This document describes a study on the alkali digestion and ethanolysis of cacao pod husks to produce ethyl levulinate. Cacao pod husks account for 75% of the cacao crop and are considered waste. The study involved preparing and conditioning the husks, extracting cellulose via alkali digestion, and converting the cellulose to ethyl levulinate through ethanolysis and purification. Results showed alkali digestion with 0.781M sodium hydroxide for 2 hours at 100°C extracted 99.46% of cellulose. Ethanolysis produced ethyl levulinate in 51.56% yield, which was purified through solvent extraction to recover 24.24% of the product. FTIR

1. Alkali Digestion and Ethanolysis of Cacao (Theobroma cacao L.)Alkali Digestion and Ethanolysis of Cacao (Theobroma cacao L.)Alkali Digestion and Ethanolysis of Cacao (Theobroma cacao L.)
Pod Husks for Ethyl Levulinate ProductionPod Husks for Ethyl Levulinate ProductionPod Husks for Ethyl Levulinate Production
Antonino, King Neil A., Calinisan, Michael Oliver O., Gamet, Arnold A., Sibayan Rose Jane L., Vargas, Rhowell V., Mission, Elaine G.
Chemical Engineering Department, College of Engineering and Technology, Pamantasan ng Lungsod ng Maynila
INTRODUCTION
Cacao (Theobroma cacao L.) pod is a tree crop that grows in the Philippines having a production of 5,427.66 MT in 2014 (Cacao (Theobroma cacao L.) pod is a tree crop that grows in the Philippines having a production of 5,427.66 MT in 2014 (Cacao (Theobroma cacao L.) pod is a tree crop that grows in the Philippines having a production of 5,427.66 MT in 2014 (Philippine Statistics Authority,Philippine Statistics Authority,Philippine Statistics Authority,
201420142014). Its beans are processed in the food industry leaving the cacao pod husk (CPH), accounting to 75% of the whole crop, which). Its beans are processed in the food industry leaving the cacao pod husk (CPH), accounting to 75% of the whole crop, which). Its beans are processed in the food industry leaving the cacao pod husk (CPH), accounting to 75% of the whole crop, which ararare considered ase considered ase considered as
wastes (wastes (wastes (Alemawor et al., 2009Alemawor et al., 2009Alemawor et al., 2009). In the Philippines, farmers commonly utilize the CPH as fertilizer, thus causing plant disease called black pod rot (). In the Philippines, farmers commonly utilize the CPH as fertilizer, thus causing plant disease called black pod rot (). In the Philippines, farmers commonly utilize the CPH as fertilizer, thus causing plant disease called black pod rot (Yapo et al.,Yapo et al.,Yapo et al.,
201420142014). There have been attempts to use it as charcoal briquettes and animal feed, but was not advisable due to its detrimental r). There have been attempts to use it as charcoal briquettes and animal feed, but was not advisable due to its detrimental r). There have been attempts to use it as charcoal briquettes and animal feed, but was not advisable due to its detrimental resuesuesults. However, CPH islts. However, CPH islts. However, CPH is
mainly composed of high proportion of cellulose (35.4%) which is a potential source in producing a valuable product such as emainly composed of high proportion of cellulose (35.4%) which is a potential source in producing a valuable product such as emainly composed of high proportion of cellulose (35.4%) which is a potential source in producing a valuable product such as ethythythyl levulinate. Ethyl levuli-l levulinate. Ethyl levuli-l levulinate. Ethyl levuli-
nate is mostly used as a diesel fuel blend component due to its oxygenate properties and also as an additive for manufacturinnate is mostly used as a diesel fuel blend component due to its oxygenate properties and also as an additive for manufacturinnate is mostly used as a diesel fuel blend component due to its oxygenate properties and also as an additive for manufacturing og og of fragrance and plasticizerf fragrance and plasticizerf fragrance and plasticizer
(e. g. cellulose plastics). Hence, this study would not only be beneficial to the processing industry but as well as to the e(e. g. cellulose plastics). Hence, this study would not only be beneficial to the processing industry but as well as to the e(e. g. cellulose plastics). Hence, this study would not only be beneficial to the processing industry but as well as to the envinvinvironment.ronment.ronment.
Diesel Fuel AdditiveDiesel Fuel AdditiveDiesel Fuel Additive FragranceFragranceFragrance Cellulose PlasticCellulose PlasticCellulose Plastic
MATERIALS AND METHODS
The experimental methods was divided into three major parts:The experimental methods was divided into three major parts:The experimental methods was divided into three major parts: [1][1][1] preparation and conditioning of cacao pod husks (size reduction, drying, grind-preparation and conditioning of cacao pod husks (size reduction, drying, grind-preparation and conditioning of cacao pod husks (size reduction, drying, grind-
ing and sieving),ing and sieving),ing and sieving), [2][2][2] extraction of cellulose (alkali digestion) andextraction of cellulose (alkali digestion) andextraction of cellulose (alkali digestion) and [3][3][3] conversion and purification into ethyl levulinate (ethanolysis, solvent extraction andconversion and purification into ethyl levulinate (ethanolysis, solvent extraction andconversion and purification into ethyl levulinate (ethanolysis, solvent extraction and
distillation) as shown in the process flow diagram (Figure 1).distillation) as shown in the process flow diagram (Figure 1).distillation) as shown in the process flow diagram (Figure 1).
