Biofuels and Bioenergy

Among different chemical pulping processes, conventional Kraft pulping process is commonly practised. In this chemical pulping process, woodchips are converted into pulp and black liquor in presence of sodium hydroxide (NaOH) and sodium sulphide (N2S). This black liquor is subjected to combustion in the recovery boiler to produce steam, used for power generation and smelt recycled to extract cooking chemical (white liquor). However, Birch wood was used for this experiment. After cooking the wood sample, the pulp was separated from the black liquor using a filter paper. Furthermore, the product was washed and dried at 105oC. The by- product obtained from cooking each particle size (0-2, 2-4 and 4-8mm); at these cooking times (30, 60 and 90mins) resulted to different strong Kraft spent liquor (SKSL) samples. A liquid-liquid extraction (LLE) was carried out on the SKSL’s using Hexane as the separation solvent. The results obtained from analysing the extract using a GC/ MS and a thermogravimetric analysis (TGA), indicate that particle size 0- 2mm contain higher percentage of extractable biocrude that can be converted to value-added products In summary, the result obtained from the TGA and GC/MS analysis has shown that black liquor has the potential to improve the sustainability and economic viability of Kraft pulping mills when used as a feedstock in Kraft bio-refinery to produce value- added product.