Activated Carbon from Lignin-based Black Liquor Coagulated by Polyaluminium Chloride

Black liquor obtained from the pretreatment process in bioethanol plant was coagulated by Polyaluminium Chloride (PACl). The optimum sludge was evaluated by varying PACl dosage. Further, the sludge from coagulation process was prepared for activated carbon with the physical activation process. The preparation was carried out with two different methods: single step activation and two-step activation. In single step activation, dried sludge of black liquor were activated directly using the furnace at 575̊C for 3 h. In two-step activation, dried sludge was carbonized at 575̊C for 3 h and subsequently activated with raised temperature at 725̊C for 1 h. Investigated properties of lignin PACl-based activated carbon in single (LPACl-based AC 1) and two-step activation (LPACl-based AC 2) in the present study included its surface area and peak component analysis. It was found that PACl 1% (w/v) dosage addition to black liquor in constant speed 200 rpm for 10 minutes followed by slow stirring process 50 rpm for 2 hours and 24 hours settlement served optimum coagulation behaviour to deliver precipitation. Surface area (SBET) of LPACl-based AC 1 was found higher than LPACl-based AC 2. This preliminary study was conducted to evaluate influence process variable for the further study of activated carbon production as utilization of black liquor to establish sustainable recycling process, consequently supported the environmental and practical value.