Modification Of Coconut Activated Carbon Particles For CO₂ Adsorption From Flue Gas

The global climate warming is the most significant environmental problem that faced by mankind in the twenty-first century,and CO2 gas emission from fossil fuels combustion is one of the main reasons that lead to the global climate warming.Emission control of CO2 gas has become an important research direction in the field of energy and environment in the world,and various methods of CO2 gas capture have been constantly proposed and further researched.The activated carbon,rich pore structure and stable surface-chemical property,has become a kind of efficient absorbents of CO2 gas separated from flue gas.In this paper,the modified experiment was based on the commercial coconut activated carbon particles,and the modified activated carbon particles were used for CO2 gas capture.This work aims to find a kind of absorbent,which has stable and high adsorption capacity.And,it would be used as the theoretical basis for further development of high efficient adsorbent of CO2 gas.In this paper,the commercial coconut activated carbon particles were used as the carriers,the modified activated carbon particles were prepared with two different methods,In the first method,the activated carbon particles were cleaned by the ultrasonic cleaner firstly,and then modified with the modifiers.In the second method,the activated carbon particles were activated with KOH solution firstly,and then modified with the modifiers.and then the modified activated carbon particles with high adsorption capacity were characterized by using the thermal analyzer,the specific surface area and pore size analyzer,X-ray diffraction test methods.The main research conclusions were listed as follows:(1)In the process of ultrasonic cleaning,ultrasound could promote the dispersing effect of cleaner on the activated carbon pore,so that the specific surface area of the activated carbon particles was increased.When the ultrasonic time was more than 120 min,the cavitations effect of ultrasound would make the activated carbon pore collapse and broke into small particles,the specific surface area of activated carbon particles decreased.(2)In the process of reactivation of activated carbon by KOH activated method,according to the characterization results from the specific surface area and pore size analyzer,scanning electron microscopy and X-ray diffraction,the pores of activated carbon raw materials could be reamed with KOH solution under the condition of high temperature,so that the specific surface area and the average pore diameter of activated carbon particles were increased.Besides,the pore channels and surface of activated carbon particles were cleaned,so that the surface of activated carbon became smoother.(3)In the process of modification of activated carbon,long stirring time would make the pores of activated carbon collapse and the particles broke;compared with the static treatment method,ultrasonic treatment would make more modifying agent(potassium carbonate)attach on the surfaces and pore channels of modified activated carbon particles,which enhanced the adsorption capacity.When the ultrasonic time more than 100 min,the pores of modified activated carbon particles were be collapsed and particles were be broken into small particles since long time of ultrasonic cavitations,thus the adsorption capacity of modified activated carbon particles declined.(4)Firstly,the activated carbon particles were activated again under the activation conditions of the activation time of 60 min,and the activation temperature of 800 ?.Then,after the process of activation,the activated carbon particles were chosen as carrier for modifying,whose size was bigger than 1.43 mm.And then the activated carbon particles were modified under the modified conditions of stirring time of 30 min,ultrasonic time of 100 min,and the 8%(wt)potassium carbonate as modifier.The modified activated carbon particles were used for CO2 gas adsorption experiment from flue gas would get the maximum 7.03%adsorption capacity of CO2 gas.In other words,1g modified activated carbon would absorb 1.6 mmol CO2.The modified activated carbon particles still remained high stability and high adsorption capacity after seven cycle adsorption desorption experiment.