHMXk[OH] kL2

(2)

In this reaction regime, all of the dissolved explosive reacts within the film, but the reaction is not fast enough to significantly deplete the hydroxide concentration within the film. The very fast reaction regime, like the fast pseudofirst-order reaction regime, assumes that all of the dissolved explosive reacts within the film. The very fast reaction equation is more general, however, because this equation considers the depletion of hydroxide concentration within the film.

-1 + Evf =

x

1+

4Ei(Ei - 1) Ha2

2(Ei - 1)

(3)

Ha2

x

[OH] Ei ) 1 + ν[HMX]aq Ha )

x

DOH DHMX

DHMXk[OH] kL2

Figure 2. Reaction region plot over the experimental temperature range studied. Ecalc is the enhancement factor, Ei is the instantaneous enhancement factor, and Efpf is the pseudo-first-order enhancement factor. A 1.5 M NaOH concentration, 400 rpm stirring rate, 50 mL liquid volume, and 5 cm reactor diameter were used.

equation developed by Gordon for OH-.20 The determination of the mass-transfer coefficient, kL, is discussed in detail later. The reaction order n is first order in HMX. The solubility of HMX was determined using the expression developed by Kramer and Kuehne21

[HMX]ppm ) 1.04 × 10[0.025T (°C)]

Neither of the criteria given by eqs 6 and 7 are met for most of the experiments in this study. Therefore, eq 3 is required to model the reaction behavior over the range of our experimental conditions. The interfacial surface area, a, may be expressed as

a) (4)

(5)

If the kinetic rate is much greater than the masstransfer rate, then each reactant is completely consumed when it encounters the other reactant, and the instantaneous reaction model is used. For this regime, the enhancement factor, Ei, is given by eq 4. The fast pseudo-first-order reaction regime and the instantaneous reaction regime represent limiting-case behaviors for the very fast reaction regime. Equation 3 is relatively complex, so one would prefer to use it only when the observed reaction rate cannot be accurately predicted by eq 2 or by eq 4. These relatively simple expressions can be used if one of the following criteria are met:

Ecalc > 0.95 Efpf

(6)

Ecalc > 0.95 Ei

(7)

Figure 2 shows estimated values for the ratios given in eqs 6 and 7. The reaction rate constant, k, was determined using the Arrhenius expression from Heilmann et al.14 Diffusivities were determined using the Wilke-Change equation for HMX and the NerstHaskell equation using the empirical concentration

(8)

R θ dp v

(9)

The term R is the ratio of wetted particle surface area to particle volume, θv is the volume fraction of solid HMX in the slurry, and dp is the particle diameter. The theoretical value of R for a distribution of uniform spherical particles would be 6. However, in this study R was calculated by minimizing the calculated errors between the experimental data and the model predictions. The diameter dp is calculated by using a shrinking ball model and assuming a constant particle population. For the HMX particles in both the HMX crystals and the PBX 9404 molding powder, the initial dp value was the mean particle diameter calculated from the HMX particle size distributions determined by Skidmore et al.8 for PBX 9501. For the HMX crystals and PBX 9404 molding powder, the diameters were 234 µm and 134 µm, respectively. The size distribution for PBX 9404 assumed that the NC binder quickly degrades at 70 °C, releasing the HMX particles from the PBX 9404 molding powder agglomerates. Therefore, the mean particle size for the PBX 9404 molding powder was the same as the mean diameter of its HMX constituents. For the PBX 9501 molding powder, the mean diameter for the molding powder agglomerates was used. In PBX 9501, the Estane binder does not quickly degrade and the HMX crystals are not released from the PBX 9501 molding powder agglomerates. Therefore, the diameter of the molding powder agglomerates is more representative of the interfacial surface area. For both the PBX 9501 and PBX 9404 consolidated pieces, the smallest dimension of the consolidated piece was used. The smallest dimension for the PBX 9501 consolidated

Ind. Eng. Chem. Res., Vol. 38, No. 6, 1999 2257 Table 3. Surface Area Constant, r, for HMX, PBX 9404, and PBX 9501

a

explosive

representative diameter

surface area constant, R

correlation coefficient, r

95% confidence level

HMX crystals HMX crystals PBX 9404 molding powder PBX 9501 molding powder PBX 9501 consolidated piece PBX 9404 consolidated piece

