Activation of Spent Bleaching Earth

WORLD ACADEMIC JOURNAL OF BUSINESS & APPLIED SCIENCES-MARCH-OCTOBER 2013 EDITION

International Journal of Chemistry (IJC)

OCTOBER 2013 VOL.1, No.8

Activation of Spent Bleaching Earth for
Dehumidification Application
John K. Mathaga 1 , Thomas F.N. Thoruwa 2 & Gerald K. Muthakia 3
1

Department of Chemistry, Kenyatta University, P.O. Box 43844-00100, Nairobi, Kenya
Department of Engineering, Kenyatta University, P.O. Box 43844-00100, Nairobi, Kenya
3
Department of Chemistry, Kimathi University College of Technology, P.O. Box 657-1010,Nyeri, Kenya
2

Accepted 16 October 2013
Abstract
To circumvent the current pollution-prone disposal of the spent bleaching earth (SBE), an experimental program
was conducted to recover the waste SBE and to use it for air dehumidification application. Waste SBE was
obtained from the damping site of the oil industry, and the entrained oil was recovered via hexane extraction
while the remaining hydrocarbons were oxidized with 30% H2O2 and heat at 550 oC. This reactivation procedure
affords oil useful in other ole-chemical applications and active SBE for air dehumidification. For the purpose of
adsorbent development, SBE regeneration was found to follow two routes, solvent extraction followed by
oxidation using 30% H2O2 which retains the elasticity of the clay crucial in molding the adsorbents and thermal
processing at 550 oC after molding. Experiments were carried out in batch system, and the effects of parameters
including, activation temperature, contact time, The sorption characteristic of the adsorbent established two
peaks when activated at 550 oC and 650 0C with a capacity of 27.07 and 26.63% respectively. The regenerated
SBE proved to be a promising adsorbent for moisture since its sorption capacity was higher than that of clay
(15%) which is commonly used as commercial desiccant.
Key Words: Activation; Spent Bleaching Earth; Dehumidification.
1. Introduction
Bleaching process, the third step in edible oil manufacture refers to the adsorptive cleansing of edible oils; simply,
the purification stage (Patterson, 1992). In oil bleaching, many methods exist which include; hydrogenation, heat
treatment at 220 oC, alkali treatment and oxidative bleaching. However, on an industrial scale, acid treated calcium
Montemorillonites clay commonly referred to as bleaching earth (BE) is prioritized in removing a variety of
undesired impurities which could otherwise impart colour, odour and taste to the refined product (Patterson, 1989).
Normally, this method employs two techniques (Wambu et al., 2009) namely; The percolation method in which the
oil is filtered through granular product of 250-200 μm (or 10-60 mesh) essentially at low temperatures whereby the
coloring matter get adsorbed by the soil as the oil passes through or contact processes in which the oil is put in
contact with finely ground clay of about 74 μm (or less than 200 mesh) for predetermined period of time to
equilibrate. Filter pressing operation then separates the oil at temperatures in the range of 150- 300 oC.
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The impurities removed in this process includes chlorophyll, β-carotene (and their derivatives), residual soaps,
fatty acids, phosphatides and trace metals (Pollard et al., 1993). Activated carbon is also periodically used in the
admixture with virgin bleaching earth for the removal of trace quantities of polynuclear aromatic hydrocarbons
(PAH) from edible oils (Larsson et al., 1987). These contaminants, some of which are suspected human
carcinogens, are sufficient to be of concern to edible oil processors.
Spent bleaching earth (SBE) on the other hand is the solid waste or the filter cake obtained from this process. It
contains impurities adsorbed from the crude oil with considerable quantities of entrained oil that is quantified
approximately 30 to 40% (Wachira et al., 2005). Direct landfills are the most common current mode of disposal
particularly in Kenya which poses an acute environmental pollution.
The re-use of SBE and the concomitant recovery of residue oil has been a recurrent focus of research in recent
years (Mana et al., 2007, 2008, Wambu et al., 2009). SBE regeneration has been attempted by solvent extraction
(Cheah and Lion, 2002). Solvent extraction followed by thermal processing (Boukerroi and Ouali, 2000),
preliminary acid impregnation followed by thermal processing (Mana et al., 2007, Wang and Lin, 2000) and the
product obtained reported to posses similar properties as virgin bleaching clays. The regenerated spent bleaching
