Ind. Eng. Chem. Prod. Res. Dev. 1984, 2 3 , 250-252
250
Synthesis of Diethylaminoethyl Cellulose on Cotton Fabric Ronald W. Rousseeu;
James K. Ferrell, and Robert F. Reardon
Department of Chemical Engineering, North Carolina State University, Raleigh, North Carolina 27650
The synthesis of diethylaminoethyl cellulose was investigated to develop a model relating degree of substitution on the cellulose to reaction conditions. Experimental data providing a base for the model were obtained by reacting cotton fabric with monochloroethyldiethylamheat 25 O C . The mcdei was used to predlct satisfactorily the degree of substitution on complete garments. All reactions were conducted at conditions that maintained fabric properties.
Reaction Kinetics of Amine with Cellulose Diethylaminoethyl (DEAE) cellulose has several useful properties, including a basic functionality that can be used in separations involving ion exchange. For example, Graham and Fook (1982) discussed the separation of proteins by using DEAE cellulose for that purpose. In the present research, development of a cotton fabric with ion-exchange capabilities was needed to remove organic acids from aqueous solutions that passed through the fabric. Fabric properties such as strength, structure, and feel had to be maintained while giving the material the ability to separate the acids from the solution. As with all cellulose derivatives, the appearance and structural properties of DEAE cellulose depend upon the degree of substitution (D.S.) of the amine group onto the cellulose substrate. Accordingly, control of the reaction is critical for maintenance of a proper balance between fabric properties and ion-exchangecapacity. The kinetics of the synthesis reaction were examined so that a model could be developed relating D. S. to reaction conditions. This model could then be used to design a reaction system and procedure to produce DEAE cellulose with a specified D.S. Synthesis of DEAE cellulose was reported by McKelvey and Benerito (1967). Although a reaction mechanism was not given, monochloroethyldiethylamine and cellulose react with the following stoichiometry Cell-OH
+ (C2H5)2-N-(CHz),-C1
+
Cell-O-(CH2)2-N-(C2H,),
NaOH
NaCl
+ HzO (1)
Experimental Section Several variables in the synthesis reaction were examined, including amine concentration, ratio of fabric mass to amine mass, and reaction time. Reaction temperature was held at 25 "C because this was thought to be representative of conditions that would be used commercially and to minimize degradation. Test reactions were conduded in a 3-L glass resin kettle. The kettle was stirred vigorously with a glass and Teflon impeller, and the temperature was controlled by placing the resin kettle in a constant-temperature bath located in a hood. The preferred procedure used in these studies was as follows. A dried sample of fabric (approximately 15 g) was mercerized and placed in a kettle containing 1.5 L of 2 N NaOH. The temperature of this mixture was adjusted to 25 OC and the desired amount of amine, at the reaction temperature, was added to the kettle. The reaction mass was stirred at the reaction temperature for a specified period of time. Then the resulting treated fabric was placed in a 1 N NaOH solution for 15 min, followed by rinsing for 15 min in 1 N HC1. The fabric was soaked overnight in 0.1 N NaOH, rinsed in water until washings 0196-4321/84/1223-0250$01.50/0
Table I. Degree of Substitution (D.S.) as a Function of Amine Concentration (C,) and g of Fabric/g of Amine (B) run
c A >M
B
D.S.
1
0.432 0.167 0.133 0.254 0.058 0.167 0.167 0.117 0.234 0.084 0.253
0.203 0.452 0.528 0.204 0.949 0.312 0.156 0.267 0.134 0.322 0.322
0.041 0.100 0.116 0.060 0.200 0.078 0.021 0.044 0.038 0.085 0.079
2 3 4 5 6 7 8 9 10
11
were neutral to phenolphthalein, and dried in ambient air. Visual observation of the reaction vessel contents indicated that the reaction involved a three-phase mixture consisting of two liquid phases and a solid intermediate. This made mixing critically important to product uniformity. Since DEAE cellulose has basic ion-exchange properties, the D.S. of the treated fabric was determined by measuring the amount of acid taken up by the fabric when it was placed in a known concentration of standard acidic solution. In this determination a small section of the fabric (2 to 3 g) was washed and air dried. The sample was then desiccated, weighed, and placed in a mixture of 50 mL of standardized hydrochloric acid (0.1 N) and 50 mL of 1N sodium chloride. The flask was purged with nitrogen to prevent sample degradation and allowed to sit for at least 12 h. A 50-mL aliquot of the liquid in the flask was removed and titrated with standardized NaOH (0.1 N) using phenolphthalein indicator. Determination of the D.S. from this procedure is illustrated by an example calculation given by Rousseau et al. (1983). Results The roles of amine concentration and the ratio of fabric mass to amine mass on the resulting D.S. at equilibrium were examined through a series of 11experiments. In these experiments, the reaction conditions were maintained for 12 h, which corresponded to complete reaction. Results of these experiments are given in Table I. A multivariable regression analysis of the data was used to obtain the expression D.S. = 0 . 5 7 C ~ l " B ~ ' ~ ~ (2) where CA is the initial amine concentration in moles per liter and E is the initial ratio of fabric mass to amine mass. Figure 1 shows the fit of eq 2 to the data. In a second series of 14 experiments, the initial fabric to amine ratio E was held constant at 0.147 g of fabric/g of amine, while the initial amine concentration CA was 0 1984 American Chemical Society
Ind. Eng. Chem. Prod. Res. Dev., Vol. 23, No. 2, 1984 251 0.20
-
0.19
-
0.18
0.10 0
0.09
-
0.08
0.16
-
E
0.15
-
f
0.14
-
Lo
0.13
-
0.17
I
0.06
D
0.05
0
a3
e
: I
0.04
E
0.12
;
0.1 1
0.03
Lo
0.10
0.02
0 D
0.01
0.07
0.06
0 03
:..:.;
::: 0 02
0 01 0
01
0 2
03
(Amine M o l a r i t y ) '
0 4
0 5
06
( W l F a b r i c l W l Amme)'
07
l4
Figure 1. Equilibrium degree of substitution as a function of initial conditions.
