Preparation of activated carbons from cotton stalk by microwave assisted KOH and K2CO3 activation

The activated carbons prepared from cotton stalk with different activation agents (KOH and K2CO3) under microwave radiation were investigated. The effects of different activation conditions on the adsorption capacities of activated carbons were studied. The frequency test (F-test) was utilized in statistics to analyze the significant effects of the factors. The properties of activated carbons prepared under optimum conditions were investigated using the following measurement: N2 adsorption isotherms at −196 °C, SEM and FTIR. Finally, the samples were used in removal of methylene blue. The results showed that radiation time and radiation power were the greatest impact factor on adsorption capacities of the activated carbon prepared with KOH and K2CO3, respectively. Optimum conditions were different in the two prepared process. Compared with cotton stalk, different functionalities on the carbon surfaces were formed. In addition, chemical activation could develop both microporosity and mesoporosity. KOH generated a greater micropore volume than K2CO3 did. Compared with conventional heating method, microwave heating method could shorten the processing time and reduce the consumption of KOH. The equilibrium data of the adsorption was well fitted to the Langmuir isotherm for both activated carbons.