# Alternative Briquette Material Made from Palm Stem Biomass Mediated by Glycerol Crude of Biodiesel Byproducts as a Natural Adhesive

^{1}

^{2}

^{3}

^{4}

^{5}

^{6}

^{7}

^{*}

## Abstract

**:**

^{2}on the briquette quality. The quality of the obtained briquettes is analyzed through the observation of important properties which involve the heating value and the compressive strength using Response Surface Methodology (RSM). The results showed that the produced briquettes had an optimum heating value of 30,670 kJ/kg, while their loaded charcoal particles resulted from the mesh sieve of 80, in which there was a charcoal loading of 53 g and it pressed at 93.1821 bar, whereas, the compressive strength value of the briquette was 100,608 kg/cm

^{2}, which loaded charcoal particles from the mesh sieve of 100, the charcoal-adhesive ratio of 53:47 (wt) and the pressure of 93.1821 bar.

## 1. Introduction

^{2}/day of solar power, 3–6 m/s of wind power, and 161.5 million SBM of biofuels [21]. However, those renewable energy resources are not exploited optimally because this requires high technological skills and investigation. On the other hand, biofuel has been an attractive resource as a renewable, green, and economical energy source to maintain energy sustainability in Indonesia. For this purpose, the Indonesian government policy through Presidential Instruction No. 1 of 2006 accompanied by the Minister of Energy and Mineral Resources Regulation No. 25 of 2013 has been revealed to trigger the national concern on biofuel ISO. The regulation has been an obligation to use biofuel sources produced from biomass as an alternative fuel for maintaining domestic energy needs [22]. This means that the utilization of biofuel derived from biomass needs to be increased so that it can comply with national needs and support the government programs in realizing sustainable development for providing renewable resources for Indonesian people [22,23].

^{k}factorial with n

_{F}factorial runs, 2

^{k}axial runs, and n

_{c}center runs. Figure 1 describes CCD for k = 3 factors so it has 8 factorial runs, 6 axial runs, and 6 center runs. In fact, there is another design for fitting response surfaces, the Box–Bhenken Designs. These designs are formed by combining 2

^{k}factorials with incomplete block designs. The result of the designs is very efficient in the number of runs.

## 2. Materials and Methods

## 3. Experiment

^{2}and a pressure time of 10 s [42]. The tools were made by the Energy Conversion Laboratory at Universitas Riau. The obtained briquettes were dried naturally under the sun’s light exposure for 5 h. Finally, the briquette product was tested for heating value by using a bomb calorimeter and compressive strength using a Universal Testing Machine (A&D Company, Tensilon RTF-2430, Capacity 30 KN, Tokyo, Japan).

## 4. Central Composite Design (CCD)

^{k}= 2

^{3}= 8 points), six axial or star points, and six center points. The two level was represented by 2

^{k}(one minimum level and one maximum level) which was powered k, where k was the number of factors, the other words were (−1,−1,−1), (−1,−1,1), (−1,1,−1), (−1,1,1), (1,−1,−1), (1,−1,1), (1,1,−1), and (1,1,1). Six axial points consisted of (−α,0,0), (+α,0,0), (0,−α,0), (0,α,0), (0,0,−α), and (0,0,+α). Six center points were six (0, 0, 0) points. The value of an alpha (α) for this CCD was fixed at 1.68. The value was from $\mathsf{\alpha}={\left({n}_{F}\right)}^{1/4}$, where ${n}_{F}$ was the number of cube points [41]. The combination of the cube points, the axial points, and center points are shown in Figure 1.

_{0}+ β

_{1}X

_{1}+ β

_{2}X

_{2}+ β

_{3}X

_{3}+ β

_{11}X

_{1}

^{2}+ β

_{22}X

_{2}

^{2}+ β

_{33}X

_{3}

^{2}+ β

_{12}X

_{1}X

_{2}+ β

_{13}X

_{1}X

_{3}+ β

_{23}X

_{2}X

_{3}

_{i}and X

_{j}represent the variables in code, b

_{0}is the offset term, b

_{j}is the linear effect, b

_{ij}is the first-order interaction effect, and b

_{jj}is the squared effect.

## 5. Results and Discussion

#### 5.1. Raw Material and Product Characterization

_{2}and X

_{3}can be calculated in the same way.

