Journal of Renewable Energy.
Electrical, and Computer Engineering, x .
x-xx Journal of Renewable Energy.
Electrical, and Computer Engineering Vol.
No.
March 2022, 1-6 e-ISSN: 2776-0049 DOI: https://doi.
org/10.
29103/jreece.
Research Original Article Hydrolysis of coffee pulp as raw material for bioethanol production:
sulfuric acid variations Mawaddah1.
Adi SetiawanaA2 Zulnazri3 Almia Permata Putri3 Naseer A.
Khan4 & Vishal Jain5 1Magister Program in Renewable Energy Engineering.
Faculty of Engineering.
Universitas Malikussaleh.
Bukit Indah, 24352.
Lhokseumawe.
Indonesia 2Mechanical Engineering Department.
Faculty of Engineering.
Universitas Malikussaleh.
Bukit Indah, 24352.
Lhokseumawe.
Indonesia 3Chemical Engineering Department.
Faculty of Engineering.
Universitas Malikussaleh.
Bukit Indah, 24352.
Lhokseumawe.
Indonesia 4Department of Chemical Engineering.
University of Engineering and Technology (UET) Peshawar.
Khyber Pakhtunkhwa (KPK), 25120.
Pakistan 5Sharda University.
Greater Noida.
India Corresponding Author: adis@unimal.
id | Phone: 628116701699 Received: January 20, 2022 Revision: February 18, 2022 Accepted: March 15, 2022 Abstract Indonesia has enormous biomass resources due to its land territory is mostly surrounded by forests and agricultural One of the main agricultural commodities is Gayo Arabica coffee.
Coffee agro-residue such as coffee-pulp contains glucose, organic matter, protein, nitrogen and high minerals.
Therefore, coffee pulp can be a potential raw material for bioethanol production.
In order to develop an effective technology for bioethanol production from coffee-pulp, it is necessary to investigate in early the way of glucose can be effectively prepared.
In this preliminary investigation, glucose products ware prepared using two methods, i.
method-I under several main-stages including extraction, delignification, and hydrolysis.
While, under method-II, the sample was directly hydrolyzed at 100a CC for 4 h.
Under both methods, hydrolysis process to get glucose was performed by adding sulfuric acid (H 2SO.
at various concentrations .
%, 10 wt.
% and 12 wt.
%).
Based on analysis results, the highest glucose level, i.
17 % was obtained from method-II by adding 8 wt.
% sulfuric acid.
The less the amount of sulfuric acid added, the higher the glucose level No difference in pH was found from both methods.
The color of glucose produced under method-I is clearer compared to those prepared under method-II.
Keywords: Coffee waste.
glucose and sulfuric acid Introduction Concerns about environmental issues as well as the need for energy and chemical resources have increased researchers in using sustainable resources derived from biomass (Mirnezami et al.
, 2020.
Nawaz et al.
, 2.
Bio-fuel production from lignocellulosic biomass has received global attention and can reduce greenhouse gas emissions and can minimize the use of fossil energy through the use of renewable energy (Halder et al.
, 2.
Lignocellulosic biomass is one of the most abundant, sustainable and renewable resources that can be converted into bio-chemicals, bio-polymers and biofuels (Culaba et al.
, 2.
Biofuel production, one of which is bioethanol, is currently very dependent on starch and sugar (Wang et al.
, 2.
In this context, bioethanol produced from lignocellulosic biomass does not compete with food crops, is cheap and easy to obtain compared to conventional agricultural raw materials.
Lignocellulose mainly consists of carbohydrate polymers .
ellulose and hemicellulos.
, aromatic polymers .
and other substances such as lipids, minerals, fibers and a number of other bioactive compounds and phytochemical compounds (Sarsaiya et al.
, 2019.
Tu & Hallett, 2.
Lignocellulosic materials such as agricultural waste are renewable resources that are waste for sugar production through the conversion of hydrolyzate biotechnology to produce food, liquid fuels and chemicals.
(Ab Rasid et al.
, 2021.
Hoang et al.
, 2.
Furthermore, the saccharification process is carried out in a medium catalyzed by acids or enzymes.
