Monitoring Quality of Soda Black Liquor of Oil Palm Empty Fruit Bunch Fibers in Terms of Storage Time and Temperature

Abstract

Kualiti likuor hitam daripada proses pemulpaan tandan buah sawit kosong ditentukan melalui kaedah pemencilan langsung lignin soda dengan asid hidroklorik 10% pada tiga nilai pH iaitu 2, 4 dan 6. Kaedah memusnah seperti pengoksidaan nitrobenzena dan penentuan kandungan abu digunakan dalam kajian ini. pH 2 didapati memberi dapatan lignin yang tertinggi. Melalui ujian pengoksidaan nitrobenzena vanilin adalah sebatian utama yang mewakili 44.9–52.1% daripada jumlah produk. Siringaldehid pula merupakan sebatian kedua utama yang mewakili 23.1–30.8%, dan seterusnya diikuti pula oleh p–hidroksibenzaldehid. Kelembapan dan kandungan abu bagi sampel lignin yang dipencilkan pada pH 6 adalah yang tertinggi diikuti oleh pH 4 dan pH 2 terutamanya apabila disimpan lama. Kajian ini mendapati, bagi kedua–dua suhu penyimpanan, lignin soda perlu dipencilkan sebelum mencapai tempoh penyimpanan selama 15 hari untuk mengelakkan kadar aktiviti biodegredasi yang tinggi. Kata kunci: Likuor hitam, lignin, serat tandan buah sawit kosong, masa penyimpanan, suhu penyimpanan The quality of black liquor from oil palm empty fruit bunch fibers pulping was determined through direct isolation of soda lignin using 10% hydrochloric acid at three pH fractions, i.e. pH 2, pH 4 and pH 6. Destructive methods such as nitrobenzene oxidation and ash contents determination were used in the study. pH 2 was found to be the most preferable fraction due to the highest lignin yield. Nitrobenzene oxidation showed that the predominant compound was vanillin, which was in the range of 44.9–52.1% of the total product. Syringaldehyde was the second major compound (ca. 21.5–30.8%), followed by p–hydroxybenzaldehyde. The moisture and the ash contents of pH 6 fraction were the highest followed by pH 4 fraction and pH 2 fraction, especially at longer storage time. Soda lignin has to be isolated in less than 15 days of storage regardless of storage temperature to prevent high rate of biodegradation activities. Key words: Black liquor, lignin, oil palm empty fruit bunch fibers, storage time, storage temperature