Ind. Eng. Chem. Process Des. Dev. 1985, 2 4 , 1225-1230 Lo, T. C.; b i r d , M. H. I.; Hanson, C. "Handbook of Solvent Extraction"; Wiley: New York, 1983. Marek. J. Report Luwa AG, Zurich, 1970. Oldshue, J. Y.; Rushton, J. H. Chem. Eng. Prog. 1952, 4 8 , 297-306. Scheibel, E. G.; Karr, A. E. Ind. Eng. Chem. 1950, 4 2 , 1048-1057. Scheibei, E. G. AIChEJ. 1956, 2 , 74-78. Steiner, L.; Horvath, M.; Hartland, S. Ind. Eng. Chem. Process Des. Dev. 1978, 17, 175-182.
1225
Steiner, L.;Hartland, S. Chem. Eng. Prog. lg80, 7 6 , 60-82. Stichlmair, J. Chem. h g . Tech. 1980, 52, 253-255. Wlrz, W. Swiss Patent 424 723, 1967. Zuhike, G. Graduierungsarbeit, Fachhochschule Koln, 1978.
Received for review September 11, 1984 Accepted January 22, 1985
Measurement and Prediction of Vapor-Liquid Equilibrium for an H-Coal and an SRC Coal Liquid with and without Hydrogen Ho-Mu Lin, William A. Leet, Hwayong Kim, and Kwang-Chu Chao" School of Chemical Engineering, Purdue Universi~,West Lafayette, Indiana 47907
Vapor-liquid equilibrium (VLE) has been experimentally determined for an Woal coal liquid produced from a Wyodak, WY, coal and for an SRC coal liquid from an Illinois No. 6 coal. The VLE measurements of the coal liquids with and without hydrogen were performed at temperatures up to 710 K and pressures to 25 MPa. Inspections are reported for the normal boiling point, molecular weight, and specific gravity of the VLE overhead and bottoms fractions as well as for the true boiling point (TBP) fractions of the total coal liquids. The VLE data are correlated with the Cubic Chain-of-Rotators equation of state.
Knowledge of vapor-liquid equilibrium (VLE) of coal liquid by itself and in a mixture with hydrogen is basic to the technology of coal conversion. Experimental VLE data of highly asymmetric mixtures of light gases and model compounds have been summed up by Sebastian et al. (1981 a-c) and Radosz et al. (1982). Correlation of the data has been reported by the same authors and by El Twaty and Prausnitz (1980), Wilson et al. (1981), Watanasiri et al. (1982), Gray et al. (1983), and Kim et al. (1985). Experimental data on VLE of coal liquids are scarce and limited to reports by Henry (1980),Lin et al. (1981),Sung (1981), Wilson et al. (1981), and Lin et al. (1985). We report in Chart I experimental data and correlation of the VLE of the two coal liquids. The first coal liquid was produced from the H-Coal PDU (Process Development Unit) in the syncrude mode by using Wyoming subbituminous coal from the Wyodak mine. The PDU was operated by Hydrocarbon Research, Inc. A detailed description of the process and operation conditions was given by Merdenger (1982). The second coal liquid was obtained from the operation of the Wilsonville Advanced Coal Liquefaction R & D Facility, Wilsonville, AL, on Illinois No. 6 coal. The process is a combination of a Solvent Refined Coal (SRC) unit, a Critical Solvent Deashing (CSD) unit, and a Hydrotreater (HTR) unit. Lewis (1982) provided information in detail on the operation conditions and product analyses. The VLE measurements were made in a flow apparatus at temperatures up to 710 K and pressures to 25 MPa. All condensate samples from cell effluents were collected and inspected for the boiling point, molecular weight, and density at 298.2 K. The feed coal liquids were fractionated by distillation under vacuum, and the resulting fractions were also inspected. The experimental VLE data are correlated with the Cubic Chain-of-Rotators (CCOR) equation of state (Kim et al., 1983). Experimental Apparatus a n d Results A flow apparatus was used in this work for the VLE measurements to minimize thermal decomposition of the coal liquid at the high temperatures of interest. A detailed description of the apparatus and experimental procedure 0196-4305/85/1124-1225$01.50/0
T a b l e I.