234 µm 234 µm 134 µm 1.4-6 mm 2.54 cm 0.635 and 2.54 cm

1.6a 5.0b 9.0 3.7 2 70

0.95 0.89 0.94 0.98 0.95 0.96

0.86 < F0.025 < 0.98 0.55 < F0.025 < 0.98 0.84 < F0.025 < 0.98 0.89 < F0.025 < 1.0 0.77 < F0.025 < 0.99 0.68 < F0.025 < 1

100 mL reactor. b 2 L reactor.

pieces was 2.54 cm. For PBX 9404 the smallest dimension measured either 2.54 or 0.625 cm. The liquid mass-transfer coefficient kL was determined using Kosmolgoroff’s theory of isentropic turbulence5-8 and a correlation developed by Kawase and Moo-Young.5 Kosmolgoroff’s theory of isentropic turbulence assumes that the mass-transfer coefficients are only a function of temperature and agitation power. Given the amount of energy put into the system by the agitator, the mass-transfer coefficient can be determined. There is some doubt about the validity of the theory because it has been found that the mass-transfer coefficient also depend on both impeller type and position.22 However, Kosmolgoroff’s theory is a widely accepted approach for agitated vessels. Application of the Model. The model was applied to HMX, PBX 9404, and PBX 9501. The results for the surface area factor, R, are shown in Table 3. For HMX, R was higher for the 2 L reactor than it was for the 100 mL reactor. This was also shown in the Na2CO3 hydrolysis of HMX.11 This may be due to greater mixing of the HMX particles in the 2 L reactor. When HMX is loaded into the reactor, some of the HMX clumps. The higher turbulence of the 2L reactor impeller, in contrast to the stirrer bar sitting on the bottom of the 100 mL reactor, breaks up the clumps, increasing the wetting of the HMX particles. This increases the wetted interfacial surface area. For PBX 9404, there is not an apparent difference in the rate for the 2 L and 100 mL reactors. This is because when the PBX 9404 molding powder is loaded, it does not clump. This was also observed in Na2CO3 hydrolysis.11 To test if the wetting effect was significant, two experiments were performed at very low (170 rpm) stirring rate. At this stirring rate, the floating HMX particles are not wetted to the same degree as for the higher stirring rate. In this case, the value for R was much closer to that determined in the 100 mL reactor, 2.5. The reason that R for PBX 9404 is greater than that for HMX is because of the particle size and particle size distribution used in the model. If the predicted particle size is lower than the actual value, R is low. If the predicted particle diameter is larger than the actual value, R is high. The particle sizes calculated for PBX 9404 and the 3:1 dry blend of coarse and fine HMX from different sources can vary from 110 to 134 µm.8,23 Therefore, any error in predicting the particle diameter of the HMX crystals can cause a significant change in R. For the PBX 9501 consolidated pieces, the value of R was slightly lower than the molding powder. The effect of time at temperature for the PBX 9501 consolidated piece is shown in Figure 3. The plot shows that when the experiment is performed at 150 °C, the time required for greater than 90% reaction is 1.5-2 h. For the experiments run at 120 °C, only 30-40% of the PBX 9501 consolidated piece was destroyed after 3 h. For the

Figure 3. Effect of time at the temperature set point on the reaction rate. The explosive was a PBX 9501 consolidated piece. The base concentration varied between 1.5 and 6 M with a solid loading of 0.1 g/g at 150 °C. The piece had a 2.54 cm diameter and was 2.54 cm in length.

Figure 4. Parity plot comparing the experimental and calculated final explosive conversion for HMX, PBX 9404, and PBX 9501. The gas-liquid film theory, very fast reaction regime equations were used to calculate the final conversion.

base hydrolysis of PBX 9501 consolidated pieces, performing the experiment at temperatures approaching 150 °C is essential for practicable reaction times. For a PBX 9404 consolidated piece, the value for R was an order of magnitude higher than the other explosive formulations. This is due to the significant crumbling of the PBX 9404 consolidated piece. This results in both consolidated PBX 9404 and HMX crystals to be present in the reactor at the same time. Therefore, an appropriate, representative diameter is impossible to determine. In this study, the representative diameter was the initial consolidated piece diameter. This appears to underpredict the interfacial surface area by a factor of 10. The model predicted the final conversion of the explosive within 15% over all of the conditions studied with an average deviation of only 10% as shown in Figure 4. The effect of temperature both on the accuracy of the model and on the overall reaction rate is shown in Figure 5. Increasing the set-point temperature from 95 to 150 °C increased the reaction rate by a factor of 10.

