Ekstraksi kitin dari cangkang rajungan bagian kerapas telah dilakukan dengan hasil persentase rendemen sebesar 11,64%. Kitin hasil ekstraksi digunakan untuk sintesis kitin nanofiber. Sintesis kitin nanofiber dilakukan menggunakan metode ultrasonikasi dengan alat ultrasonic processor, daya 750 watt yang diatur pada frekuensi 20 kHz, amplitudo 60%, dan pulse on/off (1s/1s) selama 6 jam di suhu 15°C. Pembentukan komposit kitin/CuO dan kitin/CB/CuO dilakukan dengan menambahkan CuO 0,5% (b/b) dan 1% (b/b) Carbon Black (CB) HAF 330 ke dalam padatan kitin nanofiber dengan lama pengadukan ± 24 jam. Dilakukan freezing dryer dengan pemanasan di suhu 53°C dalam kondisi vakum selama semalam. Hasil karakterisasi FTIR-ATR menunjukkan gugus fungsi kitin yang teridentifikasi adalah gugus O-H, N-H, C-H, C-N, C=O, dan C-O-C. Keberadaan komposit CuO dan CB teridentifikasi dengan adanya puncak pada 666,2853 cm-1 yang menunjukkan vibrasi khas dari CuO dan puncak 1635,822 cm-1 yang menunjukkan adanya vibrasi khas dari CB. Hasil SEM pada sampel yang dilakukan freezing dryer memiliki rentang diameter nanofiber 15-21 nm, sedangkan pada sampel yang tidak dilakukan freezing dryer rentang diameternya antara 23-30 nm. Secara visual sampel yang melalui freezing dryer memiliki struktur serat yang lebih jelas dan ukurannya lebih seragam. Dari pengukuran sudut kontak diketahui adanya penambahan CB (filler) dapat memperlambat laju difusi dan menaikkan nilai sudut kontak kitin nanofiber. Aktivitas antibakteri pada sampel diidentifikasi secara kualitatif dengan terbentuknya zona hambat di daerah sekitar sampel dan secara kuantitatif diketahui besar persentase kematian bakteri E. coli pada sampel komposit kitin/CuO sebesar 65,65%.

Extraction of chitin from crab’s carapace shell has been done with the final yield of 11.64%. Extracted chitin is used for the synthesis of nanofiber chitin. The synthesis of nanofiber chitin was performed using ultrasonication method with ultrasonic processor, 750 watts of power set at 20 kHz frequency, 60% amplitude, and on/off pulse (1s/1s) for 6 hours at 15°C. The solid of nanofiber chitin was obtained by separation from its dispersing medium (aquadest) by centrifugation. The formation of chitin/CuO and chitin/carbon/CuO composites was performed by adding CuO 0.5% (w/w) and 1% (w/w) Carbon Black (CB) HAF 330 into solid nanofiber chitin with stirring time ± 24 hours. The remainder aquadest on the nanofiber chitin and its composites were removed by vacuum filtration. The result was then dried and frozen with liquid nitrogen. Freezing Dryer was conducted at 53°C under vacuum condition overnight. The characterization of FTIR-ATR is performed to identify the functional group. The identified chitin function groups are O-H, N-H, C-H, C-N, C=O, and C-O-C. The peak at 634 cm-1 were corresponded to the Cu-O deformation vibration. The SEM indicated that in the sample processed by the freezing dryer has a more akin fiber structure than those which do not. CuO and CB materials were identified from EDX and FTIR results. Contact angle measurements were made by comparing the rate of water diffusion with oil on the sample surface. The addition of CB reduced the diffusion rate by being able to fill the space void on the nanofiber fibers. An antibacterial test was performed to observe the ability to inhibit bacterial growth in the sample shown by the formation of clean zone in the area around the sample.

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