G Model
JIEC 3540 1–5
Journal of Industrial and Engineering Chemistry xxx (2017) xxx–xxx
Contents lists available at ScienceDirect
Journal of Industrial and Engineering Chemistry
journal homepage: www.elsevier.com/locate/jiec
1
Extraction-based recovery of RDX from obsolete Composition B
2 Q1 a a a a, b
Hyewon Kang , Hyejoo Kim , Chang-Ha Lee , Ik-Sung Ahn *, Keun Deuk Lee
3 a
Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul 120-749, South Korea
4 b
Agency for Defense Development, Daejeon 305-600, South Korea
A R T I C L E I N F O A B S T R A C T
Article history:
Received 3 November 2016 Recovery of explosives from obsolete ammunition has been considered an eco-friendly alternative to
Received in revised form 20 July 2017 conventional dumping or detonation disposal methods Composition B, made of 2,4,6-trinitrotoluene
Accepted 26 July 2017
(TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and paraffin wax, has been used as the main
Available online xxx
explosive filling in various munitions. It was selected as a model explosive for this study. TNT was
extracted from Composition B by exploiting the different solubilities of TNT and RDX in acetonitrile. After
Keywords:
removing paraffin wax by hexane washing, RDX was recovered from unused Composition B with a purity
Composition B
higher than 99% and a yield of 84%.
Recovery
© 2017 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering RDX Chemistry. Extraction Demilitarization
5 29
Introduction destroyed using the following techniques: dumping at sea, outdoor
30
burning, open detonation, and detonation in a mine tunnel [9,10].
6 31
Ammunition has a limited service life and must be disposed of In the case of dumping at sea, munitions stored in boxes and metal
7 32
at a certain stage [1]. Large quantities of unused ammunition are canisters or containers are transferred to ships. In this process,
8 33
stored throughout the world [2]. For example, Composition B, a leakage of munitions is unavoidable and can cause serious damage
9 34
mixture of two explosives (hexahydro-1,3,5-trinitro-1,3,5-triazine to marine ecosystems. Hence, dumping at sea has been banned by
10 35
(RDX) and 2,4,6-trinitrotoluene (TNT)) and wax, has been used as the London Convention and other related agreements [2]. Outdoor
11 36
the main explosive filling in artillery projectiles, rockets, land burning has been carried out in areas that satisfy the following
12 37
mines, and various other munitions. The term “Composition” in requirements: (1) no danger of the fire spreading; (2) absence of
13 38
Composition B has been used for any explosive material made of flammable objects; (3) dimensions of at least 20 m  20 m; (4)
14 39
RDX. Other RDX-derived explosives that have a long history of presence of an excavated channel of 0.5 m width and 0.25 m depth
15 40
application include Composition A and Composition C. Composi- around the combustion area; and (5) warning signs marking the
16 41
tion A consists of RDX and a small amount (1–9% w/w) of combustion area. Open detonation disposal in a blast chamber has
17 42
plasticizing wax [3,4]. The original Composition C was developed been rarely performed. Open burning and open detonation (OBOD)
18 43
by the British during World War II, but was standardized as methods have been recognized as simple and economical
19 44
Composition C when introduced to the US. It consists of RDX, a processes for the destruction of munitions; however, they cause
20 45
mineral oil-based plasticizer, and a phlegmatizer [3,5,6]. Compo- air pollution due to the release of NOx, acidic gases, and fine dust
21 46
sition C-4 is the most well-known explosive among Composition C [2,11,12] and soil contamination by heavy metals [13]. Detonation
22 47
explosives and has been used not only for military purposes (e.g., in in a mine tunnel has been mostly carried out in an old abandoned
23 48
the Vietnam War) but also in acts of terrorism. Hence, large mine. The tunnel should have a depth of at least 900 m while being
24 49
amounts of Composition explosives have been produced and covered with hard rocks. Moreover, the mine must be equipped
25 50
stored since World War II for its high explosive yield [7,8]. In with emergency bunkers with air conditioning systems indepen-
26 51
addition to posing a potential hazard, storage of surplus ammuni- dent of the main ventilation system. Because of environmental
27 52
tion is undesirable because of the cost and space requirements. pollution and safety issues, the disposal of unused munitions by
28 53
Thus, stockpiles of ammunition have been conventionally these conventional techniques has been strictly forbidden by
54
environmental laws and banned in numerous countries [2,11,12].