Acid catalyzed hydrolysis is divided into two processes, namely the low temperature concentrated acid process or the high temperature dilute acid process, depending on the operational conditions and the nature of the raw materials (Harsono et al.
, 2.
One of the plantation wastes that is abundant and has high economic value is coffee waste.
The biggest coffee producing countries are Brazil .
,776 tons/yea.
Vietnam .
,900 tons/yea.
Colombia .
tons/yea.
Indonesia .
tons/yea.
, and Ethiopia .
tons/yea.
(Duarte et al.
, 2.
Indonesia is the fourth largest producing country in the world, one of which is Central Aceh Regency, where the majority of the population lives in the coffee farming sector Journal of Renewable Energy.
Electrical, and Computer Engineering, 2 .
1-6 (Setiawan et al.
, 2019, 2.
When the harvest season arrives, the farmers dispose of the coffee husks they produce into the environment and not use them.
As Chen explained, arabica coffee rind produces glucose (Chen & Jhou, 2.
and contains high organic matter, reducing sugar, protein, nitrogen, and minerals (Hoseini et al.
, 2.
So that a further study is needed regarding the utilization and processing of Arabica coffee coolies waste into bioethanol raw materials.
In many countries, including Indonesia, bioethanol has been used as a fuel blending material (S.
Aiman.
, 2.
Therefore, the bioethanol industry continues to grow.
In the period from 2013 to 2014, six large-scale bioethanol industries from lignocellulosic biomass have been established, with production capacities between 30 to 110 million liters per year, with raw materials for municipal waste, wheat straw, corn waste, or various other agricultural wastes (Aiman, 2.
In the Table 1, the development of bioethanol research from time to time are described with various sources of biomass.
Table 1.
Bioethanol research development (Hajar et al.
, 2.
Raw (Suga.
/L) Fermentation Ethanol .
/L) No.
Bacteria Name
cerevisiae RL11
30aoC, 20a0a rpm, 48 h
MTCC 173
Sorghum
30aoC, 120a rpm,96 h
thin CBS 6054
giant reed
30aoC, 150a rpm, 96 h
cerevisiae KL17
Galactose 30aoC, 20a0a rpm, 28 h
CHFY0201
32oC, 120a rpm, 66 h
CHY1011
cerevisiae ZU10 32oC, 120a rpm, 66 h Corncob 30aoC, 180a rpm, 72 h .
Ref.
(S.
Mussato.
Machado.
Carneiro, (C.
Sathesh-Prabu, (D.
Scordia.
Cosentino.
Lee, 2.
(J.
Kim.
Ryu.
Huh, 2.
(G.
Choi.
Um.
Kim, (G.
Choi.
Um.
Kim, 2.
(J.
Zhao.
L, 2.
Sugar Concentration .
Ethanol Concentration .
Ethanol Productivity The ethanol production process depends on the type of feedstock used.
In general, there are three main steps in the production of ethanol, obtaining a solution containing fermentable sugars, converting the sugar into ethanol by fermentation and separating and purifying the ethanol.
Raw materials are usually pretreated to reduce their size and facilitate subsequent processing.
Then, hemicellulose and cellulose will be hydrolyzed into fermentable sugars.
Yeast is given the responsibility of fermenting this sugar into ethanol.
Separation technology is used to separate ethanol from water before it can be used as fuel (Hajar et al.
, 2.
This study aims to develop an effective way for glucose preparation as initial stage of investigation for bioethanol production from Arabica coffee pulp.
The glucose ware prepared using two methods, i.
method-I under several mainstages including extraction, delignification, and hydrolysis.
The second method was a direct-hydrolysis process of coffeepulp at 100a CC for 4 h.
The effect of sulfuric acid concentrations on the glucose level, pH and color were analyzed to find out the best method for glucose preparation.
Materials & Methods The raw material used in this research was coffee pulp sourced from coffee a plantation in Aceh Tengah District.
Aceh.
The term of coffee pulp refers to the outer skin of coffee cherry peeled off during the process.
The coffee pulp sample was initially cleaned-up and dried in an oven at 100 CC for 3 h.