earth (RSBE) has then found numerous applications such as removal of basic dyes from aqueous solution (Mana et
al., 2007), biological treatment and land farming, fuel supplements (Daido, 1987), toxic metals and organic group
adsorption (Wambu et al., 2009, Mehmet et al., 2003), cement manufacture (Wachira et al., 2005) among others.
Dehumidification is a process of water removal from the atmosphere which has wide application ranging from
preservation of stored material, industrial processes, condensation prevention, humidity control in air-conditioned
spaces such as offices and supermarkets among others (Zhang et al., 2005). This process is accomplished through
refrigeration or absorption by liquid desiccants and /or adsorption by solid desiccants which maintains the relative
humidity to the desired level. The inadequate electric power supply in most parts of the tropics and the high cost of
fossil fuels favors the use of desiccant for dehumidification applications over refrigeration (Thoruwa et al., 2000).
Dehumidification using desiccants is a process by which liquid or solid sorbent materials extract moisture from the
surrounding air to the sorbents. Typically, the sorbent moisture content is a function of the relative humidity (RH)
of the surrounding air as presented by Hamed (2003). The driving force for moisture absorption is the vapour
pressure differential attributed to lower vapour pressure on the sorbents compared to the surrounding air. When
exposed to low moisture content, low vapour pressure builds which results in attainment of equilibrium upon
exposure to high RH environment thus removing water from air (Zhang et al., 2005). The cosmic limitation of high
relative humidity has led to a wide acceptance of desiccant technology which has found new ventures in hospitals,
hotels and supermarkets recently (Ahmed, 2005). More materials that are hygroscopic in nature are thus constantly
investigated for their potential in low cost desiccant development.
Traditionally, ceramic materials dominated the desiccant market (William and Lu, 2002). Clayey materials have
unique properties that make them suitable for dehumidification application in that, they consists of closed packed
regular alteration of Si-O and Al-O sheets with inter-lamellar spaces punctuating each set of the sheets which
holds water molecules. Moreover, they are plenty available at low cost Mooney et al. (1952). Since SBE is
essentially contaminated clay, and no work has been devoted in the past on the regeneration of SBE for
dehumidification application, the current work reports the findings of the convenient route for the activation of
the SBE for dehumidification application.
2. Material and Methods
2.1 Preparation of material
Spent bleaching earth samples were collected from a damping site of the Kapa oil refineries an oil company
which is about five kilometer from Nairobi. Samples were air-dried and stored in desiccators for regeneration
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experiments.
2.2 Heat Reactivation
The air dried samples (10 g) were measured, placed in a crucible and transferred into a furnace where they were
heat reactivated at temperatures of 550 oC for 12 hours (Al-zahrani and Alhamed, 1976). The heat reactivated
spent bleaching earth was then cooled in a desiccators for 24 hours. The adsorbent development procedure were
similar to those described by Thoruwa et al., 2000, where cool hydrocarbon free samples were sprayed with 20%
of the net dry weight mixture of distilled water to form a hand paste. About 0.6 g of the paste formed was
weighed and moulded into spherical balls of approximately 1cm in diameter.
2.3 Hexane Extraction Experiments
Separate 5.0 g portions of the remaining air-dried spent bleaching earth (SBE) samples were weighed and placed
in eight 1000 ml Erlen-Meyer conical flasks containing 5, 10, 15, 20, 25, 30, 35, and 40 ml of hexane solvent and
the flasks labeled 1:1, 1:2 to 1:8 respectively to reflect the respective content ratios. The mixture in each flask
was then magnetically stirred for 12 hrs. Upon completion of the extraction step, the solvent extract and the SBE
were separated by suction filtration using Buchner funnel and residue designated hexane extracted spent
bleaching earth (HESBE) (Wambu et al., 2009). The oil and hexane on the other hand were separated by the use
of a Soxhlet apparatus and the percentage of the extracted oil (PEO) for each mixing ratio calculated by the
following relation (Cheah and Lion 2002),

