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All Journal Eksergi: Chemical Engineering Journal CHEESA: Chemical Engineering Research Articles FLUIDA Industrial Research Workshop and National Seminar Gunung Djati Conference Series Jurnal Teknik Kimia dan Lingkungan al Kimiya : Jurnal Ilmu Kimia dan Terapan
Manfaati, Rintis
Jurusan Teknik Kimia, Politeknik Negeri Bandung
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Characteristics of Electric Current in The Electrolysis of Acid and Alkaline Water Production for Health Kurniawan, Ekki; Raharjo, Jangkung; Manfaati, Rintis; Yulinda, Yulinda
al Kimiya: Jurnal Ilmu Kimia dan Terapan Vol. 12 No. 1 (2025): June 2025
Publisher : Department of Chemistry, Faculty of Science and Technology, UIN Sunan Gunung Djati Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15575/ak.v12i1.39460

Abstract

Acidic and alkaline water with potential health benefits can be produced through the process of electrolysis. In addition to the applied voltage, electric current is a crucial parameter in the electrolysis process. The energy consumed during electrolysis can be determined by measuring the voltage, electric current, and duration of operation. This study aims to investigate the characteristics of electric current during the electrolysis of mineral water to produce Electrolyzed Reduced Water (ERW) and Electrolyzed Oxidized Water (EOW), commonly referred to as alkaline and acidic water, respectively. The electrolysis current is monitored at specific time intervals (0, t₁, and t₂) throughout the process. In the initial stage (from 0 to t₁), the current increases exponentially, similar to the charging current behaviour of an inductor (L). In the second stage (from t₁ to t₂), the current decreases exponentially, resembling the discharge of a capacitor (C). In the final stage (after t₂), the current stabilizes and remains nearly constant, analogous to current flow through a resistor (R). A novel aspect of this study is the introduction of an equivalent RLC transient circuit model to describe the dynamic behaviour of electrolysis current. In this model, the electrolysis process is represented by a series RLC circuit with a switch operating sequentially at 0 (inductor charging), t₁ (capacitor discharging), and t₂ (resistive steady state). To the best of our knowledge, this RLC-based interpretation of electrolysis current behaviour in the context of ERW and EOW production has not been previously reported.
Hydrolysis of Waste Cooking Oil Using Rhizopus oryzae to Produce Free Fatty Acids Manfaati, Rintis; Connery Manurung, Prans; Muhamad Nur Rojab; Keryanti, Keryanti
Fluida Vol. 16 No. 1 (2023): FLUIDA
Publisher : Department of Chemical Engineering, Politeknik Negeri Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35313/fluida.v16i1.4496

Abstract

Waste cooking oil is waste produced from palm oil after it has been heated and fried at high temperatures, and it can pollute the environment. One effort to reuse waste cooking oil is a fermentation processe that produces free fatty acids with the help of Rhizopus oryzae as a biocatalyst. Variations in initial substrate concentration ranged from 10 g/L to 70 g/L, followed by varied types of nitrogen sources, namely malt extract, beef extract, (NH2)2CO, NH4Cl, and (NH4)2SO4 at a concentration of 70 g/L to determine free fatty acid concentration. Fermentation was carried out for 7 days. The analysis carried out included the concentration of free fatty acids, biomass, and YP/X value. The optimum initial used cooking oil substrate was obtained at a concentration of 30 g/L with a YP/X value of 13.63%, a free fatty acid concentration of 2.13 g/L and a dry cell weight of 15.48 g/L. The best nitrogen source is beef extract with a Yp/x value of 11.78%, a free fatty acid concentration of 2.02 g/L and a dry cell weight of 17.0 g/L
A Comparative Study of Coconut Shell and Melinjo Shell as Carbon Sources for Bio-Briquette Production Augustina, Nadya; Manfaati, Rintis; Rizky, Alfiani; Yusuf, Yusmardhany; Adhitasari, Alfiana
Eksergi Vol 21 No 2 (2024)
Publisher : Prodi Teknik Kimia, Fakultas Teknik Industri, UPN "Veteran" Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31315/e.v21i2.10180