TBP D i s t i l l a t i o n and I n s p e c t i o n of Wyoming C o a l
Liquid
cut feed 1 2
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
residue
wt % distilled
Tb,K
~(298.2K), g/cm3
MW
1.08 1.23 2.01 1.76 1.42 2.01 2.05 2.58 2.05 2.23 2.43 2.51 2.04 2.75 2.13 1.57 2.86 2.02 2.21 2.13 1.94 2.33 2.04 2.06 2.45 2.11 2.40 2.36 2.35 2.11 2.11 1.79 1.88 1.32 29.68
562 467 475 483 492 494 498 501 508 512 515 517 521 525 529 533 535 538 542 547 550 553 556 558 561 563 568 571 575 581 585 588 592 597 601 652
0.9477 0.8964 0.9095 0.9068 0.9052 0.9053 0.9089 0.9145 0.9162 0.9112 0.9076 0.9074 0.9134 0.9214 0.9225 0.9190 0.9170 0.9180 0.9248 0.9310 0.9300 0.9295 0.9335 0.9438 0.9540 0.9544 0.9426 0.9298 0.9364 0.9514 0.9518 0.9514 0.9556 0.9645 0.9654 1.0098
206 142" 151 152 165 165 170 171 176 173 177 180 181 180 183 187 191 193 194 194 196 199 197 198 198 199 199 203 203 204 206 211 213 212
212 268
"Estimated from boiling point; MW too low for osmometer measurement.
was presented by Lin et al. (1985). The hydrogen gas used was purchased from Airco with a minimum purity of 99.95%. Neither coal liquid nor hydrogen gas was recycled back to the system. 0 1985 American Chemical Society
1226
Ind. Eng. Chem. Process Des. Dev., Vol. 24, No. 4, 1985
Chart I coal liq 1 2
sample r
0.
LO-2326
run no. 130-93
81763
236
supplier
coal source
Hydrocarbon Research, Inc. (H-Coal PDU) Catalytic, Inc. (Wilsonville SRC-I)
Wyoming (Wyodak mine) Illinois No. 6 (Burning Star No. 2 mine)
1 1-
Table 11. TBP Distillation and Inspection of Illinois Coal Liquid cut wt % distilled Tb,K ~(298.2K), g/cm3 MW feed 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 residue
0.49 0.75 1.26 1.67 1.80 2.04 2.16 2.10 2.69 2.39 2.41 2.14 2.54 2.30 1.31 2.78 1.91 2.23 2.25 62.78
625 459 472 481 495 510 519 529 539 551 559 563 568 577 585 588 593 598 603 609 662
0.9884 0.8625 0.8861 0.8986 0.9067 0.9099 0.9150 0.9203 0.9258 0.9347 0.9423 0.9475 0.9483 0.9541 0.9608 0.9649 0.9650 0.9680 0.9718 0.9729 1.0239
239 138O 150a 158 166 175 179 187 189 195 196 200 205 206 210 216 218 219 224 226 273
---'"'-h
10-
:
0 9-
702 5 K
0 80 7-
G815K
B a05
652GK
\
*-O 0 G4:
o
0 2-
"Estimated from boiling point; MW too low for osmometer measurement.
