Structure,Performance And Evaluation Of Soda Lignin Based Activated Carbon Prepared By Hydrothermal Carbonization

Activated carbon is a porous material with high carbon content.Due to its large specific surface area and pore volume as well as excellent adsorption property,activated carbon is widely used in various industrial fields.The hydrothermal carbonization is a new carbonization method in recent years.Through the systematic analysis of soda lignin based the structure and properties of activated carbon,can not only we master the process of preparing activated carbon by hydrothermal carbonization-activation,to evaluate and analyze the life cycle of soda lignin based activated carbon,to know the cost of the preparation process,but also to produce high performance for industrial production activated carbon lays the foundation and has important practical and theoretical guiding significance.In this study,the soda lignin extracted from the papermaking black liquor as the raw material was converted into hydrochar by hydrothermal carbonization,followed by activation to prepare soda lignin based activated carbon.The effects of different hydrothermal carbonization temperatures,activator types and ratios on the structure of activated carbon were investigated.The structure and performance of activated carbon were characterized by Scanning electron microscopy and X-ray photoelectron spectroscopy.The life cycle assessment of soda lignin based activated carbon was analyzed via the aspects of carbon dioxide emissions,economic cost and time cost.The main conclusions of this study are as follows:?1?The higher the carbonization temperature,the more vigorous the reaction,and the lower the yield,ash content of the hydrochar,the content of oxygen and oxygen functional groups,the greater the content of fixed carbon and carbon.Besides,compared to pyrochar,hydrochar has rough surface and abundant honeycomb pore structure which is more suitable to be precursor for activated carbon.?2?Optimal technology conditions for preparation of soda lignin based activated carbon by hydrothermal carbonization-activation:250?of hydrothermal carbonization temperature,KOH activation,1:3 of impregnation ratio,800?of activation temperature,1 h of activation time.Under this condition,the obtained activated carbon showed 2631 m²/g of specific surface area,1.153 cm³/g of total pore volume,1.75 nm of the average pore diameter and more micropores,which were better than those of soda lignin based activated carbon preparation by pyrochar and commercial activated carbon.The carbon dioxide adsorption value of the obtained activated carbon was 100 mg/g,which had more excellent adsorption performance compared with other carbon materials.?3?In the life cycle assessment of soda lignin based activated carbon,the net carbon dioxide emission of 1 kg was 27.093 kg CO₂-eq,the production process was environmentally friendly.The economic cost was about 11,600 yuan/t and the time cost was 30 h/t,reducing production time was the key to reducing economic cost.