PEO =

M1 − M 2
× 100
M1

Where, M 1 is the mass of dry SBE before regeneration and M 2 is the weight of dry hexane regenerated SBE.
The total oil content was also determined by total combustion method in a separate experiment by burning 5 g of
the SBE sample at 1000 oC. The average of total weight loss of these samples was 45%. Loss on ignition for the
virgin bleaching clay was found to be 14%. The average moisture content was also determined by oven drying 5
g of the SBE at 110 oC for 24 hours which recorded 6%. Thus, the average of the total oil content from the
calculations was established as 25% (Folleto et al., 2002). The HESBE were oven dried at 80 oC for 3hrs and
then allowed to cool in desiccators. The dry HESBE samples were then weighed and sprayed with doubly
deionized water (DDW) to form a medium hard paste which was used in moulding spherical balls of
approximately 1cm in diameter which were used as adsorbents (Tretiak and Abdallah, 2009).
2.4 Oxidation of the Hexane Residues
The hexane residues (HESBE) obtained in the procedure 2.3 above were oven dried at 100 oC for 12 hours and
transferred in desiccators to cool. 30.00 g of dry HESBE were weighed and transferred in a 1000ml beaker, 90
ml of 30% H2O2 solution was added and the content of the beaker warmed to temperatures of 80 oC. 15 ml
increment of 30% H2O2 solution were added every time the reaction subsided until a total of 150 ml was
consumed. The oxidized samples were then washed with DDW and the water removed by centrifugation (model
6000 series centurion at 600*10 RPM for 3 min) (Nebergell et al., 1995). The solid samples were then sprayed
with DDW to form a moderately hard paste and moulded into spherical balls of about 1cm in diameter.
2.5 Sorption Determination of Adsorbents
The sorption properties of the adsorbents obtained in procedure 2.4 above were determined through a method
proposed by (Young, 1967). The spherical adsorbents were placed in an oven and dried for three hours at 110 oC.
The temperature was increased to 200 oC and samples heated for three hours. The samples were then transferred
into a muffle furnace and different batches fired at 300, 400, 500, 550, 600, 650 and 700 oC. These heat activated
314


adsorbents were cooled in desiccators for the sorption determination. The sorption studies were carried out in
sealed beakers where the samples were held by wire mesh above saturated solutions of LiCl, MgCl2, K2CO3,
Mg(NO3)2, NaCl and KNO3 which provided 11.3, 32.78, 43.16, 52.89, 75.5 and 93.58% relative humidity (RH)
environment respectively (Young, 1967). The same procedure was repeated using virgin bleaching earth
adsorbents and results compared.
3. Results and Discussion
3.1 Regeneration of Spent Bleaching Earth
The restoration of spent bleaching earth (SBE) for dehumidification application was found to involve three major
steps: An extraction step to remove a majority of entrained oil, about 62.5% by weight of the entrained oil, an
oxidation step to remove the majority (25%) of remaining carbonaceous adsorbates which are not removed by
the preceding extraction step, and the heat reactivation to remove the rest of hydrocarbons (12.5%) and to open
up the adsorption sites of the clay. In the present work, the results for all the three steps in the restoration of SBE
for air dehumidification applications are provided and tabulated in tables 1 and 2.
3.1.1 Optimization of Hexane to Spent Bleaching Earth Mixing Ratio
Results of table 1 below reports the amount of oil removed from the spent bleaching earth (SBE) by different SBE
to hexane mixing ratios. From the results, it was apparent that more hexane in the media extracted more oil. There
was an increase in the ability of extraction from the ratio of 1 g to 1 ml SBE to hexane which extracted about 22.5%
as compared to 1g to 8 ml which extracted 25.1% of the entrained oil. For the restoration of SBE, a ratio of 1g SBE
to 5ml hexane which extracted 24.8% was chosen as the activation ratio which compared with results obtained by
(Kheang et al., 2006). The hexane was found to extract mainly the oil content of the SBE which was recording a
total mass of around 25% by weight of the dry SBE samples.
The Hexane residues could not be moulded into spherical balls since the residues did not mix well with the
deionized water which was attributed to the remaining hydrocarbons which are hydrophobic, thus the need of the
oxidation step. From the average results obtained above, the ratio of 1:5 (1 g SBE to 5 ml hexane) was chosen
and used in the treatment of SBE in the solvent extraction step. Solvent extraction was done using a soxhlet
extractor where the solvent was regenerated to minimize the regeneration cost. The solvent was replaced several
times until the cloudiness disappeared from the content siphoned.
Table 1. The Amount of Oil Removed by Different Ratios of Hexane from the SBE
Ratio of SBE: Hexane

Mass of the SBE
used (M1)

Mass of the SBE after
extraction (M2)

