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All Journal HAYATI Journal of Biosciences VALENSI Reaktor International Journal of Renewable Energy Development JURNAL KIMIA SAINS DAN APLIKASI JURNAL TEKNOLOGI KIMIA DAN INDUSTRI Eksergi: Chemical Engineering Journal Bulletin of Chemical Reaction Engineering & Catalysis R.E.M (Rekyasa Energi Manufaktur) Jurnal Food Science and Technology Journal (Foodscitech) Molekul: Jurnal Ilmiah Kimia ASEAN Journal of Chemical Engineering Jurnal Pengabdian Kepada Masyarakat (JPKM) Tabikpun Jurnal Riset Teknologi Pencegahan Pencemaran Industri Journal Of World Science Journal of Bioresources and Environmental Sciences Eduvest - Journal of Universal Studies Bookchapter Alam Universitas Negeri Semarang Journal of Bioresources and Environmental Sciences International Journal of Renewable Energy Development Bulletin of Chemical Reaction Engineering & Catalysis Asian Journal of Social and Humanities JURNAL REKAYASA KIMIA & LINGKUNGAN
Marcelinus Christwardana
Department Of Chemistry, Diponegoro University, Jl. Prof. Sudarto, SH., Tembalang, Semarang, Central Java
Aerospace Engineering Agriculture, Biological Sciences & Forestry Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Earth & Planetary Sciences Economics, Econometrics & Finance Education Electrical & Electronics Engineering Energy Engineering Environmental Science Health Professions Industrial & Manufacturing Engineering Languange, Linguistic, Communication & Media Law, Crime, Criminology & Criminal Justice Materials Science & Nanotechnology Neuroscience Social Sciences

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Kombinasi Proses Elektrokoagulasi Oksidasi Lanjut Berbasis O3/GAC Pada Limbah Cair Industri Batik Enjarlis Enjarlis; Singgih Hartanto; Marcelinus Christwardana; Boy Frando Sijabat; Ode Resa Fatlan
Jurnal Rekayasa Kimia & Lingkungan Vol 14, No 1 (2019): Jurnal Rekayasa Kimia & Lingkungan (June, 2019)
Publisher : Chemical Engineering Department, Syiah Kuala University, Banda Aceh, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23955/rkl.v14i1.12274

Abstract

Gabungan proses Elektrokoagulasi-Oksidasi Lanjut (EC-OL) berbasis O3/GAC merupakan teknologi alternatif untuk mengolah limbah cair industri Batik. Limbah cair industri batik mengandung Bahan Berbahaya dan Beracun, mempunyai COD 500 - 3000 ppm, BOD 1200 ppm dan TSS 10.000 ppm serta tidak memenuhi Baku Mutu Lingkungan.Tujuan penelitian gabungan EC-OL pada limbah cair batik yaitu menentukan: (a) waktu optimum proses Elektrokoagulasi (EC), (b) dosis ozon dan jumlah karbon aktif yang tepat pada Oksidasi Lanjut berbasis O3/GAC (OL), dan (c) pengaruh gabungan proses Elektrokoagulasi-Oksidasi Lanjut (EC-OL) berbasis O3/GAC terhadap konstanta laju degradasi kontaminan organik (k) dalam limbah cair industri Batik. Pada gabungan proses EC-OL, untuk elektrokoagulasi digunakan elektroda Al, kuat arus 1 A tetap, dan waktu proses (20, 40 dan 60 menit) dan Oksidasi Lanjut (OL) dilakukan pada dosis ozon (0,0625; 0,125 dan 0,1875 gr O3/liter) dan massa GAC (10, 20 dan 30 gram). Parameter uji yang digunakan yaitu nilai COD, Total suspention solid (TSS) dan warna limbah. Dari hasil percobaan diperoleh: (a) waktu proses elekrtrokoagulasi terbaik selama 60 menit dengan penurunan COD 54 % dan TSS 31%, (b) pada proses OL berbasis O3/GAC diperoleh dosis ozon terbaik sebesar 0,125 gr O3/L dan massa GAC sebanyak 30 gram dengan penurunan COD 61,11% dan TSS 15,33% dan (c) Pada gabungan proses EC-OL penurunan COD terjadi sebesar 95,08% dan TSS 81,39% dan konstanta laju degradasi kontaminan organik sebesar 0,6931 min-1.
The Influence of Various Substrates on Power Generation in The Operation of Yeast Microbial Fuel Cells Christwardana, Marcelinus; Joelianingsih, J.; Yoshi, Linda Aliffia
Reaktor Volume 22 No.2 August 2022
Publisher : Department of Chemical Engineering, Faculty of Engineering, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/reaktor.22.2.36-41

