Production of Bioethanol Gel from Sugar Cane Waste with Carbopol

as Alternative Fuel

Wilza Fithri Az-zahra, N. Nurlina Harahap, S. Haidar Putra and M. Zulham Efendi Sinaga*

Chemistry Department, Faculty of Mathematic and Natural Science, Universitas Sumatera Utara, Medan 20155,

Sumatera Utara, Indonesia

Keywords: Bioethanol, Bioethanol Gel, Carbopol, Saccharomyces Cerevisiae, Alternative Fuel.

Abstract: Bioethanol gel is an alternative fuel innovation with gel form, that ease packaging and distributing process.

Bioethanol gel is modified bioethanol with carbopol as the thickening agent. Based on the result of the study,

bioethanol gel as alternative fuel can be produced by hydrolyzing sugar cane waste and fermented with

Saccharomyces cerevisiae for 4 days, producing bioethanol gel with 95% grade. Carbopol as thickening agent

was added to bioethanol from sugar cane waste, producing bioethanol gel. Best result obtained with the

variation of carbopol 1,8 g and NaOH 1 mL resulted to flowing gel. Characteristics of bioethanol gel are: flare

time 237 seconds, residue 0,03 g, calorific value 33.064,25 kJ/kg, and 5 g of bioethanol.

1 INTRODUCTION

Indonesia is a country with high energy

consumption in the world. Energy source that take

the first place in consumption rank is petroleum

which is an non-renewable energy source. One of

the petroleum derivatives that are widely used in

small industries and households is kerosene

(paraffin).

At present government is trying to divert the use

of kerosene to other fuels, such as gas. But this

diversion has encountered many obstacles. For

example, the number of fire cases because leaked

gas from the tube. Therefore the conversion of

kerosene does not have to be to gas fuel but also to

another energy source, such as bioethanol which is

more environmentally friendly and does not

endanger the environment.

But bioethanol also has weakness in it's physical

properties. Bioethanol is volatile, have low surface

tension, and low flash points. Causing bioethanol in

liquid form can be dangerous (Robinson, 2006). For

this, we need to modify the form of bioethanol.

Bioethanol gel is a potential innovation for further

development. The gel form ease packaging and

distribution process. In production of bioethanol gel,

thickener is needed in the form of powder such as

calcium acetate, or other thickener such as xanthan

gum, carbopol and various cellulose derivative

materials (Tambunan, 2008).

Bioethanol gel has several advantages. They are

easy to handle, packed, and stored for it does not

easily spill and flow. Some advantages over other

fuels where during combustion are not smoky, do

not cause soot, and do not produce harmful gases.

Bioehtanol gel is non-carcinogenic and non-

corrosive (Merdjan and Matione, 2003). Bioethanol

gel innovation offers its own advantages over liquid

forms of biethanol both in terms of economy and

security. Based on research conducted by Hanun

(2018), states that bioethanol gel is more economical

than paraffin.

Bioethanol gel provides a solution to the safety

of the application of household energy use because it

does not easily spill and evaporate (Lloyd and

Visagie, 2007). Because bioethanol gel has more

advantages compared to liquid bioethanol, the

researchers hope to use bagasse as a source of

carbohydrates that can be fermented into bioethanol

and the addition of carbopol as gelling agent in the

production.

2 MATERIALS AND METHODS

2.1 Materials

The materials used in this study include: bagasse,

3.5% HNO

, NaNO

, 2% NaOH, 2% Na

aquadest, 1.75% Na-Hypochlorite, 17.5% NaOH,

124

Az-zahra, W., Harahap, N., Putra, S. and Sinaga, M.

Production of Bioethanol Gel from Sugar Cane Waste with Carbopol as Alternative Fuel.

DOI: 10.5220/0008857501240129

In Proceedings of the 1st International Conference on Chemical Science and Technology Innovation (ICOCSTI 2019), pages 124-129

ISBN: 978-989-758-415-2

iodine solution, HCl 30%, 10% NaOH, benedict

solution, MgSO

.7H

O, KH

, (NH

)

, bread

yeast, carbopol, NaOH 1N, soil oil, spritus and

gasoline.

2.2 Procedure

2.2.1 Bioethanol Making

Cellulose Isolation.