2258 Ind. Eng. Chem. Res., Vol. 38, No. 6, 1999

Acknowledgment We gratefully acknowledge the DOE/DoD Memorandum of Understanding for funding this research. We also thank Joe Repa and Stephen Newfield for their support and guidance. Special thanks go to Rhonda McInroy, John Kramer, John Sanchez, Ed Eaton, Michael Hiskey, and Jose Archuleta for their assistance and helpful discussions. Literature Cited

Figure 5. Effect of the temperature set point on the model accuracy and the overall reaction rate. The explosive was PBX 9404. The base concentration was 1.5 M with a solid loading of 0.1 g/g.

Figure 6. Effect of mixing on the reaction rate. The explosive is HMX. The base concentration was 1.5 M with a solid loading of 0.1 g/g at 130 °C.

The effect of the mixing energy on the reaction rate is shown in Figure 6. Two experiments were performed at each energy level. The mixing energy is the agitation power imparted to the fluid per unit mass solution. It is a function of solution viscosity, stirring rate, stirring diameter, and liquid volume. The results show that, above a mixing energy of 1-1.5 W/kg, increasing the mixing has little effect. Conclusions The kinetics of the base hydrolysis of HMX, PBX 9404, and PBX 9501 using NaOH were investigated. At a temperature of 150 °C, the PBX 9404 was over 99% destroyed in less than 1 min. For PBX 9501 at 150 °C, the time to at least 99% destruction was on the order of 2 h for a 2.54 cm diameter × 2.54 cm length piece. The hydrolysis rate was modeled by using a solid-liquid mass-transfer model. The model predicted to within an average of 10 wt % the final conversion for HMX crystals, PBX 9501, and PBX 9404. The values of the interfacial surface area parameter, R, were 9 for PBX 9404 molding powder, 4 for HMX crystals, 3.7 for PBX 9501 molding powder, 2 for PBX 9501 consolidated pieces, and 70 for PBX 9505 consolidated pieces. The PBX 9404 formulation had the fastest reaction rate and for a consolidated piece was 35 times as fast as the consolidated PBX 9501. Except for PBX 9404 consolidated pieces, the interfacial surface area was well represented by the mean particle size for the HMX crystals, the mean particle size for the PBX 9404 molding powder, and the smallest piece dimension for the PBX 9501 consolidated pieces. For PBX 9404, an accurate method for determining the total interfacial surface area still needs to be developed.

