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Abstrak :
Tandan Kosong Sawit (TKS) adalah limbah biomassa industri kelapa sawit, dengan kandungan utamanya meliputi selulosa, hemiselulosa, dan lignin, yang dihasilkan dalam jumlah berlimpah setiap tahunnya di Indonesia. Hemiselulosa pada TKS dapat dikonversi menjadi senyawa furfural dengan terlebih dahulu melakukan praperlakuan untuk merusak struktur lignoselulosa dan menghilangkan lignin. Produksi furfural berbasis biomassa melalui reaksi hidrolisis berkatalis asam menghasilkan produk samping berupa asam levulinat dan asam format yang sangat tergantung pada kondisi reaksi. Pada penelitian ini dilakukan optimasi kondisi reaksi hidrolisis TKS yang meliputi waktu, suhu, dan konsentrasi asam, secara simultan terhadap yield furfural dengan Response Surface Methodology (RSM). TKS dengan ukuran 30 - 40 mesh pertama-tama diberikan praperlakuan alkali berbantuan gelombang mikro dengan menggunakan NaOH dan NH₄OH. Variasi praperlakuan dengan NaOH meliputi konsentrasi basa (1; 2; 3 %), daya microwave (280; 560; 840 W), dan waktu (3; 6; 9 menit). Sedangkan variasi praperlakuan dengan NH₄OH meliputi konsentrasi basa (7,5; 10; 12,5 %), daya microwave (280; 560; 840 W), dan waktu (3; 6; 9 menit). Uji kandungan lignin sesuai SNI 0492:2008, FTIR dan SEM dilakukan untuk mengetahui pengaruh praperlakuan. Efek konsentrasi basa, daya microwave, dan waktu dianalisis menggunakan RSM. Praperlakuan menggunakan NaOH dengan konsentrasi basa 2%, daya microwave 840 W, dan waktu 9 menit menghasilkan TKS dengan kadar lignin terendah sebesar 7,58%. Selanjutnya hidrolisis dilakukan terhadap TKS hasil praperlakuan pada kondisi tersebut dengan variasi waktu reaksi (20; 40; 60 menit), suhu (140; 160; 180 °C), dan konsentrasi H₂SO₄ (0,3; 0,5; 0,7 M). Konsentrasi furfural, asam levulinat, dan asam format dalam fraksi cair hidrolisis kemudian dianalisis menggunakan HPLC. Optimasi respons konsentrasi furfural dilakukan dengan RSM pada software Design Expert menggunakan model Box-Behnken. Hasil optimasi menunjukkan konsentrasi furfural tertinggi sebesar 2481ppm dapat diperoleh pada waktu reaksi 60 menit, suhu 141 °C, dan konsentrasi H₂SO₄ 0,3 M. Oil Palm Empty Fruit Bunch (OPEFB) is biomass waste from palm oil industry, with the main content including cellulose, hemicellulose, and lignin, which is produced in abundant quantities every year in Indonesia. Hemicellulose in OPEFB can be converted into furfural by first doing pretreatment to damage the lignocellulose structure and to remove lignin. Biomass-based furfural production through acid-catalyzed hydrolysis reaction produces by-products such as levulinic acid and formic acid which is highly dependent on the reaction conditions. In this study, the optimization of the hydrolysis reaction conditions of OPEFB was carried out which included time, temperature, and acid concentration, simultaneously on furfural yield with Response Surface Methodology (RSM). The 30-40 mesh OPEFB was first given microwave assisted alkali pretreatment using NaOH and NH₄OH. Pre-treatment variations with NaOH included alkaline concentrations (1; 2; 3%), microwave power (280; 560; 840 W), and time (3; 6; 9 minutes). While pre-treatment variations with NH₄OH included alkaline concentrations (7,5; 10; 12,5%), microwave power (280; 560; 840 W), and time (3; 6; 9 minutes). Test on lignin content according to SNI 0492:2008, FTIR and SEM were carried out to determine the effect of pretreatment. The effects of alkaline concentration, microwave power, and time were analyzed using RSM. Pre-treatment using NaOH with alkaline concentration of 2%, microwave power 840 W, and 9 minutes could produce OPEFB with the lowest lignin content of 7,58%. Subsequently hydrolysis was carried out on the pretreated OPEFB in these conditions with variations in reaction time (20; 40; 60 minutes), temperature (140; 160; 180 ° C), and H₂SO₄ concentrations (0,3; 0,5; 0,7 M ) The furfural concentration, levulinic acid, and formic acid in the hydrolysis liquid fraction were then analyzed by using HPLC. Optimization of furfural concentration response was done by RSM in Design Expert software using the Box-Behnken model. The optimization results show that the highest furfural concentration of 2481 ppm can be obtained at the reaction time of 60 minutes, temperature of 141 °C, and H₂SO₄ of concentration 0,3 M.