Table 11. Degree of Substitution (D.S.) as a Function of Reaction Time: Fabric to Amine Ratio at 0.147 g of Aminelg of Fabric and Amine Concentration at 0.374 M run reaction time D.S. 12 13 14 15 16 17
18 19 20 21 22 23 24 25
Expected Equilibrium Value = 0.080
0.07
17 h 24 h 18 h 12 h 6h 2h 4h 0 min 110 min 120 min 60 min 90 min 15 min 30 min
0.081
0.088 0.074
0.089 0.074 0.096 0.069 0.001
0.064 0.056 0.059 0.058 0.029 0.043
0.374 M. Identical reaction batches were allowed to run for varying times to give the data shown in Table II. From the previous experiments, equilibrium conversion at these conditions should result in a D.S. of 0.080. Using this as a guide, Figure 2 was constructed to show D.S. as a function of reaction time for fixed reaction conditions. The samples produced in these runs were uniform and had maintained their fabric integrity and texture, but a slight yellowing and shrinkage were also noted. Reaction of Complete Undershirts Shirts were provided by the U.S. Army Natick Research and Development Laboratories for tests of the reaction procedure. One set of the shirts was white, 1/4-sleeve, 1, Class 1,large (42-44) and another was olive green (OG), 1/4-s1eeve,OG-109, Type 1, Class 2, medium (38-40). The objectives of these tests were twofold: first, to test the procedure for synthesis of undergarments that have anion-exchange functionality and, second, to determine effects of the synthesis procedure on the physical dimensions and properties of the shirts. All the shirts were reacted under identical conditions with monochloroethyldiethylamine. The fabric to amine ratio was 0.15 g of fabric/g of amine, and the amine concentration was 0.374 M. These conditions should have
1
I 2
4
6
8
10
12
14
16
18
20
22
24
R e a c t i o n Time (hours)
Figure 2. Degree of substitution as a function of time at an initial fabric to amine ratio of 0.147 g of fabric/g of amine and amine concentration of 0.374 M.
Table 111. Results of Individual Shirt Treatments white shirts green shirts no. D.S. no. D.S. I 0.079 I 0.123 I1 0.046 I1 0.138 I11 0.050 I11 0.145 resulted in a modified fabric with a D.S. of about 0.08. Measured D.S. obtained for six shirts are given in Table III. The OG shirts appear to have been more reactive than the white shirts, perhaps because of fabric modifications that occurred during the dyeing process. A variation in the reaction pprocedure was examined by comparing products obtained by reactions on two groups of three white shirts. In these experiments the fabric to amine ratio was 0.50 g of fabric/g of amine and the amine concentration was 0.374 M. Reaction time was 4 h. After mercerization, the first batch of three shirts was reacted with monochloroethyldiethylamiiewithout NaOH present, while the second batch was reacted in the presence of 2 N NaOH. The average D.S. on the shirts reacted in the absence of NaOH was 0.004; when the reaction medium contained NaOH the average D.S. was 0.058. The order of magnitude difference in these results shows that the caustic is mandatory for satisfactory reaction. Another variation of the reaction procedure was conducted on a small sample of material that had not undergone mercerization. The fabric to amine ratio was decreased to 0.146 g of fabric/g of amine, while the amine concentration was held at 0.374 M. The reaction time was also lengthened to 12 h. The D.S. resulting from this test was 0.012, significantly lower than that expected with mercerization. Reaction Intermediates and Safety During the course of the study described above, more was learned regarding the mechanism of the desired synthesis reaction. A precipitate was observed to form early in the reaction, but it eventually redissolved. The following mechanism is consistent with these observations. intermediate reactive specie formation (solvolysis)
E
+j"'
( C Z H ~ ) ~ N ( C H ~S b)W~ C(CzHgIpN, I
CI-
(3)
CH2
Cell-OH
+ OH-
-
(aziridinium)
Cell-0-
+ H20
(4)
Ind. Eng. Chem. Prod. Res. Dev. 1904, 23, 252-256
252
product formation
under a hood. The instability of the aziridinium complex should ensure that it is not present in the finished fabric.
