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All Journal Jurnal Ilmiah Teknik Kimia
Nita Widyastuti
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Chemical Engineering, Chemistry & Bioengineering Chemistry

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MODEL MATEMATIKA EKSTRAKSI COFFEE OIL DARI LIMBAH AMPAS KOPI BERDASARKAN PERBEDAAN TEMPERATUR Mega Mustikaningrum; Rara Ayu Lestary; Nita Widyastuti; Fikrah Dian Indrawati Sawali
Jurnal Ilmiah Teknik Kimia Vol. 9 No. 1 (2025): JURNAL ILMIAH TEKNIK KIMIA
Publisher : Program Studi Teknik Kimia, Universitas Pamulang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32493/jitk.v9i1.44507

Abstract

In the past decade, coffee productivity, particularly instant coffee production, has experienced significant growth. This increase has generated more coffee grounds as a by-product, which is now widely utilized in the cosmetics and energy sectors, especially for producing coffee oil. Optimization of coffee oil isolation methods continues to be developed to improve efficiency. This study aims to obtain optimal values for the coffee oil diffusivity parameter (Da) and extraction rate constant (k). Coffee grounds extraction was performed using Hexane solvent with the aid of ultrasonic waves through a bath-type sonicator. The research was conducted with variations in temperature (30°C and 40°C) and extraction time (30, 60, 90, and 120 minutes). The research results showed that the coffee oil diffusivity values at temperatures of 30°C and 40°C were 9.93 x 10⁻¹⁰ and 9.99 x 10⁻¹⁰ dm²/s, respectively. The extraction rate constants obtained at each temperature were 0.450 and 0.667 dm/s.
Transformation of Agricultural Waste into Silica–Cellulose Microsponge Adsorbent for Optimization of Waste Cooking Oil as Biodiesel Feedstock Sipayung, Rosmawati; Rahma Amalia; Rara Ayu Lestary; Nita Widyastuti; Oki Alfernando; Ira Galih Prabasari; Nazarudin; Putri Ananda; Intan Nandia Sakti
Jurnal Ilmiah Teknik Kimia Vol. 10 No. 1 (2026): JURNAL ILMIAH TEKNIK KIMIA
Publisher : Program Studi Teknik Kimia, Universitas Pamulang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32493/jitk.v10i1.54342

Abstract

The utilization of used cooking oil as a biodiesel feedstock is hindered by its high free fatty acid (FFA) content, which interferes with the transesterification process. This study aims to reduce FFA levels through adsorption using a silica–cellulose-based microsponge adsorbent synthesized from rice husk ash and corn cob waste. The investigated process variables include adsorbent mass (1, 3, 5 g), temperature (30, 45, 60 °C), contact time (30, 60, 90 minutes), and silica-to-cellulose ratios (40:60, 50:50, 60:40). FTIR analysis revealed characteristic peaks of Si–O–Si (~1053 cm⁻¹) and Si–O (~795 cm⁻¹) indicating the presence of amorphous silica, while the O–H stretching (~3200–3500 cm⁻¹) of cellulose appeared weaker due to silica dominance on the surface. This confirms the successful formation of the silica–cellulose composite with strong chemical interaction. Furthermore, Brunauer–Emmett–Teller (BET) analysis showed a specific surface area of 87.77 m²/g with mesoporous characteristics, confirming the microsponge structure with high affinity toward polar molecules such as FFA. The optimum conditions were obtained at 5 g adsorbent mass, 30 °C, 60 minutes contact time, and a 60:40 silica-to-cellulose ratio, achieving an FFA reduction efficiency of 49.62%. These physicochemical properties make the adsorbent efficient, energy-saving, and environmentally friendly, highlighting the great potential of agricultural waste transformation into active materials for pre-purification of used cooking oil toward sustainable biodiesel production.
Co-Authors Fikrah Dian Indrawati Sawali Intan Nandia Sakti Ira Galih Prabasari Mega Mustikaningrum Nazarudin Oki Alfernando Putri Ananda Rahma Amalia Rara Ayu Lestary Rosmawati Sipayung