(1) Flesner, R. L.; Dell’Orco, P.; Bishop, R. L.; Spontarelli, T.; Uher, K. Pilot-Scale Base Hydrolysis Processing of HMX-Based Plastic Bonded Explosives; LA-UR-96-1798; Los Alamos National Laboratory: Los Alamos, NM, 1996. (2) Bird, B. R.; Stewart, W. E.; Lightfoot, E. N. Transport Phenomenom, 1st ed.; John Wiley and Sons: New York, 1960; pp 532, 620. (3) Treybal, R. E. Mass-Transfer Operations, 3rd ed.; McGrawHill: New York, 1980, pp 522-533. (4) Bishop, R. The Base Hydrolysis of High Explosives at Temperatures Above the Normal Boiling Point of Water. Ph.D. Dissertation, University of Wyoming, Laramie, WY, 1999. (5) Kawase, Y.; Moo-Young, M. Solid-Turbulent Fluid Heat and Mass Transfer: A Unified Model Based on the Energy Dissipation Rate Concept. Chem. Eng. J. 1987, 36, 31-40. (6) Kawase, Y.; Moo-Young, M. Volumetric Mass Transfer Coefficients in Aerated Stirred Tank Reactors with Newtonian and Non-Newtonian Media. Eng. Res. Des. 1988, 66, 284-288. (7) Kawase, Y.; Moo-Young, M. Mass Transfer at a Free Surface in Stirred tank Bioreactors. Trans. Inst. Chem. Eng. 1990, 68, 189-194. (8) Skidmore, C. S.; Phillips, D. S.; Son, S. F.; Asay, B. W. Characterization of HMX Particles in PBX 9501; LA-UR-97-2596; Los Alamos National Laboratory: Los Alamos, NM, 1997. (9) Kasprzyk, D. J. Agglomeration Characteristics of a Plastic Bonded Explosive. Masters in Chemical Engineering Thesis, University of Wyoming, Laramie, WY, 1998. (10) Velarde Experimental Operating Instructions for PBX Preparation; Los Alamos National Laboratory: Los Alamos, NM, 1989. (11) Bishop, R. L.; Flesner, R. L.; Dell’Orco, P. C.; Spontarelli, T.; Larson, S. A.; Bell, D. A. The Application of Gas Liquid Film Theory to Base Hydrolysis of HMX Powder and HMX Based Plastic Bonded Explosives Using Sodium Carbonate. Ind. Eng. Chem. 1998, 37, 4551-4559. (12) Bishop, R. L.; Flesner, R. L.; Dell’Orco, P.; Spontarelli, T.; Bell, D.; Kramer, J. Base Hydrolysis Kinetics of HMX-based Explosives using Sodium Carbonate; LA-UR-96-1818; Los Alamos National Laboratory: Los Alamos, NM, 1996. (13) Heilmann, H. Physico-Chemical Treatment of Water Contaminated with the High Explosive RDX and HMX Using Activated Carbon Adsorption and Alkaline Hydrolysis. Ph.D. in Civil Engineering and Environmental Engineering Thesis, University of California at Los Angeles, Los Angeles, CA, 1996. (14) Heilmann, H. M.; Weismann, U.; Stenstrom, M. K. Kinetics of the Alkaline Hydrolysis of High Explosive RDX and HMX in Aqueous Solution and Absorbed to Activated Carbon. Environ. Sci. Technol. 1996, 30, 1485-1492. (15) Croce, M.; Okamoto, Y. Cationic Micellar Catalysis of the Aqueous Alkaline Hydrolysis of 1,3,5-Triaza-1,3,5-trinitrocyclohexane and 1,3,5,7-Tetraaza-1,3,5,7-teranitrocyclooctane. J. Org. Chem. 1979, 44, 2100. (16) Hoffsommer, J.; Kubose, D.; Glover, D. Kinetic Isotope Effects and Intermediate Formation for the Aqueous Alkaline Homogeneous Hydrolysis of 1,3,5-Triaza-1,3,5-trinitrocyclohexane (RDX). J. Phys. Chem. 1977, 81, 380-385. (17) Walter, J. F. Formaldehyde Second Addition. ACS Monogr. 1953, 120. (18) Spontarelli, T.; Buntain, G. A.; Flesner, R. L.; Sanchez, J. A.; Unkefer, P. J. An Engineering System Using Base Hydrolysis for Complete Destruction of Energetic Materials; International Symposium on Energetic Materials Technology, Orlando, FL, 1994; American Defense Preparedness Association: Hopkins, MN, 1994; pp 55-61. (19) Heilmann, H. K.; Stenstrom, M. K.; Hesselmann, R. P. X.; Wiesmann, U. Kinetics of the Aqueous Alkaline Homogeneous

Ind. Eng. Chem. Res., Vol. 38, No. 6, 1999 2259 Hydrolysis of High Explosive 1,3,5,7-Tetraaza-1,3,5,7-Tetranitrocyclooctane (HMX). Water Sci. Technol. 1994, 30, 53-61. (20) Reid, R. C.; Praunitz, J. M.; Sherwood, T. K. The Properties of Gases and Liquids, 3rd ed.; McGraw-Hill Book Company: New York, 1977. (21) Kramer, J. F.; Kuehne, T. Base Hydrolysis Modeling. Presentation, Amarillo, TX, 1995. (22) Nienow, A. W. Agitated Vessel Particle-Liquid Mass Transfer: A Comparison between Theories and Data. Chem. Eng. J. 1975, 9, 153-160.

(23) Archuleta, J. Particle Size, BET Surface Area, and Pore Distribution for HMX-F 82C000E094 and HMX-C H83-L030-50. Data Sheet 4/11/97; Los Alamos National Laboratory: Los Alamos, NM, 1997.

Received for review August 7, 1998 Revised manuscript received February 22, 1999 Accepted March 7, 1999 IE980522B