T. Endah, Buhani, Suharso
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Therefore, in this research cocodust immobilization is done to improve stability of biomass cocodust with supporting matrix such as silica gel. The result is used as adsorbent to adsorb
CdII and PbII ions from solution.
2. Materials and methods
Manufacture adsorbent Cocodust obtained from the compound 22A Hadimulyo metro, Lampung. Cocodust
derived from coconut released from the husk taken, then the coconut coir dust cocodust collected obtained from coconut husk. Cocodust made into a homogeneous of the same size.
Cocodust cut using a cutter and sieved using Siever Fritsch with a size of 150-200 m, after thats washed using aquabidest 3 times. Then dried in an oven at 100ºC for 24 hours
Mehrasbi et al., 2009.
Immobilization of biomass cocodust Biomass cocodust in diameter 150-200 mfrom 22A Hadimulyo metro, Province
Lampung, Indonesia was chemically modified in two step. Firstly, cocodust was activated by silica gel from TEOS. Immobilized by silica gel used a procedure Buhani, 2010. The observe
surface morphology before and after immobilized using SEM analysis. Analysis of adsorbent material which interaction with metal ion, functional group was carried out using IR.
Adsorption process Adsorbat solution made of Cd NO
3
.4H
2
O and Pb NO
3 2
in a concentration of 1000 ppm as the mother liquor. Adsorption was performed using 20 mg of adsorbent and 50 mL
of ion CdII and PbII with a variation of pH between 2-10 stirred using a shaker at 100 rotasion min
-1
at a temperature of 25ºC. Kinetics adsorption was studied using first and pseudo second order on the variation of the contact time between 0-90 minutes. Variations
in the concentration of metal ions is used to determine the maximum absorption of between 0 -100 mg L
-1
. Isotherm adsorption Langmuir and Freundlich models can provide information absorption that occurs in the general adsorbent.
3. Results and discussion
Infrared spectra to identify the functional groups of cocodust biomass, silica gel and cocodust immobilization results are presented in Figure 1. The cluster functions contained in
the adsorbent can be observed. There is a change in the absorption band cocodust immobilization. At a frequency of 462.92 cm
-1
is indicated as vibration of Si-O-Si and at 794.67 cm
-1
indicate the presence of Si-O stretching vibration Si-O-Si. The absorption at 964.41 cm
-1
is vibration Si-O on Si-OH. Strong absorption bend at a frequency of 1087.85 cm
-1
shows the stretching vibration of Si-O of the Si-O-Si. Ribbon at a frequency of 1635.64 cm
-1
is vibration asymmetry C = O is derived from silica. There are a few peaks that disappear after immobilized, such as frequencies between 1200 1500 cm
-1
that characterizes the lignocellulose and overton between 1600 2000 cm
-1
. But there is also a peak at cocodust immobilization obtained from pure cocodust ie at a frequency of 548, 08 cm
-1
for Si-O stretching vibration; 1527 cm
-1
there is a little lignin, and at a frequency of 2931.80 cm
-1
for CH stretching. The results shown in the identification of functional groups immobilized
cocodust biomass formed a perfect mix between the silica and cocodust.
Immobilization cocodust biomass with silika as adsorbent for CdII and PbII ions in solution
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Figure 1. Functional groups of cocodust biomass, silica gel and cocodust immobilization.
Cocodust biomass surface morphology before and after diimobilisasi observed using SEM, as shown in Figure 2. In Figure 2b shows that the biomass cocodust after immobilized
with silica gel looks more stable. Silica gel chosen as the supporting matrix because it has a large surface and side active as silanol -SiOH and siloxane Si-O-Si which can chemical
bonding with functional groups contained in cocodust, the abundance of silica with a seemingly SEM image look lighter or brighter.
a b
Figure 2. SEM image: a cocodust active, and b cocodust imobilization.