_{f}was the degree of freedom. The F

_{0}value for each response to the heating value can be seen in Table 4.

^{2}then the heating value is 25,205 kJ/kg, see equation below. The heating value is not a maximum point.

^{2}then the compressive strength is 5.633 kg/cm

^{2}, see equation below.

^{2}) of the heating value was 90.5%, which means that the model could explain heating value accurately because it was near 100%. For compressive strength, the main effects of A, B, and C, and the interaction effect of AB were significant (Table 5, Figure 6 and Figure 7). The R

^{2}of compressive strength was 87.6%, which means that the compressive strength could be largely explained by A, B, and C through the model. The Mean Absolute Percentage Errors (MAPEs) of the heating value and compressive strength were 1.681% and 27.575%, respectively, and the Root Mean Square Errors (RMSEs) were 708.304 and 0.836, respectively.

#### 5.2. Heating Value Analysis

^{2}, while the lowest heating value of 21,968.2 kJ/kg was obtained under conditions of an adhesive composition of 80:20 palm oil charcoal and a pressing pressure of 100 kg/cm

^{2}. At 80 mesh particle size, the highest heating value of 28,089.6 kJ/kg was found at an adhesive composition of palm stem charcoal 53:47 and a pressing pressure of 110 kg/cm

^{2}, and the lowest heating value of 22,445.7 kJ/kg was obtained in the adhesive composition against palm stem charcoal 87:13 and the pressing pressure of 110 kg/cm

^{2}. Likewise, with the particle size of 100 mesh, the highest heating value of 27,630.7 kJ/kg was obtained in the composition of the adhesive against charcoal palm 60:40 and the pressing pressure of 100 kg/cm

^{2}, while the lowest heating value of 22,889.2 kJ/kg was obtained at an adhesive composition of 80:20 and a pressing pressure of 100 kJ/cm

^{2}. Figure 5 shows that the changing particle size gave different heating values under the same pressing pressure conditions and adhesive composition.

#### 5.3. Compressive Strength Analysis

^{2}, the highest compressive strength of 4.929 kg/cm

^{2}was obtained under the conditions of the adhesive composition of 60:40 palm oil charcoal and 100 mesh particle size, while the lowest compressive strength of 0.86 kg/cm

^{2}was obtained under the adhesive composition conditions against charcoal stem 60:40 and 60 mesh particle size (Figure 8). At the pressing pressure of 110 kg/cm

^{2}, the highest compressive strength of 5346 kg/cm

^{2}was found in the composition of the adhesive against palm oil charcoal 70:30 and the particle size of 120 mesh, and the lowest compressive strength of 1.202 kg/cm

^{2}was found in the composition of the adhesive against the oil palm charcoal 70:30 and 50 mesh particle size. Likewise, with the pressing pressure of 120 kg/cm

^{2}, the highest compressive strength of 7526 kg/cm

^{2}was found in the composition of the adhesive against palm bar charcoal 60:40 and 100 mesh particle size, while the lowest compressive strength of 1010 kg/cm

^{2}was found in the composition of the adhesive against the charcoal palm stem 60:40 and 60 mesh particle size.

^{2}was obtained under 60 mesh particle size conditions and pressing pressures of 100 kg/cm

^{2}, while the lowest compressive strength of 1302 kg/cm

^{2}was obtained under 100 mesh particle size conditions and pressing pressures of 100 kg/cm

^{2}. In the composition of the adhesive against palm oil charcoal 70:30, the highest compressive strength of 5.346 kg/cm

^{2}was obtained under 120 mesh particle size conditions and a pressing pressure of 110 kg/cm

^{2}and the lowest compressive strength at 1.202 kg/cm

^{2}under 50 mesh particle size conditions and a pressure pressing of 110 kg/cm

^{2}. Likewise, for the adhesive composition of palm bar charcoal 60:40, the highest compressive strength of 7526 kg/cm

^{2}was obtained under 100 mesh particle size conditions and a pressing pressure of 120 kg/cm

^{2}, while the lowest compressive strength of 0.86 kg/cm

^{2}was found under 60 mesh particle size conditions and 100 kg/cm

^{2}pressing pressure. Figure 9 shows that the composition of the changing matrix gave a different compressive strength under the same conditions of particle size and pressing pressure.

