The 4th International S eminar on Sciences [602446]

The 4th International S eminar on Sciences

THERMOGRAVIMETRY STUDY ON PYROLYSIS OF RICE HUSK
FOR POTENTIAL HIGH PURITY SILICA PRODUCTION

Casnan1,4, ErlizaNoor1, Hartrisari Hardjomidjojo1, Irzaman2, EtiRohaeti3

1Agroindustrial Technology Department, Agricultural Technology Faculty , Bogor Agricultural University
2Physics Department, Mathematics and Natural Science Faculty , Bogor Agricultural University
3Chemistry Department, Mathematics and Natural Science Faculty , Bogor Agricultural University
4Program Study of Mathematics Education , STKIP Muhammadiyah Kuningan

Email: [anonimizat]

Abstract

Pyrolysis is the chemical decomposition of organic material through a process of heating without
or with a bit of oxygen or other reagents, so the raw material will break the chemical structure into
a gas phase. Charcoal of rice husk can be processed to produce of silicon dioxide (silica) by
pyrolysis process, the pyrolysis of silica obtained with a yield of 16.85%. Charcoal of rice husk
contain ing silica reached 72.1% and increased up to 94.95% when burned at 700oC for 6 hours,
and rice husk ash contains about 80% – 90% of silica in the dry condition, so charcoal and rice husk
ash can be used as Alternative sources of silica and silicon. The pre-treatment rice husk of pyrolysis
to produce of silica could affect the mass conversion and selectivity of the resulting silica product.
Rice husk with pre -treatment (rice husk leached with HCl solution) obtained a mass conversion of
73% with the yie ld of 27% rice husk ash. Rice husk without pre -treatment obtained high selectivity
with purity of silica about 75.75% of silica and carbon impurities.

Keywords : Pyrolysis, Rice Husk, Silica, Leached Process . Commented [G1]: Inserted: a
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Introduction
The combustion chamber can be processed for the manufacture of silica by pyrolysis process,
silica pyrolysis obtained by yield 16.85% (Dongmin et al. 2011, Masrur . 2013). The rice husk
contains silicon oxide reaches 72.1% and increases to 94.95% when burned at 700oC for 6 hours
(Hikmawati . 2010, Madrid . 2012), whereas rice husk ash in dry condition contains silicon oxide in
the amount of 80% – 90% (Konstantinos et al. 2013, Givi et al. 2010), so that charcoal and rice
husk ash can be used as an alternative source of silica and si licon producers (Real et al. 1996;
Subbukrishna et al. 2007; Muthadhi et al. 2010). Silica is widely applied for the manufacture of
various industrial products with silica specifications according to the requirements, some of the
industries that use silica include cosmetics, electron ics, films, toothpicks (Houston. 1972). Other
research , to produce silica -rich silica husk with calcination process is used in the construction of
insulating or cera mic materials (Farook and Anwar . 2010), other applications incl ude catalysts,
filler materials (eg . paper, paint, rubber, polymer) and some other types of additives, abrasives,
insulators and damp ers / adsorbents (Jamal and Ali. 2013, Zaynab et al. 2015). Abu Silica with
amorphous properties, has high value as a su bstitute for cement or additives (Oyekan and Kamiyo.
2011), in the pr oduction of zeolite (Yue et al. 2012) and other ceramic applications (Sembiring et
al. 2014). Studies on the production and application of rice husk ash have been carried out, but
there i s still a gap about the optimization of treatment conditions and their relationship to the
characteristics of rice husk ash. In this case, to produce highly reactive and pure silica, some
conditions are very important to obtain an amorphous structure and t he abs ence of reacting carbon
(Madrid. 2012).
Pyrolysis is the chemical decomposition of organic matter through the process of heating
without or little oxygen or other reagents, so that raw materials will break down the chemical
structure i nto a gas phase (Lam K L et al. 2012). Preliminary treatment in the pyrolysis process of Commented [G7]: Deleted:,
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rice husk for the manufacture of silica affects the mass conversion and the selectivity of the
resulting silica products. Rice husk with initial treatment obtain s a high selectivity with 75.75%
silica purity and carbon impurities (Sigit. 2016).

Materials
The materials used in this study were rice husk, HCl, and A quabides .

Methods
The process of Silica Making from Rice husk is shown in Figure 1.

.

Figure 1. Silica Making Process from Rice Husk with Pretreatment
(Washing Process Using Acid Solution)
Start
Washing process using 3% Technical HCl (Stirling on hotplate
with 240 rpm speed for 2 hours)

Rice husks are washed with Aquabides to a neutral pH
Drying of rice husk after washing with Aquabides

Combustion of rice husk
Buried in chaff
Burning of charcoal In the furnace (60 g)

Test the EDX characterization

Silica Commented [G10]: Inserted: s

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Results and Discussion
Rice husk is a lignocellulose material like other biomass but contains high silica. The
chemical composition of rice husk consist of 50% cellulose, 25 – 30% lignin, and 15 – 20% silica
(Bakri. 2008) Some rice husk components have the potential to be used a s silica raw materials
because of their potential for polarisation, that is for organic matter (about 75 -80wt%, basically
cellulose, hemicellulose, and Lignin) and mineralization for minerals (about 15 -20wt% Especially
silica) (Madrid . 2012). The com position of Charcoal Chemical before and after at pyrolysis at 700
oC for 6 hours for high enough silica that is 94.95% and other chemic al components as shown in
Table 1. The final product of silica produced from the rice husk in the pretreatment w ith the HCl
conversion process obtained a hi gh purity of 75 .75% (Sigit. 2016).

