International Research Journal of Plant Science (ISSN: 2141-5447) Vol. 2(6) pp. 186-190, June, 2011
Available online http://www.interesjournals.org/IRJPS
Copyright © 2011 International Research Journals
Full Length Research Paper
Immobilization of Konkoli (Maesopsis eminii) Leaves
with Calcium Alginate and Study of its Swelling
Behavior
S. A. Osemeahon., J. T. Barminas, I. I. Nkafamiya and D. I. Esenowo
Department of Chemistry, Federal University of Technology, Yola, Nigeria
Accepted 29 June, 2011
The swelling behavior in aqueous solution of calcium alginate immobilized konkoli leaves (KIL)
was investigated. An immobilized blend of 50/50 admixture of konkoli leaves/sodium alginate was
cross-linked with 0.12M CaCl2 to give KIL. The swelling behavior of the blend showed that the
uptake increases with increase in konkoli leaves concentration in KIL as well as pH while
decreasing with increase in ionic strength and temperature. The study presents KIL as a potential
biosorbent for industrial use.
Keywords: Konkoli leaves, Immobilization, Swelling behavior.
INTRODUCTION
Konkoli seed gum is widely used as a thickener in soup
and other traditional baked food products because of high
viscosity, binding and swelling propensity (Barminas and
Eremosele, 2002). The need for improved membrane
composition as a superabsorbent using available
polymeric materials has been subjected to expensive
research (Lee and Lin, 2000; Hegazy, et al, 2001).
Superabsorbent has a wide industrial application in area
such as diapers, napkins, soil for agriculture and
horticulture, gel actuation, water blocking tapes, medicine
for drug delivery system and adsorbent pad (Lee and Lin,
2000). These swollen polymeric networks have found
application in numerous technological fields such as
material for contact lenses and protein separation,
matrices for cell encapsulation, tissue engineering and
device for control of release of pharmaceutically active
protein (Hannik and Van Klostrum, 2002; Hoffman, 2002).
In these applications, water retention, dehydration and
absorbency play a striking role. As at now there are some
scientific research work done on the seed gum
(galactomannan) derived from konkoli seed (Barminas
and Eremosele, 2002; Osemeahon et al., 2007, 2008).
*Corresponding author E- mail: sundayosemeahon@yahoo.com
The seed of konkoli yields once annually for man and
animal to compete for the small quantity produced.
Galactomannan present in konkoli seed gum is known to
exhibit a suitable hydrophilicity and swelling capacity
(Barminas and Eromosele, 2002, Barminas et al, 2005).
Moreover, the grafting of the gum blend with
polyacryamide and sodium alginate has produced a
membrane used for bioremediation (Osemeahon et al.,
2007, 2008). However, nothing has yet been reported on
the industrial use of konkoli leave which are abundantly
available all round the year and wasting away in the wild
at the moment.
In this study, we set out to prepare and immobilize
konkoli leaves, with an objective of studying its swelling
behaviors so as to ascertain its industrial potential.
MATERIALS AND METHODS
Materials
Sodium alginate, calcium chloride, sodium hydroxide,
hydrochloric acid were obtained from the British Drug
House (BDH). konkoli leaves were sampled from Kurmi
Local Government Area of Taraba State, Nigeria. All
materials were used as supplied.
Osemeahon et al. 187
Preparation of Konkoli Leaves
The konkoli (Maesopsis eminii) leaves were completely
dried at room temperature of 30o C . It was then be
pounded in a mortar into powder and sieved through
100µm sieve screen to produce a fine powder. The
sieved material was packed in a polythene bag for further
use. This crude sample was dissolved in water without
purification. First, 4.0g of the leave powder was dissolved
in 100ml of water and left to stand for 12 hours.
Preparation of Sodium Alginate and Calcium Chloride
Sodium alginate was prepared by weighing 4.0g and
3
making it up to 100cm mark in a volumetric flask with
distilled water. This was left overnight for complete
dissolution to give 4% w/w. calcium chloride, 0.12M, was
prepared by weighing 13.32g into 1L flask and made up
to the mark with distilled water (Wuyep et al., 2007).
