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Life cycle assessment (LCA) refuse derived fuel (RDF) waste in pusat inovasi agro teknologi (PIAT) Universitas Gadjah Mada as alternative waste management for energy Titi Tiara Anasstasia; Muhammad Mufti Azis; Imam Haryanto; Rio Arya Pratama
Indonesian Journal of Life Cycle Assessment and Sustainability Vol 2, No 1 (2018)
Publisher : Indonesian Life Cycle Assessment Network (ILCAN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (318.25 KB) | DOI: 10.52394/ijolcas.v2i1.71

Abstract

Pusat Inovasi Agroteknologi (PIAT) handles institutional waste generated from Universitas Gadjah Mada (UGM). Waste from UGM is called Institutional Solid Waste (ISW) reaches 1,427.27 kg / week. In this study, Life Cycle Assessment (LCA) analysis was used as a tool to calculate and evaluate the environmental impact of potential ISW conversion to densified Refused Derived Fuel (dRDF) with gate to gate framework system. For simulation, OpenLCA software equipped with Ecoinvent database was used in this work. The results showed that conversion of combustible inorganic waste into densified Refuse Derived Fuel (dRDF) along with conversion of organic waste into compost gave following environmental impacts: global warming potential of 1.3E+00 kg CO2 eq, acidification 3.9E-03kg SO4 eq., eutrophication 7.1E-01 kg P eq., human toxicity 1.2E+00 kg 1.4-dichlorobenzene and terrestrial ecotoxicity 6.1E-02 kg 1.4-dichlorobenzene. By separating combustible from non-combustible inorganic waste may significantly improve the quality of dRDF as well as the quantity of compost. The substitution of coal using dRDF combined with the selling of compost is a feasible option. In addition, our results also showed that installation of exhaust gas emission control could further reduce the environmental impact of dRDF production. An economic evaluation was also conducted to evaluate the scenario of converting ISW into dRDF and compost. This option appeared to be profitable, provided that no restrictions to the processed waste, steady flow of dRDF product to the end-users, and the presence of standard price for dRDF.
Life Cycle Assessment (LCA) of Refused Derived Fuel and Biogas as Products as Option of Sleman Regency Municipal Solid Waste Management Muhammad Abdul Ghony; Muhammad Mufti Azis; Titi Tiara Anasstasia
Indonesian Journal of Life Cycle Assessment and Sustainability In Press
Publisher : Indonesian Life Cycle Assessment Network (ILCAN)

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Sustainable municipal waste management is a big challenge for cities in Indonesia such as Sleman Regency, in D.I.Yogyakarta. Waste to Energy (WtE) is one of the methods in municipal waste management. Energy recovery from municipal waste is expected to produce electricity and/or thermal energy and thereby may reduce the amount of waste transferred to landfills. This study aims to evaluate the environmental impact of two energy recovery scenarios of municipal solid waste management in Sleman Regency. Here, we investigated 3 option for MSW management: direct combustion of once sorted waste to produce energy (O-1) , an integrated combustion of inorganic waste through the formation of densified Refuse Derived Fuel (RDF) followed by energy production (O-2) and scenario which are including dRDF and biogas followed by energy production (O-3). The environmental impacts from both scenarios were computed with Life Cycle Assessment (LCA) simulation by using OpenLCA software. The impact assessment include global warming potential (GWP), acidification potential (AP), eutrophication potential (EP) and human toxicity potential (HTP). The LCA simulation results showed that the GWP value of O-1, O-2 and O-3 are 0,6741 kg CO2eq / kWh, 0. 65863 kg CO2eq / kWh, and 0,574 kg CO2eq/kWh respectively. The AP, EP and HTP values for O-3 are consistently lower than that of O-2 and O-3. Thus, the LCA simulation results showed that MSW conversion into dRDF and biogas as a part of WtE technology is more environmentally friendly than direct combustion of MSW to energy.
Pemodelan Dinamika Awal Adsorpsi Na2S dalam Kolom Bahan Isian Biji Salak (Salacca Zalacca) Irma Atika Sari; Muhammad Mufti Azis; Siti Syamsiah; Sutijan Sutijan
Jurnal Rekayasa Proses Vol 9, No 1 (2015)
Publisher : Departemen Teknik Kimia Fakultas Teknik Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jrekpros.24523

