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All Journal Reaktor International Journal of Renewable Energy Development TEKNIK Rotasi METANA BERKALA FISIKA JURNAL KIMIA SAINS DAN APLIKASI JURNAL TEKNOLOGI KIMIA DAN INDUSTRI Analisis: Jurnal Studi Keislaman Geoplanning : Journal of Geomatics and Planning Jurnal Riset Pendidikan Matematika Bulletin of Chemical Reaction Engineering & Catalysis Jurnal Riset Industri Mesin JUPE : Jurnal Pendidikan Mandala Universitas Muhammadiyah Yogyakarta Undergraduate Conference Proceeding Bulletin of Chemical Reaction Engineering & Catalysis Journal of Chemical Engineering Research Progress JURNAL REKAYASA KIMIA & LINGKUNGAN
I. Istadi
Department Of Chemical Engineering, Diponegoro University, Jl. Prof. Soedarto, Kampus UNDIP Tembalang, Semarang 50239
Agriculture, Biological Sciences & Forestry Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Earth & Planetary Sciences Economics, Econometrics & Finance Education Energy Engineering Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mathematics Mechanical Engineering Physics Public Health Social Sciences

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Backmatter (Publication Ethics, Copyright Transfer Agreement for Publishing Form) Istadi, Istadi
Bulletin of Chemical Reaction Engineering & Catalysis 2025: BCREC Volume 20 Issue 1 Year 2025 (April 2025)
Publisher : Masyarakat Katalis Indonesia - Indonesian Catalyst Society (MKICS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.9767/bcrec.20365

Abstract

Backmatter (Publication Ethics, Copyright Transfer Agreement for Publishing Form)
Backmatter (Publication Ethics, Copyright Transfer Agreement for Publishing Form) Istadi, Istadi
Bulletin of Chemical Reaction Engineering & Catalysis 2025: BCREC Volume 20 Issue 2 Year 2025 (August 2025)
Publisher : Masyarakat Katalis Indonesia - Indonesian Catalyst Society (MKICS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.9767/bcrec.20396

Abstract

Backmatter (Publication Ethics, Copyright Transfer Agreement for Publishing Form)
Effect of Ni-Co Ratio on ZSM-5 Catalyst Performance in Palm Oil Hydrocracking for Biofuel Production Istadi, I.; Riyanto, Teguh; Permatasari, Astrid Eka; Dinara, Daniella Cipta
Reaktor Volume 25 No.1 April 2025
Publisher : Department of Chemical Engineering, Faculty of Engineering, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/reaktor.0.0.%p

Abstract

Biofuel derived from vegetable oil can be utilized as a vehicle fuel with various advantages, such as renewability, environmental friendliness, and sustainable availability. One of the methods for converting vegetable oil into biofuel is hydrocracking. This study investigates Ni-Co/ZSM-5 catalyst with Ni-Co metal ratios of 1:0.5, 1:1, and 1:1.5 to examine their effects on the catalyst characteristics and performance in the hydrocracking process of palm oil into biofuel. The catalyst synthesis was carried out using the co-impregnation method with ultrasound assistance, followed by characterization using XRD and XRF. The hydrocracking process was conducted at a temperature of 450℃ and a WHSV of 0.1 min-1, while the gas product was analyzed using GC and liquid product was distilled. XRF results showed that the actual Ni-Co ratio did not significantly differ from the designed ratio. XRD analysis indicated crystal agglomeration at a 1:1.5 ratio due to competition between Ni and Co metal particles diffusing into the zeolite pores, as well as the presence of dislocations and crystal defects. Differences in catalyst characteristics resulted in variations in yield, selectivity, and gas distribution in the hydrocracking process. The catalyst with a Ni-Co ratio of 1:1.5 exhibited the highest liquid product yield and biogasoline selectivity but also produced a higher concentration of CO, CO2, and C2 gases. It is associated with the breakdown of triglycerides into fatty acids, which subsequently fragment into shorter-chain biofuel components.
Metaphorical Thinking CoRelEx Spatial Students on Trigonometry Word Problem Solving Ability Kursius, Catherine Mentaya; Muttaqien, Anwar; Istadi, Istadi
Jurnal Riset Pendidikan Matematika Vol. 12 No. 1 (2025): May 2025
Publisher : Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Negeri Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21831/jrpm.v12i1.83173