Difference
mass

in

% of oil in the
SBE

1:1

5.0001

3.8769

1.1232

22.5

1:2

5.0004

3.8452

1.1552

23.1

1:3

5.0006

3.7953

1.2053

24.1

1:4

5.0008

3.7758

1.2250

24.5

1:5

5.0000

3.7584

1.2416

24.8

1:6

5.0003

3.7524

1.2479

25.0

1:7

5.0004

3.7459

1.2515

25.1

1:8

5.0006

3.7428

1.2578

25.1

3.1.2 Solvent Oxidation of Hexane Residues
Since hexane removed about 62.5% of the organic matter present in SBE samples, the hexane residues samples
were oxidized with 30% H2O2 according to procedure given in claim of U.S. patent NO. 5,468,701, 1995, this
oxidized about 25% by mass of the total organic matter in SBE. For the oxidation to be realized, it was necessary
to raise the temperature of the mixture to 80 oC to initiate the oxidation process. This is because the process
315


involves bond breakage which is endothermic process thus requiring heat energy from the surrounding for
activation. Once the reaction starts, the process is self satisfactory in terms of heat energy required since the
energy released in the formation of the CO2 and H2O is enough for the process to proceed. The two processes
recorded an organic matter content of 35% by weight of SBE. The results for the organic content oxidized by the
H2O2 are given in the table 2 below.
Table2. The amount of entrained hydrocarbons extracted by oxidation process
Wt of the HESBE

Wt of the oxidized HESBE

Charge in mass

% HC

A

30.02

26.34

3.68

12.3

B

30.02

25.05

4.97

16.6

C

30.10

28.13

1.97

6.5

D

30.00

28.58

1.42

4.7

Key:
HESBE-Hexane Extracts Residues
HC- Hydrocarbon
Wt- Weight
Oxidized samples were then heat reactivated at temperatures of 550 oC. This process removed about 12.5% of
the entrained organic compounds in the SBE which indicated that hexane and hydrogen peroxide reactivation
process did not remove all the entrained organic matter. These results agreed with results presented by other
studies (Wambu et al., 2009), who established that the SBE has an organic matter content of about 40%. The
results obtained were confirmed by a parallel studies on the same sample through total combustion method in the
determination of moisture and ash content as described in procedure 2.3.
3.1.3 Reactivation Procedure on Adsorbent Development
For the purpose of dehumidification, spherical balls were made by preparing medium hard paste before and after
each and every activation step. It was found that, before treatment, the spent bleaching earth could not mix with
water to form the paste required for moulding the adsorbents since hydrocarbons are hydrophobic. The hexane
extracted samples (HESBE) also did not mix with water to develop the medium hard paste for the adsorbent
moulding. The heat reactivation alone at temperatures of 550 oC where the hydrocarbons present are oxidized to
water and carbon (IV) oxide interfered with the elasticity of the SBE hence the moulding was not possible with
these samples. The hydrogen peroxide step produced samples that could be mixed with water and moulded into
desired shapes.
The results presented in tables 1 and 2 above indicated that the solvent extraction and H2O2 oxidation process did
not remove the entire entrained hydrocarbons from the SBE. Thermal processing was hence paramount in order
to remove approximately 5% of the entrained HC after the two regeneration steps as well as reactivating the
sorption sites of the adsorbent.
3.2 Sorption
The results for the sorption at various processing temperature are summarized in table 3 and graphically by the
figure 1 below. The balls regenerated at 100, 200, 300 and 400 oC were observed to be dark in colour which
was attributed to the incomplete combustion of hydrocarbons after H2O2 oxidation step (Wachira et al., 2005).
The results of samples processed at 100 oC and 200 oC were not included due to excessive wetting on the surface
as well as cracking and spalling of these balls after exposing them to high humid environment. Samples
processed at 300 oC and 400 oC recorded similar results upon exposure to high RH but their change in weight
could be monitored as the phenomena was less compared to samples processed below 300 oC. This was
associated to incomplete combustion of the hydrocarbons in these adsorbents which could have sealed the pores
316