0 1-
For the description of the coal liquids, 35 true boiling point (TBP) cuts were made from the Wyoming coal liquid and 20 cuts from the Illinois coal liquid. Normal boiling point Tb, molecular weight MW, and density p at 298.2 K were experimentally determined for the cuts by the methods described by Lin et al. (1985). Table I shows the results for the Wyoming coal liquid and Table I1 for the Illinois. A substantial portion of both liquids remained unvaporized at the end of the TBP fractionation at about 3 mmHg. Experimental VLE data for the Wyoming coal liquid are reported in Table I11 at five temperatures: 545, 622, 652, 682, and 702 K. Both the overhead and bottoms fractions were inspected for Tb, MW, and p , and the results are included in Table 111. Figure 1shows the same data with pressure as a function of weight percent vaporization at various temperatures. Figure 2 shows the phase diagram of this coal liquid obtained by interpolation and extrapolation of Figure 1. Table IV presents the experimental VLE data of the Wyoming coal liquid in mixtures with hydrogen. The measurements were made at three temperatues (545,620, and 700 K) and at four pressures (10,15,20, and 25 MPa). The data reported in the table include temperature, pressure, weight percent vaporization, concentration of hydrogen in the vapor and liquid phases, and the inspection of the overhead and bottoms effluents freed of hydrogen. Figures 3 and 4 show the mole fraction of hydrogen in the VLE bottoms and overhead streams, respectively. The Illinois coal liquid is heavy and does not vaporize to an appreciable extent when heated by itself to the temperatures of this study. We report no data for the vaporization of this coal liquid by itself. The Illinois coal liquid does vaporize when mixed with abundant hydrogen and heated up to the temperatures of this work. Table V presents the VLE data at three tem-
0;
\ 621 9 K
3-
\ 545 e K do
1'0
3'0
o o V A 0 Experimental Data
to
io
40
7b
8'0
9'0
W t %VaportzatIon
Figure 1. VLE of Wyoming coal liquid.
l2I t
I .O G -
a
0.4
1
0 21
0'
550
600
650
700
T, K
Figure 2. Phase diagram of Wyoming coal liquid.
peratures (542,622,702 K) and four pressures (5, 10, 15, and 20 MPa). Figures 5 and 6 show the hydrogen mole fraction in the liquid and vapor phases, respectively. At least two samples were taken from the overhead and bottoms effluents at any one condition of temperature, pressure, and flow. The reported weight percent vapori-
Ind. Eng. Chem. Process Des. Dev., Vol. 24, No. 4, 1985
Table 111. Eauilibrium Vaporization of Wyoming Coal Liauid id. no. T,K P, MPa w t % vaporiz 545.7
0.152
4.2
545.5
0.127
13.6
622.3
0.359
34.6
622.3
0.347
38.0
621.6
0.305
50.2
621.5
0.239
67.2
621.9
0.195
81.3
652.3
0.662
13.3
652.8
0.581
36.0
~
phase
Tbt K
~(298.2K), g/cm3
MW
V L V L V
529 563 544 565 547 578 544 581 556 587 559 595 559 601 540
0.9155 0.9491 0.9307 0.9501 0.9243 0.9585 0.9259 0.9616 0.9294 0.9625 0.9279 0.9834 0.9336 0.9837 0.9211
548 582 557 587 555 594 560 605 549 578 555 590
0.9256 0.9562 0.9266 0.9613 0.9290 0.9682 0.9313 0.9787 0.9252 0.9516 0.9264 0.9564 0.9306 0.9652 0.9337 0.9712 0.9332 0.9806 0.9263 0.9601 0.9343 0.9651
185 210 189 210 187 209 191 218 192 214 188 231 192 228 187 208 191 210 195 213 196 224 196 226 200 215 187 217 198 217 210 216 193 226 194 220 198 214
L V L V L V L V L V
L 652.8
0.514
44.2
652.3
0.445
57.0
650.9
0.371
73.6
681.7
0.897
22.7
681.6
0.810
35.3
681.6
0.695
60.3
681.4
0.651
67.1
680.5
0.608
73.5
702.4
1.058
33.6
702.6
0.919
58.5
1227
V
L V L V L V L V L V L V L V L V L V L V L
594 561 593 562 600 552 573 555 588
Experimental D a t a
O010
15
P .’
MPa20
25
I
0.801
10
I
15
20
25
P . MPa
Figure 3. Solubility of hydrogen in Wyoming coal liquid.
Figure 4. Mole fraction of hydrogen in saturated vapor of hydrogen
zation and hydrogen mole fractions represent mean values of the multiple samples. Correlation of the Data In our previous report (Lin et ai., 1985), we compared experimental VLE data on a Kentucky No. 9 coal liquid with calculated results from the Cubic Chain-of-Rotators (CCOR) (Kim et al., 1983), the Soave (1972), the modi-
fied-Soave of Radosz et al. (1982),and the Grayson-Streed (1963) correlations. Values of critical temperature (T,), critical pressure (p,), and acentric factor (w) for coal liquid TBP fractions were required in the calculations. We examined various correlation methods and found that the Lin-Chao correlation (1984) gave acceptable results in
+ Wyoming coal liquid.