Immobilization of the Konkoli Leaves
25ml of viscous layer of dissolved konkoli leaves was
thoroughly mixed with 25ml of 4% stock solution of
sodium alginate and stirred vigorously for even mixing in
a 250ml beaker. The mixture was subsequently poured
into another beaker containing 30ml of 0.12M calcium
chloride solution. The reaction was allowed retention time
of 1hour for complete precipitation. The precipitated
blend solid were filtered and allowed to dry at room
temperature (300C). The dried solid mass was stored in a
polyethene bag for further use.
The above process was repeated by mixing another
set of blend with 4%of the stock solution of the sodium
alginate and konkoli leave admixture at a ratio of 50: 0,
45: 5, 40:10, 35:15, 30: 20, and 25/25. The precipitates
so obtained were dried and kept separately for further
use (Wuyep et al., 2007).
Determination of Water Uptake
The modified tea bag method reported by Barminas et al
(2005) was employed. This involves the immersion of
known weight of immobilized solid blend in excess
distilled water inside a polythene bag. The assembly was
pre-weighed and hermitically sealed and left for 4 hours
at 300C to attain equilibrium. At the end of the equilibrium
period, excess solution was carefully sucked out using a
micro-syringe and the bag with the wet sample weighed.
Percentage water uptake was calculated as follows:
Water uptake (%) = [(W s –W g)/W g] x 100/1 Where W g
and W s represents weights of the dry and wet
immobilized ‘konkoli’ leave respectively.
Determination of the Effect of Temperature on Water
Uptake
The effect of temperature on water uptake was examined
by immersing a known weight of the immobilized sample
in distilled water for 4 hours using the modified tea bag
method. The sample was kept at a constant temperature
for 4 hours using a regulated water bath. At the end of
this period, the water uptake was determined as reported
earlier. The procedure was repeated for various
temperatures ranging between 30 and 800C. In each
case, the average of three determinations was taken
(Barminas et al., 2005).
Determination of the Effect of Ionic Strength on Water
Uptake
A known weight of the dry sample was immersed in
excess solution of sodium chloride of various
concentrations (0.1-1.0g w/w) using the modified tea bag
method. At the end of the equilibration period of 4 hours
the percentage water uptake was calculated using the
formula reported earlier (Barminas et al., 2005).
Determination of the Effect of Time on Water Uptake
The effect of contact time on water uptake was
examined. Different sets of sample having equal amount
the immobilized leaves were immersed in distilled water.
The percentage uptake of each sample was determined
at different time interval ranging from 30 minutes to 24
hours.
Determination of Effect of the pH on the Water Uptake
The water uptake characteristics of the immobilized
sample at different pH values (pH 2-12) was investigated
at 250C using the modified tea bag method earlier
discussed. A standard 1.0M HCl and 1.0M NaOH were
used to adjust the solution to the required pH as the case
may be. The process was repeated at different pH within
the range stated above to ascertain the influence of
hydrogen ion concentration on the water uptake.
RESULTS AND DISCUSSION
Immobilization of konkoli leaves
The konkoli leaves has low density, little rigidity and poor
mechanical strength. Its immobilization was achieved by
entrapping or caging it within the matrix of Calcium
alginate. Similar report has been reported by Ju et al.,
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Int. Res. J. Plant Sci.
Calcium alginate
L+ NaAlg + CaCl2 (aq)
Konkoli leaves
Figure 1: Schematic of Immobilization of konkoli leaves by
Figure 2: Effect of concentration of konkoli leaves on the water uptake
(2002).
Calcium alginate, where L is konkoli leaves and
sodium alginate.
The immobilization of the konkoli leave by calcium
alginate may be liken to the cooperating but interpenetrating net-work existing between calcium alginate
and poly(N-isopolyacryamide) as demonstrated by Ju et
al. (2002). Similarly, In the immobilization the degree of
freedom of movement of the konkoli leaves in the
biomass is checked by the inter-polymeric network of
calcium alginate as shown in the schematic diagram in
Figure 1, where bold lines indicates the guluromannuronate co-polymeric chain, and in between them,
the konkoli leaves form a light broken shadow lines.
It has been established that molecular chain of
sodium alginate (SA) contains hydroxide (--OH) groups.
