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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 98 Documents
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The Influence of Aqua Regia Usage in the Leaching and Extraction Process of Silica from Coal Fly Ash Perwitasari, Perwitasari; Anggorowati, Heni; Ulfa, Uli; Shabrina, Husna Muizzati; Adhiatma, Agus
Equilibrium Journal of Chemical Engineering Vol 8, No 1 (2024): Volume 8, No 1 July 2024
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v8i1.86969

Abstract

Waste from coal-burning power stations and other sectors that rely on coal as a source of energy is one of the environmental issues. Fly ash obtained from burning coal causes pollution in the surrounding environment. Subsequently, a great deal of study was conducted on the application of flying ash coal. Among the techniques for making use of the flying ash of coal is the extraction of silica. This study carried out silica leaching using Aqua Regia (a combination of HCl and HNO₃) with various ratios of 1:1, 1:3, and 3:1. The leaching process was carried out at varying temperatures of 30, 45, 60, 75, and 90 °C, with a leaching time of 1 and 2 hours. Precipitates containing silica were analyzed for their levels using XRF. The results of the study show that the ratio HCl:HNO₃ 3:1 is able to extract more silica than other solvent ratios.Keywords:Silica, Fly Ash, Leaching, HCl, HNO₃
Green Energy from Palm Kernel Shell Gasification – dual fuel engine performance analysis Putro, Firman Asto; Pranolo, Sunu Herwi; Waluyo, Joko; Hantoko, Dwi; Aditama, Agapeano; Utomo, Mochamad Wahyu
Equilibrium Journal of Chemical Engineering Vol 8, No 1 (2024): Volume 8, No 1 July 2024
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v8i1.83497

Abstract

Electricity generation in Indonesia is mainly generated from non-renewable fuels. Based on these problems, this research utilizes palm kernel shells to be converted into producer gas as secondary fuel for a 5 kW diesel engine. Through a gasification process equipped with a cooling and gas cleaning system, low tar gas is fed to the diesel engine with variations of gas flow rate ratio to combustion air. A dummy load is installed to investigate the effect of load on diesel consumption. The diesel engine vibration increases due to using two fuel types was measured by installing a vibration meter. The research results show that the higher the load and the greater the ratio of producer gas injected, the less diesel consumption. At a gas ratio of 4:1 and an increase of load from 1 to 5 kW, the diesel fuel flow rate reduces by 25 - 31%. The most significant reduction in diesel consumption occurred at a load of 5 kW, valued at 38.49%. On the other hand, increasing the gas ratio causes an increase in diesel engine vibration. The research results showed an increase in engine vibration of 5.84% - 10.25%. The largest vibration was recorded at a load of 5 kW with a value of 92.4 m/s².Keywords:Gasification, Palm Kernel Shell, Dual Fuel Engine, Diesel Consumption, Diesel Engine Vibration
Bead Gel Preparation from Cassava Baggase Grafted Acrylamide and Carrageenan Distantina, Sperisa; Banowati, Dea Espina; Aprian, Laura Hanifa; Kaavessina, Mujtahid
Equilibrium Journal of Chemical Engineering Vol 8, No 2 (2024): Volume 8, No 2 December 2024
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v8i2.85999

Abstract

Abstract. This research intends to prepare bed gels for medium of plant growth. Bead gels were prepared by grafting cassava bagasse by acrylamide with ammonium persulfate (APS) as the initiator using microwave energy. This research aims to examine the effect of the ratio of acrylamide to APS initiator on the swelling capacity. Briefly, cassava bagasse powder 1 g in 80 ml distilled water was mixed with acrylamide and APS to form grafted polimer by applying microwave. The resulted grafted polymer powder then was mixed with carrageenan to create bead gels. The formed bead gel was soaked in distilled water to test the swelling capacity. The highest swelling capacity in this research is 1183.333% at a ratio of 0.1 g APS : 15 g acrylamide and 1213.33% at a ratio of 10 g acrylamide : 0.1 g APS. Therefore, the swelling capacity increases with an increase in the ratio of acrylamide and APS. From the results of swelling capacity and FTIR, it can be concluded that the grafting process of cassava bagasse and acrylamide has been successfully conducted. Keywords:Ammonium persulfate, Bead gel, Grafting microwave, Swelling capacity, Cassava bagasse
Utilization of Indigofera tinctoria L. Waste for the Production of Environmentally Friendly Biobriquettes Waluyo, Joko; Abimanyu, Fachri Candra; Wardhani, Anindhea Sitta Kusuma; Pradani, Dhiah Cendikia; Prasetyo, Fahri Chandra; Widharmo, Frizas Yardena; Utami, Helvita Fajar; Utomo, Septian Warsito
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.v10i1.98010