Abstract

Several carbon substrates were tried, including glucose commercial, pro analysis glucose, commercial sugar, and yeast extract - peptone - d glucose (YPD) medium to improve the efficiency of the single chamber microbial fuel cell (MFC). The power production of various electron donors was investigated using baker yeast Saccharomyces cerevisiae. Voltage and power density generation were used to establish the pattern of substrate use. In addition, electrochemical analysis of the anodic biofilm was performed. S. cervisiae was shown to successfully consume YPD medium by anode respiration with a higher power density of 18.40±1.98 mW/m2, followed by pro analysis glucose (9.41±1.15 mW/m2), commercial glucose (1.30±0.10 mW/m2), and commercial sugar (0.04±0.01 mW/m2). Furthermore, a clear relationship was established between power density generating rate and voltage output. Voltages produced were 0.16±0.02 V, 0.13±0.03 V, 0.03±0.01 V, 0.01±0.00 V for YPD medium, pro analysis glucose, commercial glucose, and commercial sugar, respectively in MFC. The weight of biofilm indicated that yeast attachment was significantly more common in YPD medium than in other MFC-operated media. This study discovered that the substrate type in the anodic compartment regulates the formation of anodic biofilm.
Condenser Replacement Life Prediction Based on Condenser Back Pressure Loss Factor Using Simple Life Cycle Cost Management Method: Economic Life Putra, Alam Eka; Tamtomo Kiono, Berkah Fajar; Christwardana, Marcelinus
Eduvest - Journal of Universal Studies Vol. 5 No. 3 (2025): Eduvest - Journal of Universal Studies
Publisher : Green Publisher Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.59188/eduvest.v5i3.44795

Abstract

Energy demand in Indonesia continues to increase, in line with the government's efforts to balance economic and population growth. In this context, the government-designed electricity supply policy prioritizes the use of coal as the main source of energy until 2050. Power plants face challenges in asset management, particularly in the replacement and maintenance of equipment such as condensers. This study aims to determine the economic life of condensers in Steam Power Plants (PLTU) with a capacity of 300 MW, as well as analyze the life cycle costs using the Simple Life Cycle Cost Management (LCCM) method. This method considers direct and indirect costs in decision-making related to equipment maintenance and replacement. The study also identified factors that affect the operational efficiency of the condenser, including backpressure and operational conditions. The results of the analysis show that careful monitoring and evaluation of the economic life of the condenser can optimize operating costs and improve the energy efficiency of the generation system. This study provides strategic recommendations for asset management in power generation, prioritizing a holistic approach in decision-making related to equipment maintenance and replacement. Thus, this research is expected to contribute to the development of more efficient energy policies in Indonesia.
Enhanced Anode Performance in Yeast Microbial Fuel Cells via Optimized Calcination of Eggshell Using Response Surface Method Christwardana, Marcelinus; Kuntolaksono, Satrio; Joelianingsih, J.; Maulana, Achmad Yanuar
Jurnal Kimia Sains dan Aplikasi Vol 28, No 4 (2025): Volume 28 Issue 4 Year 2025
Publisher : Chemistry Department, Faculty of Sciences and Mathematics, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jksa.28.4.183-194