The cross-linking of the OH groups in SA with calcium ion
forms a network through bridge (Xiao et al., 2002). This
insoluble network immobilizes soluble konkoli leaves
gum, and the insoluble biomass to obtain the immobilized
konkoli leaves (KIL)
Effect of Concentration of Konkoli Leaves on the
Water Uptake
Figure 2 shows the effect of the concentration of konkoli
leaves on water uptake. It is observed that the water
uptake by KIL increases with increase in concentration of
konkoli leaves. This result is in agreement with various
reports (Osemeahon et al., 2007; Barminas et al, 2005
and Ju et al., 2002). The development is explained by an
increase in hydrophilicity of KIL with increase in the
amount of konkoli in the absorbent (Barminas et al,
2005). This also indicates that the percentage mass
uptake by KIL depends on the amount of leaves in the
absorbent. The water uptake recorded in this work
(290%) is relatively higher than that of konkoli seed gum
(275%) as reported Barminas et al (2005). This also
shows that leaves may be a better absorbent than seed
gum.
Effect of Temperature on the Water Uptake
The effect of temperature on water uptake by KIL is
shown in Figure 3. It can be seen that the water uptake
decreases sharply from 30 to 500C. Normally, gas
permeability through the polymeric membranes increases
with temperature. However, the condensable gases or
vapor, the sorption behavior may have more complicated
temperature dependency (Barminas et al., 2005). The
present result may be due to:
(a) The inherent molecular structure of the polymer
precursor (konkoli leaves),
(b) Contraction of the KIL molecules with increase in
temperature to give a more compacted form of
membrane which causes the pore to be narrower and the
suction sites be hidden or inaccessible to the water
molecules. Similar report has been reported by Barminas
Osemeahon et al. 189
Figure 3: The effect of temperature on water uptake
Figure 4: The Effect of ionic strength on water uptake
Figure 5: Effect of contact time on water uptake
et al, (2005),
(c) Dissolution of the low molecular weight polymer and
non cross-linked polymer with increasing temperature.
The ionic osmotic pressure between the biomass and
external solution decreases as the ionic strength of the
salt solution increases (Barminas et al, 2005), that is the
water absorbency decreases when the ionic strength in
the external increases.
Effect of Ionic Strength on Water Uptake
The effect of ionic strength on water uptake is shown in
Figure 4. It can be observed that the absorbency
decreases with increasing ionic strength. This is due to
difference in ionic osmotic pressure between the KIL
sorbent and the external solution (Lee and Lin, 2000).
Effect of Time on Water Uptake
The effect of contact time on water uptake of KIL is
shown in figure 5. It is observed that the rate of water
uptake increases rapidly within the first 30 minutes and
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Int. Res. J. Plant Sci.
Figure 6: Effect of pH on the water uptake
then for the next 3 hours takes up water very gradually
until equilibrium is reached. Perhaps, the rapid swelling of
the KIL could be due to the swelling capacity and density
of the polymer network. Also, hydrophilicity of the network
and the nature of the polymer may also be a factor (Toti
and Aminabhavi, 2002). The observed plateau from 4 to
8 hours marks the saturation point as the equilibrium is
established.
Effect of the pH on the Water Uptake
The uptake of water by KIL was investigated and the
results are as shown in figure 6. In pH range of 1.0 to 7.0,
the percentage absorbency changed from 261.2 to
368.67%. Show a steady incremental difference of
107.57%. However, from pH 7.0 to 12.0, the percentage
water uptake jumped from 368.67 to 786.86% showing a
very sharp difference in increment of water uptake range
of 390.9%. This shows the amount of water absorbed by
KIL between the pH values 7.0 to 12.0 is three times as
much as the one drawn between pH values of 1.0 to7.0.
On the whole, the percentage absorption trend increases
with the increasing pH values, which show that alkaline
pH favors higher water uptake by KIL biomass. This is
due to the presence of the –OH group in solution with
increasing pH value (Yen-peng and Sung, 2000).
CONCLUSION
In this work konkoli leaves was successfully immobilized
with calcium alginate. The immobilized konkoli leaves
(KIL) displayed a reasonable water absorption rate, which
diminished as the temperature and ionic strength
increases. An increased in konkoli leaves concentration
in KIL and pH of the sorption environment increase the
moisture uptake, thus increasing the chances of the
biomass being used for the remediation of the waste
water. This work presents KIL as a potential sorbent for
industrial use.
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