1228
Ind. Eng. Chem. Process Des. Dev., Vol. 24, No. 4, 1985
Table IV. Vapor-Liquid Equilibrium in Mixtures of Hydrogen id. no. 1
T, K
p , MPa
wt % vaporiz
544.9
10.20
5.8
2
545.0
15.24
7.7
3
544.9
20.41
5.8
4
544.9
25.37
2.1
5
619.2
10.20
11.3
6
620.1
15.57
7.1
7
619.9
20.16
13.7
8
623.9
25.20
25.9
9
700.4
10
700.7
15.20
33.0
11
700.2
20.44
59.1
12
700.7
25.20
28.2
9.991
26.3
phase V
concn of H, g(H2)/g(coalliq) mol fract 0.857 1.246 X 1.115 1.851 X 1.188 2.570 X 1.423 3.058 X 0.224 1.538 X 0.294 2.435 X 0.365 3.226 X 0.439 4.150 X 0.0611 1.941 X 0.0919 3.023 X 0.131 4.086 X 0.127 5.467 X
L V L V L V L V L V L V
L V L V L V L V L V L
Table V. Vapor-Liquid Equilibrium in Mixtures of Hydrogen id. no. 1
T,K
p , MPa
wt % vaporiz
542.7
5.507
8.8
2
542.4
10.10
4.8
3
542.7
15.19
3.8
4
542.7
20.51
6.0
5
622.5
6
622.5
10.13
24.2
7
622.5
15.16
14.8
8
622.4
20.26
11.3
9
702.0
5.057
50.5
10
701.9
10.11
26.5
11
702.1
15.31
32.1
12
703.4
20.20
10.9
5.133
8.2
phase V
L V L V L V L V L V
L V L V
L V
L V L V L V L
+ Wymoing Coal Liquid 0.9874 0.1139 0.9902 0.1603 0.9908 0.2072 0.9926 0.2381 0.9521 0.1358 0.9634 0.1961 0.9715 0.2461 0.9760 0.2988 0.8559 0.1628 0.8970 0.2342 0.9248 0.3084 0.9219 0.3551
inspect of effluent freed of H2 p(298.2 K), g/cm3 MW
Tb,K 528 568 531 569 535 568 530 567 541 575 544 571 540 572 548 574 553 568 554 576 557 583 553 573
0.9162 0.9527 0.9181 0.9485 0.9200 0.9486 0.9164 0.9439 0.9208 0.9527 0.9212 0.9492 0.9183 0.9544 0.9244 0.9536 0.9286 0.9534 0.9312 0.9587 0.9338 0.9624 0.9287 0.9575
184 208 182 208 186 205 189 206 179 206 181 202 188 204 187 207 196 202 191 204 190 220 188 203
+ Illinois Coal Liquid
concn of H, g(HJ/g(coal liq) mol fract 1.095 0.495 X 1.857 0.943 X 2.279 1.548 X 3.018 2.066 X 0.218 0.639 X 0.468 1.201 x 10-3 0.597 1.849 X 0.704 2.456 X 0.0707 0.744 X 0.131 1.601 X 0.198 2.343 X 0.210 3.175 X
0.9907 0.0572 0.9947 0.1028 0.9955 0.1567 0.9966 0.2013 0.9561 0.0729 0.9789 0.1310 0.9837 0.1877 0.9862 0.2363 0.8857 0.0881 0.9346 0.1651 0.9557 0.2286 0.9589 0.2809
inspect of effluent freed of H, p(298.2 K),g/cm3 MW
Tb,K 547 627 536 618 536 623 527 611 529 598 543 599 533 603 537 608 563 636 569 598 553 615 565 601
0.9230 0.9958 0.9445 0.9943 0.9249 0.9913 0.9264 0.9927 0.9367 0.9929 0.9468 1.0022 0.9424 0.9965 0.9404 0.9954 0.9654 1.0131 0.9544 0.9995 0.9580 1.0013 0.9512 0.9942
196 247 204 245 196 242 194 246 201 248 200 253 204 252 205 254 221 262 220 249 220 255 224 248
equilibrium vaporization calculations. With T,, p , , and thus estimated, the CCOR equation appears to agree with the Kentucky coal liquid data. We extend in this work the CCOR equation to correlate VLE data of the Wyoming coal liquid and the Illinois coal liquid and their hydrogen mixtures. Details of the VLE calculations with the CCOR equation have been described by Lin and coworkers (1985). Table VI compares the calculated results with experimental VLE data for Wyoming coal liquid by itself. The calculation searches for the temperature that produces the experimentally observed weight percent vaporization at the experimental pressure. The interaction constants, k,, and kb.,,in the CCOR equation are treated as zero. The w
Ind. Eng. Chem. Process Des. Dev., Vol. 24, No. 4, 1985 1229 Table VI. Comparison of the CCOR Equation Calculated VLE with ExDerimental Results for Wyoming Coal Liquid wt%
id. no.