Abstract

The aim of this research was to investigate the influence of adding Melinjo shells on the quality and efficiency of charcoal-based bio-briquettes. A combination of coconut shells and Melinjo shells in various ratios was utilized in the study. The briquettes were produced through a carbonization process at a temperature of 300°C for 60 minutes, with tapioca flour used as a binder. Subsequently, the briquettes underwent testing to determine moisture content, ash content, volatile matter, and calorific value. The research findings indicated that all briquettes met the calorific value requirements set by the Indonesian National Standard (SNI), exceeding 5,000 cal/g. The addition of Melinjo shells resulted in a reduction in ash and volatile matter content but also led to a decrease in calorific value. Based on the analysis, the optimal composition obtained was 90 grams of coconut shells and 10 grams of Melinjo shells, producing briquettes with a calorific value of 5,582 cal/g, ash content of 3.76%, and volatile matter content of 6.65%. Therefore, further research is recommended to identify easily combustible components in Melinjo shells to ensure their potential in reducing the amount of ash produced when the briquettes are burned.
Utilization of Coconut Shell and Coffee Grounds as Briquettes Using the Carbonization Method Adhitasari, Alfiana; Manfaati, Rintis; Paramitha, Tifa; Zahwa, Keisya Adellia; Setiawan, Kiranna Shalmadevy; Yusuf, Yusmardhany
Eksergi Vol 22 No 3 (2025)
Publisher : Prodi Teknik Kimia UPN "Veteran" Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31315/eksergi.v22i3.15128

Abstract

Biomass-based briquettes offer a renewable energy alternative that can help reduce CO₂ emissions. Coconut shells and coffee grounds are promising waste materials due to their high calorific value. This study aimed to optimize the composition and carbonization time in producing briquettes from these two materials. The briquettes were prepared following SNI 01-6235-2000 and export briquette standards. The process included drying, carbonization at 300 °C for 60, 90, 120, 150, and 180 minutes, sieving, mixing, molding, and drying. Coconut shells and coffee grounds were mixed at weight ratios of 9:1, 8:2, 7:3, 6:4, and 5:5 with a total of 46.5 grams and 8.5 grams of adhesive. Briquette quality was evaluated based on moisture content, ash content, volatile matter, density, calorific value, and fixed carbon. The 9:1 composition yielded the highest calorific value of 6,472 cal/g, while a carbonization time of 90 minutes produced the best calorific value of 6,504 cal/g. The results show that a high proportion of coconut shells with limited coffee grounds and optimal carbonization time can produce briquettes with high energy potential, suitable for use as an alternative fuel.
Optimization of Agitation Speed and Aeration Rate for Fungal Protein Production from Tofu Whey Using Aspergillus oryzae in a Stirred Tank Bioreactor Keryanti, Keryanti; Manfaati, Rintis; Fauzan, Rizky; Ramadhani, Fauziah; Krista, Gustin Mustika; Ferawati, Yohana Fransiska; Santoso, Budi
Jurnal Teknik Kimia dan Lingkungan Vol. 10 No. 1 (2026): April 2026
Publisher : Politeknik Negeri Malang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.33795/jtkl.v10i1.7813

Abstract

Fungal protein, derived from microbial biomass, offers a sustainable protein source and can be produced through fermentation. However, the utilization of tofu whey, an abundant agro-industrial by-product in Indonesia, as a substrate for fungal protein remains underexplored. This study optimizing both agitation speed and aeration rate for Aspergillus oryzae fermentation in a stirred-tank bioreactor. Fermentation was conducted in a 5 L stirred-tank bioreactor with a 3 L working volume for 48 hours at an initial pH of 5 and a temperature of 35℃. Agitation speeds of 150, 200, 250, and 300 rpm were tested at a constant aeration rate of 1.0 vvm to determine the optimum mixing condition. The agitation speed that yielded the highest dry cell weight was then used as the basis for further aeration experiments (0, 0.5, 1.0, and 1.5 vvm). The optimum conditions were obtained at 150 rpm and 1.0 vvm, resulting in a dry cell weight of 7.1 g/L and a protein content of 6.83% (w/w). These findings demonstrate the potential of valorizing tofu whey into fungal protein while highlighting the need for further multi-parameter optimization to enhance protein levels toward single-cell protein standards.
Co-Authors Aida Fitri Aini Alfiana Adhitasari Andini Puspita Dewi Anggraeni, Nani Aqqilla Mardhiyana Ari Marlina Augustina, Nadya Baskoro, Hibah Connery Manurung, Prans Dede Dini Rahman Dwi Budi Santoso Ekki Kurniawan Fauzan, Rizky Ferawati, Yohana Fransiska Hariyadi, Tri Herliana, Hanafiah Hibah Baskoro Jangkung Raharjo Keryanti, Keryanti Krista, Gustin Mustika Muhamad Nur Rojab Muhammad Muhlis Rifai Neng Sri Widianti Nunung Kurniasih, Nunung Paramitha, Tifa Ramadhani, Fauziah Retno Indarti Rifai, Muhammad Muhlis Rispiandi Rispiandi Rizky, Alfiani Saripah Saripah Setiawan, Kiranna Shalmadevy Sudrajat Harris Abdulloh Tri Hariyadi Unung Leoanggraini Yulinda yulinda Yusuf, Yusmardhany Zahwa, Keisya Adellia