75 g of bagasse was putted into a beaker glass. Then

1000 mL of 3.5% HNO

and 10 mg NaNO

were

added. The mixture is heated by thermostat for 2

hours at 80°C. Then filtered and the residue was

washed with distilled water to pH = 7. To the

residue, 375 mL of 2% NaOH and 375 mL of 2%

was added. The mixture was heated by

thermostat for 1 hour at 50°C. Then it's filtered and

washed with distilled water to pH = 7. The residue

was added with 500 mL of Na-Hipochlorite 1.75%,

then heated using a thermostat for 30 minutes at

100°C which then was filtered and washed with

distilled water to pH = 7. 500 mL of NaOH 17.5%

was added and heated by thermostat for 30 minutes

at 80°C. Then filtered and washed the residue with

distilled water to pH = 7. To the residue was added

500 mL of 1.75% Na-Hipochlorite and heated for 5

minutes at 100°C. It was filtered and washed with

distilled water to pH = 7. After that the residue was

dried in the oven at 60°C then let it cooled down in

desiccator. Enough cellulose is putted onto a drip

plate and then dripped with iodine 0.1 solution

which will show positive cellulose test if there is no

color change and FTIR analysis is performed.

Cellulose Fermentation.

0.5 g of cellulose bagasse was putted into a 250 mL

erlenmeyer glass and 5 mL of distilled water was

added. 8 mL of 30% HCl was added to the mixture.

Erlenmeyer was covered with cotton and aluminum

foil before it was heated in thermostat at 80°C for 1

hour. The mixture was cooled to room temperature,

10% NaOH was added to get pH = 4–4.5, and then

filtered. 1 mL of filtrate was piped into a test tube

and 5 mL of Benedict's solution was added. It was

heated in a thermostat to form red brick deposits.

100 mL of glucose solution from hydrolysis of

bagasse was poured into a 250 mL Erlenmeyer glass.

0,1502 g of MgSO

.7H

O; 0,1306 g of KH

; and

1,2021 g of (NH

)

was added. The mixture was

sterilized using autoclave at 121°C for 1 hour and

then cooled. Bread yeast was added as much as 6

grams. Fermented for 2, 4, and 6 days. The

fermented product was then distilled at 78°C and

tested for ethanol using an alcohol hydrometer.

2.2.2 Making Bioethanol Gel

Thickener was added to bioethanol which has been

obtained from bagasse to form bioethanol gel. 100

mL of bioethanol was poured into a beaker glass and

stired with a speed of 1000 rpm, while 1.2 grams of

carbopol was added slowly. The glass beaker was

covered and the mixture was stirred continously for

45 minutes. Then 1 mL of 1 N NaOH is added to

form the bioethanol gel. The same experiment was

conducted with variation amount of carbopol (0.8 gr,

1 gr, 1.4 gr, 1.6 gr, and 1.8 gr) and 1 mL of NaOH.

2.3.3 Characterization

Stability and Flame Color Test for Bioethanol Gel.

5 grams of bioethanol gel was takken and putted into

a porcelain dish and then burned. The color and

flame of bioethanol gel combustion were observed

and recorded.

Ignition Time Test.

1 and 5 grams of bioethanol gel was putted into a

porcelain dish. Stopwatch was turned on when the

attempt to burn bioethanol gel was performed and

turned off when the flame appear.

Burned Bioetanol Gel Weight Test.

5 grams of bioethanol gel was putted into a porcelain

dish and then burned until the gel cannot burn again

(remaining ash and other solids). The residue then

weighed, where the weight of the bioethanol gel that

burns is the different between initial weight and final

weight.

Heat Test.

Testing of heat value refers to Robinson (2006),

carried out to determine the level of heat produced

by each sample of bioethanol gel in units of calories

(cal). The first step to measure the heating value

was, bioethanol gel was burned in the C200

Kalorimeter Bomb where the combustion product is

then cooled again to reach room temperature. The

energy used to cool combustion products is

equivalent to the energy available in fuel.

Movable Heat Test.

The transferred heat test or water boiling test was

done to determine the effectiveness of the fuel in

reference to Robinson (2006). Movable heat can be

measured by inserting 100 mL of water into a beaker

Production of Bioethanol Gel from Sugar Cane Waste with Carbopol as Alternative Fuel

125

glass and the initial temperature was measured. 15 g

of bioethanol gel was putted into a porcelain then

burned to heat 100 ml of water in a beaker glass.

After boiling water, the heat transferred is calculated

by calculating how much gel bioethanol is used for

this process.

3 RESULTS AND DISCUSSIONS

3.1 Bioethanol Making

3.1.1 Cellulose Isolation

Isolation of cellulose bagasse through several stages.

Starting from the delignification stage with addition

of HNO

and NaNO

, at this point impurities from

bagasse are removed and cellulose was produced.

Then proceed with pulping with NaOH and Na

with 1: 2 ratio, this process is delignification

(removal of lignin) and will produce yellowish-

white cellulose. For the removal of dyes on

cellulose, bleaching with NaOCl is carried out.

Hypochlorite ions which are strong oxidants will

break ether bonds in lignin structure, consequently

the color of cellulose pulp becomes white. To

produce pure α-cellulose, 17.5% NaOH was added

to dissolve β-cellulose and produce α-yellowish

white cellulose. In other words, bleaching is needed

to produce white α-cellulose.