D. MPa
1 2 3 4 5 6
7 8 9 10 11 12 13 14 15 16 17 18 19 AAD," %
0.152 0.127 0.359 0.347 0.305 0.239 0.195 0.662 0.581 0.514 0.445 0.371 0.897 0.810 0.695 0.651 0.608 1.058 0.919
T,K
vaporiz (exptl) 4.2 13.6 34.6 38.0 50.2 67.2 81.3 13.3 36.0 44.2 57.0 73.6 22.7 35.3 60.3 67.1 73.5 33.6 58.5
calcd 557.2 552.9 629.4 629.2 628.7 625.9 624.7 663.4 664.4 659.8 657.3 655.9 639.0 690.0 690.2 689.0 687.7 711.6 710.3
exptl 545.7 545.5 622.3 622.3 621.6 621.5 621.9 652.3 652.8 652.8 652.3 650.9 681.7 681.6 681.6 681.4 680.5 702.4 702.6
dev % 2.12 1.37 1.15 1.11 1.14 0.70 0.46 1.71 1.78 1.08 0.77 0.78 1.66 1.23 1.26 1.12 1.06 1.31 1.10 1.20
0 A 0 Experimental Data
0.80
5
20
15
10
P , MPa Figure 6. Mole fraction of hydrogen in saturated vapor of hydrogen
+ Illinois coal liquid.
AAD = absolute average deviation.
temperatures are compared in the table with the experimental values. The CCOR equation is found to give temperatures consistently too high with a maximum deviation of 11.5 K. The average absolute deviation of 1.2% amounts to about 7.7 K. The deviations are larger than those reported previously for the Kentucky coal liquid. Table VI1 summarizes the calculated vaporizations of the Wyoming coal liquid in mixtures with hydrogen from the CCOR equation. The calculations were performed to match the experimental weight percent vaporization of coal liquid at the experimental pressure and the ratio of hy-
drogen to coal liquid in the total feed. The hydrogen interaction constants K,, and kbij required in the calculations with the CCOR equation were obtained from the correlations of Lin and co-workers (1985). The VLE calculations are again predictive. The experimental equilibrium data of this work were not used in any way for adjustment of the equation constants. The calculated temperature is compared in the table with the experimental value. The average absolute deviation of 1.11% in temperature corresponds to about 6.8 K. Table VI1 also shows the K values of hydrogen calculated at the searched
+
Table VII. Comparison of the CCOR Equation Calculated VLE with Experimental Results for Hydrogen Wyoming Coal Liquid T,K hydrogen K value id. no.
