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Adsorption of aqueous benzene onto hydrophobic and hydrophilic surfaces
Colloids and Surfaces, 28 (1987) 327-329 Elsevier Science Publishers B.V., Amsterdam
327 -
Printed
in The Netherlands
Brief Note Adsorption of Aqueous Benzene onto Hydrophobic and Hydrophilic Surfaces* LEO A. NOLL IIT Research Institute, National Institute for Petroleum and Energy Research, Barlesville, OK 74005 (U.S.A.) (Received
19 January
1987; accepted in final form 21 July 1987)
INTRODUCTION
There are few data in the literature on the adsorption calorimetry of hydrocarbons out of aqueous solution onto mineral surfaces. This property is of interest in petroleum recovery and in environmental considerations, such as the transport through the soil of hydrocarbons from leaky tanks or oil spills. The present data are also helpful in making thermal corrections for adsorption in calorimetric equipment [ 11. MATERIALS
AND PROCEDURE
Benzene was chosen as the hydrocarbon for the measurement of the interaction of an aqueous hydrocarbon with mineral surfaces because it has the highest solubility of common hydrocarbons in water: 1,777 ppm or a mole fraction of 0.00410 [ 21. An excess of reagent grade benzene was added to distilled deionized water and the solution was shaken daily for a week, then the solution was allowed to stand for a week before use. The solution and the calorimeter were maintained at 25’ C. The mineral solids used were the following: Davison grade 62 silica gel, SiO,; Florisil, a magnesia silica; alumina, gas chromatographic base material H-151, *This report was prepared as account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
0166-6622/87/$03.50
0 1987 Elsevier Science Publishers
B.V.
328 TABLE 1 Plateau values for adsorption
calorimetry
of benzene on minerals
Mineral
BET specific surface area (m’g-‘)
EnthaIpy (mJ m-*)
Amount adsorbed (pm01 m-‘)
Energy per mole (kJ mol-‘)
Molecular parking area (nm’ molecule-‘)
Si02 Florisil
-0.11 - 0.054 0.00
0.88 0.65 0.03
-0.13 - 0.083 -
1.9 2.5
A1203
340 240 181
C,,SiO,
268
- 1.46
5.52
- 1.35
0.30
manufactured by Coast Engineering Laboratory ( A1203) ; and reverse phase silica, made by grafting C!,,H,, groups onto the above silica gel and end-capping with methyl groups, C,,SiO,. The first three of these minerals are hydrophilic; the last is hydrophobic. The BET specific surface areas of these solids are listed in Table 1. An LKB 2107-030 flow adsorption calorimeter was used to measure enthalpies, and a Knauer differential refractometer was used to provide information for the calculation of surface excess (adsorption). The use of these instruments, experimental techniques and calculation procedure has been described previously [ 3,4]. RESULTS
AND DISCUSSION
The results of the adsorption calorimetry experiments are given in Table 1. The standard deviation of these results is 2 6%. The amount adsorbed and the thermal results are normalized to the BET surface area of the minerals. The interaction of benzene with A1203 from water is zero within experimental precision. This reflects the high interaction of water with the alumina surface; benzene cannot compete with it. The interaction of benzene with the other two water-wet surfaces shows slight preferential adsorption of benzene and is exothermal. It amounts to only a tenth of a kJ per mole of benzene. The molecular parking area for benzene on reverse phase silica is 0.30 nm’. Gregg and Sing [ 51 cite a molecular area of 0.40 nm’ for flat, 0.25 nm* for upright, and 0.31 nm* for random orientation. The molecular parking area on ClsSi02 indicates that the adsorption is at least a monolayer. The heat per mole is small, but about 10 times that in the case of the waterwet surfaces. ACKNOWLEDGEMENT
This work was performed for the U.S. Department of Energy at the National Institute for Petroleum and Energy Research under Cooperative Agreement DE-FC22-83FE60149.
329
REFERENCES 1 2 3 4 5
Stanley J. Gill, personal communication. Clayton McAuliffe, J. Phys. Chem., 70 (1966) 1267. Leo A. No11 and Thomas E. Burchfield, Colloids Surfaces, 5 (1982) 33. Leo A. No11 and Thomas E. Burchfield, DOE/BETC/RI-82/7, June 1982,42 pp. S.J. Gregg and K.S.W. Sing, Adsorption, Surface Area and Porosity, 2nd edn, Academic Press, London, 1982, p. 81.
