A number of countries in the world are competing to develop new renewable energy sources along with the reduction in energy reserves from fossil sources. Indonesia is also developing this renewable energy source, one of which is energy from biomass.
Coconut shell briquette is one of the development of biomass energy, but the development of adhesive types is still continuing researched. This research aims to determine the characteristics of coconut shell briquettes with various types of briquette adhesives.
The study was conducted by reducing the size of the coconut shell charcoal to pass the size of 40 mesh, then mixed with various adhesive variations with a proportion of 15%. The mixture of charcoal flour with adhesive (tapioca, clay, and bentonite) is moistened and printed in a cylindrical form and then dried with a cabinet drier.
After drying each product was analyzed for water content, ash content, volatile matter content, fixed carbon content and calorific value by ASTM D-3175 method. Then the mean was calculated and analyzed for variance and Duncan’s test.
The results of the research concluded that briquettes with all types of perkat meet quality standards both for water content, ash content, carbon content bound and calorific value. Except for the levels of volatile substances still do not meet the standards. The highest calorie value is shown in briquette products with tapioca adhesive treatment with a value of 6314.46 cal / g.
The Indonesian government has launched the search and use of new and renewable energy sources through legislation that has been established with the DPR. One of these energy sources is biomass energy, which is an alternative energy to replace fossil fuels (petroleum) because of some of its beneficial properties, namely it can be used sustainably because it is renewable (renewable resources), relatively does not contain sulfur so it does not cause air pollution. (Arni et al, 2014).
Indonesia is an agricultural country where most of the income of the population is from farming. In addition to the harvest that will be consumed, this system will also produce agricultural waste and processing of agricultural products in large quantities. Various types of waste can be processed into biomass energy, including: wood waste, plant and agricultural waste, processed agricultural waste and others (Wilk et al, 2015).
Coconut commodity produces various main products such as: coconut milk, coconut oil, VCO, grated coconut and others. The by-products of the processing are in the form of waste, including: coconut shells, coir, dregs and others. Therefore, the use of coconut shells into briquettes is an alternative in handling waste which will be converted into products for energy fulfillment. Various types of adhesives in the manufacture of briquettes that can be used such as: tapioca, glutinous rice flour, clay, bentonite, tar, etc.
Coconut shell has the potential to become coconut shell briquettes with advantages in terms of calorific value and water content. However, the selection of the right type of adhesive will affect the quality of the resulting briquette product, especially its calorific value. The purpose of the study was to see the characteristics of coconut shell briquettes with various types of briquette adhesives.
II. RESEARCH METHODS
Materials and Equipment The materials in this study were coconut shell charcoal obtained from the Harapan Baru market, tapioca flour, clay and bentonite from the Palm Oil Laboratory of the Samarinda State Agricultural Polytechnic.
The equipment used included: a cylindrical briquette mold, a set of Toshniwal brand carbon analyzers, cabinet dryers, glassware for proximate tests of moisture content, ash content, volatile matter content, bound carbon content, and calorific value. Charcoal Making and Testing Coconut shell charcoal was reduced in size until it passed 40 mesh, then mixed with various types of adhesives (tapioca, clay, bentonite) at 15% of the shell charcoal for each adhesive.
After the dough is moistened with a little water to make it easy to print and press on the briquette printer, then the briquettes are put in the cabinet dryer. After the dry briquettes were analyzed water content, ash content, volatile matter content, carbon content and calorific value using the ASTM D-3175 method (Kurniawan, 2008).
Data Analysis The data obtained were then analyzed using the Analysis of Variance (ANOVA) test to assess the significance of the difference between the average values obtained. Data with significant differences will be analyzed by Duncan further testing. The data analysis process was carried out using SPSS 16.0 software.
III. RESULTS AND DISCUSSION
Moisture Content Moisture content is one of the quality parameters of the briquettes, which will affect the calorific value of the briquettes. The results of the analysis of water content in the study are as shown in Table 1.
Based on Table 1, it can be seen that each treatment has an average water content value of ± 2.72% to 2.94%. The moisture content of coconut shell charcoal briquettes has met the standards of Japanese (6-8%), British (3-6%), American (6%) and Indonesian (8%) briquettes (FAO, 1996).
The analysis of variance is as shown in Table 2. The water content of a good standard of Indonesian briquettes, namely coconut shell charcoal briquettes, ranges from 2.72% to 2.94%. This shows that the average value of water content in each treatment has met the quality requirements of the SNI standard, which is <8% (Arni et al, 2014).
The adhesive used gives a difference in the water content produced. This is in accordance with the research of Kong, et al (2014), that the type of adhesive and the percentage of adhesive have a significant effect on the water content contained in the briquettes. In addition, the raw material also affects the high water content in the briquettes because its structure consists of 6 C atoms which form a hexagonal lattice that allows water vapor to be trapped in it and does not evaporate under oven drying conditions (Nurmalasari and Afiah, 2017).