Abstract

Biofiltration is a promising method for gas purification due to its efficiency and low operating cost. One way to utilize biofiltration is in biogas purification where H2S is removed from the biogas product. The presence of H2S may cause severe corrosion in biogas processing facilities. By the use of biofilter, H2S is dissolved and adsorbed on packing material. This study investigated the adsorption process that occured during the beginning of biofilter operation. Na2S has been used as a model compound for H2S with packing material from snake fruit seeds. In this study, we have investigated the influence of liquid flowrate and inlet concentration of Na2S solutions. Na2S solution was fed from the top part of the column and trickled down through the snake fruit seed bed. The dissolved sulfide left the column from the bottom part which was then collected in a sample bottle and analized periodically with UV-VIS spectrophotometer. A one dimensional mathematical model of the adsorption column with respect to z direction was proposed to describe the adsorption behavior. In addition, Freundlich isotherm was used to describe the solid-liquid adsorption equilibrium. The experimental results showed that low flowrates i.e. 1.59 and 2.97 mL/s gave larger adsorption capacities than higher flowrate i.e. 3.96 and 5.58 mL/s. In addition, the influence of inlet concentrations to the breakthrough characteristics were found to be negligible. The fitting results estimated the values of DL=1.3174.10-7 m2/s, α=1.002.10-4 and n=12.661. As a result, it could be concluded that the axial diffusion had small influence on the adsorption of Na2S solution. In addition, the small value of α as well as large value of n indicated that the adsorption capacity of snake fruit seeds was relatively small. Keywords : snake fruit seed, biofiltration, adsorption, adsorption equilibrium, Na2S, sulfide Biofiltrasi adalah teknologi yang menjanjikan dalam pemurnian gas karena efisiensi yang tinggi serta biaya operasi yang rendah. Salah satu pemanfaatan biofiltrasi yang cukup menjanjikan adalah pemurnian biogas dimana gas H2S dipisahkan dari produk biogas akhir. Keberadaan gas H2S pada biogas dapat menyebabkan korosi pada peralatan pemrosesan biogas. Dalam biofilter, H2S akan terlarut dan kemudian akan teradsorpsi pada bahan isian. Penelitian ini mempelajari proses adsorpsi yang terjadi di awal proses biofiltrasi terhadap sulfida terlarut. Disini, larutan Na2S telah digunakan sebagai komponen model H2S untuk dijerap dengan bahan isian biji salak. Variabel proses yang dipelajari adalah variasi laju alir cairan dan variasi konsentrasi input larutan Na2S. Larutan Na2S dilewatkan pada kolom biofiltrasi dari atas melewati bahan isian biji salak, kemudian sulfida terlarut yang keluar pada kolom bawah ditampung dalam botol sampel dan dianalisis pada berbagai waktu dengan menggunakan UV-VIS spektrofotometer. Pemodelan matematika proses adsorpsi telah disusun dengan model adsorpsi 1 dimensi ke arah z. Persamaan kesetimbangan yang digunakan menggunakan persamaan kesetimbangan Freundlich. Hasil percobaan menunjukkan bahwa dengan debit aliran yang kecil seperti 1,59 dan 2,97 mL/det didapatkan penjerapan yang lebih besar jika dibandingkan dengan debit aliran besar seperti 3,96 dan 5,58 mL/det. Sementara itu, pengaruh konsentrasi umpan terhadap karakteristik kurva breakthrough relatif kecil. Hasil fitting memberikan nilai DL=1,3174.10-7 m2/s, α=1,002.10-4 dan n=12,661. Dengan demikian, secara umum dapat disimpulkan bahwa difusi longitudinal pada kolom adsorpsi berperan kecil terhadap proses adsorpsi sulfida. Sedangkan nilai α yang kecil serta n yang besar pada persamaan Freundlich menunjukkan kapasitas penjerapan biji salak yang relatif kecil. Kata kunci: biji salak, biofiltrasi, adsorpsi, kesetimbangan adsorpsi, Na2S, sulfide
Mathematical Modelling and Simulation of Hydrotropic Delignification Indah Hartati; Wahyudi Budi Sediawan; Hary Sulistyo; Muhammad Mufti Azis; Moh Fahrurrozi
Jurnal Rekayasa Proses Vol 13, No 1 (2019)
Publisher : Departemen Teknik Kimia Fakultas Teknik Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (586.363 KB) | DOI: 10.22146/jrekpros.42364

