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Optimization of Acetone Concentration and Reflux Ratio for Enhanced Oil Extraction from Spent Bleaching Earth: A Response Surface Methodology Approach Monica, Clarissa Putri; Anggraeni, Verendria Putri Caesar; Sumada, Ketut; Sari, Ni Ketut; Pujiastuti, Caecilia
Indonesian Journal of Environmental Management and Sustainability Vol. 9 No. 4 (2025): December
Publisher : Magister Program of Material Science, Graduate School of Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/ijems.2025.9.4.183-191

Abstract

Spent bleaching earth with an oil content exceeding 3% is classified as hazardous and toxic waste, requiring appropriate processing prior to environmental disposal. Extraction is one effective method for processing spent bleaching earth. This study focuses on the optimization of oil extraction from spent bleaching earth using acetone as a solvent, specifically analyzing the effects of solvent concentration and reflux ratio on oil recovery efficiency and evaluating the quality of recovered bleaching earth for potential reuse in vegetable oil refining processes. The extraction method employed was soxhlet extraction using acetone as the solvent. Five different acetone concentrations (50%, 60%, 70%, 80%, and 90%) were tested in combination with five reflux ratios (2, 3, 4, 5, and 6), creating a total of 25 experimental conditions. Response surface methodology (RSM) was utilized to optimize these parameters and identify the ideal conditions for maximum oil recovery. The experimental design and statistical analysis were conducted using Design Expert 13.0.5.0 software. The quality of recovered bleaching earth was assessed against Indonesian National Standards (SNI) for potential reuse applications. The optimization results indicated optimal conditions of 69.15% acetone concentration and a reflux ratio of 4, yielding a maximum oil recovery rate of 17.52%. Analysis of the recovered bleaching earth showed that while it met most SNI standards for bleaching earth quality parameters, the pH remained acidic (below neutral), indicating that alkaline pretreatment would be necessary before the material could be effectively reused in vegetable oil bleaching processes. The study demonstrates that acetone-based soxhlet extraction can effectively recover oil from spent bleaching earth while producing a secondary product suitable for reuse after appropriate pH adjustment.
Sintesis Dan Karakterisasi Katalis Zeolit Basa Menggunakan Metode Hidrotermal Untuk Transesterifikasi Biodiesel Dharmawan, Valda Ashila; Muhammad Zainul Fata; Ni Ketut Sari
Jurnal Serambi Engineering Vol. 11 No. 2 (2026): April 2026
Publisher : Faculty of Engineering, Universitas Serambi Mekkah

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Abstract

Penelitian ini mensintesis dan mengkarakterisasi katalis zeolit basa melalui optimasi rasio Si/Al (1:1–5:1) sebagai x dan pH pencucian (7–11) menggunakan metode hidrotermal dengan komposisi molar 20 Na₂O : 8 Al₂O₃ : x SiO₂ : 400 H₂O. Pengujian aktivitas katalitik dilakukan melalui reaksi transesterifikasi minyak kelapa sawit dengan metanol pada suhu 70°C selama 180 menit. Response Surface Methodology (RSM) digunakan untuk menentukan kondisi optimal dengan yield biodiesel sebagai variabel respon. Hasil penelitian menunjukkan peningkatan rasio Si/Al dari 1:1-5:1 konsisten meningkatkan yield biodiesel pada seluruh rentang pH. Yield tertinggi sebesar 82,387% dicapai pada rasio Si/Al 5:1 dengan pH 9. Optimasi menggunakan Response Surface Methodology (RSM) dengan model kuadratik menghasilkan perolehan biodiesel optimal 82,537% pada rasio Si/Al 4,975 dan pH 8,912, dengan ketepatan model yang tinggi (R² = 0,9976, Adjusted R² = 0,9957, Predicted R² = 0,9844, dan desirability = 1,000). Karakterisasi SEM menunjukkan bentuk kristal oktahedral dengan ukuran partikel 4,569-14,000 μm, sedangkan analisis XRF memastikan rasio Si/Al aktual sebesar 2,28. Biodiesel yang dihasilkan memenuhi standar SNI 7182:2015 dengan massa jenis 877 kg/m³ dan viskositas kinematik 4,69 cSt, menunjukkan bahwa katalis zeolit basa mampu digunakan untuk proses transesterifikasi biodiesel.
Synthesis and Characterization of Hydroxyapatite from Crab Shell Waste (Scylla Serrata) Using the Precipitation Method Nisa, Assholihatun; Dinda Putri Arnindi; Ni Ketut Sari
Jurnal Serambi Engineering Vol. 11 No. 2 (2026): April 2026
Publisher : Faculty of Engineering, Universitas Serambi Mekkah