Hydrolysis of dried coffee pulp was carried out by varying the concentration of sulfuric acid, i.
8, 10 and 12 wt.
% H2SO4 with a hydrolysis time of four hours at a temperature of 100a CC.
In this investigation, there were two methods have been used to produce glucose, i.
method-I by using several stages including extraction, delignification, and hydrolysis.
The second method is direct hydrolysis method where 100 g dried coffee-pulp was hydrolyzed at 100a CC for 4 h.
The procedures are detailed in Figure 1.
For hydrolysis.
H 2SO4 was used by diluting to concentrations of 8, 10 and 12 %.
Delignification process was carried out by using 65 vol.
% HNO 3 .
itric aci.
NaNO2.
Na2SO3.
15% NaOCl solution, 50% H2O2 solution and distilled water.
As raw material.
Gayo Arabica coffee pulp was initially cleaned and dried in the oven at 100 CC for 3 h.
The dried coffee pulp was then ground and sieved to O 80 mesh size.
A 100 grams of coffee pulp powder was placed into a glass beaker, mixed with 3.
5% HNO3 solution and 3 mg of NaNO2, then heated on a hot plate at 100 CC for 2 h.
Resulting substrate was filtered and washed until the filtrate was neutral.
The next step is delignification process by adding 250 ml of 2 vol.
% NaOH and 2 vol.
% Na2SO3 solution and heated at 50 CC for 1 hour.
After that, the extract was filtered and Journal of Renewable Energy.
Electrical, and Computer Engineering, 2 .
1-6 Next, the bleaching process was carried out by adding 85 ml of 75 vol.
% NaOCl solution and heated at boiling temperature for 30 minutes, then filtered and washed until the pH of the filtrate was neutral.
The second bleaching process was performed with 10 vol.
% H2O2 solution and dried in an oven for 1 hour at 60 CC.
The results obtained in the form of The extracted cellulose was put into an Erlenmeyer flask as much as 5 grams and added with 100 ml of distilled water and 100 ml of H2SO4 .
t concentration of 8%, 10%, 12%).
Then the solution was hydrolyzed at 100 CC for 4 hours.
Method - I Start Coffee Pulp Cleaning and drying in oven for 3 h at 10a0aoC Grinding and sieving to 80 mesh 100 g of coffee pulp powder is mixed with HNO3 and NaNO2 then heated for 2 h at 10a0aoC Method - II Extract filtration and washing Start Coffee Pulp Delignification process by adding 2 wt.
NaOH and 2 wt.
% Na2SO3, then heated at 50AC for 1 h.
Cleaning and drying in an oven for 3 h at 10a0aoC Extract filtration and washing 1st bleaching by adding 75% NaOCl and boiling for 30 min followed by filtration and washing Grinding and sieving to 80 mesh size 2nd bleaching by washing with 10 wt.
% H2O2
followed by drying at 60AC for 1 h Coffee Pulp powder Cellulose Hydrolysis process for 4 hours at a temperature of 10a0aoC with a variation sulfuric acid .
%, 10a%, 12%) Hydrolysis process for 4 hours at a temperature of 10a0aoC with a variation sulfuric acid .
%, 10a%, 12%) Glucose Glucose Glucose Level Analysis Glucose Level Analysis Figure 1.
Methods for extracting glucose from Gayo Arabica coffee pulp Sample Analysis In this investigation, the pH level of glucose products was measured using a Mediatech digital pH meter.
Glucose concentration was measured by using Brix Refractometer with measuring range 0-32%, resolution 0.
2%, working temperature 10-30a CC.
Results and Discussion The results of the pH measurement and the color of glucose sample are shown in Table 2 for the process carried out by method-I and method-II.
The pictures of glucose produced from both methods are displayed in Figure 2.
Table 2.
The results of the analysis of pH and color changes of the glucose samples of coffee waste.
Method Variation of sulfuric acid Method I Method II concentration (%) Color Color Clear Brown Based on pH measurement results, it was found that the methods I and II did not show a significant change in the pH This indicates that the addition of sulfuric acid did not affect the acidity of the glucose produced.