p, MPa
w t % vaporiz (exptl)
1 2 3 4 5 6 7 8 9 10 11 12 AAD. 70
10.20 15.24 20.41 25.37 10.20 15.57 20.16 25.20 9.991 15.20 20.44 25.20
5.8 7.7 5.8 2.1 11.3 7.1 13.7 25.9 26.3 33.0 59.1 28.2
calcd 532.3 538.0 548.7 550.3 608.2 613.1 619.5 630.9 687.2 689.9 699.1 703.6
exptl 544.9 545.0 544.9 544.9 619.2 620.1 619.9 623.9 700.4 700.7 700.2 700.7
dev % -2.32 -1.28 0.70 1.00 -1.78 -1.12 -0.07 1.12 -1.88 -1.54 -0.15 0.42 1.11
calcd 8.88 6.33 5.01 4.32 7.27 5.15 4.24 3.62 5.08 3.76 3.13 2.64
exptl 8.67 6.18 4.78 4.17 7.01 4.91 3.95 3.23 5.26 3.83 3.00 2.60
dev % 2.49 2.56 4.69 3.74 3.69 4.75 7.57 12.22 -3.33 -1.95 4.53 1.63 4.43
+
Table VIII. Comparison of the CCOR Equation Calculated VLE with Experimental Results for Hydrogen Illinois Coal Liquid T,K hydrogen K value id. no. 1 2 3 4 5 6 7 8 9 10 11 12
AAD, %
p, MPa
w t % vaporiz (exptl)
5.51 10.10 15.19 20.51 5.13 10.13 15.16 20.26 5.06 10.11 15.31 20.20
8.8 4.8 3.8 6.0 8.2 24.2 14.8 11.3 50.5 26.5 32.1 10.9
exptl 542.7 542.4 542.7 542.7 622.5 622.5 622.4 622.5 702.0 701.9 702.1 703.4
calcd 528.2 520.3 526.0 531.1 609.4 618.0 615.9 620.3 703.4 692.1 695.5 696.0
dev % -2.67 -4.08 -3.07 -2.14 -2.10 -0.72 -1.06 -0.34 0.20 -1.40 -0.94 -1.05 1.65
exptl 17.320 9.676 6.353 4.951 13.115 7.473 5.241 4.174 10.053 5.661 4.181 3.414
calcd 15.630 9.175 6.504 5.157 14.330 7.905 5.686 4.561 11.543 6.365 4.646 3.706
dev % -9.76 -5.17 2.37 4.16 9.26 5.78 8.50 9.28 14.82 12.43 11.13 8.56 8.43
1230
Ind. Eng. Chem. Process Des. Dev. 1985, 24,1230-1239
temperatures. The agreement between the calculated and experimental results is reasonable. Similar results for the Illinois coal liquid in mixtures with hydrogen are reported in Table VIII. The calculations with the CCOR equation for this coal liquid are not as good as those for the Wyoming coal liquid. The calculated K value of hydrogen deviates from the experimental by 8.4% on the average, which is about twice that for the Wyoming coal liquid. The calculated flash vaporization temperature deviates from the experimental by 1.6% on the average, corresponding to about 10 K. The largest deviation is observed for datum no. 2 for which the calculated temperature is low by 22 K. The relatively large deviations appear to be due to the large amount of residue (62.78%) of the Illinois coal liquid which remained unvaporized at the end of the TBP fractionation. The calculation should be improved if the residue can be better characterized. Acknowledgment Funds for this research were provided by the Electric Power Research Institute through research Project RP-367. Catalytic, Inc., and Hydrocarbon Research, Inc., supplied coal liquids. T. M. Guo performed the VLE calculations. Literature Cited
Grayson, H. G.; Streed, C. W. Paper presented at the 6th World Petroleum Conference, Frankfurt am Main, Qermany, June 19-26, 1963; Paper 20, Sec. VII. Henry, R. M. "Vapor-Liquid Equilibrium Measurements for the SCR-I I Process"; DOE/ET/ 1004-1, Gulf Science and Technology Co.: Pittsburgh, PA, Oct 1980. Kim. H.; Lin, H. M.; Chao K. C. Paper presented at the Proceedings of the 3rd Pacific Chemical Engineering Congress, Seoui, Korea, May 8-1 1, 1983; Vol. 11, p 321. Kim, H.; Lin, H. M.; Chao, K. C. Ind. Eng. Chem. Fundam., in press. Lewis, H. E. Plant Manager, Quarterly Technical Progress Report, Jan.March, 1982, Catalytic, Inc., Wilsonville, AL. Dist. Category UC-Sod, DOE/ET/10154-122. Lin, H. M.; Chao, K. C. AIChE J. 1984,30, 981. Lin, H. M.; Kim, H.; Guo, T. M.; Chao, K. C. Ind. Eng. Chem. Process Des. Dev. in press. Lin, H. M.; Sebastian, H. M.; Simnick, J. J.; Chao, K. C. Ind. Eng. Chem. Process Des. Dev. 1981,2 0 , 253. Merdenger, M. Final Report to US. Department of Energy (DOE Contract DE-AC05-77ET-10152) and the Electric Power Research Institute (AP2623, Research Project 238-3). Hydrocarbon Research, Inc., Lawrenceville, NJ, Oct 1962. Radosz, M.; Lin, H. M.; Chao, K. C. Ind. €no. Chem. Process Des. Dev. 1982,2 1 , 653. Sebastian, H. M.: Lin, H. M.; Chao, K. C. AIChE J. 198la,2 7 , 138. Sebastian, H. M.; Lln, H. M.; Chao, K. C. Ind. Eng. Chem. Fundam. 1981b, 20 - , 346 - . ..
