活性炭在超声条件下碱洗和改性及对CO_2的吸附研究

Study on CO_2 adsorption with activated carbon alkaline cleaned and modified under ultrasonic condition

实验以椰壳颗粒活性炭为载体,活性炭在超声条件下经过碱洗后负载改性,用于吸附CO_2气体.研究在碱洗过程中的碱洗液浓度和超声时间对活性炭的清洗作用的影响,以及在改性过程中的搅拌时间、超声时间、改性剂对改性活性炭的吸附性能的影响,并采用热重分析、比表面积和孔径分析对碱洗后的活性炭、改性活性炭进行表征.结果表明:活性炭的碱洗条件是5 mol·L-1的KOH溶液,超声时间120 min;改性条件是搅拌时间30 min,超声时间100 min,10%(质量分数)的碳酸钾作为改性剂,对CO_2气体的吸附量达到1.5 mmol·g^(-1).研究表明:超声能够促进碱洗液在活性炭孔道中的分散效果,进而增强对活性炭的清洗作用;超声能使改性剂在孔道中良好分布,提高改性活性炭对CO_2气体的吸附性能.改性过程中,超声时间过长会导致孔道坍塌并颗粒破碎,致使吸附性能下降.

In this experiment,coconut shell activated carbon particles were used as the carriers,the activated carbon particles alkaline cleaned and modified under ultrasonic condition were used for the adsorption of CO_2 gas. This paper focuses on the influences of alkaline agent concentration and ultrasonic time in the process of alkaline cleaning of activated carbon,and the influences of the stirring time,ultrasonic time and modifying agents in the process of modification of activated carbon. The alkaline cleaned and modified activated carbon particles were characterized by TGA and ASAP2020.The results show that the adsorption capacity of CO_2 gas of the modified activated carbon particles was1. 5 mmol·g- 1 when the alkaline cleaning conditions were KOH solution of 5 mol·L- 1 and ultrasonic time of 120 min,and the modified conditions were stirring time of 30 min,ultrasonic time of 100 min,and 10%（ mass fraction） potassium carbonate as modifier. Research shows that ultrasound could promote the dispersion effect of alkaline agent on activated carbon pore,so that the pore cleaning effect on activated carbon would be enhanced. Besides,modifiers were distributed in pores very well by ultrasound,thus the adsorption performance of modified activated carbon particles for CO_2 gas could be improved. However,when ultrasonic time was too long in the process of modification,the pore would be collapsed and broken into small particles,and then the adsorption property declined.