Meanwhile, in term of glucose color, there was a significant difference.
from method-I, a white color was produced, this is due to the process experienced in method I went through several stages and a new bleaching process occurred followed by a hydrolysis process for four hours, so that the resulting product was white.
While in method II the resulting color tends to be brown, this is due to the direct hydrolysis process without going through the extraction and delignification process.
shown in Figures 2 and 3.
Journal of Renewable Energy.
Electrical, and Computer Engineering, 2 .
1-6 .
Figure 2.
Glucose products after filtering process, .
under method-I and .
method-II .
Figure 3.
Glucose products .
method I and .
method II Glucose Level (%) From Figures 2 and 3 there is a difference in the color of the glucose produced, in method I it is white and method II is brown, the results of the study show that in method II the highest glucose product is obtained compared to the first Figure 4 shows the glucose levels resulting from the analysis using the Brix Refractometer.
Coffee Skin Glucose Levels Method I Coffee Skin Glucose Level Method II Amount of sulfuric acid H2SO4 (%) Figure 4.
Glucose levels from coffee husk waste with variations in the amount of H 2SO4 Figure 4 shows that the more sulfuric acid is added, the lower the glucose level produced is as in method II, but it is different from method I, the highest glucose level is at a concentration of 10% wt H2SO4 which is 10%.
In method I the glucose obtained is lower than in method II, but the color of the glucose produced is white.
This lower glucose level is Journal of Renewable Energy.
Electrical, and Computer Engineering, 2 .
1-6 caused in the Extraction process there is a decrease in cellulose content caused by the reduced solubility of hemicellulose into NaOH solution, because most of the water has been used by NaOH to dissolve, so the water in the solution becomes This decrease in hemicellulose causes an increase in the content of cellulose and lignin in one lignocellulose bond.
In the extraction process, the lignin compounds have not been degraded, only softening occurs, so that the hemicellulose which was originally bound by lignin becomes free and most of it can be dissolved into NaOH solution.
Meanwhile, because lignin only softens, only a small part of it dissolves in NaOH or even nothing dissolves.
In addition, the decreased cellulose content was due to the presence of a regular open structure of cellulose and the cellulose molecules were freely dispersed in the solvent (NaOH).
With the structure of cellulose being freely dispersed in the solvent, it is expected that cellulose will be carried away by the solvent during the filtering process.
Meanwhile, because lignin only softens, only a small part of it dissolves in NaOH or even nothing dissolves.
In addition, the decreased cellulose content was due to the presence of a regular open structure of cellulose and the cellulose molecules were freely dispersed in the solvent (NaOH).
With the structure of cellulose being freely dispersed in the solvent, it is expected that cellulose will be carried away by the solvent during the filtering process.
Meanwhile, because lignin only softens, only a small part of it dissolves in NaOH or even nothing dissolves.
In addition, the decreased cellulose content was due to the presence of a regular open structure of cellulose and the cellulose molecules were freely dispersed in the solvent (NaOH).
With the structure of cellulose being freely dispersed in the solvent, it is expected that cellulose will be carried away by the solvent during the filtering process (Lestari et al.
, 2.
Unlike the case in method II which is directly related to the hydrolysis process by obtaining a higher amount of glucose and is brown in color.
Conclusions Glucose produced from Gayo Arabica coffee pulp has been prepared at various sulfuric acid concentrations as initial stage in bioethanol production.
Glucose content, pH and the color of glucose products were tested in order to decide the best method for bioethanol production.
Based on the results of this investigation, the highest glucose level was obtained from method-II by adding 8 wt.
% sulfuric acid.
The less the amount of sulfuric acid added, the higher the glucose level Under method-I, hydrolysis with 8 wt.
% sulfuric acid produced glucose level as high as 10% only.
No difference in pH was found from both methods.
The color of glucose produced under method-I is clearer compared to those prepared under method-II.
Acknowledgments The authors would like to thank Shafira Riskina and Siti Nurjannah for their help during sample preparation and authors also thanks to the Institute for Research and Community Services (LPPM).
Universitas Malikussaleh for their support on this research.
References