Abstrak :
Penggunaan Tandan Kosong Kelapa Sawit TKKS sebagai bahan baku bioetanol generasi kedua menghasilkan limbah lindi hitam yang kandungan utamanya adalah lignin. Sebagai senyawa polimer fenolik, gugus hidroksifenolik pada lignin memungkinkannya bertindak sebagai antioksidan. Pada penelitian ini, isolat lignin lindi hitam diuji aktivitasnya sebagai antioksidan pada biodiesel. Lignin diperoleh dengan pertama-tama melakukan praperlakuan TKKS dengan metode organosolv pada suhu 170 C selama 2,5 jam dan dilanjutkan dengan melakukan isolasi lignin teknis. Isolat lignin ditambahkan ke dalam biodiesel dengan variasi konsentrasi 500, 1000, dan 1500 ppm. Lignin komersial dan antioksidan sintetik butylated hydroxytoluene BHT digunakan sebagai kontrol positif. Uji stabilitas oksidasi biodiesel dilakukan dengan metode Rancimat. Sedangkan uji aktivitas antioksidan dilakukan dengan menghitung bilangan asam, bilangan peroksida, dan viskositas kinematik biodiesel pada pekan ke-0, 1, 2, 3, dan 4. Karakteristik isolat lignin organosolv yang diperoleh dari penelitian ini meliputi: rendemen lignin 13,7 kadar lignin 64,5 bobot ekuivalen 1822,1 g/ekuivalen dan kadar hidroksifenolik 6,8. Spektrum FTIR lignin organosolv menunjukkan kesamaan pita serapan dengan lignin komersial. Penambahan lignin organosolv, lignin komersial, dan BHT mampu menghambat laju oksidasi biodiesel dengan urutan aktivitas antioksidan dari yang terbesar hingga yang terkecil secara berturut-turut yakni BHT, lignin komersial, dan lignin organosolv. ......Utilization of Palm Oil Empty Fruit Bunch POEFB as second generation bioethanol feedstock produces black liquor waste which the main content is lignin. As phenolic polymer compound, the hydroxyphenolic group in lignin enables it to act as antioxidant. In this study, lignin isolate from black liquor was tested for their activity as antioxidants in biodiesel. Lignin was obtained by first performing POEFB pretreatment by organosolv method at 170 C for 2.5 hours and followed by technical lignin isolation. Lignin isolate was added to biodiesel with variation of concentration 500, 1000, and 1500 ppm. Commercial lignin and synthetic antioxidant butylated hydroxytoluene BHT were used as positive control. The biodiesel oxidation stability test was performed by Rancimat method. While antioxidant activity test was done by identifying the acid number, peroxide number, and kinematic viscosity of biodiesel at week 0, 1, 2, 3, and 4. Characteristics of organosolv lignin isolate obtained from this research include lignin yield 13,7 64.5 lignin content equivalent weight of 1822.1 g equivalent and hydroxyphenolic content of 6.8. The organosolv lignin FTIR spectrum shows the similarity of absorption bands to commercial lignin. The addition of organosolv lignin, commercial lignin, and BHT are able to inhibit the rate of oxidation of biodiesel with the sequence of antioxidant activity from the largest to the smallest successively BHT, commercial lignin, and organosolv lignin.