Abstract

Problems in the reality of our lives require mathematics to be solved often using analogies in their solutions or also called metaphors. The condition of these problems requires students to develop abilities that emphasize the development of relationships between mathematical concepts and real phenomena in the surrounding environment. The method used in this study is descriptive qualitative with purposive sampling. The study was conducted at a public senior high school in Central Kalimantan during the 2024–2025 academic year, with 3 spatial students as subjects with Visual, Auditory and Kinesthetic learning styles in class X room H. This study aims to determine the metaphorical thinking process of students when solving trigonometry word problems. By using metaphorical thinking skills, students' mathematical understanding process becomes more meaningful because they can see, form, and map mathematical concepts to real concepts according to experience.
Total Net Energy Assessment for Rule-of-Thumb Applications in Multicomponent Distillation Separation Strategy Istadi, Istadi; Riyanto, Teguh
Journal of Chemical Engineering Research Progress 2025: JCERP, Volume 2 Issue 1 Year 2025 (June 2025)
Publisher : UPT Laboratorium Terpadu, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.9767/jcerp.20402

Abstract

Energy saving in separation systems, particularly in distillation systems, is a research field that has attracted considerable innovative approaches. A distillation system is an essential separation process, yet it is inefficient in using thermal energy, and may operate with adverse environmental impact as it discharges a large amount of thermal energy into the environment. In this work, several Sequences Designs of Distillation Column Network are proposed to be compared with respect to Total Net Energy of each sequence design. Applying the Rule of Thumb of Distillation Strategy for separating multicomponent mixtures is important by performing the easiest separation first (largest relative volatility), that is, the one least demanding of trays and reflux, and leaving the most difficult to the last. From all sequence designs results, Sequence-A shows the lowest Total Net Energy (9,750,720.88 kJ/h), because the Sequence-A follows the strategy/procedure for separation of multicomponent using distillation column network. Decreasing the relative volatility affects on increasing number of tray and recycle ratio required for distillation process and decreasing the Net Energy. Copyright © 2025 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
Analysis of CaCO3 Impregnation on HY Zeolite Surface Area, Pore Size, and Activity in the Catalytic Cracking of Palm Oil to Biofuels Febriansyar, Rosyad Adrian; Riyanto, Teguh; Istadi, I.
TEKNIK Vol. 43, No. 1 (2022): May 2022
Publisher : Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/teknik.v43i1.44579

Abstract

Fossil energy sources are currently decreasing, requiring the development of alternative energy sources. Vegetable oil is a raw material for alternative renewable energy supplies. This study produced biofuels from vegetable oil using calcium carbonate (CaCO3)-impregnated HY catalysts. In addition, this study aimed to investigate the effect of CaCO3 impregnation on the surface area and the catalytic activity of catalysts in the palm oil cracking process to produce biofuels. The HY catalyst was modified by the wet impregnation method in 5 wt% CaCO3 solution and was further calcined at 550°C for three h. Furthermore, the catalysts were tested in a continuous fixed-bed catalytic reactor at 450°C. The catalyst properties were characterized using Brunauer–Emmett–Teller (BET) surface area, Barrett–Joyner–Halenda (BJH) for pore size distribution, and X-Ray Diffraction (XRD) for crystal structure and phases. The results showed that the addition of CaCO3 decreased surface area and pore volume; however, the pore size increased, which resulted in the production of heavy hydrocarbons. Interestingly, the introduction of CaCO3 enhanced the yield of Organic Liquid Product (OLP) and diesel-range hydrocarbons selectivity to reach 79.09% and 30.54%, respectively. Furthermore, the introduction of CaCO3 increased deoxygenation activity.
The Influence of Identity Politics in Contemporary Islam Karimullah, Suud Sarim; Bahrudin, Moh.; Istadi, Istadi
Analisis: Jurnal Studi Keislaman Vol 23 No 2 (2023): Analisis : Jurnal Studi Keislaman
Publisher : Universitas Islam Negeri Raden Intan Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24042/ajsk.v23i2.19010

