The Suitability of Some Egyptian Smectitic Clays for Mud Therapy
The present study was carried out to assess the suitability of smectitic clays from Fayum, G. Hamza and G. Um Qamar, Egypt, for application in mud therapy. The textural, mineralogical and chemical composition of the Egyptian claystones showed that they are comparable to those of muds used in pelotherapy in several other countries (for example, Italy, Spain, Turkey and Portugal). The Egyptian claystones have good heat capacities and their pastes can be applied in different treatments. The trace elements present in the claystones, namely, As, Pb, Cu, Zn, Co, Ni and Cr are within the normal ranges of average natural mud and shale and they are of no significant concern for human health in mud applications.
Received: January 17, 2012;
Accepted: February 25, 2012;
Published: April 03, 2012
Historically, mud therapy has been used since Ancient Egyptian, Greek and Roman
periods to cure skin, stomach and intestinal ailments, as well as for cosmetic
purposes. With growing health tourism in several countries, the feasibility
of using mud in spas received much attention over the past few decades (Mascolo
et al., 1999; Carretero, 2002; Veniale
et al., 2004; Carretero et al., 2006).
There are two main types of mud therapy: geotherapy, in which virgin clays
are mixed with water and then applied to different parts of the body; and pelotherapy,
in which the virgin clays are mixed with normal water, sea water or mineral
water and left to mature for months to the so-called peloids and
then applied to the body in spas. The effects of mud therapy in treating several
diseases have been demonstrated by experimental and clinical data. The mud treatment
helps in alleviating the pain and improving the functional status of the patients
with rheumatic and arthritic conditions and the antibacterial and anti-inflammatory
action of the mud has a beneficial effect on skin diseases (Von
Tubergen and van der Linden, 2002; Flusser et al.,
2002; Codish et al., 2005; Pittler
et al., 2006; Odabasi et al., 2008;
Stojkovic and Sremcevic, 2011).
In spas, the muds used have generally been subjected to maturation. The resulting
solid-liquid mixture was defined by the International Society of Medical Hydrology
as peloid and the treatment with this mud has been referred to as pelotherapy.
In this respect, the word peloid was derived from the Greek word pelos which
means mud. However, the term peloid, as used in mud therapy, should not be confused
with the same term introduced by Mckee and Gutschick (1969)
in sedimentary carbonate petrology. In the latter, a peloid is a sand-sized
grain with an average size of 100-500 μm, composed of microcrystalline
carbonate. (Tucker et al., 1990; Flugel,
2004). To avoid such confusion, the present authors use the term mud therapy
rather than pelotherapy.
Not all muds can be used for mud therapy. The suitability of the mud depends
on its physico-chemical properties and mineralogical composition. . The clay
mineral content and type determine desirable properties such as high swelling
, high specific surface area and cation exchange capacity and high specific
heat, (Cara et al., 2000a, b).
The mud should also meet certain requirements of purity, in particular microbial
and toxic metal contamination (Summa and Tateo, 1998;
Vreca and Dolenec, 2005). Some recent investigations
showed the necessity of studying the geochemical composition of the muds used
in therapy due to their toxicity and possible resorption through the skin (Summa
and Tateo, 1999; Tateo et al., 2009).
The present research gives the results of a study carried out to examine the suitability of smectitic clays, from two main localities in Egypt, for application in mud therapy.
MATERIALS AND METHODS
Nine composite samples of smectitic clays were collected from Fayum Depression
and Gebel Hamza-Gebel Um Qamar area along the Cairo-Ismailia Road (Fig.
1). The samples collected from Fayum Depression were from the interbedded
claystone, siltstone and quartz sandstone facies of Qasr El-Sagha Formation
of Late Eocene age. Those samples collected from Gebel Hamza-Gebel Um Qamar
area were from the claystone-sandstone-carbonate facies of Lower Miocene deposits.
The textural characteristics of the samples were determined by wet sieving
and the pipette method (Tucker, 1988) and the percentages
of sand, silt and clay fractions were plotted in the triangular diagram of Folk
(1974), to classify the samples.
The mineralogical composition of the samples was determined by X-ray powder
diffraction (XRD) analysis, according to the method described by Poppe
et al. (2001). Two types of analyses were made: the first for the
bulk powdered samples to determine the clay and non-clay minerals present and
the second analysis for the determination of clay minerals present in the separated
clay fraction (<2 μm).
The chemical composition of the mud samples (major and selected trace elements) was determined using Energy Dispersive X-ray Fluorescence (EDXRF) at the Mineralogical Institute, Karlsruhe, Germany.