Abstract

A B S T R A C TDelignification is a fundamental step in bio-refinery for lignocellulose feedstock processing. Hydrotropic delignification is considered as a promising alternative compared to other conventional delignification processes due to the use of mild chemicals. In this paper, a quantitative description of hydrotropic delignification for a cylindrical biomass particle is presented by using fundamental concepts of chemical kinetics and transport processes. The development of hydrotropic delignification model was based on following assumptions: i) lignin in the biomass is immobile, ii) delignification is considered as a simultaneous process which involves intra-particle diffusion of hydrotropic agent followed by second order reaction for lignin and hydrotropic chemical, as well as intra-particle product diffusion. Finite difference approximation was applied to solve the resulting partial and ordinary differential equations. The simulation results of the proposed model may describe the concentration profiles of lignin, hydrotropic agent and soluble product distributions in a cylindrical solid particle as a function of radial position and time. In addition, the model could also predict the concentration of hydrotropic agent and soluble product in the liquid phase as well as the yield and conversion as a function of time. A local sensitivity analysis method using one factor at a time (OFAT), has been applied to investigate the influence of particle size and hydrotropic agent concentration to the yield and conversion of the hydrotropic delignification model. Validation of the proposed model was conducted by comparing the numerical results with an analytical solution for a simple case diffusion in cylinder with constant surface concentration and in the absence of chemical reaction. The validation result showed that the hydrotropic delignification model was in good agreement with the analytical solution.Keywords: cylindrical particle; delignification; hydrotropic; modelling; simulation A B S T R A KDelignifikasi merupakan tahap penting dalam proses biorefineri biomassa berlignoselulosa. Delignifikasi hidrotropi adalah salah satu alternative proses yang memiliki beberapa kelebihan dibandingkan proses-proses delignifikasi konvensional karena tidak menggunakan bahan kimia berbahaya. Dalam artikel ini disajikan deskripsi kuantitatif proses delignifikasi hidrotropi untuk partikel berbentuk silinder dengan menggunakan konsep fundamental kinetika reaksi dan proses-proses perpindahan. Penyusunan model proses delignifikasi hidrotropi dilakukan berdasarkan asumsi-asumsi bahwa i) lignin pada biomassa bersifat immobile, ii) proses delignifikasi dipandang sebagai suatu rangkaian proses simultan yang terdiri atas proses difusi intrapartikel senyawa hidrotrop, reaksi order dua terhadap lignin dan senyawa hidrotrop, serta difusi intrapartikel produk delignifikasi. Finite difference approximation (FDA) digunakan untuk menyelesaikan persamaan simultan berbentuk persamaan diferensial ordiner dan persamaan diferensial parsial dalam tahap pemodelan. Hasil simulasi memberikan gambaran profil distribusi konsentrasi lignin, konsentrasi senyawa hidrotrop dan produk delignifikasi di dalam partikel padatan yang berbentuk silinder sebagai fungsi posisi dan waktu. Model yang dikembangkan juga dapat memprediksi konsentrasi senyawa hidrotropik dan produk di fasa cairan, serta yield dan konversi sebagai fungsi waktu.  Metode analisis sensitivitas lokal, yakni metode one factor at a time (OFAT), digunakan untuk mengkaji pengaruh ukuran partikel dan konsentrasi senyawa hidrotropik terhadap yield dan konversi proses delignifikasi. Validasi model yang diajukan dilakukan dengan membandingkan hasil analisa numerik dengan hasil penyelesaian analitis untuk kasus difusi pada silinder dengan konsentrasi permukaan yang konstan serta tidak melibatkan reaksi kimia. Hasil validasi model menunjukkan bahwa model delignifikasi hidrotropi yang diajukan memiliki kesesuaian yang tinggi dengan hasil penyelesaian analitis.Kata kunci: delignifikasi; hidrotropi; pemodelan; silinder; simulasi
Studi Penambahan Etilena Glikol dalam Menghambat Pembentukan Metana Hidrat pada Proses Pemurnian Gas Alam Muslikhin Hidayat; Danang Tri Hartanto; Muhammad Mufti Azis; Sutijan Sutijan
Jurnal Rekayasa Proses Vol 14, No 2 (2020)
Publisher : Departemen Teknik Kimia Fakultas Teknik Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jrekpros.59871

