ENHANCEMENT OF REDUCING SUGAR PRODUCTION FROM OIL PALM EMPTY FRUIT BUNCH BY PRETREATMENT USING ORGANIC ACID IN PRESSURIZED REACTOR. Organic acids are potential to create more environmentally friendly process in the pretreatment of lignocellulosic biomass for bioethanol production. This study was aimed to investigate the influence of organic acid pretreatment in reducing sugar production in a pressurized reactor with various resident times and temperatures on enzymatic hydrolysis of OPEFB. Two different organic acids (maleic acid and oxalic acid) were used in the pretreatment of oil palm empty fruit bunch (OPEFB) using a pressurized reactor. Factorial design using three different temperatures (170, 180, and 190°C) and four resident times (15, 30, 45, and 60 min) were employed, followed by enzymatic hydrolysis. Each condition conducted two repetitions. Analysis was conducted on the reducing sugar that was produced after saccharification by means of the severity factor of each pretreatment condition. Maleic acid showed higher reducing sugar yield with lower severity factor than oxalic acid with the same operating conditions. The highest yield of reducing sugars (80.84%) was obtained using maleic acid at 170 for 60 minutes with severity factor of 1.836. Keywords: bioethanol; organic acid pretreatment; pressurized reactor; severity factor; oil palm empty fruit bunches; Abstrak Asam organik berpotensi dalam membantu proses praperlakuan dari biomassa lignoselulosa untuk memproduksi bioetanol yang ramah lingkungan. Penelitian ini bertujuan untuk mengetahui pengaruh asam organik, suhu dan waktu operasi terhadap produksi gula pereduksi dengan reaktor bertekanan pada tandan kosong kelapa sawit. Dua asam organik yang berbeda yaitu asam oksalat dan asam maleat digunakan untuk proses praperlakuan tandan kosong kelapa sawit (TKKS) dengan bantuan reaktor bertekanan. Dalam proses praperlakuan digunakan tiga suhu yang berbeda yaitu suhu 170, 180, dan 190°C dan empat waktu operasi 15, 30, 45, dan 60 min yang dilanjutkan dengan proses hidrolisis enzimatis. Setiap kondisi dilakukan dua kali pengulangan. Analisa yang digunakan adalah analisa uji gula pereduksi dan severity factor pada kondisi tiap praperlakuan. Asam maleat menunjukkan hasil yang lebih baik dengan severity factor yang lebih rendah dibandingkan menggunakan asam oksalat dengan kondisi operasi yang sama. Hasil yang didapatkan menunjukkan bahwa praperlakuan tandan kosong kelapa sawit dengan bantuan reaktor bertekanan memiliki rendemen gula pereduksi optimum sebesar 80,84% dengan menggunakan asam maleat pada suhu 170°C selama 60 menit dengan severity factor sebesar 1,836. Kata kunci: bioetanol; praperlakuan asam organik; reaktor bertekanan; severity factor; tandan kosong kelapa sawit.
Autoclave-assisted weak acid pretreatment of oil palm empty fruits bunches for fermentable sugar production