Abstract

This study aims to explore the potential of calcined eggshells as an economical and effective anode material in microbial fuel cells (MFCs). This research examines the enhancement of calcined eggshells as an anode material in MFCs by operating condition optimization using the Response Surface Method (RSM). The experimental findings underscore the substantial influence of temperature and the eggshell/NaOH ratio on voltage and maximum power density (MPD). Raising the calcination temperature from 550°C to 700°C improves both voltage and MPD, with peak performance seen at 700°C. Nonetheless, performance stabilizes above 850°C. The eggshell/NaOH ratio is significant, with enhancements seen at an optimum ratio of 4. ANOVA analysis indicates that the model accounts for 79.89% of the variability in voltage and 82.74% in MPD, while the modified R-squared values imply possible overfitting. Optimal calcination parameters (704.55°C and a ratio of 2.52) improve the microstructural characteristics of calcined eggshells and crystallinity, which are essential for electron transport and bacterial adhesion. SEM study indicates a morphological transition to a rough, porous structure, whilst XRD and FTIR investigations validate the conversion from calcium carbonate to calcium hydroxide, enhancing electrochemical characteristics. This study highlights the promise of optimized calcined eggshells as economical and effective materials for microbial fuel cells, advancing sustainable energy and materials science.
Use Of Machine Learning With The Long Short Term Memories Method As The Basis For Cleaning And Performance Of Steam Turbine Condensers For Gas And Steam Power Plants Utomo, Tony Suryo; Christwardana, Marcelinus; Syachrir, Guntur
Journal of World Science Vol. 4 No. 5 (2025): Journal of World Science
Publisher : Riviera Publishing

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.58344/jws.v4i5.1411

Abstract

This research focuses on the design of a bidirectional reinforced concrete slab for a 5-storey apartment building located on Jalan Pemuda, Semarang, following SNI 1726:2019 standards. The objective is to compare the results of the direct design method (DDM) using Excel with ETABS v18 software, analyzing the accuracy of traditional methods in modern structural designs. The study employed a practical approach, incorporating various design parameters such as beam dimensions, span length, dead and live loads, and material strengths (f'c and fy). The results indicate that although there is a slight difference between the methods, they exhibit similar trends. The study found that increased load leads to higher moments, while larger beams and higher concrete strength reduce reinforcement requirements. However, discrepancies between the methods were observed due to rounding errors in the DDM. The research suggests refining moment calculation techniques and enhancing software tools for more accurate slab designs. The findings are essential for improving design accuracy in both academic and professional practice, particularly for earthquake-resistant structures.
Use of Machine Learning-Based Health Index With K-Nearest Neighbors Method to Maintain Desalination Plant Performance Gas and Steam Power Plants Applications Harmoko, Udi; Christwardana, Marcelinus; Rizkan, Muhammad
Asian Journal of Social and Humanities Vol. 3 No. 7 (2025): Asian Journal of Social and Humanities
Publisher : Pelopor Publikasi Akademika

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.59888/ajosh.v3i7.549

Abstract

This study presents the implementation of a Machine Learning-Based Health Index utilizing the K-Nearest Neighbors (K-NN) algorithm for predictive maintenance in desalination plants within gas and steam power plants. The research focuses on optimizing the maintenance schedule of the Block 3 Priok Desalination Plant, which is critical for providing high-quality distilled water for power generation. This study aims to develop and integrate a predictive maintenance framework into PLN’s digitization system, allowing for automated monitoring and optimized servicing schedules. Unlike the previous application of K-NN in Block 4, which utilized five health indices for performance classification, Block 3 requires an expanded model incorporating at least seven input parameters due to its multi-effect desalination process. By refining the predictive model and increasing data parameterization, this study seeks to enhance maintenance accuracy, minimize operational downtime, and improve overall desalination efficiency. By leveraging historical operational data and real-time monitoring, the K-NN model predicts the health index of desalination components with 98% accuracy. Implementing this approach minimizes downtime, optimizes maintenance schedules, and enhances energy efficiency. The results demonstrate that AI-driven predictive maintenance significantly improves reliability, reduces costs, and supports energy sustainability goals.
EKSPLORASI POTENSI SPIRULINA DALAM PENANGANAN LIMBAH OLI BEKAS KENDARAAN Amalia, Andin Vita; Haris, Amnan; Heriyanti, Andhina Putri; Amelia, Rizki Nor; Rifa’atunnisa, Rifa’atunnisa; Soeprobowati, Tri Retnaningsih; Christwardana, Marcelinus
Bookchapter Alam Universitas Negeri Semarang Vol. 5 (2025)
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/ka.v5i1`.273