^{2}was obtained under the conditions of the adhesive composition against palm oil charcoal 80:20 and a pressing pressure of 120 kg/cm

^{2}, while the lowest compressive strength of 0.86 kg/cm

^{2}was obtained under the condition of the adhesive composition against oil palm charcoal 60:40 and the pressing pressure 100 kg/cm

^{2}. At 80 mesh particle size, the highest compressive strength of 4871 kg/cm

^{2}was found in the composition of the adhesive against palm oil charcoal 70:30 and the pressing pressure of 126 kg/cm

^{2}, and the lowest compressive strength of 1205 kg/cm

^{2}was found in the composition of the adhesive against palm oil charcoal 70:30 and the pressing pressure of 93 kg/cm

^{2}. Likewise, with the particle size of 100 mesh, the highest compressive strength of 7526 kg/cm

^{2}was found in the composition of the adhesive against palm bar charcoal 60:40 and the pressing pressure of 120 kg/cm

^{2}, while the lowest compressive strength of 1302 kg/cm

^{2}was found in the composition of the adhesive against charcoal palm stems 80:20 and 100 kg/cm

^{2}pressing pressure. Figure 10 shows that the change in particle size gave a different heating value under conditions of the same pressing pressure and adhesive composition.

^{2}. The optimal compressive strength was 10.0608 kg/cm

^{2}which was obtained by particle size 120 mesh, adhesive composition 46.8179% wt, and pressure pressing 93.1821 kg/cm

^{2}. Besides Figure 11, the optimal heating value can be also seen in the model of Equation (5):

#### 5.4. Briquette Density

^{3}.

## 6. Conclusions

^{2}resulted while using charcoal from the sieving process using a sieve of 100 mesh, the matrix composition 53:47 wt, and the pressure of 93.1821 bar. Whereas the lowest compressive strength of 0.86 kg/cm

^{2}resulted from using charcoal particles produced with a metal mesh of 60, a matrix composition of 60:40 wt, and a pressure of 100 bar.

