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Equilibrium Journal of Chemical Engineering
Published by Universitas Sebelas Maret
ISSN : -     EISSN : 26223430     DOI : https://dx.doi.org/10.20961/equilibrium.v4i1.42852
Core Subject : Science, Engineering,
Chemical Engineering, Chemistry & Bioengineering Chemistry Energy Engineering Materials Science & Nanotechnology
Equilibrium Journal of Chemical Engineering (EJChE) publishes communication articles, original research articles and review articles in :. Material Development Biochemical Process Exploration and Optimization Chemical Education Chemical Reaction Kinetics and Catalysis Designing, Modeling, and Process Optimization Energy and Conversion Technology Thermodynamics Process System Engineering and products Membrane Technology Food Technology Bioprocess Technology Chemurgy Technology Waste Treatment Technology Separation and Purification Technology Natural Dyes Technology
Arjuna Subject : Teknik Kimia (semua kategori) - Kimia Proses dan Teknologi
Articles 100 Documents
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Study on the Effect of Cyanide Concentration on Gold Leaching Recovery in Ore at PT Indo Muro Kencana Putri GF, Frideni Yushandiana; Karimah, Armitha Lisanul; ., Sulaeman
Equilibrium Journal of Chemical Engineering Vol 7, No 2 (2023): Volume 7, No 2 December 2023
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v7i2.77833

Abstract

ABSTRACT. Indonesia is a country that has abundant natural resources, including non-renewable natural resources such as various types of metals, natural gas, petroleum and others. Besides that, Indonesia also has an important role in supplying the world's gold raw materials. Therefore, it is necessary to develop technology and science in the mining industry, especially gold to increase process optimization and increase the added value of the mining products themselves. One of the gold extraction processes can be carried out hydrometallurgically using the cyanidation method using agitator leach, as was done at PT Indo Muro Kencana. Process optimization is carried out with various test work, such as leaching tests, by varying the operating parameters of the leaching. The variations of parameters used in this study are the cyanide concentrations at 600 ppm, 700 ppm, and 800 ppm. The results of the analysis show that the optimal cyanide concentration for leaching of PT Indo Muro Kencana's gold ore is 600 ppm by controlling the Rate rate control.Keywords:Cyanidation, Gold, Leaching, Extraction.
Gamma Spectrometric Analysis of Natural Radionuclides and Radiological Hazards in Ilmenite Sand Esther Mutiara Santallum Ekklesia Tibalia; Farida Diyah Hapsari; Tamaratritania Citta Trisnantari; Geraldi Rahanra; Muhammad Ikhsan Taipabu
Equilibrium Journal of Chemical Engineering Vol 10, No 1 (2026): Volume 10, No 1 July 2026 (First Online)
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v10i1.116251

Abstract

Ilmenite sand, categorized as Naturally Occurring Radioactive Material (NORM), contains radionuclides derived from the uranium and thorium decay series. The present work investigates radionuclide concentrations in ilmenite sand collected from a mineral processing facility to evaluate associated radiological hazards using gamma spectrometry. Activity measurements were performed with a gamma spectrometry system calibrated for energy and efficiency using a Eu-152 reference source. Environmental background radiation was measured separately to correct spectral data during analysis. Prior to measurement, samples were dried, homogenized, and sealed in airtight containers to establish radioactive equilibrium between parent radionuclides and their progeny. Radionuclide activities were quantified based on characteristic gamma-ray peak energies. The measured activity concentrations were 472.98 Bq/kg for Ra-226, 302.20 Bq/kg for Th-232, and 10.68 Bq/kg for K-40. Radiological hazard parameters, including radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin), and absorbed dose rate, were subsequently calculated. The estimated annual effective dose was 0.492 mSv/year, remaining below the recommended public exposure limit of 1 mSv/year. These findings indicate that, despite relatively elevated radionuclide activities, the resulting radiation exposure levels remain within acceptable safety limits. Overall, gamma spectrometry demonstrates reliable capability for radionuclide identification and radiological risk assessment in mineral-based materials.
Polymers as Versatile Excipients Drug Delivery in Pharmaceutical Formulations: Innovations, Challenges, and Future Prospects Maudy Pratiwi Novia Matovanni; Yusri Risyad Sulaiman; Joanne Rizma Pramitha; Teodora Merry Meriba V.J. Br. Lumban Raja; Gefira Anelia Fauzi
Equilibrium Journal of Chemical Engineering Vol 9, No 2 (2025): Volume 9, No 2 December 2025
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v9i2.103724