Abstract

The gas processing facilities are designed to significantly reduce the impurities such as water vapor, heavy hydrocarbon, carbon dioxide, carbonyl sulfide (COS), benzene-toluene-xylene (BTX), mercaptane, and the sulfur compounds. A small amount of those compounds in natural gas is not preferable since they disturb the next processes.  It was proposed to decrease natural gas's operating temperature to -20 ⁰F to remove the impurities from natural gas. The decrease of the natural gas's operating temperature has some consequences to the gas mixers such as hydrate formation at high pressure and low temperature, solidification of ethylene glycol (EG) solution, and the icing of the surface due to low temperature on the surface of chiller (three constraints). The Aspen Hysys 8.8 was used to obtain the suitable flowrate and concentration of the EG solution injected into the natural gas. Peng-Robinson's model was considered the most appropriate thermodynamic property model, and thus it has been applied for this research. The calculation results showed that the EG solution injection would reduce the hydrate formation due to water vapor absorption in the natural gas by EG. The EG solution's flowrate and concentration were varied from 20,000-2,000,000 lb/hr and 80-90 wt.%. When the separation was carried out at the operating temperature of -20 ⁰F, the EG solution's concentration fulfilling the requirement was of 80-84 wt.% with the flowrate of EG solution of 900,000 lb/hr and even more. This amount is not operable. More focused investigation was done for the variation of the operating temperature. Increasing operating temperature significantly reduced the flowrate of EG solution to about 200,000 lb/hr. An alternative process was proposed by focusing on two concentration cases of 80 and 85 % of weight at the low flow rate of EG solution, respectively. These simulations were intended to predict impurities' concentration in the effluent of Dew Point Control Unit (DPCU). The concentrations of BTX, heavy hydrocarbon, mercaptane, and COS flowing out of DPCU were 428.1 ppm, 378.4 ppm, 104 ppm, and 13.3 ppm, respectively. The concentrations of BTX and heavy hydrocarbon are greater than the minimum standard required. It is needed to install an absorber to absorb BTX and heavy hydrocarbon. However, the absorber capacity will be much smaller than if the temperature of natural gas is not decreased and not injected by the EG solution.Keywords: DPCU gas treatment; ethylene glycol solution; hydrate formation; simulationA B S T R A KUnit pengolahan gas dirancang untuk mengurangi sebagian besar senyawa pengotor seperti uap air, hidrokarbon berat, karbon dioksida, karbonil sulfida (COS), benzena-toluena-xilena (BTX), merkaptan, dan senyawa sulfur lainnya. Keberadaan senyawa tersebut dalam gas alam berbahaya karena mengganggu proses selanjutnya walaupun dalam jumlah sedikit. Untuk membersihkan gas alam dari senyawa pengotor, maka suhu operasi gas diturunkan menjadi -20 °F. Penurunan suhu operasi gas dapat menyebabkan pembentukan hidrat pada tekanan tinggi dan suhu rendah, pembekuan larutan etilena glikol (EG), dan pembentukan lapisan es pada permukaan chiller. Aspen Hysys 8.8 digunakan untuk memperkirakan berapa kecepatan alir dan konsentrasi larutan EG yang diinjeksikan ke gas alam. Model Peng-Robinson adalah model termodinamika yang diterapkan untuk penelitian ini. Hasil simulasi menunjukkan bahwa injeksi larutan EG dapat mengurangi pembentukan hidrat karena larutan EG menyerap uap air dalam gas alam. Kecepatan alir dan konsentrasi larutan EG divariasikan dari 20.000-2.000.000 lb/jam dan 80-90 % (%b/b). Saat pemisahan dilakukan pada suhu operasi -20 °F, konsentrasi larutan EG yang memenuhi syarat adalah 80-84 % (%b/b) dengan kecepatan alir larutan EG 900.000 lb/jam atau lebih. Jumlah ini sangat banyak dan kurang layak untuk dioperasikan. Penelitian difokuskan pada variasi suhu operasi. Peningkatan suhu operasi diikuti dengan pengurangan kecepatan aliran larutan EG secara signifikan yaitu menjadi sekitar 200.000 lb/jam. Alternatif proses diusulkan dengan berfokus pada penggunaan kecepatan alir larutan EG yang rendah dengan konsentrasi larutan EG sebesar 80 dan 85 % (%b/b). Simulasi dapat memprediksi konsentrasi pengotor yang keluar dari Dew Point Control Unit (DPCU). Konsentrasi BTX, hidrokarbon berat, merkaptan, dan COS yang mengalir keluar dari DPCU berturut-turut adalah 428,1 ppm, 378,4 ppm, 104 ppm, dan 13,3 ppm. Konsentrasi BTX dan hidrokarbon berat tersebut lebih besar dari standar minimum yang disyaratkan. Oleh karena itu, diperlukan pemasangan absorber untuk menyerap BTX dan hidrokarbon berat. Namun, kapasitas absorber akan jauh lebih kecil apabila dibandingkan dengan kondisi tanpa menurunkan suhu dan menginjeksikan oleh larutan EG.Kata kunci: DPCU; larutan etilena glikol; pembentukan hidrat; simulasi 
Kinetics Modeling of Glycerol Carbonate Synthesis from Glycerol and Urea over Amberlyst-15 Catalyst Hary Sulistyo; Sabariyanto Sabariyanto; Muhammad Noor Ridho Aji; Muhammad Mufti Azis
Indonesian Journal of Chemistry Vol 19, No 4 (2019)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (13.548 KB) | DOI: 10.22146/ijc.42879