## Author Contributions

## Funding

## Conflicts of Interest

## References

- Dewan Energi Nasional. Buku Ketahanan Energi Nasional; Dewan Energi Nasional: Jakarta, Indonesia, 2014. [Google Scholar]
- Kurniawan, R.; Managi, S. Coal consumption, urbanization, and trade openness linkage in Indonesia. Energy Policy
**2018**, 121, 576–583. [Google Scholar] [CrossRef] - Idroes, R.; Yusuf, M.; Alatas, M.; Subhan; Lala, A.; Saiful; Suhendra, R.; Idroes, G.M. Marwan Geochemistry of hot springs in the Ie Seu’um hydrothermal areas at Aceh Besar district, Indonesia. IOP Conf. Ser. Mater. Sci. Eng.
**2018**, 334, 012002. [Google Scholar] [CrossRef] - Marwan; Syukri, M.; Idroes, R.; Ismail, N. Deep and Shallow Structures of Geothermal Seulawah Agam Based on Electromagnetic and Magnetic Data. Int. J. GEOMATE
**2019**, 16, 141–147. [Google Scholar] [CrossRef] - Idroes, R.; Yusuf, M.; Alatas, M.; Subhan; Lala, A.; Muslem; Suhendra, R.; Idroes, G.M.; Suhendrayatna; Marwan; et al. Geochemistry of warm springs in the Ie Brôuk hydrothermal areas at Aceh Besar district. IOP Conf. Ser. Mater. Sci. Eng.
**2019**, 523, 012010. [Google Scholar] [CrossRef] - Putri, D.R.; Nanda, M.; Rizal, S.; Idroes, R.; Ismail, N. Interpretation of gravity satellite data to delineate structural features connected to geothermal resources at Bur Ni Geureudong geothermal field. IOP Conf. Ser. Earth Environ. Sci.
**2019**, 364, 012003. [Google Scholar] [CrossRef] [Green Version] - Idroes, R.; Yusuf, M.; Alatas, M.; Subhan; Lala, A.; Muhammad; Suhendra, R.; Idroes, G.M. Marwan Geochemistry of Sulphate spring in the Ie Jue geothermal areas at Aceh Besar district, Indonesia. IOP Conf. Ser. Mater. Sci. Eng.
**2019**, 523, 012012. [Google Scholar] [CrossRef] - Marwan; Yanis, M.; Idroes, R.; Ismail, N. 2D inversion and static shift of MT and TEM data for imaging the geothermal resources of Seulawah Agam Volcano, Indonesia. Int. J. GEOMATE
**2019**, 17, 173–180. [Google Scholar] [CrossRef] - Idroes, R.; Yusuf, M.; Saiful, S.; Alatas, M.; Subhan, S.; Lala, A.; Muslem, M.; Suhendra, R.; Idroes, G.M.; Marwan, M.; et al. Geochemistry Exploration and Geothermometry Application in the North Zone of Seulawah Agam, Aceh Besar District, Indonesia. Energies
**2019**, 12, 4442. [Google Scholar] [CrossRef] [Green Version] - Erinofiardi; Gokhale, P.; Date, A.; Akbarzadeh, A.; Bismantolo, P.; Suryono, A.F.; Mainil, A.K.; Nuramal, A. A Review on Micro Hydropower in Indonesia. Energy Procedia
**2017**, 110, 316–321. [Google Scholar] [CrossRef] - Biddinika, M.K.; Indrawan, B.; Yoshikawa, K.; Tokimatsu, K.; Takahashi, F. Renewable Energy on the Internet: The Readability of Indonesian Biomass Websites. Energy Procedia
**2014**, 61, 1376–1379. [Google Scholar] [CrossRef] [Green Version] - Silitonga, A.S.; Masjuki, H.H.; Mahlia, T.M.I.; Ong, H.C.; Chong, W.T.; Boosroh, M.H. Overview properties of biodiesel diesel blends from edible and non-edible feedstock. Renew. Sustain. Energy Rev.
**2013**, 22, 346–360. [Google Scholar] [CrossRef] - Goh, B.H.H.; Ong, H.C.; Cheah, M.Y.; Chen, W.-H.; Yu, K.L.; Mahlia, T.M.I. Sustainability of direct biodiesel synthesis from microalgae biomass: A critical review. Renew. Sustain. Energy Rev.
**2019**, 107, 59–74. [Google Scholar] [CrossRef] - Handayani, N.A.; Ariyanti, D. Potency of Solar Energy Applications in Indonesia. Int. J. Renew. Energy Dev.
**2012**, 1, 33. [Google Scholar] [CrossRef] [Green Version] - Ismail, M.S.; Moghavvemi, M.; Mahlia, T.M.I. Characterization of PV panel and global optimization of its model parameters using genetic algorithm. Energy Convers. Manag.
**2013**, 73, 10–25. [Google Scholar] [CrossRef] - Ismail, M.S.; Moghavvemi, M.; Mahlia, T.M.I. Techno-economic analysis of an optimized photovoltaic and diesel generator hybrid power system for remote houses in a tropical climate. Energy Convers. Manag.