in addition to incomplete reactivation of the sample. The adsorbents processed at temperatures’ beyond 500 oC
recorded minimum wetting and water dripping as well as high solidity maintenance as they did not crack or spall.
This was ascribed to the complete combustion of the hydrocarbons from the host material, hence opening the
adsorption sites and ameliorated the adsorption of water molecules on the adsorbent. The water sorption results
indicated two peaks at 550 oC and 650 oC for all the samples tested. The increased moisture sorption when
processed between the temperatures of 300 oC to 400 oC was imputed to the excessive surface wetting of the
samples due to incomplete processing. The adsorption peak observed on the adsorbents reactivated at 550 oC
compared well with other findings (Tretiak and Abdallah, 2009), however the peak at 650 oC was not in literature
for solid desiccants but agreed with findings of Wambu et al., (2009) whose study reported a peak on the same
material on copper adsorption when reactivated at 700 oC. The first peak is attributed to the de-hydroxylation of
γ-aluminium trihydoxides to γ-alumina which is a more porous matrix structure upon calcinations, in addition to
the complete combustion of the hydrocarbons which results in a large moisture exchange surface area. The
second peak at 650 oC accounts for the formation of ρ-alumina (Wambu et al., 2009), another product of
calcinations of trihydroxides of aluminium which is characterized by high surface area that ameliorates the
sorption. The conversion of the aluminium trihydroxides to alumina on calcinations proceeds via partial
dehydroxylation that begins at temperatures of 225 oC converting gibbsite to Boehmite with a loss of water
followed by conversion of Boehmite to alumina from 525 oC.
Al(OH)3(s)
AlO(OH)(s) + H2O(l)
2Al(OH)3 (s)
Al2O3( s)
+ 3H2O(l)
This explains the increase on adsorption from 300 oC. The lower moisture sorption at 700 oC was as a result of the
conversion of the active alumina to relatively inert α-alumina in the range of 700 oC - 1000 oC.
Table 3. The amount of water adsorbed in % per dry weight of the sample
300

400

500

550

600

650

700

VBE

31.54

22.32

24.11

24.01

17.79

27.64

22.19

RSBE

21.32

21.87

21.85

27.07

14.64

26.63

21.91

Temp oC

Key:
VBE- Virgin bleaching earth
RSBE- Regenerated bleaching earth
Figure1. Sorption curves representing the Effect of processing temperature on RSBE and VBE adsorbents on
sorption capacity

317


4. Conclusions
The challenge for oil manufacturing industries in the environmental field is to identify and devise methods for
utilizing the spent bleaching earth. With a growing concern for the safe disposal of this material, the current
study has shown that the waste spent bleaching earth has the potential of removing water from the air and thus
can be utilized in desiccant manufacture. The reactivation efficacy of different conditions investigated showed
that solvent oil extraction followed by 30% H2O2 oxidation and thermal treatment at 550 oC are the most
effective in spent bleaching earth reactivation for this application. Thermal treatment alone was found not viable
due to its effect on elasticity of the material. Solvent extraction by hexane was found to extract oil which could
be utilized in other applications such as bio-diesel; detergent and soap manufacture thus maximizing on the
components of the waste.
However, the water sorption capacity for the material (27.07) was very low as compared to commercially
available desiccants (40-45%) and thus more research need to be conducted on the material in order to enhance
its sorption efficiency.
Acknowledgements
I would like to appreciate Kenyatta University for the partial scholarship and a place that afforded me to carry
out the research. Credit goes to technical staff of food science department of Jomo Kenyatta University of
Science and Technology for their support on sorption studies.
References
1. Ahmed, M.H. (2005). Experimental Investigation on the Adsorption/Desorption Processes using Solid
Desiccant in an Inclined-Fluidized Bed. J of Renewable Energy; 30: 1913-1921.
2. Al-zahrani, A.A. and Alhamed, Y.A., (1976). Regeneration of spent bleaching clay by calcinations
cum-acid treatment. Journal of Indian Institute of Chemical Engineering. 3 (38, n): 71-75
3. Cheah, K.Y., and Lion, S.W., (2002) “Regeneration of Spent Bleaching Clay.” Malaysia Palm Oil Board,
Kaula Lumpur, Malaysia.
4. Daido, M. (1987). A Recovery and Re-Use System for Fatty Oils from By-Products & Waste Materials
of Vegetable Oil Production. Conservation and Recycling; 10: 273-278.
5. Folleto, E.L., Alves, C.A., Sganzrla, L.R. and Porto, M.L. (2002). ‘Regeneration and Utilization of
Spent Bleaching Clay.’ Latin American Applied Research; 32: 205-208.
6. Hamed, A.M. (2003). Desorption Characteristics of Desiccant Bed for Solar Dehumidification/
Humidifier Air Conditioning System. Journal of renewable Energy; 28: 2099-2111
7. Kheang, L.S., Cheng, S.F., Choo, Y.M., and Ngan, M.A. (2006). A Study of Residual Oils Recovered
from Spent Bleaching Earth: Their Characteristics and Applications. American Journal of Applied
Sciences; 3 (10): 2063-2067.
8. Larsson, B.K., Eriksson, A.T., and Cervenka, M., (1987). Polycyclic Aromatic Hydrocarbonsin Crude
and Deodorized Vegetable Oils. J. Am. Oil Chem. Soc., 64, 365-370.
9. Liu, Y.F. and Wang. R.Z. (2003). Pore Structure of New Composite Adsorbent SiO2.xH2O.yCaCl2 with
High Uptake of Water from Air. J of Science in China Series; E 46(5): 551-559.
10. Mana M., Ouali M.S., and De Menorval L.C. (2007). Removal of Basic Dyes from Aqueous Solutions
with a Treated Spent Bleaching Earth. J of Colloid Interface Science 307(1): 9-16.
11. Mana M., Ouali, M.S., Lindheimer, M. and Menorval, L.C. (2008). Removal of Lead from Aqueous
Solutions with a Treated Spent Bleaching Earth. . Journal of Hazard Mater; 159(2-3): 358-364.