Figure 1. Process Flow Diagram of Ethyl Levulinate ProductionFigure 1. Process Flow Diagram of Ethyl Levulinate ProductionFigure 1. Process Flow Diagram of Ethyl Levulinate Production
1. Preparation and Conditioning of CPH1. Preparation and Conditioning of CPH1. Preparation and Conditioning of CPH
CPH were gathered from cacao plantation in Barangay V, Poblacion, Al-CPH were gathered from cacao plantation in Barangay V, Poblacion, Al-CPH were gathered from cacao plantation in Barangay V, Poblacion, Al-
fonso, Cavite and prefonso, Cavite and prefonso, Cavite and pre---treated through sizetreated through sizetreated through size reduction, drying, grinding andreduction, drying, grinding andreduction, drying, grinding and
sieving. It was found to contain 38.5% of cellulose using Gravimetric Analysissieving. It was found to contain 38.5% of cellulose using Gravimetric Analysissieving. It was found to contain 38.5% of cellulose using Gravimetric Analysis
done by Adamson University Technology Research and Development Centerdone by Adamson University Technology Research and Development Centerdone by Adamson University Technology Research and Development Center
(AUTRDC)(AUTRDC)(AUTRDC)
2. Alkali Digestion of Pre2. Alkali Digestion of Pre2. Alkali Digestion of Pre---treated CPHtreated CPHtreated CPH
Alkali digestion delignifies the cellulosic biomass where lignin andAlkali digestion delignifies the cellulosic biomass where lignin andAlkali digestion delignifies the cellulosic biomass where lignin and
some part of hemicellulose are being removed, and cellulose is recoveredsome part of hemicellulose are being removed, and cellulose is recoveredsome part of hemicellulose are being removed, and cellulose is recovered
without the production of derivatives (i.e. furfural and methylfurfural)without the production of derivatives (i.e. furfural and methylfurfural)without the production of derivatives (i.e. furfural and methylfurfural)
(((Sanchez, 2011; Harmsen et al., 2010; Sierra et al., 2008Sanchez, 2011; Harmsen et al., 2010; Sierra et al., 2008Sanchez, 2011; Harmsen et al., 2010; Sierra et al., 2008).).).
A ratio of 1:20 (g:ml) of preA ratio of 1:20 (g:ml) of preA ratio of 1:20 (g:ml) of pre---treated CPH and 0.422treated CPH and 0.422treated CPH and 0.422---0.781 M sodium0.781 M sodium0.781 M sodium
hydroxide solution were reacted under 1 to 3 hours reaction at 100hydroxide solution were reacted under 1 to 3 hours reaction at 100hydroxide solution were reacted under 1 to 3 hours reaction at 100ooo
CCC
temperature. Then, the alphatemperature. Then, the alphatemperature. Then, the alpha---cellulose was separated from the black liquorcellulose was separated from the black liquorcellulose was separated from the black liquor
through filtration.through filtration.through filtration.
Lignocellulosic Biomass + NaOH -> Carbohydrates + Lignin
Carbohydrates + Lignin + NaOH -> Alpha Cellulose + Hemicellulose
+ Lignin
3. Ethanolysis of Alpha3. Ethanolysis of Alpha3. Ethanolysis of Alpha---CelluloseCelluloseCellulose
This process depolymerizes and degrades the cellulose into glucose inThis process depolymerizes and degrades the cellulose into glucose inThis process depolymerizes and degrades the cellulose into glucose in
ethanol. The glycosidic hydroxyl groups of glucose reacts then with the hy-ethanol. The glycosidic hydroxyl groups of glucose reacts then with the hy-ethanol. The glycosidic hydroxyl groups of glucose reacts then with the hy-
droxyl groups of ethanol in a condensation reaction in the presence of androxyl groups of ethanol in a condensation reaction in the presence of androxyl groups of ethanol in a condensation reaction in the presence of an
acid catalyst forming ethyl glucoside. Then, ethyl levulinate can be obtainedacid catalyst forming ethyl glucoside. Then, ethyl levulinate can be obtainedacid catalyst forming ethyl glucoside. Then, ethyl levulinate can be obtained
from 5from 5from 5---ethoxymethylethoxymethylethoxymethyl---222---furaldehyde intermediate that was formed fromfuraldehyde intermediate that was formed fromfuraldehyde intermediate that was formed from
the dehydration of ethyl glucoside (shown in Figure 2).the dehydration of ethyl glucoside (shown in Figure 2).the dehydration of ethyl glucoside (shown in Figure 2).
AlphaAlphaAlpha---cellulose were reacted to ethanol with sulphuric acid at 88cellulose were reacted to ethanol with sulphuric acid at 88cellulose were reacted to ethanol with sulphuric acid at 88OOO
CCC
for 1for 1for 1---6 hours reaction time.6 hours reaction time.6 hours reaction time.
