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Ketalization of Glycerol and Acetone to Solketal: Effect of Temperature, Concentration & Mathematical Model Fikrah Dian Indrawati Sawali; Moh Azhar Afandy; Mega Mustikaningrum; Rara Ayu Lestary
IPTEK The Journal of Engineering Vol. 11 No. 1 (2025)
Publisher : Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12962/j23378557.v11i1.a22642

Solketal is a viable method for using glycerol, a by-product of biodiesel production. This study aims to identify the optimal operating parameters for solketal compounds generated from the glycerol ketalization reaction with acetone by using mathematical models that effectively forecast an appropriate framework for this process. This research consists of three critical phases: the ketalization reaction of glycerol with acetone, the characterization of the result solketal products, and the ketalization reaction utilizing the Amberlite IR 120 Na catalyst. The process begins by introducing glycerol and acetone in a mole ratio of 1:3, followed by mechanical Stirring at 500 rpm. The temperature is regulated using a water bath to maintain a constant reaction temperature under specified conditions of 20 °C, 120 °C, 150 °C, and 180 °C, with catalyst masses of 1%, 3%, 5%, and 7%. The mathematical model used is of exponential and polynomial order 2. The findings indicated that the optimal glycerol conversion of 46.01% was attained at 50 °C, using a 5% catalyst concentration throughout a reaction duration of 120 minutes. Second-order polynomial regression is the most appropriate mathematical model to represent this process.

Review: Advances in Magnetic Biochar-Based Cellulase Immobilization Systems for Enhancing Hydrolysis Efficiency in Second-Generation Bioethanol Nessi Rahmadani; 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.v10i1.113891

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.Keywords: Cellulase, enzyme immobilization, magnetic biochar

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. 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

Elektro-Fenton sebagai Pra-pengolahan POME Menggunakan Elektroda Fe-Grafit: Keunggulan pH Alami dan Analisis Kinetika Nita Widyastuti; Rara Ayu Lestary; Sri Mundarti; Ra'ida Raudhatussya'rifah; Hadistya Suryadri; Oki Alfernando; Nazarudin; Perdana Alfarez; Rifan Rizki
Jurnal Teknik Kimia USU Vol. 15 No. 2 (2026): Jurnal Teknik Kimia USU
Publisher : Talenta Publisher (Universitas Sumatera Utara)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32734/jtk.v15i2.23718

Palm Oil Mill Effluent (POME) with high COD concentrations (15,000–100,000 mg/L) poses significant environmental risks. This study evaluates the electro-Fenton method using Fe-graphite electrodes as a POME pretreatment unit. The impact of initial pH (4, 5.5, and 7) was examined under fixed conditions: 0.4 A current, 60-minute duration, 0.425 H₂O₂/COD ratio, 300 rpm stirring, and 3 cm electrode spacing. Results indicated the highest COD degradation at pH 7 (34.00%), followed by pH 4 (28.22%) and pH 5.5 (21.55%). The process at pH 4 was best described by a first-order kinetic model (R² = 0.8936). The novelty of this work lies in the effectiveness of the system at natural POME pH (pH 4), enabling significant degradation without pH adjustment to enhance economic feasibility. Furthermore, an 11 oC temperature rise from Joule heating accelerated hydroxyl radical (•OH) diffusion. This method shows promise as an efficient POME pretreatment for biological process integration.

Elektro-Fenton sebagai Pra-pengolahan POME Menggunakan Elektroda Fe-Grafit: Keunggulan pH Alami dan Analisis Kinetika Nita Widyastuti; Rara Ayu Lestary; Sri Mundarti; Ra'ida Raudhatussya'rifah; Hadistya Suryadri; Oki Alfernando; Nazarudin; Perdana Alfarez; Rifan Rizki
Jurnal Teknik Kimia USU Vol. 15 No. 2 (2026): Jurnal Teknik Kimia USU
Publisher : Talenta Publisher (Universitas Sumatera Utara)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32734/jtk.v15i2.23718

Palm Oil Mill Effluent (POME) with high COD concentrations (15,000–100,000 mg/L) poses significant environmental risks. This study evaluates the electro-Fenton method using Fe-graphite electrodes as a POME pretreatment unit. The impact of initial pH (4, 5.5, and 7) was examined under fixed conditions: 0.4 A current, 60-minute duration, 0.425 H₂O₂/COD ratio, 300 rpm stirring, and 3 cm electrode spacing. Results indicated the highest COD degradation at pH 7 (34.00%), followed by pH 4 (28.22%) and pH 5.5 (21.55%). The process at pH 4 was best described by a first-order kinetic model (R² = 0.8936). The novelty of this work lies in the effectiveness of the system at natural POME pH (pH 4), enabling significant degradation without pH adjustment to enhance economic feasibility. Furthermore, an 11 oC temperature rise from Joule heating accelerated hydroxyl radical (•OH) diffusion. This method shows promise as an efficient POME pretreatment for biological process integration.

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