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Development of Resource Recovery and Recycling (R3) techni-
56
ques has gained interest in demilitarization activities. For instance,
* Corresponding author. Fax: +82 2 312 6401.
57
E-mail address: [email protected] (I.-S. Ahn). waste energy could be recovered from thermal destruction
http://dx.doi.org/10.1016/j.jiec.2017.07.036
1226-086X/© 2017 Published by Elsevier B.V. on behalf of The Korean Society of Industrial and Engineering Chemistry.
Please cite this article in press as: H. Kang, et al., Extraction-based recovery of RDX from obsolete Composition B, J. Ind. Eng. Chem. (2017), http://dx.doi.org/10.1016/j.jiec.2017.07.036
G Model
JIEC 3540 1–5
2 H. Kang et al. / Journal of Industrial and Engineering Chemistry xxx (2017) xxx–xxx
58 Table 1
operations conducted under the R3 concept while scrap metals
59 Physical properties of TNT and RDX [18–20].
could be collected and sold. Conversion of explosives to fertilizers
60
and commercial chemicals is another example of using TNT RDX
61
R3 technologies [1]. Recycling of unused and obsolete explo-
Molecular weight 227.1 222.1
62
sives/munitions is quite valuable since energetic materials are Melting temperature ( C) 80 202–204
63 Decomposition temperature ( C) 240 213
uncompromised and can be reused as commercial explosives,
3
64 Crystal density at 20 C (g/cm ) 1.6 1.8
propellants, military explosives, or fuel supplements [12,14,15].
65 Detonation velocity (m/s) 6640 8,950
For the recovery of unused explosives, the following separation
Detonation pressure (kbar) 210 350
66
methods have gained interest: melting separation, solvent Temperature of detonation (K) 2740 2600–4000
67
extraction separation, and supercritical carbon dioxide extraction
68
separation [16]. The melting separation method is based on the
69
difference between the melting points of waste explosive Experimental 110
70
components. For example, the melting point of TNT is 80 C while
71
that of RDX is 204 C. Appropriate heating to make TNT reach the Materials 111
72
molten state but ensure RDX remains solid allows their separation
73
by simple filtration. The advantages of this method are its simple 112
Composition B, RDX, and TNT were supplied by the Agency for
74
operation and that it does not require any solvent. The disadvan- 113
Defense Development (ADD) of Korea. The acetonitrile, water, and
75
tage is the safety issue caused by heating to relatively high 114
hexane used were all HPLC grade and purchased from Duksan Pure
76
temperatures. The principle of solvent extraction separation is 115
Chemicals Co., Ltd. (Ansan, Korea). The extracted solutions were
77
that, at the same temperature and in the same solvent, there is a 116
filtered through 0.2-mm PTFE membrane filters (Toyo Roshi Kaisha,
78
difference in the solubilities of waste explosive components. By 117
Ltd., Tokyo, Japan).