**2013**, 69, 163–173. [Google Scholar] [CrossRef] - Mahlia, T.M.I.; Syazmi, Z.A.H.S.; Mofijur, M.; Abas, A.E.P.; Bilad, M.R.; Ong, H.C.; Silitonga, A.S. Patent landscape review on biodiesel production: Technology updates. Renew. Sustain. Energy Rev.
**2020**, 118, 109526. [Google Scholar] [CrossRef] - Ong, H.C.; Masjuki, H.H.; Mahlia, T.M.I.; Silitonga, A.S.; Chong, W.T.; Yusaf, T. Engine performance and emissions using Jatropha curcas, Ceiba pentandra and Calophyllum inophyllum biodiesel in a CI diesel engine. Energy
**2014**, 69, 427–445. [Google Scholar] [CrossRef] - Ong, H.C.; Milano, J.; Silitonga, A.S.; Hassan, M.H.; Shamsuddin, A.H.; Wang, C.-T.; Indra Mahlia, T.M.; Siswantoro, J.; Kusumo, F.; Sutrisno, J. Biodiesel production from Calophyllum inophyllum-Ceiba pentandra oil mixture: Optimization and characterization. J. Clean. Prod.
**2019**, 219, 183–198. [Google Scholar] [CrossRef] - Martosaputro, S.; Murti, N. Blowing the Wind Energy in Indonesia. Energy Procedia
**2014**, 47, 273–282. [Google Scholar] [CrossRef] [Green Version] - Dirjen Energi Baru dan Terbarukan dan Konservasi Energi Kementrian ESDM. Statistika EBTKE; EBTKE: Jakarta, Indonesia, 2015. [Google Scholar]
- Silitonga, A.S.; Atabani, A.E.; Mahlia, T.M.I.; Masjuki, H.H.; Badruddin, I.A.; Mekhilef, S. A review on prospect of Jatropha curcas for biodiesel in Indonesia. Renew. Sustain. Energy Rev.
**2011**, 15, 3733–3756. [Google Scholar] [CrossRef] - Hedwig, R.; Lahna, K.; Idroes, R.; Karnadi, I.; Tanra, I.; Iqbal, J.; Kwaria, D.; Kurniawan, D.P.; Kurniawan, K.H.; Tjia, M.O.; et al. Food analysis employing high energy nanosecond laser and low pressure He ambient gas. Microchem. J.
**2019**, 147, 356–364. [Google Scholar] [CrossRef] - Ghaffar, S.H.; Fan, M. Structural analysis for lignin characteristics in biomass straw. Biomass Bioenergy
**2013**, 57, 264–279. [Google Scholar] [CrossRef] - Mohamad Haafiz, M.K.; Eichhorn, S.J.; Hassan, A.; Jawaid, M. Isolation and characterization of microcrystalline cellulose from oil palm biomass residue. Carbohydr. Polym.
**2013**, 93, 628–634. [Google Scholar] [CrossRef] - Hasanah, U.; Setyowati, M.; Edwarsyah; Efendi, R.; Safitri, E.; Idroes, R.; Heng, L.Y.; Sani, N.D. Isolation of Pectin from coffee pulp Arabica Gayo for the development of matrices membrane. IOP Conf. Ser. Mater. Sci. Eng.
**2019**, 523, 12014. [Google Scholar] [CrossRef] - Hasanah, U.; Sani, N.D.M.; Heng, L.Y.; Idroes, R.; Safitri, E. Construction of a Hydrogel Pectin-Based Triglyceride Optical Biosensor with Immobilized Lipase Enzymes. Biosensors
**2019**, 9, 135. [Google Scholar] [CrossRef] [Green Version] - Hasanah, U.; Setyowati, M.; Efendi, R.; Muslem, M.; Md Sani, N.D.; Safitri, E.; Yook Heng, L.; Idroes, R. Preparation and Characterization of a Pectin Membrane-Based Optical pH Sensor for Fish Freshness Monitoring. Biosensors
**2019**, 9, 60. [Google Scholar] [CrossRef] [Green Version] - Silitonga, A.S.; Shamsuddin, A.H.; Mahlia, T.M.I.; Milano, J.; Kusumo, F.; Siswantoro, J.; Dharma, S.; Sebayang, A.H.; Masjuki, H.H.; Ong, H.C. Biodiesel synthesis from Ceiba pentandra oil by microwave irradiation-assisted transesterification: ELM modeling and optimization. Renew. Energy
**2020**, 146, 1278–1291. [Google Scholar] [CrossRef] - Silitonga, A.S.; Masjuki, H.H.; Ong, H.C.; Sebayang, A.H.; Dharma, S.; Kusumo, F.; Siswantoro, J.; Milano, J.; Daud, K.; Mahlia, T.M.I.; et al. Evaluation of the engine performance and exhaust emissions of biodiesel-bioethanol-diesel blends using kernel-based extreme learning machine. Energy
**2018**, 159, 1075–1087. [Google Scholar] [CrossRef] - Direktorat Jenderal Perkebunan. Statistika Perkebunan Indonesia Komoditas Kelapa Sawit 2013–2015; Direktorat Jenderal Perkebunan: Jakarta, Indonesia, 2014. [Google Scholar]
- Wardani, L.; Massijaya, M.Y.; Machdie, M.F. Pemanfaatan Limbah Pelepah Sawit dan Plastik Daur Ulang (RPP) sebagai Papam Komposit Plastik. J. Hutan Trop.