Ash Content Ash content is the remaining part of the combustion results, in this case the ash in question is the ash from the combustion of briquettes. One of the constituents of the ash is silica, the effect is not good on the calorific value of the charcoal briquettes produced. The ash content of briquettes in each sample can be seen in Table 3. and analysis of variance as shown in Table 4.
The ash content contained in coconut shell charcoal briquettes is due to the addition of ash from the raw materials and the adhesive used both from tapioca, clay, and bentonite. The higher the adhesive content, the higher the ash produced.
The high ash content is influenced by the impurities contained in the raw material so that the mineral content in the charcoal is quite high and in the combustion process leaves a lot of ash as combustion residue. In addition, the high ash content can also be caused by external impurities that come from the surrounding environment during the briquette making process (Ristianingsih, et al. 2015).
The ash content of briquettes affects the calorific value. The smaller the ash content, the higher the calorific value (Kurniawan, 2010). So that the ash content in the manufacture of charcoal briquettes is expected to be as low as possible so that the calorific value of charcoal briquettes is high.
The lowest ash content in this study was treatment P1 of 3.77%. All ash content results in this study met the SNI requirements for Indonesian charcoal briquette standards, namely the maximum ash content of charcoal briquettes was <8% (Arni et al, 2014).
Levels of Volatile Substances Volatile matter levels are substances (volatile matter) that can evaporate as the decomposition of compounds that are still present in the charcoal other than water. The values for volatile substances are shown in Table 5, while the results of the analysis of variance are shown in Table 6.
The level of volatile substances is different for each material because it is influenced by the volatile substances contained in the material. The high content of volatile substances in charcoal briquettes will cause more smoke when ignited, if the CO is high this is not good for health and the surrounding environment (Kurniawan, 2008).
From Table 5 it can be seen that the highest volatile matter was owned by treatment P1 of 43.68% and the lowest was treatment of P2 of 34.00%. Based on the quality standards of charcoal briquettes, especially for volatile substances, it can be seen that in each country the standards differ by 15 ± 30% (Japan) and 15% for SNI. Meanwhile, in this study, the levels of volatile substances produced were 34 ± 44% so that they did not meet the standards (Arni et al, 2014).
According to Ristianingsih et al, (2015), if the water content is high, it will produce a high value of volatile substances as well. High levels of volatile substances can be caused by incomplete carbonization process. Besides, the level of volatile substances is also influenced by the temperature and time of writing.
The greater the temperature at the time of cooking so that the content of the volatile substance will be smaller. Charcoal briquettes are expected to have the lowest possible volatile matter content (Nurmalasari and Afiah, 2017).
Bound Carbon Content Bound carbon shows the amount of charcoal remaining after the devolatilization stage, namely the biomass combustion stage until all volatile components are evaporated. Bonded carbon is the percentage of carbon remaining from burning charcoal (Kurniawan, 2008). The carbon content values are shown in Table 7, while the results of the analysis of variance are shown in Table 8.
Based on Table 5, the value of bound carbon in coconut shell charcoal briquettes is (49.43-59.13)%. The lowest value of bound carbon content was 49.43% in treatment P1, while the highest value of bound carbon in treatment P2 was 59.13%. Good charcoal is one that has a high bound carbon because the combustion process requires carbon to react with oxygen to produce heat (Ristianingsih et al., 2015).
The lowest fixed carbon content obtained from this study was 49.43%. The standard value of bound carbon content for America is 58%, so that the P2 and P3 treatments meet the standards. However, for the SNI standard of 77%, it indicates that the briquettes in this study have not met the quality requirements of SNI in Indonesia (Arni et al, 2014). Calorific value The calorific value greatly determines the quality of the briquettes produced.
The higher the calorific value, the higher the quality of the briquettes produced. The calorific value needs to be known to determine the value of the heat of combustion that can be produced by briquettes as fuel. The results of the analysis of variance are shown in Table 10.
Based on the research conducted, the highest calorific value was found in treatment P1 of 6314.46 cal/g, while the lowest calorific value of this study was treatment P3 of 5177.49 cal/g. A good briquette has a high calorific value. The lowest calorific value of this study was 5177.49 cal/g.
This calorific value indicates that the calorific value of coconut shell charcoal briquettes has met the Indonesian national standard (SNI), namely the minimum calorific value in charcoal briquettes is 5000 cal/g (Kurniawan et al, 2017).
The calorific value of briquettes is reflected in the carbon content bound to the product. As a fuel, carbon is bound to change form into carbon dioxide by releasing a certain amount of energy. The bound carbon content of charcoal and charcoal briquettes is around 50 ± 95% (FAO, 1996).
Briquette products with various types of adhesives meet quality standards for moisture content, ash content, bound carbon content and calorific value. Except for the levels of volatile substances that still do not meet the standards. The highest calorific value was shown in briquettes with tapioca adhesive treatment with a value of 6314.46 cal/g.
Research by : Edy Wibowo Kurniawan*, Mujibu Rahman, Rudi Karta Pemuda
University : Program Studi Teknologi Hasil Perkebunan, Politeknik Pertanian Negeri Samarinda, Indonesia.