Abstract

ABSTRACT. Polymers have become essential excipients in pharmaceutical formulations, significantly enhancing drug delivery systems due to their versatility, biocompatibility, and specialized properties. This review discusses the role of natural  and synthetic polymers, which are favored for their biodegradability and ability to improve drug stability and controlled release. The paper highlights innovations in polymer-based drug delivery, including the development of stimuli-responsive polymers that release drugs in response to specific environmental triggers and the integration of natural and synthetic polymers to create hybrid systems. Despite the advantages, challenges such as variability in natural polymer sources, potential toxicity of synthetic polymers, and regulatory hurdles remain. Future prospects include advancements in green and sustainable polymers, personalized medicine, and the use of nanotechnology to enhance drug delivery efficacy. This comprehensive examination underscores the importance of interdisciplinary research in overcoming existing barriers and advancing polymer-based drug delivery systems to improve patient outcomes. Keywords:Polymer, Drug delivery, Natural polymer, Synthetic polymer, Stimuli-responsive
Effect of Temperature in Deep Eutectic Solvent on Chemical Composition and Structure of Lignocellulose from Corncob Yusi Prasetyaningsih
Equilibrium Journal of Chemical Engineering Vol 9, No 2 (2025): Volume 9, No 2 December 2025
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v9i2.114543

Abstract

Agricultural waste biomass has significant potential and can be processed into high-value materials. Corncobs are a biomass source with high cellulose content. Processing lignocellulosic biomass is challenging due to the complex molecular structure of the bonds. Deep Eutectic Solvents (DES) are used to break the lignin bonds of corncob lignocellulose. The delignification process using ChCl-urea at temperatures of 80 °C, 95 °C, and 110 °C for 6 hours was carried out to determine the chemical composition of corncobs before and after pretreatment. The highest cellulose content of 59.85% was obtained at 110 °C. The kinetic energy of molecules increases with higher temperatures, leading to more effective collisions. The cellulose content increases due to the breaking of ether bonds in lignin and glycosidic bonds in polysaccharides, as shown in the FTIR spectra. XRD analysis shows that the crystallinity of corncobs increases after DES pretreatment. In short, this study provides a simple and green method to prepare cellulose and an efficient utilization route of corncob.
Optimization of Chemical Dosage in External Water Treatment Plant Yulisa Nurvera Silaban; Gani Supriyanto; Rengga Arnalis Renjani
Equilibrium Journal of Chemical Engineering Vol 9, No 2 (2025): Volume 9, No 2 December 2025
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v9i2.107185

Abstract

ABSTRACT. This research focuses on determining the optimal doses of aluminum sulfate (Al₂(SO₄)₃) and soda ash (Na₂CO₃) in the water treatment process at the External Water Treatment Plant (EWTP). Improper use of chemicals can lead to waste and negative environmental impacts. Therefore, the jar test method was employed to evaluate the effect of various dose ratios on water quality parameters, including pH, Total Dissolved Solids (TDS), and turbidity. The study results indicate that the combined doses of alum and soda ash significantly impact all three water quality parameters. The optimal point is achieved at an alum:soda ash dose ratio of 1.24–1.26. This ratio provides the best balance between increasing pH, decreasing turbidity, and controlling TDS. Consequently, this research offers important recommendations for enhancing the efficiency and sustainability of the water treatment process.  Keywords:Aluminum sulfate, Optimum dose, Water quality, Soda ash, Water treatment plant
ANALYSIS OF AMMONIA ASSIMILATION KINETICS AND DETERMINATION OF SUBSTRATE INHIBITION CONDITIONS IN VARIATIONS OF MOLASSES DOSE IN A BATCH REACTOR SYSTEM Muhammad Iqbal Putra; Rizky Ibnufaatih Arvianto; Suhirman Suhirman; Adna Ivan Ardian; Denanda Clarasati Puteri; Dennis Farina Nury; Muhammad Zulfikar Luthfi; Maghfira Arum Lestari
Equilibrium Journal of Chemical Engineering Vol 10, No 1 (2026): Volume 10, No 1 July 2026 (First Online)
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v10i1.115734