**2013**, 01, 46–53. [Google Scholar] - Tumuluru, J.S.; Wright, C.T.; Hess, J.R.; Kenney, K.L. A review of biomass densification systems to develop uniform feedstock commodities for bioenergy application. Biofuels Bioprod. Biorefining
**2011**, 5, 683–707. [Google Scholar] [CrossRef] - Parthasarathy, P.; Narayanan, K.S. Hydrogen production from steam gasification of biomass: Influence of process parameters on hydrogen yield–A review. Renew. Energy
**2014**, 66, 570–579. [Google Scholar] [CrossRef] - Muslem, M.; Kuncaka, A.; Himah, T.N.; Roto, R. Preparation of Char-Fe
_{3}O_{4}Composites from Polyvinyl Chloride with Hydrothermal and Hydrothermal-Pyrolysis Carbonization Methods as Co(II) Adsorbents. Indones. J. Chem.**2019**, 19, 835. [Google Scholar] [CrossRef] - Asavatesanupap, C.; Santikunaporn, M. A Feasibility Study on Production of Solid Fuel from Glycerol and Agricultural Wastes. Int. Trans. J. Eng. Manag. Appl. Sci. Technol.
**2012**, 01, 43–51. [Google Scholar] - Umam, M.C. Optimasi Penambahan Limbah Gliserol Hasil Samping Transesterifikasi Minyak Jarak Pagar Dan Perekat Tapioka Pada Pembuatan Biomass Pellets Bungkil Jarak Pagar (Jatropha curcas L.); Institut Pertanian Bogor: Bogor, Indonesia, 2007. [Google Scholar]
- Susanty, W.; Helwani, Z. Zulfansyah Torrefaction of oil palm frond: The effect of process condition to calorific value and proximate analysis. IOP Conf. Ser. Mater. Sci. Eng.
**2018**, 345, 012016. [Google Scholar] [CrossRef] [Green Version] - Susanty, W.; Helwani, Z.; Bahruddin, B. Optimization of the Condition of Palm Frond Torrefaction Process by Utilizing Liquid Torrefaction Product as Pre-treatment for Improve Product Quality. J. Rekayasa Kim. Lingkung.
**2019**, 14, 12–18. [Google Scholar] [CrossRef] - Helwani, Z.; Zulfansyah; Fatra, W.; Fernando, A.Q.; Idroes, G.M.; Muslem; Idroes, R. Torrefaction of Empty Fruit Bunches: Evaluation of Fuel Characteristics Using Response Surface Methodology. IOP Conf. Ser. Mater. Sci. Eng.
**2020**, 845, 012019. [Google Scholar] [CrossRef] - Montgomery, C.D. Design and Analysis of Experiments, 8th ed.; John Wiley & Sons, Inc.: New York, NY, USA, 2013. [Google Scholar]
- Helwani, Z.; Fatra, W.; Arifin, L.; Othman, M.R. Syapsan Effect of process variables on the calorific value and compressive strength of the briquettes made from high moisture Empty Fruit Bunches (EFB). IOP Conf. Ser. Mater. Sci. Eng.
**2018**, 345, 012020. [Google Scholar] [CrossRef] [Green Version] - Sinaga, S. Identifikasi Sifat Fisis dan Kimia Briket Arang Dari Sabut Kelapa; Institut Pertanian Bogor: Bogor, Indonesia, 2008. [Google Scholar]
- Surono, U.B. Peningkatan Kualitas Pembakaran Biomassa Limbah Jagung sebagai Bahan Bakar Alternatif dengan Karbonisasi dan Pembriketan. J. Rekayasa Proses
**2010**, 4, 13–18. [Google Scholar] - Ilham, M.A.; Helwani, Z.; Fatra, W. Proses Densifikasi Produk Karbonisasi Pelepah Sawit menjadi Briket Menggunakan Gliserol Produk Samping Biodiesel sebagai Filler. J. Online Mhs. Fak. Tek. Univ. Riau
**2016**, 3, 1–4. [Google Scholar] - Thompson, J.C.; He, B.B. Characterization of Crude Glycerol from Biodiesel Production from Multiple Feedstocks. Appl. Eng. Agric.
**2006**, 22, 261–265. [Google Scholar] [CrossRef] - Ali, A.; Fortuna, A.D.; Restuhadi, F. Kajian Pemanfaatan Biomassa Limbah Industri Minyak Picung (Pangium Edule Reinw) Untuk Biobriket Sumber Energi Alternatif Di Desa Pulau Picung. J. Sagu
**2013**, 11. [Google Scholar] - Martynis, M.; Sundari, E.; Sari, E. Pembuatan Biobriket dari Limbah Cangkang Kakao. J. Litbang Ind.
**2012**, 2, 35. [Google Scholar] [CrossRef] [Green Version] - Subroto, H. Sartono Pengaruh Variasi Tekanan Pengepresan Terhadap Karakteristik Mekanik dan Karakteristik Pembakaran Briket Kokas Lokal. J. Tek. Gelagar Univ. Sebel. Maret Surak.
**2007**, 18, 73–79. [Google Scholar] - Sudiro, R.; Subroto, S. Karakteristik Briket Campuran Arang Kayu dan Jerami. J. Sainstech Politek. Indonusa Surak.
**2008**, 2355–5009. [Google Scholar]