327 -
Printed
in The Netherlands
Brief Note Adsorption of Aqueous Benzene onto Hydrophobic and Hydrophilic Surfaces* LEO A. NOLL IIT Research Institute, National Institute for Petroleum and Energy Research, Barlesville, OK 74005 (U.S.A.) (Received
19 January
1987; accepted in final form 21 July 1987)
INTRODUCTION
There are few data in the literature on the adsorption calorimetry of hydrocarbons out of aqueous solution onto mineral surfaces. This property is of interest in petroleum recovery and in environmental considerations, such as the transport through the soil of hydrocarbons from leaky tanks or oil spills. The present data are also helpful in making thermal corrections for adsorption in calorimetric equipment [ 11. MATERIALS
AND PROCEDURE
Benzene was chosen as the hydrocarbon for the measurement of the interaction of an aqueous hydrocarbon with mineral surfaces because it has the highest solubility of common hydrocarbons in water: 1,777 ppm or a mole fraction of 0.00410 [ 21. An excess of reagent grade benzene was added to distilled deionized water and the solution was shaken daily for a week, then the solution was allowed to stand for a week before use. The solution and the calorimeter were maintained at 25’ C. The mineral solids used were the following: Davison grade 62 silica gel, SiO,; Florisil, a magnesia silica; alumina, gas chromatographic base material H-151, *This report was prepared as account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
0166-6622/87/$03.50
0 1987 Elsevier Science Publishers
B.V.
328 TABLE 1 Plateau values for adsorption
calorimetry
of benzene on minerals
Mineral
BET specific surface area (m’g-‘)
EnthaIpy (mJ m-*)
Amount adsorbed (pm01 m-‘)
Energy per mole (kJ mol-‘)
Molecular parking area (nm’ molecule-‘)
Si02 Florisil
-0.11 - 0.054 0.00
0.88 0.65 0.03
-0.13 - 0.083 -
1.9 2.5
A1203
340 240 181
C,,SiO,
268
- 1.46
5.52
- 1.35
0.30
manufactured by Coast Engineering Laboratory ( A1203) ; and reverse phase silica, made by grafting C!,,H,, groups onto the above silica gel and end-capping with methyl groups, C,,SiO,. The first three of these minerals are hydrophilic; the last is hydrophobic. The BET specific surface areas of these solids are listed in Table 1. An LKB 2107-030 flow adsorption calorimeter was used to measure enthalpies, and a Knauer differential refractometer was used to provide information for the calculation of surface excess (adsorption). The use of these instruments, experimental techniques and calculation procedure has been described previously [ 3,4]. RESULTS
AND DISCUSSION
The results of the adsorption calorimetry experiments are given in Table 1. The standard deviation of these results is 2 6%. The amount adsorbed and the thermal results are normalized to the BET surface area of the minerals. The interaction of benzene with A1203 from water is zero within experimental precision. This reflects the high interaction of water with the alumina surface; benzene cannot compete with it. The interaction of benzene with the other two water-wet surfaces shows slight preferential adsorption of benzene and is exothermal. It amounts to only a tenth of a kJ per mole of benzene. The molecular parking area for benzene on reverse phase silica is 0.30 nm’. Gregg and Sing [ 51 cite a molecular area of 0.40 nm’ for flat, 0.25 nm* for upright, and 0.31 nm* for random orientation. The molecular parking area on ClsSi02 indicates that the adsorption is at least a monolayer. The heat per mole is small, but about 10 times that in the case of the waterwet surfaces. ACKNOWLEDGEMENT
This work was performed for the U.S. Department of Energy at the National Institute for Petroleum and Energy Research under Cooperative Agreement DE-FC22-83FE60149.
329
REFERENCES 1 2 3 4 5
Stanley J. Gill, personal communication. Clayton McAuliffe, J. Phys. Chem., 70 (1966) 1267. Leo A. No11 and Thomas E. Burchfield, Colloids Surfaces, 5 (1982) 33. Leo A. No11 and Thomas E. Burchfield, DOE/BETC/RI-82/7, June 1982,42 pp. S.J. Gregg and K.S.W. Sing, Adsorption, Surface Area and Porosity, 2nd edn, Academic Press, London, 1982, p. 81.