The result of cellulose isolation from bagasse is

white pulp, which 75g of bagasse is produced 10g α-

cellulose. The cellulose obtained was tested

qualitatively with iodine solution and showed

positive results with no color change.

The FT-IR spectrophotometric test results also

showed positive results by comparing wave number

of bagasse cellulose and commercial cellulose.

Figure 1 is the result of FT-IR spectroscopic test

which shown spectrum with vibration peak in area

of 3448.72 cm

-1

for –OH group, supported by

emergence of vibrational peaks at wave number

2900.94 cm

-1

which shows C–H stretching groups,

1064, 71 cm

-1

which shows the ether group, and the

glycoside bond in α-cellulose structure is found at

wave number 1635.64 cm

-1

(Epriadi, 2017). Figure

1. showed that the results of FT-IR cellulose bagasse

had similar wave numbers with commercial

cellulose. Research on cellulose isolation has been

carried out by several researchers including: coconut

palm petiole (Xu et al., 2015), groundnut shells

(Bano and Negi, 2017), and corncob (Gea, 2019).

Figure 1: The spectrum of sugarcane pulp and commercial

FT-IR cellulose.

3.1.2 Cellulose Fermentation

Obtained cellulose bagasse pulp is hydrolyzed with

strong acid (HCl) for breaks the polymerization

chain of cellulose into a monomeric unit glucose.

The hydrolyzed cellulose is then neutralized by

adding NaOH to pH 4–4.5. Neutralization was done

to eliminate high residual acid from hydrolysis

process so that a standard product is obtained at pH

= 4–4.5. It is the optimum pH of Saccharomyces

cerevisiae growth (Oktavia, 2013).

Table 1: Cellulose fermented bagasse.

Fermentation Time

(Day)

Bioethanol Level

(%)

9,6

18,2

10,4

The data above shown optimum time to produce

bioethanol was until the 4th day. It's also shown in

Irvan (2015)'s study, that the optimum day to

produce bioethanol from bagasse was day 4 with 8

gram yeast producing 22.63% of ethanol.

The longer fermentation time, the more

Saccharomyces cerevisiae cells multiply and more

ethanol content is produced. This was a result of

longer time make more number of active bacteria,

multiply the ability to break substrate (Oktavia,

2013). However, on the 6th day Saccharomyces

cerevisiae has died and the substrate to be consumed

has been reduced.

Distillation in this study was carried out three

times. By using simple distillation, the distillation

will produce bioethanol for the first time with levels

of 10–20% and 50–70% at second attempt.

ICOCSTI 2019 - International Conference on Chemical Science and Technology Innovation

126

Therefore, to get 90–95.5% levels, three repetitions

of distillation are performed. After being distilled,

the sample that was originally white will change

color to clear and the aroma of alcohol is smelled.

3.2 Making Bioethanol Gel

Bioethanol gel is produced by mixing with carbopol

and NaOH with slow stirring. The gel produced is

clear, in this case carbopol only acts as a gelling

agent without giving a color change to biethanol

(Wibowo, 2010). Addition of NaOH functions is to

neutralize acidic carbopol (Yogesthinaga, 2016).

The best bioethanol formulation is by adding 1.8

g of carbopol and 1 mL of NaOH. The form is

thicker than other variations. The bioethanol

produced can be seen in Figure 2.

Figure 2: Bioethanol gel.

3.3 Characterization

3.3.1 Stability and Flash Color Test for

Bioethanol Gel

According to Turns (2000), fire is a continuous heat

spread which is carried out by itself in a combustion

zone that is localized at very high speeds. One

characteristic of hydrocarbons combustion is

appearance of blue flashes in the zone of rapid

combustion in excess air conditions.

In the burning process, a good fire gives blue

color. Red color is produced due to incomplete

combustion process (Dewi, 2018). The flame of

bioethanol gel (Figure 3) is blue with an unstable

yellow to red tinge, and long-flaring flame. The red

tinge increases with addition of carbopol and NaOH

concentrations. According to Nugroho (2016), this

caused by combustion without intermediaries so the

fire seemed unstable. Turns (2000) also explained, a

long and flaming fire caused by combustion

conditions that are rich in fuel or the availability of

oxygen needed is not appropriate.

Figure 3: Bioethanol gel flame color.

3.3.2 Ignition Time Test

The combustion time test aims to see the ability of

bioethanol gel to burn until only part that cannot be

burned again remains and is calculated for a long

time until the fire is completely extinguished. The

results of measurement of combustion length of

bioethanol gel are presented in Table 2 and 3.

Table 2: Length of ignition test of 1 gram bioethanol gel.

Variation of

NaOH (mL)

Variation of

Carbopol (g)

Length of

Ignition (seconds)

0,8

1,0

1,2

101

1,4

109

1,6

120

1,8

180

Table 3: Length of ignition test of 1 gram bioethanol gel.

