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In this work, a high shear mixer (HSM) is designed to produce a higher theoretical shear rate than conventional HSM in order to induce structure degradation of cassava starch granules. Using scanning electron microscopy and transmission electron microscopy, the processed cassava starch granule surface changes are identified without any major change in the granule shape. The carbohydrate component analysis and intrinsic viscosity suggest that the structural change is led by the removal of a relatively low-molecular-weight carbohydrate component from the granule. The changes in the crystalline and thermal properties are observed by the degradation process using a HSM. The process using a rotor speed of 15 000 rpm is found to significantly induce granule surface changes and carbohydrate removal. The decrease in granule crystallinity is correlated with an increase in the granule swelling power and solubility.

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ABSTRAK EKSTRAKSI SELULOSA DARI SERBUK GERGAJI KAYU SENGON MELALUI PROSES DELIGNIFIKASI ALKALI ULTRASONIK. Kayu sengon (Albizia chinensis) merupakan salah satu jenis kayu yang melimpah di Indonesia. Kandungan selulosa pada kayu sengon cukup tinggi sebesar 41,17 %. Proses ekstraksi selulosa dari kayu sengon dapat dilakukan melalui proses delignifikasi atau penghilangan kandungan lignin. Umumnya, proses delignifikasi dilakukan dengan larutan alkali pada konsentrasi tinggi, suhu tinggi dan waktu yang lama. Agar konsentrasi alkali yang digunakan rendah dan waktu lebih pendek, proses delignifikasi dapat dilakukan dengan bantuan ultrasonik. Tujuan dari penelitian ini adalah mengetahui pengaruh kondisi operasi (suhu dan waktu) proses delignifikasi dengan ultrasonik terhadap kadar selulosa yang diperoleh. Proses delignifikasi dilakukan dengan mencampur serbuk kayu sengon (40 mesh) dengan larutan NaOH (0,3 M) dengan perbandingan 1:30 (w/v). Kondisi operasi yang digunakan adalah suhu 30°C dan 40°C pada berbagai waktu (10 menit hingga 70 menit). Setelah proses delignifikasi, produk di-bleaching dengan NaOCl hingga warnanya menjadi putih. Analisis yang dilakukan antara lain adalah metode Chesson, X-Ray Diffraction (XRD) dan Scanning Electron Microscopy (SEM). Hasil dari analisa menunjukkan bahwa kristalinitas tertinggi diperoleh sebesar 77,05 % pada 40°C selama 30 menit dan kadar lignin turun hingga mencapai 0,41%. ABSTRACT SELULOSE EXSTRACTION FROM SAW DUST OF SENGON WOOD USING BY PROCESS OF DELIGNIFITION OF ULTRASOUND ALKALINE. Sengon wood (Albizia chinensis)is one type of wood that is abundant in Indonesia. Cellulose content in sengon wood is quite high, up to 41.17 %. The process of cellulose extraction from sengon wood can be done through the process of delignification or removal of lignin content. Generally the delignification process is carried out with an alkaline solution at high concentration, high temperature and long time. In order to use lower alkaline concentration and shorter time process, the delignification process can be performed by assisted ultrasound. The purpose of this research is to study the effect of operating conditions (such as temperature and time) of ultrasonic delignification process on cellulose content in the cellulose product. The delignification process was carried out by mixing the sengon wood (40 mesh) with NaOH solution (0.3 M) at a ratio of 1:30 (w/v). The operating conditions used are 30°C and 40°C at various times (10-70 minutes). After the delignification process, the product is bleached with NaOCl until the color of product becomes white. The product was analyzed by Chesson method, XRD (X-Ray Diffraction), and SEM (Scanning Electron Microscopy). The results of the analysis showed that the highest crystallinity was 77.05 % at 40°C for 30 minutes and lignin content was decreased until 0.41%.

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