Abstract

The purpose of this study is to find the inhibitory phenomena caused by an excessive organic load and to estimate the ideal molasses dosage for ammonia assimilation by Saccharomyces spt. The experiment was carried out utilizing a batch reactor system with different molasses doses of 0, 5, 10, 15, and 20 mL at a constant starting ammonia content of 50 mg/L. Ammonia assimilation followed a pseudo-first-order model with a significant coefficient of determination R2 > 0.90 in the active dose range, according to the kinetic studies. The results confirmed that a dose of 10 mL was the optimum condition, producing the highest reaction rate constant (k) of 0.5107 day-1 and an ammonia reduction efficiency of 93.58%. On the other hand, raising dosage 20 mL caused a substrate inhibition phenomenon, which was marked by a drop in the k value to 0.2268 day-1 and a low ammonia reduction efficiency of 58.42% because of the initial acidification. The ammonia removal rate and biomass concentration (MLSS) had a very strong positive linear connection (r=0.98) according to Pearson correlation analysis, indicating that nitrogen assimilation with biomass growth-rather than physical volatilization-is the primary mechanism of removal. In order to optimize ammonia absorption performance without causing environmental toxicity, this study suggests a dose of 10 mL.
The Impact of Inject Chemical Neutralization toward the PH Change in the Reject Water Management on the Raw Water Treatment Facilities in Petrochemical Industries Rachmadi Tutuka; Ferry Ikhsandy; Rohiman Ahmad Zulkipli; Alamul Iman; Rizky Ibnufaatih Arvianto
Equilibrium Journal of Chemical Engineering Vol 9, No 2 (2025): Volume 9, No 2 December 2025
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v9i2.107710

Abstract

ABSTRACT. The water waste management in Petrochemical Industry becomes the significant challenge in maintain environmental quality—particularly in regulating pH levels in accordance with the standards set by Indonesia’s Ministry of Environment and Forestry Regulation No. 5 of 2014—chemical injection is widely employed. This method involves the addition of acidic or alkaline agents to neutralize the pH of reject water. This study evaluates the effect of varying chemical injection dosages to determine the optimal dose required to achieve a pH range of 6 to 9. The findings demonstrate a direct relationship between the increase in chemical injection dosage and changes in pH levels, where higher dosages consistently raised the pH, stabilizing at an average value of 8.2. Over a one-month monitoring period, the optimal dosage was identified as 0.085 m³, resulting in an average pH of 6.47. Excessive dosing is not only less effective but also led to increase operational costs, reaching up to IDR 872,235. Thus, optimizing chemical injection dosage is critical—not only for ensuring compliance with environmental pH standards but also for minimizing chemical consumption and reducing operational expenditures.Keywords:Inject chemicals, Wastewater treatment, pH, Reject water
Analysis Of Recent Research In Solketal Synthesis Toward Circular Economy : A Review Adna Ivan Ardian; Tamaratritania Citta Trisnantari; Dennis Farina Nury; Rizky Ibnufaatih Arvianto; Suhirman Suhirman
Equilibrium Journal of Chemical Engineering Vol 10, No 1 (2026): Volume 10, No 1 July 2026 (First Online)
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v10i1.113030