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Abstract

The utilization of crab shell waste as a calcium source represents a value-added material development strategy while simultaneously reducing environmental pollution from fishery waste. This study aimed to synthesize hydroxyapatite (HAp) derived from crab shell waste via the precipitation method and to evaluate the effect of calcination temperature (800, 900, 1000, 1100, and 1200 °C) and Na₂HPO₄ concentration (0.75, 1.3, 1.85, 2.4, and 2.95 M) on the resulting material characteristics. The crab shells were initially calcined to obtain CaO as the calcium source, followed by reaction with Na₂HPO₄ solution as the phosphate precursor to form hydroxyapatite. The synthesized product was subsequently dried and calcined according to the designated temperature variations. Characterization was carried out using XRF, XRD, and SEM analyses. XRF results indicated the dominance of Ca and P elements with a Ca/P ratio approaching the stoichiometric value of hydroxyapatite (1.67). XRD patterns confirmed the formation of crystalline HAp phases, with increasing peak intensity and sharpness at higher calcination temperatures, indicating an enhanced degree of crystallinity. Variations in Na₂HPO₄ concentration influenced phase purity and the Ca/P ratio. SEM analysis revealed sub-spherical particle morphology with a tendency toward agglomeration at higher temperatures due to sintering effects. Overall, the findings demonstrate that controlling calcination temperature and phosphate precursor concentration plays a critical role in determining the composition, crystallinity, and morphology of hydroxyapatite synthesized from crab shell waste.
Silika Gel Dari Sekam Padi Dalam Meningkatkan Kemurnian Bioetanol Ni Ketut Sari; Iva Muliatus Sohiva; Abdul Rouf
Jurnal Teknik Kimia Vol. 20 No. 1 (2025): JURNAL TEKNIK KIMIA
Publisher : Department of Chemical Engineering, Universitas Pembangunan Nasional Veteran Jawa Timur

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Abstract

Sekam padi adalah produk sisa yang berpotensi tinggi namun sering terabaikan. Kandungan silika yang sangat tinggi berkisar 87-97% sehingga dapat digunakan dan diolah mejadi berbagai produk dari industri teknologi hingga pertanian. Silika gel adalah salah satu produk berbahan baku silika yang merupakan material anorganik hasil polimerisasi asam silikat yang tersusun secara teratur. Silika gel juga salah satu adsorben hidrofilik yang dapat dimanfaatkan untuk meningkatkan kemurnian bioethanol. Tujuan dari penelitian ini adalah untuk membuat silika gel dari abu sekam padi dengan variasi pengenceran Natrium silikat dengan Aquades 1:3, 1:4, 1:5, 1:6 dan 1:7 (v/v) dan variabel waktu aging selama 3, 6, 9, 12 dan. 18 jam. Silika gel dianalisa kadar air, analisa FTIR, analisa SEM dan analisa kadar alkohol dari penggunaannya sebagai adsorben untuk meningkat kemurnian bioethanol. Hasil penelitian menunjukkan bahwa silika gel terbaik dari variasi 1:4 dan waktu aging 18 jam dengan kadar air 13,35% dan hasil FTIR paling mendekati silika konvensional(Kiesel gel 60G).
Optimization of aerobic fermentation of solid fertilizer from goat manure using response surface methodology (RSM) Rizna Aini Mandriana; Muhammad Tajul Mafachir; Mu'tasim Billah; Ni Ketut Sari; Ely Kurnianti; Suprihatin Suprihatin
Konversi Vol 15, No 1 (2026): APRIL 2026
Publisher : Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/k.v15i1.25810

Abstract

The increase in the goat population in Panceng District has resulted in an increase in the volume of goat waste which has the potential to pollute the environment if not managed properly. Goat manure has good nutrient content, but the high initial C/N ratio (30.47) indicates that the material is not yet stable and requires a fermentation process. This study aims to optimize the aerobic fermentation process using the Response Surface Methodology (RSM) with varying air flow rates (5–25 L/min) and oxidation times (16–24 days). The process was carried out in an in-vessel non-flow reactor with an active aeration system. Carbon content analysis using the Walkley–Black Modified Spectrophotometric method and nitrogen content analysis using the Kjeldahl Method and water content using the gravimetric method. The results showed that increasing the air flow rate and oxidation time caused a significant decrease in the C/N ratio from 30.47 to 11.52–17.62. The optimum conditions were obtained at an air flow rate of 20 L/min and an oxidation time of 22 days with a C/N ratio of 12.4769 and a water content of 23.3309%, and a desirability value of 1. These results show that optimization using RSM is able to produce solid organic fertilizer that meets SNI standards (<20).