The determination of the thermal characteristics of the smectitic clay samples
was carried out by the preparation of pastes using 100 g of each sample and
distilled water. The mixture was stirred until a suitable homogenous paste was
obtained. A thermometer probe was inserted in the paste and was connected to
a digital meter for recording the temperature. The container with the paste
was placed in a water bath and heated until it reached 60°C. The container
was then removed and the paste left to cool; the temperature was recorded every
5 min until it reached 30°C.
|| Location map
The cooling curves of the samples were then defined between 60 and 30°C.
Textural characteristics: Table 1 gives the results of granulometric analyses and indicates that the samples are mainly composed of clay and silt, with minor quantities of sand. According to Folks classification (Fig. 2), the samples are classified as claystone, with generally more than 75% clay. It should be noted, however, that some other samples from the localities studied are either mudstones or sandy claystones. For the purpose of the present study we selected those layers that are composed mainly of claystone.
Mineralogical composition: The XRD analyses of the whole samples revealed that they are composed mainly of clay minerals, with minor quantities of quartz and in some cases carbonate minerals (calcite). The clay minerals present are smectite and kaolinite, with minor quantities of illite (Table 1).
|| Texture and mineralogy of smectitic clays
|*In clay fraction (<2 μm), QS: Qasr El-Sagha samples
(Fayum depression), H: Gebel Hamza samples, UQ: Um Qamar samples
||Triangular diagram of folk (G Hamza samples include those
of Um Qamar)
|| Chemical composition of smectitic claystone samples
|Fe2O3: Total iron Average mud after
(McLennan, 1995), Average shale after (Turekian
and Wedepohl, 1961), QS: Qasr El-Sagha samples (Fayum depression), H:
Gebel Hamza samples, UQ: Um Qamar samples
||Relationship between average major elements in smectitic claystones
and average mud
Chemical composition: Table 2 gives the results of
the chemical analyses of the studied smectitic claystone samples, compared to
average mud (McLennan, 1995) and average shale (Turekian
and Wedepohl, 1961). The SiO2 content in the samples varies between
48.54 and 57.63% and is, on average, lower than that in average mud and average
shale. The Al2O3 varies between 20.80 and 25.20%, higher,
on average, than that in average mud and average shale (Fig. 3,
4). This is attributed to the fact that the smectitic claystone
samples contain a higher content of clay minerals and a lower content of quartz
than the average mud or average shale.
||Relationship between average major elements in smectitic claystones
and average shale
The claystone samples contain, on average, a lower percentage of K2O,
due to their lower content in illite. They also have a lower MgO and CaO and
a higher Na2O than the average mud or average shale.
The Na2O/CaO ratio in the smectitic claystone samples varies between
0.83 and 2.96 and is generally higher than 1.0. For comparison, the thermal
muds of some spas in Turkey have a Na2O/CaO ratio of 0.02-0.58 (Karakaya
et al., 2010). A high Na2O/CaO ratio indicates the presence
of swelling 2:1 clay minerals (1<Na2O/CaO<3), while a low ratio
(Na2O/CaO<1) is typical of non-swelling 2:1 clay minerals.
Table 2 gives also the concentration of some selected trace
elements in the studied smectitic claystones and Fig. 5 and
6 show a comparison between the average trace elements determined
and those present in average mud and average shale, respectively.
||Relationship between average trace elements in smectitic claystones
and average mud
||Relationship between average trace elements in smectitic claystones
and average shale
The figures indicate that As, Pb and Cu are lower in the smectitic claystones
than in average mud or average shale, whereas Cr and Mi are slightly higher.
Cooling kinetics: Figure 7-9 show
the cooling kinetic curves of the claystones from Qasr El-Sagha, Gebel Hamza
and Um Qamar, respectively. All curves show a negative correlation between temperature
and cooling time, with an average R2 of 0.9. Using the equations
introduced by Cara et al. (2000b), the heat capacity
(CP) of the pastes and the temperature (T20) after 20
min of cooling were calculated (Table 3). The results obtained
are closely similar to those of other thermal muds from Sardinia (Cara
et al., 2000b) and to those of matured peloids from Italy (Veniale
et al., 2004).