CH?
Cell-0-
+'\i -
t iCzh5)zN
C ~ I I - O - ( C H ~ ) ~ N ~ Ct~ HNaCl ~)Z
tost
CHz
(5)
with the competing reaction CHZ
OH- t {CzHgi2;'1
\
"Ow
H O ( C H ~ ) ~ N ( C ~ H ~ ) Z(6)
CH2
The aziridinium complex is a hazardous substance and, although not much is present because it reacts rapidly, precautions were taken to prevent coming in contact with this material. These precautions included handling all reagents with rubber gloves and carrying out all reactions
Acknowledgment
The financial support of this research by the U.S. Army Natick Research and Development Laboratories through Contract No. DAAK60-78C-0017 is gratefully acknowledged. Registry No. Diethylaminoethyl cellulose, 9013-34-7;monochloroethyldiethylamine, 100-35-6. L i t e r a t u r e Cited Graham, E. E.; Fook, C. F. AIChEJ. 1982, 28, 245. McKeivey, J. B.; Benerito, R. R. J . Appl. Sci. 1987, I I , 1693. Rousseau, R. W.; Ferreii, J. K.; Macnair, R. N. "Perspiration Poisoning of Protective Clothing Materials. Part IV. Adsorption of Selected Vapors and Production of Modified Undergarment Materials", Technical Report, U S . Army Natick R and D Laboratories, Natick, MA, 1983.
Received for review August 1, 1983 Accepted October 20, 1983
Microanalytical Characterization of North Dakota Fly Ash Steven A. Benson," Dlane
K. Rlndt, George 0. Montgomery, and D. Rlchard Sears
University of North Dakota, Energy Research Center, Grand Forks, North Dakota 58202
Fly ash collected from pilot-scale combustion tests of a Beulah, ND, lignite was examined by scanning electron microscope/microprobe, electron specroscopy for chemical analysis (ESCA), X-ray diffraction, and X-ray fluorescence. The fly ash collection devices used include a five-stage multicyclone and a source assessment sampling system (SASS), which are designed to collect size-fractionated cuts. Muhicyclone samples were analyzed by SEM/microprobe to determine the composition and size of individual particles. ESCA was used to determine the species associated with the surface of the particles. Larger samples collected by SASS were examined by X-ray diffraction and X-ray fluorescence. The results of characterizing the fly ash reveal that certain elements have concentrated either on the surface of the particles or in the very small particulates. This was determined by SEMImicroprobe and ESCA analysis of samples collected from each stage of the multicyclone.
Introduction
The goals of particulate research a t the University of North Dakota Energy Research Center (UNDERC) include detailed characterization of fly ash with respect to those properties which relate to controllability as well as to possible environmental hazards of emissions. The focus is entirely on low-rank western and Gulf Province coals, whose properties are distinctly different from those of eastern coals. Typically the western coals have high moisture, low sulfur, and large variations in the distribution of inorganic constituents. Beulah, a North Dakota lignite, was used in the combustion tests of primary interest to this paper. This lignite is extraordinarily variable in its inorganic constituents. For example, the sodium content can have a tenfold variation within a few hundred meters in a single seam, as reported by Cooley and Ellman (1981). The specific Beulah lignite used was selected for its high sodium content. The fly ash was generated for this research using the UNDERC Particulate Test Combuster (PTC), illustrated in the schematic in Figure 1. This unit is an axially-fired pulverized coal combustor with a nominal consumption of 34 kg of coal/h. The unit is designed to generate ash characteristic of that produced with similar fuel in a full-sized utility boiler. Axial firing maximizes the fly ash/(bottom ash + slag) ratio. The fly ash samples for analysis were collected a t the inlet to the baghouse with
two devices, a five-stage multicyclone, and a source assessment sampling system (SASS). The flues are equipped with heat exchangers permitting delivery of flue gas to the chosen control device at temperatures from -100 to 390 "C. During these tests, the PTC was equipped with an experimental baghouse because of on-going fabric filter research at UNDERC. The PTC instrumentation permits measurement of flue gas conditions such as temperature and concentrations of SO2, NO,, 02, and C02. The coal and fly ash were characterized by several analytical techniques. The inorganics of the coal were examined by an extraction technique which selectively removes the inorganics depending upon their association in the coal as reported by Schobert et al. (1981). Lowtemperature ashing with subsequent X-ray diffraction was used to identify the mineral phases of the coal. The fly ash was examined and analyzed by X-ray fluorescence, X-ray diffraction, scanning electron microscope/microprobe, and electron spectroscopy for chemical analysis (ESCA). Detailed descriptions of the equipment and techniques are given in the next section. E x p e r i m e n t a l Section Equipment and Techniques. A Kevex 0700 System
was used for quantitative elemental analyses of the major oxides. The Kevex system consists of an energy-dispersive X-ray source and a solid state Si(Li) detector capable of
0196-4321/84/1223-0252$01.50/00 1984 American Chemical Society