Abstract

Indigofera tinctoria L. is a natural source of blue dye widely used in various industries, particularly in the textile sector. One of the industries utilizing Indigofera tinctoria L. as a natural dye is CV Indigo Biru Baru, based in Puron Village, Bulu District, Sukoharjo. This company specializes in the production of batik fashion. The waste generated from processing Indigofera tinctoria L. produces significant volumes of organic material, which often goes underutilized and poses a potential environmental pollution risk. This study aims to optimize this waste by converting it into biobriquettes as an alternative fuel source. The production process involves pyrolyzing the waste at temperatures of 300–350℃ for 2 hours, followed by binding with tapioca starch paste at a 10:1 ratio, molding, and quality testing based on SNI (Indonesian National Standard). The biobriquette characterization includes proximate analysis, calorific value measurement, drop test, and yield evaluation. The results showed a moisture content of 6.9665%, ash content of 7.2025%, volatile matter content of 33.522%, fixed carbon content of 52.309%, and a calorific value of 5438.902 cal/g. Meanwhile, the hardness test indicated that only 0.042% of the mass was lost during the drop test, demonstrating excellent physical durability. With its high calorific value and superior physical characteristics, this biobriquette exhibits great potential as a renewable fuel to support sustainable energy transition in Indonesia.
Purification Optimization of Biodiesel Derived from Glyceroxide-Catalyzed Transesterification Azura, Nur; Prakoso, Tirto; Pratiwi, Meiti
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.v9i2.113221

Abstract

ABSTRACT. The washing stage is a critical step in biodiesel purification because it determines the total glycerol and water contents, which directly affect final fuel quality. This study aims to optimize the washing conditions of biodiesel produced from palm oil transesterification using sodium glyceroxide catalyst and to compare its characteristics with biodiesel produced using NaOH catalyst. Optimization was carried out using the Response Surface Methodology (RSM) with a Central Composite Design (CCD), in which the washing water to biodiesel ratio and washing temperature were used as independent variables, while total glycerol content and biodiesel water content were used as response variables. ANOVA analysis indicated that the quadratic model was statistically significant for both responses (p < 0.05), with the washing water to biodiesel ratio being the most dominant factor. The surface and contour plots revealed non-linear behavior at each optimization point. The optimum washing conditions were achieved at a water to biodiesel ratio of 1:1.9 and a washing temperature of 59 oC. The washing results demonstrated that biodiesel produced using sodium glyceroxide catalyst had lower total glycerol content and water content compared to biodiesel using NaOH catalyst, with reductions of 14.28% and 16.30%, respectively. These findings indicate that the use of sodium glyceroxide catalyst produces biodiesel that is easier to purify through the washing process and has better overall quality compared to biodiesel produced with NaOH catalyst. Keywords:Biodiesel, CCD, RSM, Sodium glyceroxide, Washing
Utilization of Wasted Cooking Oil and Essential Oil of Sweet Orange Peel (Citrus sinensis) as Aromatherapy Candles Ramadhani, Aida Nur; Malik, Arnanda Fadillah; Fitriana, Wina Rahma
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.v7i2.80308

Abstract

Abstract. Utilizations of waste cooking oil can be projected to be candles. Sweet orange (Citrus sinensis) peel, considering the large amount of this abandoned waste, also can be utilized as essential oil. This research was conducted to examine the production of aromatherapy candles by purifying the wasted cooking oil and adding the sweet orange peel essential oil. Steam distillation method was used to extract essential oils by determining the effect of raw material conditions on the yield obtained. The essential oils obtained from fresh peel was 1.87% of yield with 94.37% limonene, while dry one was 2.16% yield with 94.67% limonene by GC-MS analysis. Adsorption method by activated carbon was carried out to purify the wasted cooking oil as candle materials, varied by 7%, 10%, and 13% mass of activated carbon. The addition of the highest mass of activated carbon gave the lowest absorbance and indicated that the purified oil was the brightest. Utilization of refined wasted oil was mixed with stearin and sweet orange peel essential oil of 2%, 4%, and 6% by weight as aromatherapy candle product. Characteristics of candle was investigated by analyzing the melting point, burning time, organoleptic, and preference test for respondents and resulted that all characters meet Indonesian National Standard. Purification of wasted cooking oil varied by activated carbon mass influenced the color of the candles. The addition of essential oils influenced the smell, melting point and burning time of candle, the essential oil addition makes lower melting point and faster burning time.Keywords:Aromatherapy Candles, Sweet Orange Peel Essential Oil, Wasted Cooking Oil
Review: Advances in Magnetic Biochar-Based Cellulase Immobilization Systems for Enhancing Hydrolysis Efficiency in Second-Generation Bioethanol rahmadani, nessi
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.v10i1.113891