|| Cooling kinetic curves of Qasr El-Sagha claystones
|| Cooling kinetic curves of Hamza claystones
|| Cooling kinetic curves of Um Qamar claystones
||Moisture content and calculated heat capacity and T20
of the smectitic claystones
|CP: Heat capacity of mud paste, T20:
Temperature reached by the mud paste after 20 min of application, QS: Qasr
El-Sagha samples (Fayum depression), H: Gebel Hamza samples, UQ: Um Qamar
The smectitic clays of Fayum, G. Hamza and Um Qamar are mainly composed of
clay with less amounts of silt and minor quantities of quartz. The mineralogical
and chemical composition of these claystones are comparable to those of muds
used for mud therapy, for example the muds from Sardinia (Cara
et al., 2000a) and those from Croatia (Mihelecic
et al., 2011). The Egyptian claystones have also comparable cation
exchange capacity and specific surface area (Abayazeed and
El-Hinnawi, 2011), In addition, the Egyptian claystones have generally similar
heat capacities to those used in mud therapy.
A particular concern in using mud for mud therapy has focused on the concentration
of some trace elements, particularly heavy metals, in the muds (Mascolo
et al., 1999; Tateo et al., 2009;
Carretero et al., 2010; Rebelo
et al. 2011). These metals have been classified into three classes
(Rebelo et al., 2011): Class 1 includes Cd, Pb
and As, elements that should be essentially absent because they are known as
human toxicants or environmental hazards; Class 2 includes Mo, Ni,V, Cr,Cu and
Mn, elements that should be limited in pharmaceuticals and have less toxicity
than those in Class 1. Class 3 includes those elements that may be present as
impurities in some cosmetic products (e.g., Ba, Se, Zn and Sb). Even though
Zn has no significant toxicity, Sb is included as an element of primary toxicological
concern in cosmetics together with Pb, As, Cd and Hg.
The analyzed trace elements in the Egyptian claystones exhibited normal values
for average mud and average shale (Fig. 5, 6).
The slightly higher levels of Cr and Ni. are due to variations in lithology
and are within the natural normal ranges of these elements. For comparison,
the Dead Sea black mud used for mud therapy contains 24-26 ppm Co, 108-114 ppm
Pb and 73-108 ppm Zn (Khlaifat et al., 2010),
generally higher than those found in Egyptian claystones. Although, on average,
the latter clays contain 136 ppm Cr, which is higher than that in Dead Sea black
mud (40-66 ppm, according to Momani et al. (2009),
Portuguese muds contain higher Cr , up to 196 ppm (Rebelo
et al., 2011).
In mud therapy, the mud can be applied to different parts of the body or on
the whole body by means of masks and poultices, or even in bathing the body
partly or totally, for therapeutic or cosmetic purposes. In most cases the mud
is applied hot. In all the applications an interface between the mud and the
skin is formed in which perspiration plays an important role. In this interface
an exchange of chemical elements may take place. Ions and other compounds may
pass from the mud to the skin and enter the blood stream. Conversely, ions and
other substances may pass from the skin into the mud. In either case, sweat
is the interface between mud and skin. Tateo et al.
(2009) studied the in-vitro percutaneous migration of chemical elements
from a thermal mud mixed with mineral water. They found that the doses of Cr,
Cu, Ni, Pb and Zn supplied to the body, after 20 min of treatment, are far below
the daily dietary intakes recommended for these elements by the World Health
Organization. Carretero et al. (2010) studied
the mobility of elements in interaction between artificial sweat and muds used
in Spanish spas. They found that the heavy metals Cu, Pb, Ni and Zn are ab/adsorbed
from the sweat to the mud leading in most cases to their removal from the leached
extract. Other elements, such as Cd, Co and Cr are generally not leached. Accordingly
and due to the fact that the trace elements in the Egyptian claystones are generally
lower than those encountered in other muds used for mud therapy, these trace
elements are of no concern from the health point of view in mud treatments.
The mineralogical, chemical and thermal characteristics of the Egyptian claystones from Fayum, G. Hamza and G. Um Qamar are comparable tp those of muds used for pelotherapy in Italy, Spain, Portugal and Croatia. The Egyptian claystones have, in general, lower concentrations of heavy metals than other muds, for example the Dead Sea black mud and the presence of such elements in the claystones is of no health concern in mud treatments.
The Egyptian claystones can be used as virgin clays, mixed with water, or mineral water, or can be subjected to maturation by mixing with sea water or other combinations, according to their therapeutic use.
The authors would like to express their gratitude to Prof. Dr. Doris Stüben, Leader of the Institute of Mineralogy and Geochemistry, Karlsruhe Institute of Technology, Germany, for her kind support. Our thanks go also to Dr. U. Kramar of the same Institute for his assistance in carrying out the chemical analyses in Karlsruhe.
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