Variation of

NaOH (mL)

Variation of

Carbopol (g)

Length of

Ignition (seconds)

0,8

180

1,0

198

1,2

215

1,4

224

1,6

233

1,8

237

Data shown the best bioethanol gel burning time

is 239 seconds (3 minutes 59 seconds) on the

addition of 1.8 gram carbopol and 1 mL NaOH.

From data, it can be concluded that more carbopol

and NaOH additions able to withstand the burning

rate of bioethanol gel.

Presence of carbopol and NaOH is a retaining

factor so that the combustion becomes longer.

Increased concentration of carbopol extend the

flame because the vapor of bioethanol is trapped in

carbopol and released slowly, makes it run out

longer. When compared with liquid bioethanol, it

can be seen that bioethanol gel has increased the

Production of Bioethanol Gel from Sugar Cane Waste with Carbopol as Alternative Fuel

127

burning rate for a few seconds so it can be said that

the evaporation of bioethanol is inhibited by the

carbopol. Dewi (2018), has examined bioethanol gel

and get the same results; ignition period is increased

by addition of carbopol (1.5–2) grams.

3.3.3 Burned Bioetanol Gel Weight Test

This test is done to find out how much residue is

produced. Residue is a part of fuel that not

completely burn and left behind after the

combustion, changes, or reactions are complete. The

residual test results are presented in Table 4.

Table 4: Test for residual results.

Variation of

NaOH (mL)

Variation of

Carbopol (g)

Residue (g)

0,8

0,01

1,0

0,01

1,2

0,02

1,4

0,02

1,6

0,02

1,8

0,03

The remaining residue is the amount of

carbopol contained in the bioethanol gel which is

ensnared together with in the form of a gel, the dried

carbopol crust is brownish yellow. The data above

shown varies of residue produced in burning

process.

Wibowo (2010), stated that the more carbopol

added to 70% ethanol caused the residue to increase,

but this result was different in the bioethanol

treatment with 95% concentration. Based on the

results of the study, the increasing concentration of

ethanol produces fewer residues.

3.3.4 Heat Test

Calorific value is the most important quality

parameter for bioethanol gel as fuel. Calorific value

is the amount of heat energy stored in fuel produced

through combustion reactions. In fuel, the higher

calorie value possessed, the better quality of fuel and

higher combustion efficiency.

In this test, the best formulations were measured

from length of ignition. The calorific value obtained

from the measurement of the bioethanol gel calories

with the Calorimeter Bomb. The data are presented

in Figure 3.

Figure 3: Heat Value Test.

Calorific value is closely related to the

composition of carbon bound to a fuel. The higher

carbon bound gives higher calorific value (Yulistina,

2001 in Oktavia, 2013).

From the results of measurements using

Calorimeter Bomb, bioethanol gel heating value was

higher than liquid bioethanol. This is due to addition

of carbopol as a thickener, where carbopol is a

thickener of Lubrizol production with a molecular

formula (C

)

and has an active group of

polyacrylate acid that increased the calorifc value

(Dewi, 2018).

3.3.5 Movable Heat Test

A water boiling test is a test that determines the

performance of bioethanol gel so it can be used as a

household fuel. In this water boiling test, not all

bioethanol gel formulas were used, but the best

samples were taken, namely the addition of carbopol

1.8 g which was then compared with other fuels

such as: spritus, gasoline and kerosene. Heat transfer

data can be seen in Figure 4.

Figure 4: Heat transfer test.

In this test we use the same weight of all

materials, then measuring the temperature increased

from the heating process with the initial temperature

of water 25°C. The results of testing heat transfer

can be concluded that bioethanol gel is able to

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increase the temperature better than spritus and

kerosene but not compared to gasoline. In addition,

bioethanol has other advantages, which are odorless

and do not cause soot in process. The practical use

of bioethanol gel is directly burned, unlike other

fuels that use intermediaries such as axes (Nugroho,

2016).

4 CONCLUSIONS

Based on the results of the research it can be

concluded that bioethanol gel as an alternative fuel

can be produced from hydrolysis of bagasse pulp

and then fermented with Saccharomyces cerevisiae

for 4 days and adding carbopol as thickener. The

best results were obtained with variations of

carbopol 1.8 g and 1 mL NaOH with gel flowing

forms. The characteristics of the bioethanol gel

were: flame length 239 seconds (3 minutes 59

seconds), residue 0.03 g, heating value 33.064,25 kJ

/ kg, and 5 g bioethanol gel can raise the water

temperature to 50 °C.

ACKNOWLEDGEMENTS

The authors would like to send gratitude to Risekti

dikti for the financial support towards this research

in the PKM-PE Project 2019 and also for

Universitas Sumatera Utara which facilitated this

research.

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