Abstract

Second-generation bioethanol production utilizes abundant lignocellulosic biomass, such as agricultural residues and woody materials, without competing with food resources. Enzymatic hydrolysis of cellulose into glucose using cellulase is more environmentally friendly than conventional chemical methods; however, the practical application of free cellulase is often limited by low operational stability, sensitivity to temperature and pH fluctuations, and inhibition by compounds generated during biomass pretreatment. To address these challenges, enzyme immobilization on solid supports has been extensively investigated as an effective approach to enhance enzyme stability and enable repeated use. The incorporation of magnetic particles, typically Fe₃O₄, into biochar results in magnetic biochar, which enables rapid separation from the reaction medium using an external magnetic field and facilitates enzyme recovery and reuse. This review summarizes recent studies published between 2020 and 2025 on the application of magnetic biochar as a support for cellulase immobilization to improve the efficiency of lignocellulosic hydrolysis. Reported results demonstrate high enzyme loading capacities (up to approximately 484 mg g⁻¹ biochar), glucose yields exceeding 90%, and retention of more than 80% of enzymatic activity after 5–10 reuse cycles. Overall, magnetic biochar-based immobilization significantly enhances the thermal and pH stability of cellulase, contributing to a more efficient and economically viable saccharification process for second-generation bioethanol production.
Comparative Study of Biomass Gasification for Electricity and Methanol Production Al Rizqi, Muhammad Aldiansyah; Cahyari, Khamdan; Adnan, Muflih Arisa
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.v9i2.106863

Abstract

ABSTRACT. The Indonesian government has established several programs and policies to support the development of new and renewable energy as part of the energy transition and carbon emission reduction efforts, with a national energy mix target of 23% in 2025 and 31% in 2050. Based on data released by the Central Statistics Agency of Indonesia in 2023, East Java has a wealth of sugar cane, rice, and corn kernels of 1,129,000 tons, 9,591,420 tons, and 5,991,810 tons, respectively. Therefore, biomass wastes are attractive as a gasification feedstock. Electricity and methanol are commodities that can support the government. This study evaluated and compared both the technical performance and economic feasibility between various combinations of biomass waste feed scenarios from bagasse, rice husk, and corncob to produce various combinations of product scenarios using Aspen Plus V14 simulation which constitutes the novelty of this research. The evaluation process was conducted using the Aspen Plus V14. The operating conditions of the gasification process were determined through a sensitivity analysis of key process variables, namely temperature, pressure, and steam-to-biomass ratio, to identify their effects on the optimal composition of the produced syngas. The utilization of syngas for electricity and methanol production was also simulated using Aspen Plus V14, where the operating conditions and resulting products were evaluated based on the required energy input and the corresponding carbon emissions. The economic feasibility of the process was assessed using key financial indicators, including payback periods, Return on Investment (ROI), Internal Rate of Return (IRR), and Net Present Value (NPV). The evaluation results indicate that single feed scenario from corncob is technically and economically feasible to produce methanol and electricity under separate production scenarios. Bagasse is feasible for electricity generation, while the other biomass scenarios did not meet the evaluation criteria.Keywords:Biomass, Electricity, Methanol, Syngas,Economic
Performance and Pressure Drop Study on Shell and Tube and Double Pipe Heat Exchangers Da Silva, Teodora Maria Fernandes Brito
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.v10i1.111008

Abstract

This study aims to analyze the performance and pressure drop of shell-and-tube and double-pipe heat exchangers. Tests were conducted using water as the hot and cold fluid. The flow rate variations used were 0.8 GPM, 1.0 GPM, and 1.2 GPM. The main parameters analyzed were the pressure drop values on the shell and tube sides for the shell-and-tube type and on the inner and outer pipes for the double-pipe type. The results showed that increasing the flow rate caused an increase in pressure drop in both types of heat exchangers. In the shell-and-tube type, the highest pressure drop was 0.017 psi at a flow rate of 1.2 GPM, while in the double-pipe type, it was 0.0101 psi at the same flow rate. These values are still far below the maximum allowable limit of 10 psi, so both devices are still feasible to operate. The relationship between the parameters (DG/μ)av and (ΔP)av shows an increasing trend with increasing fluid mass rate, indicating that viscosity and flow velocity affect pressure loss along the heat exchanger.
Characteristic of the CaO-MgO Material Derived from Dolomite via Precipitation-Dehydration Method Matovanni, Maudy Pratiwi Novia; Sumada, Ketut; Muljani, Srie; Pertiwi, Beta Cahaya
Equilibrium Journal of Chemical Engineering Vol 9, No 1 (2025): Volume 9, No 1 July 2025
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v9i1.104095

Abstract

Abstract. This research utilized dolomite rock (CaMg(CO2)2) to produce CaO-MgO material using precipitation-dehydration. The precipitation-dehydration method was carried out by dissolving dolomite in 10% hydrochloric acid (HCl) solvent and precipitating in 2 N sodium hydroxide (NaOH) solution at a temperature of 80 oC. The resulting products were analyzed using Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX) and Brunauer-Emmett-Teller (BET). The acidity level of the solution was analyzed by using a pH meter. The analysis results using SEM-EDX show that the material has a characteristic chemical composition with a Ca/Mg ratio less than 1. The results of BET show that the average surface area, average pore volume, average pore size and average particle diameter are 71.1213 m2/g, 0.1081 cc/g, 20.5165 nm, and 36 nm, respectively. The solution's acidity (pH level) in precipitation-dehydration is 8-8.5. It is identified that precipitation-dehydration can be used for CaO-MgO recovery and further application in catalyst materials.Keywords:Dolomite rock, Calcium oxide, Magnesium oxide, Precipitation-dehydration

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