Abstract

Indonesia’s growing biodiesel production has caused a large surplus of crude glycerol, which becomes both an economic and environmental problem. The study present a systematic chemical engineering perspective on how glycerol can be transformed into solketal, a compound that can act as a biofuel additive and green solvent. The discussion is based on a systematic reading method of twelve research papers published between 2018 and 2024, specifically discuss the development of catalysts related to this process. The contrasting performance between catalyst efficiency and its industrial implementation become a concern. It shows Zeolites and MOF catalyst exceed other types of catalysts by using process intensification in laboratory. But in contrast, their stability lower when associated with impurities found in feedstock, followed by heat-related problems. On the other side, simple and cheaper catalysts such as acid-treated clays still show steady activity even in less clean feedstocks, making them more realistic for larger scale operation. The review also points out that improving catalyst lifetime and using new process approaches like microwave heating are important to make the process more economical. Overall, this study suggests that creating catalysts which can resist impurities together with better process design is necessary to make glycerol utilization more sustainable and in line with Indonesia’s circular economy plan.
Performance Analysis of a 1-1 Shell-and-Tube Intercooler for Compressed Air Cooling Systems Farida Diyah Hapsari; Hana Nikma Ulya; Esther Mutiara Santallum Ekklesia Tibalia; Sabrianah Badaruddin; Alif Nur Laili Rachmah
Equilibrium Journal of Chemical Engineering Vol 10, No 1 (2026): Volume 10, No 1 July 2026 (First Online)
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v10i1.116048

Abstract

This study presents an evaluation of a 1-1 shell-and-tube heat exchanger (Intercooler-2) utilized in a multi-stage air compressor. The evaluation was conducted using plant operational data and classical heat exchanger analysis methods, including heat balance, overall heat transfer coefficient under clean (Uc) and operating (Ud) conditions, dirt factor (Rd) and pressure drop (ΔP). The calculation results show a heat transfer rate of 557,640.622 Btu/h with a true temperature difference of 113.774 °F, indicating an adequate thermal driving force. The flow on the shell side is in the turbulent regime (Re ≈ 79,952), while the tube side shows laminar flow (Re ≈ 829), which limits the optimization of convective heat transfer of water as a cooling medium. The overall heat transfer coefficient under clean conditions of 25.627 Btu/h.ft².°F decreased to 23.125 Btu/h.ft².°F due to a fouling factor (Rd) of 0.004. The pressure drop values on both sides are still well below the permitted limits, so the unit is declared operationally feasible. However, the presence of fouling and laminar flow regime on the tube side indicates the potential for performance improvement thru optimization of water flow rate and periodic cleaning. This study emphasizes the importance of periodic performance evaluation to maintain the efficiency and reliability of heat exchanger operations in air compression systems.
Characterization and Application of Activated Carbon from Palm Oil Fuel Ash (POFA) Activated with H₃PO₄ for Surfactant Adsorption in Household Laundry Waste: Review Article Shofie Chandra Ningtyas; Glen Laura Situmorang; Hadistya Suryadri; Rara Ayu Lestary; Rosmawati Sipayung
Equilibrium Journal of Chemical Engineering Vol 10, No 1 (2026): Volume 10, No 1 July 2026 (First Online)
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v10i1.113459

Abstract

ABSTRACT. The rapid growth of laundry businesses has increased the generation of wastewater containing surfactants, particularly Linear Alkyl Benzene Sulfonate (LAS), which can negatively affect aquatic ecosystems if discharged without proper treatment. Adsorption is considered one of the most effective and economical methods for surfactant removal. Palm Oil Fuel Ash (POFA), a by-product of the palm oil industry with high silica content, has attracted attention as a potential precursor for activated carbon. However, studies discussing the characteristics and adsorption performance of H₃PO₄-activated POFA for surfactant removal from household laundry wastewater remain limited and scattered. This review was conducted by analyzing 30 national and international publications published between 2021 and 2025, collected from Google Scholar, ScienceDirect, and other scientific databases using keywords related to POFA, H₃PO₄ activation, surfactants, and adsorbents. The reviewed literature shows that H₃PO₄ activation significantly improves the physicochemical properties of POFA by increasing surface area and pore volume, introducing active functional groups, and enhancing its amorphous structure. Characterization through BET, FTIR, and XRD analyses confirms its suitability as an adsorbent. Previous studies also reported high removal efficiencies for surfactants, COD, BOD, phosphates, and heavy metals, indicating the effectiveness of activated carbon-based adsorption processes. In conclusion, H₃PO₄-activated POFA has strong potential as an environmentally friendly and value-added adsorbent for laundry wastewater treatment. Further experimental studies are required to optimize activation conditions and evaluate adsorption performance under practical operating conditions.Keywords: Palm oil fuel ash (pofa), H₃PO₄  activator, Surfactant, Laundry waste, Environmentally friendly adsorbent

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