Abstract

Synthesize of glycerol carbonate from glycerol and urea is an attractive path as glycerol carbonate has a large potential as a green solvent. The aim of the present study was to develop a kinetic model of glycerol carbonate synthesis with amberlyst-15 resins as a catalyst. The investigation was carried out at various temperatures from 353 to 383 K and catalyst loading from 0.25 to 1 wt.% of glycerol. The experimental results indicated that both temperature and catalyst loading have an important effect on the glycerol conversion. According to the experimental result, the highest glycerol conversion was found 36.90% which was obtained using a molar ratio of urea to glycerol 1:3, catalyst loading of 1 wt.%, stirrer speed of 700 rpm, the temperature of 383 K and reaction time of 5 h. A kinetic model was developed based on elementary steps that take place over the catalyst. The model estimated that the pre-exponential factor was 2.89.104 mol.g–1.min–1 and the activation energy was 50.5 kJ.mol–1. By comparing the simulation and experimental data, it could be inferred that the model could predict the trend of experimental data well over the range of temperature and catalyst loading investigated in the present study.
Mathematical Modeling of Reactive Extraction of Solute from Slab Solid Material Indah Hartati; Hary Sulistyo; Wahyudi Budi Sediawan; Muhammad Mufti Azis; Moh Fahrurrozi
Indonesian Journal of Chemistry Vol 20, No 2 (2020)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (16.081 KB) | DOI: 10.22146/ijc.47181

Abstract

Reactive extraction is gaining higher attention due its wide application in various solute separation processes. Here, a mathematical model of reactive extraction in slab has been proposed. The model was developed by considering simultaneous processes of active compound intra particle diffusion, second order elemental reaction of solute-active compound, and intra-particle product diffusion. The obtained partial differential equations (PDEs) were solved using Finite Difference Approximation (FDA) method by using realistic parameters. Concentration profile as well as product yield were evaluated as a function of time. As a result, the model proposed here may serve as a basis design for reactive extraction unit. Sensitivity analyses was conducted to inspect the influence of slab thickness, diffusivity and reaction rate constant to the product yield. Eventually, model validation was conducted by comparing the simulation results with analytical solutions for special cases. Validation results showed that the model gave good agreement with the analytical solution.
Solketal Production by Glycerol Acetalization Using Amberlyst-15 Catalyst Hary Sulistyo; Edwin Nur Huda; Tri Sarifah Utami; Wahyudi Budi Sediawan; Suprihastuti Sri Rahayu; Muhammad Mufti Azis
ASEAN Journal of Chemical Engineering Vol 20, No 1 (2020)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ajche.52455