318


12. Mehmet, M., Kizilcikli, I., Bicer, O. and Tuncay, M. (2003). ‘Removal of MCPA from Aqueous
Solutions by Acid Activated Spent Bleaching Earth. ’ Journal of Environmental Science; 38(6):
813-827.
13. Mooney, R.W., Keenan, A.G. and Wood, L.A. (1952) Adsorption of Water Vapour by
Montmorillonite. II. Effect of Exchangeable Ions and Lattice Swelling as Measured by X-Ray
Diffraction. Journal of the American Chemical Society, 74: 1371-1374.
14. Nebergell, R.S., Kucharz, C.J. and Taylor, d.R., (1995). Process for Regenerating Acid-Activated
Bentonite Clays and smectite Catalysts. U.S Patent NO. 5,468,701.
15. Patterson, H.B.W., (1992). Bleaching and Purifying Fats and Oil: theory and Practice. American Oil
Chemists’ Society Press.
16. Patterson, J.W. (1989). Industrial Waste Reduction. Environ Science technology; 23: 1032-1038.
17. Pollard, S.J.T., Sollars, J.C., and Perry R. (1993). The Reuse of Spent Bleaching Earth: A Feasibility
Study in Waste Minimization for the Edible Oil Industry. Journal of Science Direct; 45: 53-58.
18. Thoruwa, T.F.N., and Ben-Abdullah, N., (1988). Moisture Sorption Characteristics of Solid Clay
Supported CaCl2 CSAE paper No. 88-407.
19. Tretiak and Abdallah (2009). Sorption and Desorption Characteristic of Packed Bed of Clay-CaCl2
Desiccant Particles. Journal of Solar Energy; 1861-1870.
20. Wachira, J.M., wa Thiong’o J.K., and Muthakia, G.K. (2005). Low Cost Pozzolana Based Cement from
Industrial and Agricultural Waste Materials, J. of civ. Eng. Research and Practice. 2(1): 15-21.
21. Wambu, E., Muthakia, G.K., Wa-Thiongo, J.K. and Shiundu, P.K. (2009). “Regeneration of Spent
Bleaching Earth and its Adsorption of Copper (II) ions from aqueous solution.” Journal of Applied
22. Wang. I. H., and Lin C.I., (2000) “Kinetics of Heat Regeneration of Spent Bleaching Clay”, Journal of
Chemical Engineering. Japan; 33 (3): 522-525
23. William, J.L., and Lu, N. (2002). Water Vapor Sorption Behavior of Smectite-Kaolinite Mixtures. Clay
and Clay Minerals, vol 50, No 5, 553-561.
24. Zhang, X.J., Sumathy, Y.J., and Wang, R.Z. (2005). Parametric Study on the Silica-Gel Calcium
Chloride Composite Desiccant Rotatory Wheel Employing Fractal BET Adsorption Isotherm, Journal of
Energy; 29: 37-51.

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