**Figure 1.**CCD Model of Bricket Material Prepared from Palm Stem Biomass (Modified from [41]).

**Figure 5.**Graphic and contour of surface response of the adhesive composition and pressing pressure effect on the heating value of particle size (

**a**) 60 (

**b**) 80, and (

**c**) 100 mesh.

**Figure 8.**Graph and contour of surface response influences the adhesive composition and particle size to compressive strength at the pressing pressure (

**a**) 100 (

**b**) 110, and (

**c**) 120 kg/cm

^{2}

**Figure 9.**Graph and contour of the surface response of the effect of particle size and pressing pressure on the compressive strength and the adhesive composition (

**a**) 80:20 (

**b**) 70:30, and (

**c**) 60:40.

**Figure 10.**Graph and contour of the surface response of the effect of the adhesive composition and pressing pressure on compressive strength on particle size (

**a**) 60 (

**b**) 80, and (

**c**) 100 mesh.

Variable | Coding | Unit | Levels | ||||
---|---|---|---|---|---|---|---|

−α | −1 | 0 | 1 | α | |||

Particle size | X_{1} | mesh | 46.4 | 60 | 80 | 100 | 113.6 |

Adhesive composition | X_{2} | %wt | 13.2 | 20 | 30 | 40 | 46.8 |

Pressure pressing | X_{3} | Kg/cm^{2} | 93.2 | 100 | 110 | 120 | 126.8 |

No. | Characteristic | Unit | Palm Stem | Palm Stem Charcoal | Palm Stem Briquettes |
---|---|---|---|---|---|

1 | Heating Value | kJ/kg | 18,123.615 | 21,699.59 | 21,968.2–28,089.6 |

2 | Water Content | %-b | 9.10 | 5.03 | 5.5 |

3 | Volatile Matter Content | %-b | 76.9 | 22.19 | 19.73 |

4 | Ash Content | %-b | 2 | 0.74 | 0,.45 |

5 | Carbon bound Content | %-b | 12 | 69 | 71.4 |

6 | Compressive Strength | kg/cm^{2} | - | - | 0.86–7.526 |

7 | Density | gr/cm^{3} | - | - | 0.72–1.06 |

**Table 3.**Summary of various research responses to the heating value (

**Y1**) and compressive strength (

**Y2**).

Std | Run | Natural Variable | Coded Variable | Response | |||||
---|---|---|---|---|---|---|---|---|---|