Abstract

Glycerol, as a by-product of biodiesel production, has recently increased due to the rapid growth of the biodiesel industry. Glycerol utilization is needed to increase the added value of glycerol. Glycerol can be converted to solketal, which can be used as a green fuel additive to enhance an octane or cetane number. Conversion of glycerol to solketal was conducted via acetalization reaction with acetone using amberlyst-15 as the catalyst. The objective of present study was to investigate the effect of some operation conditions on glycerol conversion. Furthermore, it also aimed to develop a kinetic model of solketal synthesis with amberlyst-15 resins. The experiment was conducted in a batch reactor, equipped with cooling water, thermometer, stirrer, and a water bath. The variables that have been investigated in the present work were reaction temperature, reactants molar ratio, catalyst loading, and stirrer speed for 3 hours of reaction time. Temperatures, reactants molar ratio, and stirrer speed appeared to have a significant impact on glycerol conversion, where the higher values led to higher conversion. On the other hand, in the presence of catalyst, the increase of catalyst loading has a less significant impact on glycerol conversion. The results showed that the highest glycerol conversion was 68.75%, which was obtained at 333 K, the reactant’s molar ratio was  4, the amount of catalyst was 1 wt%, and stirrer speed of 500 rpm. Based on the pseudo-homogeneous kinetic model, the resulting kinetic model suitable for this glycerol capitalization. The value of parameters k and Ea were 1.6135 108 min-1 and 62.226 kJ mol-1,respectively. The simulation model generally fits the experimental data reasonably well in the temperature range of 313-333 K.
The Influence of Carbon Tax on the Feasibility of Industrial Project: A Case Study of Heat Exchanger Replacement at PT Kaltim Methanol Industri, Indonesia Wingo Wira Dewanatan; Muhammad Kurniawan Adiputra; Imam Karfendi Putro; Soni Hartanto; Jonas Kristanto; Muhammad Mufti Azis
ASEAN Journal of Chemical Engineering Vol 20, No 2 (2020)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ajche.59515

Abstract

Petrochemical industries have faced growing pressure to decrease their carbon emission from direct and indirect sources. This work aims to demonstrate a carbon tax’s introduction to a feasibility study on the heat exchanger (HE) replacement project at PT Kaltim Methanol Industri, Indonesia. The project was aimed to avoid methanol release as much as 48.88 MT/year. The release of methanol can also be associated with CO2 emission with an emission factor of 0.6 ton CO2e/ton methanol. Here, we investigated the influence of inclusion and exclusion of carbon tax to monetize the CO2 release. From the project investment point of view, carbon tax inclusion is expected to increase the cost-saving. Introduction of the carbon tax as high as 10 USD/ton CO2e with 5% annual increase gives IRR value of 7.06% with Payout Time (PoT) of ca. 11 years. The IRR value without carbon tax scenario is 6.68 % with the same range of PoT. Hence, the inclusion of carbon tax may increase the feasibility of the project. This work has demonstrated the positive role of the carbon tax to increase the feasibility of a project which inlines with the national initiatives to curb the CO2 emission from chemical industries. It is also worth noting that introduction of carbon tax should be accompanied by a reorganization of government incentives, including several financial policies to create a conducive atmosphere for investors in Indonesia.
Kinetic Study of Subcritical Water Extraction of Carbohydrate from Microalgae Nannochloropsis sp. Nur Baiti Listyaningrum; Muhammad Mufti Azis; Sarto Sarto; Anis Nurdhiani Rosdi; Mohd Razif Harun
ASEAN Journal of Chemical Engineering Vol 21, No 1 (2021)
Publisher : Department of Chemical Engineering, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/ajche.60015

Abstract

Microalgae contain a significant amount of carbohydrates that can be converted further to produce valuable compounds. To extract carbohydrates from microalgae, sub-critical water extraction (SWE) is a viable and novel method. Compared to other existing chemical and biological extraction methods, SWE is more economical, effective, and efficient in terms of process conditions. This process uses high temperature and pressure of water at just below supercritical conditions to keep water at a liquid state. This study aims to investigate the factors that affect the extraction yield of carbohydrates from microalgae Nannochloropsis sp. using the SWE process. The extraction was carried out at a temperature of 160 – 320 oC, a duration of 5 – 25 min, and microalgal biomass loading of 5 - 25% w/v. The kinetics study was conducted in an extraction time of 5 – 25 min at 200 oC and 5% (w/v) biomass loading. A simplified kinetic model based on a consecutive reaction was used to describe carbohydrate production and decomposition via SWE. It was found that the maximum yield of total carbohydrate was 18.04 g/100 g which was obtained at 200 oC, 10 min, and 5% (w/v) microalgal biomass loading. The carbohydrate concentration was decreased as the temperature, extraction time and microalgal biomass loading increased. This result indicated that the SWE is a promising extraction method for carbohydrate recovery from microalgae, and the factors investigated here had a significant effect on the extraction process. The proposed kinetic model was also able to capture the experimental data well within the range of operating conditions studied in this work.