Preparation Of Coconut Shell And Lignin Based Activated Carbon By Alkali Activation And Its Phenol Adsorption Properties

The phenolic compounds contained in the industrial sewage are extremely toxic to human beings and the environment,and are recognized as the priority pollutants in water bodies in the world.In this paper,a series of biomass based activated carbons were prepared by one-step high-temperature Na OH activation using coconut shell carbon and three typical industrial lignin lignin as raw materials.Phenol was used as a model compound to systematically study the effects of activation temperature,different lignin,adsorption conditions（dose of adsorbent,adsorption temperature and p H value）on the performance of the adsorbent to remove phenol,and the adsorption kinetics,adsorption isotherms and thermodynamics.The research results of coconut shell activated carbon showed that:（1）With the increase of activation temperature of coconut shell carbon based activated carbon（BAC-T）,its specific surface area first increased and then decreased.When the activation temperature was800℃,the specific surface area reached the maximum of 1069 m²/g;（2）When the pyrolysis temperature is 800℃,the BAC-800 adsorbent has the best adsorption performance for phenol.When the adsorption temperature was 30℃and BAC-800 adsorbent was 2g/L,the phenol removal rate reached 97.5±1.3%.The adsorption is mainly carried out byπ-πinteraction with hydrogen bond and hydrophobic effect.（3）The adsorption process of phenol on BAC-800adsorbent can be described by pseudo-first-order kinetic model and Langmuir isothermal adsorption model,and the adsorption is mainly monolayer adsorption.The research results of three representative industrial lignin based activated carbon showed that:（1）when the activation temperature was 800℃,the specific surface area of corn straw lignin based activated carbon（CSLAC-T）reached the maximum(1679 m²?g^-1),and the phenol adsorption performance was the best.（2）The suitable adsorption conditions of lignin-based activated carbon were as follows:adsorption temperature 30℃,adsorbent0.75g/L,adsorption time 80min;（3）The order of magnitude of phenol removal performance of different adsorbents was:CSLAC-800>BLAC-800>LSAC-800.Under appropriate conditions,the adsorption capacities of CSLAC-800,LSAC-800 and BLAC-800 for phenol are 612 mg?g^-1,557 mg?g^-1and 593mg?g^-1respectively.（4）The adsorption of phenol on CSLAC-800 and BLAC-800 conforms to the pseudo-second-order kinetic model and Freundlich isothermal adsorption model.However,the adsorption of phenol by LSAC-800conforms to the pseudo-first-order kinetic model,pseudo-second-order kinetic model and Freundlich isothermal adsorption model.The thermodynamic parameters showed that the three lignin-based activated carbons spontaneously exothermic adsorption of phenol.