Effect of pH In this study the influence of pH studied by varying pH and adsorbent interactions of
metal ions in the range of 2-10 and shown in Figure 3 with a concentration of 100 mg L at a temperature of 25ºC. Increased binding of metal ions affected by the increase of H
+
ions on the surface of the adsorbent. Adsorption of CdII and PbII ions optimum at pH 6, the pH is
a balance between the number of H
+
ions and metal ions resulting in competition maximum, so that the data obtained adsorption of metal bound to the adsorbent perfectly CdII and
PbII ions respectively 14.57 and 14.03 mg g
-1
. At pH 2 solution resulting in competition between H
+
excess ions with the metal ions in solution. Charged metal ions is less reactive than the H
+
ions are bemuatan +1 so that the seizure of the H
+
ions and metal ions in solution which causes the metal ions adsorbed only slightly. At pH 4 acid solution still included so that
the metal is absorbed already increased but is still less than the maximum. At pH 8-10 alkaline conditions occur that cause excess OH groups in the solution and the deposition process
Fan, 2012.
T. Endah, Buhani, Suharso
SWUP
BC.59
Kinetics adsorption Kinetics adsorption was used to study the kinetics of CdII and PbII ions in solution
by biomass cocodust modified silica. Adsorption pseudo first order kinetics and second are used in this study. Methode using a batch model liquid-solid system. Presented the values of
the comparison first and pseudo second order in Table 1.
Tabel 1. Perbandingan kinetika pseudo orde satu dan dua untuk ion CdII dan PbII. Pseudo Orde satu
Pseudo Orde dua
k
1
menit
-1
x 10
-3
q
e
mg g
-1
R
2
k
2
menit
-1
q
e
mg g
-1
R
2
CdII 400
250 0.460
8.472 0.264
0.958 PbII
3 125
0.282 111.550
0.0530 0.963
From the results of the average constant k
1
and qe than shown in Table 1 shows the pseudo first order models are not appropriate for immobilization cocodust adsorption
process, so it is used second pseudo order kinetic model. The equation for the second pseudo order kinetics follow
= +
, 1
where q
e
is the adsorption capacity, and k
2
constants second order that can produce slop and intercept, it can be shown in equation 1. The value of the equation k
2
and qe are shown in Table 1. From the results seen that the adsorption models kinetika followed pseudo second
order.
Isoterm adsorption Base on according to corelation cooficient value Cn to C Langmuir isoterm adsorption
in equation 2 was gotten regresion in CdII and PbII ions 0.804; dan 0.92. Energy value 0 Table 2, shown spontanious adsorption. Value of k to show adsorption affinity adsorbent.
The more increasing of k adsorbent affinities of biosorbent great. Adsorption to PbIICdII ions, it becauses of PbII ions is a intermediet metal and radius PbII more CdII ions. So,
according to HSAB theory that OH
-
is a hard base. That PbII ion, it is easier to bond OH
-
than CdII.
Table 2. Comparation Langmuir and Freundlich isoterm adsorption models at CdII and PbII ions to Cocodust biomass imobilisation.
Langmuir Isoterm Adsorption
q
e
mgg b
R
2
nm molg x 10
-4
K 10
3
E kJmol CdII
11.70 2.04
0.80 10.40
4.79 -20.99
PbII 12.80
0.55 0.92
6.25 29.09
-25.46
Freundlich Isoterm Adsorption
k intersep R
2
n 1slope CdII
0.20 0.94
1.94 PbII
0.59 0.98
2.08
After that is plot used model equation Langmuir and Freudlich isoterm adsorption. Freundlich isoterm adsorption model was gotten regrestion that get to perfect each 0.944;
dan 0.985. The result of plot corelation between log Q
e
and log C
e
, it shown that CdII and
Immobilization cocodust biomass with silika as adsorbent for CdII and PbII ions in solution
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PbII ions adsorption following Freundlich isoterm adsorption. It is because of shaped multy layer from adsorbat moleculs at surface, it is heterogen. The result of compare Langmuir and
Freundlich isoterm adsorption it showed at Table 2.
4. Conclusion and remarks