79
choosing a suitable organic solvent where a molecular explosive of
80
interest is completely soluble, but other components are not, the 118
Extraction of RDX and TNT
81
target explosive can be obtained after recrystallization. The
82
advantages of solvent extraction separation are that high temper- 119
To completely extract TNT from Composition B, 1.5 mL of
83
atures are not required and safety is not breached. However, the 120
acetonitrile was mixed with 2.0 g of Composition B at room
84
use of organic solvents may increase the cost of separation and 121
temperature. Considering that the mass fraction of TNT in
85
recovery, causing secondary pollution. Supercritical carbon dioxide 122
Composition B is about 40% and 100 g of TNT is soluble in 100 g
86
has been used for chemical extraction. It is inert, non-flammable, 123
of acetonitrile at 20 C, 1.5 mL of acetonitrile is about twice the
87
and non-explosive. The relatively low critical temperature and 124
amount needed to dissolve 0.8 g of TNT present in 2.0 g of
88
pressure of CO (e.g., 31.1 C and 72.9 atm) relieves us from the 125
2 Composition B. Mixtures of acetonitrile and water were also tested
89
concern of damaging the explosives. Such low toxicity, environ- 126
as extracting solvents to see if there was a change in the fraction of
90
mental impact, and concern for safety issues have led to an 127
TNT in the extractant due to the addition of water.
91
increase in the number of studies on the use of supercritical CO for 128
2 In order to investigate the effect of the extraction time (i.e., the
92
extracting molecular explosives. Once they are extracted in 129
mixing time of Composition B and acetonitrile) on the separation
93
supercritical CO , they can be obtained after recrystallization. 130
2 of RDX from TNT, extraction times of 5, 30, and 60 min were
94
However, the solubility of some explosives (e.g. TNT) in 131
examined. The mixture was then filtered through a 0.2-mm PTFE
95
supercritical CO is much lower than that in common organic 132
2 membrane filter. Undissolved materials, which consisted of RDX
96
solvents. Moreover, the operation cost is suspected to be much 133
and paraffin wax, were washed four times with 5 mL of hexane to
97
higher than those for melting and solvent extractions. These 134
remove the paraffin wax. The resulting RDX flake was filtered
98
disadvantages reduce the practical applicability of supercritical 135
through a 0.2-mm PTFE membrane filter.
99
CO for recycling waste explosives. 136
2 Prior to the extraction of RDX and TNT, Composition B was
100
In this work, a method for recovery of RDX from Composition B 137
washed with hexane in order to assess the efficiency of paraffin
101
is investigated based on the principle of solvent extraction 138
wax removal. Moreover, Composition B was treated with a mixture
102
separation. The structures of TNT and RDX are shown in Fig. 1. 139
of acetonitrile and hexane to investigate the possibility of
103
Their physical properties including their solubilities in various 140
simultaneous TNT extraction and paraffin wax removal.
104
solvents are summarized in Tables 1 and 2. As shown in Table 2,
105
acetonitrile showed the largest difference in the solubilities of TNT Analysis 141
106
and RDX. Paraffin wax is not soluble in acetonitrile. Hence,
107
acetonitrile was selected and used in this study as the organic 142
RDX and TNT were quantitatively analyzed using an HPLC
108
solvent, which preferentially extracted TNT from Composition B. 143
system (Younglin Acme 9000, Young Lin Instrument Co., Ltd.,
109
Paraffin wax was then removed by hexane washing [17]. 144
Anyang, Korea) equipped with a UV absorbance detector (Younglin
145
730D). The separation was performed on a C-18 column (5 mm
146
particle size, 250 mm  4.6 mm, 110 Špore size, Phenomenex Inc.,
147
Torrance, USA). A 50:50 (v/v) mixture of water and acetonitrile was
Table 2
Solubility of TNT and RDX in various solvents (g/100 g solvent at 20 C) [21,22].
Solvent TNT RDX
Acetone 109 8.2
Acetonitrile 100 5.5
Water 0.007 0.013 a
Methanol 0.354 0.025
Ethanol 1.23 Insoluble
a
Fig. 1. Chemical structures of TNT and RDX. Determined in this study.
Please cite this article in press as: H. Kang, et al., Extraction-based recovery of RDX from obsolete Composition B, J. Ind. Eng. Chem. (2017), http://dx.doi.org/10.1016/j.jiec.2017.07.036