Table 1. Composition of Charcoal Chemical before and after combustion at 700 oC for 6 hours
(Ragini P et al. 2014)
Chemical Components Charcoal Rice Husk Ash
SiO 2 72.1 94.95
Al2O3 0.30 0.39
Fe2O3 0.15 0.26
CaO 0.43 0.54
Na2O 0.50 0.25
K2O 0.72 0.94
MnO 0.15 0.16
TiO 2 0.05 0.02
MgO 0.70 0.90
P2O5 0.06 0.74
Loss on burning Process 24.3 0.85
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The TGA curve explains the process of mass loss to the temperature in the pyrolysis process
with various stages on phase change of materials because of the heating process. The stages of
phase change on the pyrolysis process is divided into 5 stages, as shown in Table 2. The rice husk
TGA curve with pre -treatm ent showing the mass loss as a function of temperature is shown in
Figure 1, with a heating rate of 1 oC / min.

Figure 1. Results of TGA Rice Husk with pre -treatment (Leached with HCl)

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Table 2. Data of TGA Rice Husk Results with pre -treatment
Condition
of Husk Heating
Rate
(oC/min) Decay
Stage Temperature
range (oC) Mass loss
(%wb) Time
(min) Rate of
Mass loss
(%/min)
Leaching
with HCl 1 I 39,7 – 134,9 4,7684 95,2 0,05009
II 134,9 – 218,7 0,0378 83,8 0,00045
III 218,7 – 530,3 70,9013 311,6 0,22754
IV 530,3 – 645,0 0,8033 114,7 0,00700
V 645,0 – 903,6 -1,8005 258,6 -0,00696
VI 903,6 – 973,6 -3,3567 70 -0,04795

Temperature range for multiple stages of mass loss and mass loss level in the above pyrolysis
process as shown in Table 2. The first step, Mass loss in the sample with pre -treatment was
4,7684 %. At this stage, the process of removing water vapor from the ma terial occurs. S econd
place here only applies the mass reduction in the sample with pre treatment of 0 .0378 %. At this
stage, much less than other levels. This stage is considered as a transition stage, this is possible due
to the loss of water vapor (if any), CO 2 gas, and others. Third Stage The loss of volatile matter
mass is about 70,9013 % with pre -treatment. Volatile material mass is 0,22754%/ minute. The
fourth stage The loss of volatile matter mass other is about 0,8033 % with pre -treatment. Volatile
material mass is 0,00700%/ minute. According to A bdullah 2010 , the most reactive compound,
hemicelluloses decomposes at between 200 to 350 ⁰C, whereas cellulose from 305 to 375 ⁰C and
lignin steadily over of 250 to 500 ⁰C. The fif th stage of the TGA curve, which shows a decrease
and mass increase gradually, in the pre -treatment sample increased by 1,8005 %. At this stage, there Commented [G25]: Deleted: –

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is a solid carbon burning (fixed). Initially, the rate of combustion was high at the 3rd stage. But
after a while, the curve dropped drastically. The six th stage of the TGA curve, which shows the
mass increase gradually, in the pre -treatment sample increased by 3 ,3567%. Some reported that
pyrolysis of heavier volatiles such as lignin occurs from temperature as low as 150 up to 900 ⁰C
since it is more thermally stable in contrast to cellulose and hemic elluloses (Abdullah et al. 2010) .
The results of EDX analysis of rice husk ash with pre -treatment as shown in Figure 2.
Analysis data obtain 75.75% silica purity with carbon impurities.

Figure 2. EDX Silica Spectrum Pattern on Rice Husk Ash (Sigit. 2016)

The final product Silica produced from the rice husk in the pretreatment with the HCl
conversion process obtain a high purity of 75 .75% as shown in Table 3. Some research results
indicate that rice husk washing process using acid solution during pyrolysis process , there was a
significant dec rease of husk mass. In the Wash ing and leaching stage, almost 30% by weight of
husk is lost. The weight loss of rice husks occurs in calcination, where the skin weight is reduced
by about 80%. The overa ll value that refers to the initial weight is 86%. Cleaning and acid leaching
are used to remove im purities from silica products. Leach ing steps are highly efficient in removing
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zinc (85%). Regarding other metals, water purification also allows the removal of impurities closer
to 45 -65% (Madrid et al., 2012).

Table 3. Results of EDX Silica Analysis with Pre -treatment
Element Heating Rate
1°C/ min
Oksigen 66.98
Silikon 25.25
Carbon 10.77
Rubidium –
Calcium –
Aluminium –
Fluorine –
Purity (%) 75.75

Conclu sion
The method of converting rice husk before the pyrolysis process can produce high purity
of silica reaching 75 .75% since the washing process using acid solution can remove the elemental
(metal oxide) that is in the charcoal or in the rice husk ash.

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