(Extraction of Cellulose Using Conventional and Deep Eutectic Solvent (DES) Methods from Corncobs)
Oleh : Fitri Gadi Mantika (21/475878/PTK/13897) – Magister Teknik Kimia
INTISARI
Selulosa merupakan biopolimer yang paling melimpah, ramah lingkungan dan tersebar luas di alam. Selulosa ini dapat diaplikasikan pada berbagai macam produk, terutama sebagai bahan tambahan dalam pembuatan komposit bioplastik untuk meningkatkan sifat mekanisnya. Pengambilan selulosa dari biomassa lignoselulosa (lignin, hemiselulosa, dan selulosa) umumnya dilakukan dengan metode konvensional, yaitu alkali treatment, bleaching treatment, dan hidrolisis asam. Namun metode ini memiliki beberapa keterbatasan seperti penggunaan air yang tinggi, dihasilkan air limbah asam, dan tidak ramah lingkungan. Seiring dengan upaya penerapan keberlanjutan (sustainability), maka perlu adanya perkembangan inovasi industri dengan konsep green chemistry. Deep eutectic solvent (DES) ialah pelarut organik hijau untuk fraksinasi dan pemurnian komponen biomassa (lignoselulosa) menjadi berbagai produk akhir, termasuk selulosa.
Penelitian ini bertujuan untuk mengetahui pengaruh perbedaan proses pengambilan selulosa antara metode konvensional dan proses DES terhadap yield dan karakteristik selulosa yang dihasilkan. Penelitian ini diawali dengan preparasi bahan baku serbuk tongkol jagung (STJ) dan pembuatan pelarut DES. DES yang digunakan terdiri dari 2 jenis, yaitu campuran DES asam (ChCl dan Asam Oksalat Dihidrat) dan DES basa (Gliserol dan kalium karbonat (K2CO3)). Metode konvencional dilakukan dengan tahapan alkali treatment (NaOH, 60°C, 1 jam), bleaching treatment (NaClO2, 75°C, 2 jam), dan hidrolisis asam (H2SO4, 40°C, 1 jam). Proses DES dilakukan pada suhu 90°C selama 4 jam. Total waktu reaksi, massa STJ, rasio massa STJ:pelarut (1:20, g/mL), dan kecepatan pengadukan (400 rpm), dijaga tetap. Hasil Penelitian diperoleh% yield selulosa metode konvensional sebesar 36,28%, lebih kecil dibandingkan proses DES (asam maupun basa). Namun kemurnian selulosa metode konvensional paling tinggi dengan% removal lignin mencapai 99,02%. DES asam (ChCl:AOD) selektif dalam menghilangkan hemiselulosa, sedangkan DES basa (Gly:K2CO3) lebih dominan dalam menghilangkan lignin. Karakteristik selulosa masing-masing sampel (awal dan setelah perlakuan) dilakukan dengan analisa FTIR (gugus fungsi), XRD (kristalinitas), PSA (ukuran partikel), Zeta Potensial (kestabilan suspensi), dan SEM-EDX (morfologi permukaan). Indeks kristalinitas selulosa paling tinggi didapatkan dengan metode konvensional yaitu 87,3%. Selulosa yang dihasilkan dengan metode konvensional, DES asam, dan DES basa memiliki ukuran dan morfologi permukaan yang beragam dan masing-masing masuk dalam tipe ukuran selulosa yang berbeda.
Kata kunci: DES; Hidrolisis Asam; Selulosa; Tongkol Jagung.
ABSTRACT
Cellulose is the most abundant biopolymer in nature, environmentally friendly, and widely distributed. It finds applications in various products, particularly as an additive in bioplastic composite materials to enhance mechanical properties. Cellulose extraction from lignocellulosic biomass (comprising lignin, hemicellulose, and cellulose) is commonly achieved through conventional methods such as alkali treatment, bleaching treatment, and acid hydrolysis. However, these methods have limitations including high water usage, generation of acidic wastewater, and environmental impact. In line with sustainability efforts, there is a need for industrial innovation using green chemistry principles. Deep eutectic solvent (DES) represents a green organic solvent used for fractionation and purification of biomass components (lignocellulose), including cellulose. This study aims to investigate the impact of different cellulose extraction processes— conventional methods versus DES processes—on the yield and characteristics of the resulting cellulose.
The study began with the preparation of corn cob powder (CCP) raw material and the formulation of DES solvents. Two types of DES were used: an acidic mixture (Choline Chloride and Oxalic Acid Dihydrate) and a basic mixture (Glycerol and Potassium Carbonate (K2CO3)). The conventional method involved alkali treatment (NaOH, 60°C, 1 hour), bleaching treatment (NaClO2, 75°C, 2 hours), and acid hydrolysis (H2SO4, 40°C, 1 hour). The DES process was conducted at 90°C for 4 hours. Reaction time, CCP mass, CCP mass ratio (1:20, g/mL), and stirring speed (400 rpm) were kept constant. The research results showed that the cellulose yield using the conventional method was 36.28%, which was lower compared to both acidic and basic DES processes. However, the conventional method yielded the highest cellulose purity, with lignin removal efficiency reaching 99.02%. The acidic DES (ChCl:AOD) was selective in removing hemicellulose, whereas the basic DES (Gly: K2CO3) was more effective in lignin removal. The cellulose characteristics of each sample (before and after treatment) were analyzed using FTIR (functional groups), XRD (crystallinity), PSA (particle size), Zeta Potential (suspension stability), and SEM-EDX (surface morphology). The highest crystallinity index of cellulose was achieved with the conventional method at 87,3%. Cellulose produced via conventional, acidic DES, and basic DES methods exhibited diverse particle sizes and surface morphologies, each falling into different cellulose size categories.
Keywords: DES; Acid Hydrolysis; Cellulose; Corn Cob.