Abstract

The study investigates the significant impact of identity politics in contemporary Islam on political and social stability, considering the crucial role of media and communication in such dynamics. This study uses a literature study method that involves an integrative and comprehensive analysis of literature to collect, review, and analyze various sources of relevant information. The study results stated that identity politics in contemporary Islam is central to shaping political and social dynamics worldwide. By influencing the perceptions and actions of individuals and groups, identity politics in Islam can significantly impact political and social stability within a country, especially in intergroup tensions. In addition, the role of media and communication has also proved crucial in shaping the image and narrative of Islamic identity politics, both positively and negatively. Therefore, a deep understanding of the complexities of identity politics in Islam and concerted efforts to promote mutual understanding, dialogue, and peace are key to confronting the challenges of identity politics in contemporary Islam.
Backmatter (Publication Ethics, Right Transfer Agreement for Publishing Form) Istadi, Istadi
Bulletin of Chemical Reaction Engineering & Catalysis 2025: BCREC Volume 20 Issue 3 Year 2025 (October 2025)
Publisher : Masyarakat Katalis Indonesia - Indonesian Catalyst Society (MKICS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.9767/bcrec.20481

Abstract

Backmatter (Publication Ethics, Right Transfer Agreement for Publishing Form)
Steady-State and Dynamic Simulation Study of Reactive Distillation for FFA Esterification in Biodiesel Synthesis Kusumaningtyas, Ratna Dewi; Prasetiawan, Haniif; Nugroho, Daniel Setiyo; Wulandari, Ajeng Riswanti; Istadi, Istadi; Hisyam, Anwaruddin
Jurnal Rekayasa Kimia & Lingkungan Vol 16, No 1 (2021): Jurnal Rekayasa Kimia & Lingkungan (June, 2021)
Publisher : Chemical Engineering Department, Syiah Kuala University, Banda Aceh, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23955/rkl.v16i2.19857

Abstract

Reactive distillation (RD) holds promise for process intensification in biodiesel production since it integrates reaction and separation. It simplifies the process and enhances the conversion of the equilibrium limited reactions. To ensure the stability in RD operation, sensitivity study and process control simulation are necessary. In this work, RD was employed for free fatty acid (FFA) esterification of mixed non edible oils in biodiesel synthesis. Non edible oils used were waste cooking oil, crude jatropha oil, and crude nyamplung oil (Calophyllum inophyllum L). Simulation was conducted using ASPEN Plus V8.8. Sensitivity study was carried out to determine the effects of the operating condition alteration. A dynamic simulation was performed as a Proportional-Integral-Derivative (PID) controller tuning. It was revealed that the highest FFA conversion was 85%, achieved at the feed stage of 7, distillate rate of 0.22 kmol/hr, and oil to methanol molar ratio of 1:5. Level, pressure and temperature controls were installed in RD. Then, a dynamic simulation was applied as a PID controller tuning. Three different controller tuning methods, viz. Ziegler-Nichols, Cohen-Coon, and Internal Model Control, were studied. The best PID parameter was obtained by using Cohen-Coon method which provided fastest rise time, lowest settling time and lowest overshoot.
Kemampuan Pemecahan Masalah Matemtis Pada Materi Teorema Pyhtagoras Ditinjau Dari Gaya Belajar Visual Dan Auditorial Siswa Kelas Viii Di Smp Negeri 2 Sampit Rakhmawati, Astri; Istadi, Istadi; Astuti, Fajar
JUPE : Jurnal Pendidikan Mandala Vol 8, No 2 (2023): JUPE : Jurnal Pendidikan Mandala (Juni)
Publisher : Lembaga Penelitian dan Pendidikan Mandala

