Preparation and Characterization of Activated Carbon from Kraft Lignin via KOH Activation

摘要

Kraft lignin (KL), which is largely obtained from Kraft pulping process, is typically utilized to generate steam, electricity, and heat. The huge amount of KL can also be utilized for various purposes such as producing biofuels, chemicals, and materials. In this work, industrial waste KL was used to prepare activated carbons (ACs) with high surface area and large pore volume via KOH activation method. The effects of pretreatment methods of KL, activation methods, and activation conditions on the pore structures and the yield of ACs were investigated. The prepared ACs were characterized by XRD, SEM, FT1R, and N_2 adsorption at - 196℃. The results showed that the pore structure and the yield of ACs were closely related to the various pretreatment methods, activation methods, and conditions. A 26% carbon yield of AC with the maximum BET surface area of 2762.5 m~2/g and pore volume of 132 cm~3/g was obtained under the following activation condition (a) KOH to acid pretreatment KL mass ratio of 4, (b) activation temperature of 750℃, (c) activation duration of 2 h, and (d) N_2 flow rate of 160 cm~3/min. The activating agent KOH can be recovered partially and the washing water discharge can also be minimized by reuse process.