Abstract

Oli merupakan pelumas mesin kendaraan bermotor yang memiliki peran penting dalam menjaga kinerja dan umur panjang mesin. Namun, setelah digunakan, oli bekas harus segera diganti karena sifatnya yang sudah terdegradasi dan mengandung berbagai kontaminan berbahaya. Sayangnya, pengelolaan limbah oli bekas di masyarakat masih sangat terbatas. Oli bekas umumnya hanya dimanfaatkan untuk melumasi baut dan rantai, dicampur dengan solar sebagai bahan bakar alternatif, atau bahkan dibuang dan ditampung tanpa proses pengolahan yang memadai. Hal ini berpotensi menimbulkan pencemaran lingkungan, terutama karena kandungan bahan kimia beracun dan logam berat yang dapat mencemari tanah dan badan air. Salah satu pendekatan yang mulai dikembangkan untuk mengatasi permasalahan ini adalah pemanfaatan mikroorganisme seperti mikroalga. Spirulina, salah satu jenis mikroalga, diketahui memiliki kemampuan sebagai agen bioremediasi yang efektif karena mampu menyerap polutan (bertindak sebagai sorben), mengubah senyawa berbahaya menjadi bentuk yang lebih aman, serta mengakumulasikannya dalam struktur tubuhnya. Spirulina telah berhasil digunakan untuk mengolah berbagai jenis limbah, seperti limbah tahu, minyak jelantah, dan limbah industri batik. Karakteristik limbah oli yang memiliki kemiripan dengan minyak jelantah, terutama karena keduanya berasal dari fraksi minyak bumi, maka spirulina memiliki potensi besar untuk digunakan dalam bioremediasi limbah oli bekas.
Pembuatan Eco-enzyme Berbasis Limbah Rumah Tangga pada Pondok Pesantren untuk Mencapai Sustainable Development Goals Christwardana, Marcelinus; Lusiana, Retno Ariadi; Suyati, Linda; Gunawan, Gunawan; Widodo, Didik Setiyo
Jurnal Pengabdian Kepada Masyarakat (JPKM) TABIKPUN Vol. 5 No. 3 (2024)
Publisher : Faculty of Mathematics and Natural Sciences - Universitas Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jpkmt.v5i3.170

Abstract

Pondok pesantren memiliki karakteristik khusus dalam sistem pendidikan. Salah satu program tersebut adalah pelatihan wirausaha, yang bertujuan untuk membekali santri dengan keterampilan berwirausaha guna mendukung kemandirian mereka di masyarakat. Artikel ini membahas implementasi workshop pembuatan eco-enzyme di Pesantren Al-Mahbubiyah, Gamping Sleman, yang terbukti efektif dalam memberikan pengetahuan dan keterampilan kepada santri. Workshop ini memberikan pengalaman langsung kepada santri melalui praktek yang dipandu oleh fasilitator berpengalaman dan dilengkapi dengan sesi tutorial untuk memperkuat pemahaman mereka. Keseluruhan kegiatan ini berkontribusi positif dalam meningkatkan keterampilan santri dalam pembuatan eco-enzyme. Upaya ini diharapkan dapat meningkatkan kesadaran dan keterampilan dalam pengelolaan lingkungan, memberikan dampak signifikan bagi keberlanjutan lingkungan dan kesejahteraan masyarakat.
Synthesis and Antibacterial Activity of Chitosan-Cinamaldehyde/AgNp Schiff Base Composite Huda, Muhammad Badrul; Rinaryadi, Kemilau Permata Hati; Ngadiwiyana, Ngadiwiyana; Christwardana, Marcelinus; Sarjono, Purbowatiningrum Ria; Ismiyarto, Ismiyarto
Jurnal Kimia Valensi Vol. 11 No. 1 (2025): Jurnal Kimia VALENSI
Publisher : Department of Chemistry, Faculty of Science and Technology Syarif Hidayatullah Jakarta State Islamic University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15408/jkv.v11i1.45121