ξ_{1} | ξ_{2} | ξ_{3} | X_{1} | X_{2} | X_{3} | Y1 | Y2 | ||

1 | 15 | 60 | 20 | 100 | −1 | −1 | −1 | 21,968.2 | 1.611 |

2 | 3 | 100 | 20 | 100 | 1 | −1 | −1 | 22,889.3 | 1.302 |

3 | 1 | 60 | 40 | 100 | −1 | 1 | −1 | 25,238.4 | 0.86 |

4 | 8 | 100 | 40 | 100 | 1 | 1 | −1 | 27,630.7 | 4.929 |

5 | 4 | 60 | 20 | 120 | −1 | −1 | 1 | 25,193.5 | 3.818 |

6 | 18 | 100 | 20 | 120 | 1 | −1 | 1 | 25,038.7 | 1.530 |

7 | 19 | 60 | 40 | 120 | −1 | 1 | 1 | 27,352.7 | 1.010 |

8 | 6 | 100 | 40 | 120 | 1 | 1 | 1 | 25,009.5 | 7.526 |

9 | 20 | 46.4 | 30 | 110 | −1.68 | 0 | 0 | 25,093.5 | 1.202 |

10 | 9 | 113.6 | 30 | 110 | 1.68 | 0 | 0 | 25,193.5 | 5.346 |

11 | 13 | 80 | 13.2 | 110 | 0 | −1.68 | 0 | 22,445.7 | 1.756 |

12 | 11 | 80 | 46.8 | 110 | 0 | 1.68 | 0 | 28,089.6 | 2.377 |

13 | 7 | 80 | 30 | 93.2 | 0 | 0 | −1.68 | 22,934.1 | 1.205 |

14 | 17 | 80 | 30 | 126.8 | 0 | 0 | 1.68 | 27,352.7 | 4.871 |

15 | 10 | 80 | 30 | 110 | 0 | 0 | 0 | 24,245.6 | 2.149 |

16 | 5 | 80 | 30 | 110 | 0 | 0 | 0 | 25,326.4 | 2.319 |

17 | 16 | 80 | 30 | 110 | 0 | 0 | 0 | 24,834.9 | 2.916 |

18 | 12 | 80 | 30 | 110 | 0 | 0 | 0 | 24,794.9 | 2.856 |

19 | 2 | 80 | 30 | 110 | 0 | 0 | 0 | 25,326.4 | 3.230 |

20 | 14 | 80 | 30 | 110 | 0 | 0 | 0 | 25,148.7 | 2.040 |

Response | Source of Variance | DF | SS | MS | F-Value | p-Value |
---|---|---|---|---|---|---|

Heating Value | Regression | 9 | 47,878,095 | 5,319,788 | 10.60 | 0.000 ** |

Error | 10 | 5,016,949 | 501,695 | |||

Lack of Fit | 5 | 4,160,719 | 832,144 | 4.86 | 0.054 | |

Pure Error | 5 | 856,230 | 171,246 | |||

Total | 19 | 52,895,044 | ||||

Compressive Strength | Regression | 9 | 49.5564 | 5.5063 | 7.87 | 0.002 ** |

Error | 10 | 6.9958 | 0.6996 | |||

Lack of Fit | 5 | 5.8389 | 1.1678 | 5.05 | 0.050 | |

Pure Error | 5 | 1.1569 | 0.2314 | |||

Total | 19 | 56.5522 |

Source | p-Value of Heating Value | p-Value of Compressive Strength |
---|---|---|

Constant | 0.000 * | 0.000 * |

A—Particle Size | 0.671 | 0.002 * |

B—adhesive composition | 0.000 * | 0.031 * |

C—Pressure Pressing | 0.001 * | 0.006 * |

A^{2} | 0.932 | 0.354 |

B^{2} | 0.693 | 0.547 |

C^{2} | 0.868 | 0.373 |

AB | 0.801 | 0.000 * |

AC | 0.013 * | 0.641 |

BC | 0.018 * | 0.883 |

R^{2} | 0.905 | 0.876 |

MAPE | 1.681 | 27.575 |

RMSE | 708.304 | 0.836 |

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Helwani, Z.; Ramli, M.; Rusyana, A.; Marlina, M.; Fatra, W.; Idroes, G.M.; Suhendra, R.; Ashwie, V.; Mahlia, T.M.I.; Idroes, R.
Alternative Briquette Material Made from Palm Stem Biomass Mediated by Glycerol Crude of Biodiesel Byproducts as a Natural Adhesive. *Processes* **2020**, *8*, 777.
https://doi.org/10.3390/pr8070777

**AMA Style**

Helwani Z, Ramli M, Rusyana A, Marlina M, Fatra W, Idroes GM, Suhendra R, Ashwie V, Mahlia TMI, Idroes R.
Alternative Briquette Material Made from Palm Stem Biomass Mediated by Glycerol Crude of Biodiesel Byproducts as a Natural Adhesive. *Processes*. 2020; 8(7):777.
https://doi.org/10.3390/pr8070777

**Chicago/Turabian Style**

Helwani, Zuchra, Muliadi Ramli, Asep Rusyana, Marlina Marlina, Warman Fatra, Ghazi Mauer Idroes, Rivansyah Suhendra, Viqha Ashwie, Teuku Meurah Indra Mahlia, and Rinaldi Idroes.
2020. "Alternative Briquette Material Made from Palm Stem Biomass Mediated by Glycerol Crude of Biodiesel Byproducts as a Natural Adhesive" *Processes* 8, no. 7: 777.
https://doi.org/10.3390/pr8070777