Sebastian, H. M.; Lin. H. M.; Chao, K. C. Ind. Eng. Chem. Process Des. Dev. 1981c,2 0 , 508. Soave, G. Chem. Eng. Sci. 1972. 2 7 , 1197. Sung, C. Ph.D. Thesis, University of Ptttsburgh, PA, 1981. Watanasiri, S.; Brule, M. R.; Starling, K. E. AIChE J. 1982,28, 626. Wilson, G. M.; Johnston, R. H.; Hwang, S. C.; Tsonopoulos, C. Ind. Eng. Chem. Process Des. Dev. 1981,2 0 , 94.
El-Twaty. A. I.; Prausnitz, J. M. Chem. Eng Sci. 1980,35, 1765. Gray, R. D.; Heidman, J. L.; Hwang, S. C.; Tsonopoulos, C. Nuid Phase Equilib. 1983, 13, 59.
Received for review October 9, 1984 Accepted M a r c h 11, 1985
Characterization of Adsorption Affinity of Unknown Substances In Aqueous Solutions Kumaraswamy JayaraJtand Chi Tlen' Department of Chemical Englneering and Materials Science, Syracuse University, Syracuse. New York 132 10
An aqueous solution with a large number of unknown adsorbates may be approximated by one with a fewer number of pseudospecies identified by their Freundlich constants. A procedure is proposed which calculates the pseudospecies composition from total adsorbate equilibrium concentration data obtained from batch contacting measurements. The method is applied to a number of wastewater systems to demonstrate its utility and validity.
The development of rational design methods in adsorption is handicapped by the fact that adsorption-treated aqueous solutions frequently contain a number adsorbates which cannot be completely identified. The dynamics of any adsorption process is defined by its stoichiometry, the equilibrium relationship between the solution and adsorbed phases, and the rate of the adsorption process, with the equilibrium relationship and rate parameters attributed to the adsorbate-adsorbent system. Because of a lack of information on the adsorbate identity and concentration, a rational design development based on adsorption theories becomes impractical. In recent years, a few investigators have suggested procedures to characterize the adsorption affinity of such solutions. Frick (1980) proposed that organics present in 'Present address: Honeywell Inc., Bloomington, MN 55420. 0196-4305/85/1124-1230$01.50/0
river water may be grouped into three categories: nonadsorbable, moderately adsorbable, and highly adsorbable. Each of these can be identified by their Freundlich constants, A and n. On the basis that the calculated concentration values which correspond to certain specified conditions must agree with experimental values, the Freundlich constants were determined, and the total organic carbon concentration was apportioned into the three categories. A more rigorous procedure was adopted by Kage (1980) and Okazaki et ai. (1980,1981). These investigators contended that for a solution containing a large number of adsorbates, the parameters characterizing the adsorption affinity of the individual adsorbates are described by their Langmuir constants, a and b. These constants may range from zero to infinity. Such a solution is, therefore, described by its adsorbate concentration frequency function m(a,b),defined as such that the concentration of adsor0 1985 American Chemical
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