Figure 2. Process Flow Diagram of Ethyl Levulinate ProductionFigure 2. Process Flow Diagram of Ethyl Levulinate ProductionFigure 2. Process Flow Diagram of Ethyl Levulinate Production
RESULTS AND DISCUSSIONS
The result showed that the percentage conversion for all the trials haveThe result showed that the percentage conversion for all the trials haveThe result showed that the percentage conversion for all the trials have
minimal differences indicating that the repetition of the process is accepted.minimal differences indicating that the repetition of the process is accepted.minimal differences indicating that the repetition of the process is accepted.
Thus, the average of mass of product solution, which is 615.978g, was deter-Thus, the average of mass of product solution, which is 615.978g, was deter-Thus, the average of mass of product solution, which is 615.978g, was deter-
mined in order to cover the random variations of results with process con-mined in order to cover the random variations of results with process con-mined in order to cover the random variations of results with process con-
version of 51.56%.version of 51.56%.version of 51.56%.
3. Solvent Extraction3. Solvent Extraction3. Solvent Extraction
After the toluene was mixed with the solution, the results showed thatAfter the toluene was mixed with the solution, the results showed thatAfter the toluene was mixed with the solution, the results showed that
extracted ethyl levulinate has the average percent recovery of 24.2493 %.extracted ethyl levulinate has the average percent recovery of 24.2493 %.extracted ethyl levulinate has the average percent recovery of 24.2493 %.
1.1.1.Alkali Digestion of PreAlkali Digestion of PreAlkali Digestion of Pre---treated CPHtreated CPHtreated CPH
Table showed that significant response yields for 0.781 M sodium hydrox-Table showed that significant response yields for 0.781 M sodium hydrox-Table showed that significant response yields for 0.781 M sodium hydrox-
ide solution and 2 hours reaction time was 99.4678% at 100ide solution and 2 hours reaction time was 99.4678% at 100ide solution and 2 hours reaction time was 99.4678% at 100ooo
C temperature.C temperature.C temperature.
The response indicates that almost all unnecessary components (i.e. ligninThe response indicates that almost all unnecessary components (i.e. ligninThe response indicates that almost all unnecessary components (i.e. lignin
and hemicellulose) were removed, thus, highest extraction of alphaand hemicellulose) were removed, thus, highest extraction of alphaand hemicellulose) were removed, thus, highest extraction of alpha---cellulosecellulosecellulose
was observed.was observed.was observed.
2.2.2. Ethanolysis of AlphaEthanolysis of AlphaEthanolysis of Alpha---CelluloseCelluloseCellulose
Figure 3. FTIR Spectra of Standard and Extracted Ethyl LevulinateFigure 3. FTIR Spectra of Standard and Extracted Ethyl LevulinateFigure 3. FTIR Spectra of Standard and Extracted Ethyl Levulinate
Source: FTIR Testing, Adamson University, 2015Source: FTIR Testing, Adamson University, 2015Source: FTIR Testing, Adamson University, 2015
T h e e x p e r i m e n tT h e e x p e r i m e n tT h e e x p e r i m e n t
showed that the producedshowed that the producedshowed that the produced
ethyl levulinate’s spectraethyl levulinate’s spectraethyl levulinate’s spectra
conformed to the standardconformed to the standardconformed to the standard
spectra of the commerciallyspectra of the commerciallyspectra of the commercially
---available as presented inavailable as presented inavailable as presented in
Figure 3.Figure 3.Figure 3.
CONCLUSION AND RECOMMENDATION
This study confirmed that cacao pod husks (CPH) which is a lignocellulosic biomass rich in cellulose, is a potential raw mateThis study confirmed that cacao pod husks (CPH) which is a lignocellulosic biomass rich in cellulose, is a potential raw mateThis study confirmed that cacao pod husks (CPH) which is a lignocellulosic biomass rich in cellulose, is a potential raw materiariarial for the production ofl for the production ofl for the production of
ethyl levulinate. Moreover, the extraction of the cellulose components of CPH using alkali digestion was proven by the resultethyl levulinate. Moreover, the extraction of the cellulose components of CPH using alkali digestion was proven by the resultethyl levulinate. Moreover, the extraction of the cellulose components of CPH using alkali digestion was proven by the results os os of the experiment. The alphaf the experiment. The alphaf the experiment. The alpha---
cellulose produced successfully undergone ethanolysis process and solvent extraction; the result of which was confirmed by thcellulose produced successfully undergone ethanolysis process and solvent extraction; the result of which was confirmed by thcellulose produced successfully undergone ethanolysis process and solvent extraction; the result of which was confirmed by the Fe Fe FTIR analysis of the ethylTIR analysis of the ethylTIR analysis of the ethyl
levulinate was formed.levulinate was formed.levulinate was formed.
On the other hand, it is recommended to to consider other essential parameters and operating conditions that may influence thOn the other hand, it is recommended to to consider other essential parameters and operating conditions that may influence thOn the other hand, it is recommended to to consider other essential parameters and operating conditions that may influence the ce ce conversion and pro-onversion and pro-onversion and pro-
duction processes.duction processes.duction processes.
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