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.58258/jupe.v8i2.5559

Abstract

Penelitian ini bertujuan untuk mendeskripsikan kemampuan pemecahan masalah matematis siswa ditinjau dari gaya belajar. Penelitian ini adalah penelitian kualitatif dengan pendekatan deskripsi kualitatif. Penelitian ini dilaksanakan di SMP Negeri 2 sampit. Subjek penelitian ini adalah 6 orang siswa dari 31 siswa dikelas VIII ruang A, 2 subjek visual dan 2 subjek auditorial. Instrumen yang digunakan yaitu angket gaya belajar, tes soal, dan wawancara. Data diperoleh dianalisis dengan cara reduksi data, penyajian data, dan penarik kesmpulan. Pengecekan keabsahan data menguunakan teknik triagulasi. Pemecahan masalah matematis dianalisis berdasarkan 4 indikator menurut Polya yaitu: (1) memahami masalah, (2) merencanakan pemecahan masalah, (3) menyelesaikan rencana pemecahan masalah, (4) mengecek/memeriksa kembali. Kemampuan pemecahan masalah matematis merupakan permasalahan yang diarahkan untuk mendapatkan suatu jawaban dengan cara berpikir. Berdasarkan hasil analisis data pemecahan masalah matematis siswa dengan menggunakan langkah Polya ditinjau dari gaya belajar adalah (1) Pada subjek SV1 dengan gaya belajar visual mampu dalam memahami masalah dengan cara membaca soal didalam hati, melakukan perencanaan pemecahan masalah, mampu melakukan perhitungan dengan tepat, dan tidak melakukan pemeriksaan kembali. Pada subjek SV2 dengan gaya belajar visual mampu dalam memahami masalah, melakukan perencanaan pemecahan masalah, belum mampu melakukan perhitungan dengan tepat, dan tidak melakukan pemeriksaan kembali. (2) Pada subjek SA1 dengan gaya belajar auditorial mampu dalam memahami masalah, melakukan perencanaan pemecahan masalah, mampu melakukan perhitungan dengan tepat, dan mampu melakukan pemeriksaan kembali hanya saja pada soal nomor 1 saja. Pada subjek SA2 dengan gaya belajar auditorial tidak mampu dalam memahami masalah dengan cara membaca soal didalam hati, melakukan perencanaan pemecahan masalah, mampu melakukan perhitungan dengan tepat, dan melakukan pemeriksaan kembali.
Co-Authors Ajeng Riswanti Wulandari Amalia, Rahma Amin N.A.S. Amin Amin Nugroho Aminuyati Anggun Kurniawan Anindita Indriana Aniyati Khoiriyah Anwar Muttaqien, Anwar Anwaruddin Hisyam Anwaruddin Hisyam Ardian D. Yudhistira Ardian Dwi Yudhistira Aribowo, Windarto Astri Rakhmawati Atanasius Priharyoto Bayuseno Bahrudin, Moh. Bambang Pramudono Bambang Tri Nugroho Bintang Ayu Kalimantini Chusnul Khotimah D. A. Rahmawati D. Intaningrum Daniel Setiyo Nugroho Daniel Setiyo Nugroho, Daniel Setiyo Dian Rahmayanti Didi D. Anggoro Didi D. Anggoro Didi D. Anggoro Didi D. Anggoro Didi Dwi Anggoro Dinara, Daniella Cipta Dini Wulandari Dorothy Hoo Wei Ling Dyah Hesti Wardhani Eko Hidayanto Fachmy Adji Pangestu Setiawan Fajar Astuti Febriansyar, Rosyad Adrian Haniif Prasetiawan Heri Mulyanti Heri Sutanto Herlina Hidayati Iis Nurhasanah Inshani Utami Inshani Utami Karimullah, Suud Sarim Kursius, Catherine M. Kursius, Catherine Mentaya Luqman Buchori M.C.T. Wahyu Utami Maryanto - Muhamad, Theobroma Guntur Nani Harihastuti, Nani New Pei Yee Nofi Marlini Nor Aishah Saidina Amin Nor Aishah Saidina Amin Nor Aishah Saidina Amin P Purwanto Pakpahan, Agnes J. Pakpahan, Andre W. S. Permatasari, Astrid Eka Purwanto . Purwanto Purwanto Purwanto Purwanto Putut Marwoto Qotrunnada, Novaya Aulia Rahmat Gernowo Ratna Dewi Kusumaningtyas Riyanto, Teguh Roikhatus Solikhah Roikhatus Solikhah Salsabila, Unik Hanifah Salsabilla, Alda Saputra, Roni Ade Sitompul, J. P Slamet Priyanto Suherman Suherman Sulistyo Sulistyo Teguh Riyanto Teuku Irfan Maulana Udin Mabruro Wahyu Ambikawati Wulandari, Ajeng Riswanti