Abstract

Chitosan is a material that has antibacterial properties. Chitosan was modified with cinnamaldehyde to form chitosan Schiff base, which acts as a capping agent in the synthesis of silver nanoparticles. The Schiff base product was modified again into a silver nanoparticle Schiff base composite to improve its ability as a capping agent and improve its antibacterial properties. This study aims to synthesize a chitosan-cinnamaldehyde/AgNP Schiff base composite (CCSB/AgNP) as an active ingredient with excellent antibacterial properties. The first stage was the synthesis of a chitosan-cinnamaldehyde Schiff base. In the second stage, the synthesis of the chitosan/AgNP composite was carried out by adding STPP with sonication and a water bath. The third stage involved synthesizing of the CCSB/AgNP composite using the same method as the second stage employing both heating and non-heating as well as sonication and non-sonication. The product was characterized using a UV-Vis spectrophotometer, FT-IR, SEM-EDX, mapping, and AAS. Antibacterial tests were performed on the synthesized product using the Total Plate Count (TPC) method. Chitosan has a molecular weight of 338080 g/mol and a degree of deacetylation of 65.09%. The Schiff base product of chitosan-cinnamaldehyde is a brownish-yellow solid with a yield of 76.9% (w/w) and a degree of substitution of 87.02%. The presence of Ag was confirmed by EDX mapping, which revealed mass percentages of 0.26%, 1.00%, and 3.97% for C/AgNP-1, C/AgNP-2, and CCSB/AgNP-2, respectively. The chitosan/AgNP product has a yield of 97% (w/w) and an SPR effect at 439 nm. The synthesis of CCSB/AgNP obtained a dark green solid with a yield of 87% (w/w) and an SPR effect at 433 nm. The antibacterial activity test yielded the highest percentage reduction in the number of bacteria in CCSB/AgNP at 3 days of observation at 95.1%, and 7 days at 94.1%. 
Co-Authors . Widayat A Abdullah Adrianus Kristyo Prabowo Adrianus Kristyo Prabowo, Adrianus Kristyo Agam Duma Kalista Wibowo Agnes Priska Tiarasukma Agnes Priska Tiarasukma Agus Afif Andin Vita Amalia, Andin Vita Andri Cahyo Kumoro Angela Nitia Nefasa Angela Nitia Nefasa Angela Nitia Nefasa Aniek Sri Handayani Athanasia Amanda Septevani, Athanasia Amanda Berkah Fajar Tamtomo kiono Boy Frando Sijabat Danny Soetrisnanto Deni Shidqi Khaerudini Dessy Ariyanti Dessy Ariyanti Didik Setiyo Widodo E. Enjarlis Ega Zahrotun Nisa Eudia Christina Wulandari Fadhilla, Putri Fania, Adhista Fatkur Rohman Fitra Pradhita Fitria Yuli Anggita Sari Gunawan Gunawan H Hadiyanto H. Hadiyanto H. Hadiyanto H. Hadiyanto H. Hadiyanto H. Hargono Hamid Hamid Hantoro Satriadi Haris, Amnan Hendrawan, Muhammad Andiri Heriyanti, Andhina Putri Heru Cahyana Huda, Muhammad Badrul I Made Aditya Suryajaya Ifa Miftahushudury Ismiyarto Ismitarto Ismojo, I. Joelianingsih . Linda Aliffia Yoshi, Linda Aliffia Linda Suyati Lisa Aditya Margaretha Praba Aulia Maulana, Achmad Yanuar Muhamad Zaini Mahdi Ngadiwiyana M.Si. S.Si. Nur Rokhati Ode Resa Fatlan Pina Tiani Purbowatiningrum Ria Sarjono Putra, Alam Eka Ratnawati Ratnawati Retno Ariadi Lusiana Rifa’atunnisa, Rifa’atunnisa Riky Yonas Rinaryadi, Kemilau Permata Hati Rizkan, Muhammad Rizki Nor Amelia S. Slamet Satrio Kuntolaksono Sidik Marsudi Singgih Hartanto Sri Widodo Agung Suedy Sudirman Sudirma Syachrir, Guntur Tony Suryo Utomo Tri Retnaningsih Soeprobowati Udi Harmoko Udi Harmoko Uray Irzandi Wahyu Zuli Pratiwi Widharyanti, Ika Dyah Yasinta Nikita Titisari Yuli Amalia Husnil Zakaria Hussein Abdurrahman