Studies on adsorption of carbon dioxide on alkaline paper mill waste using cyclic process

The adsorption/desorption cycles of the alkaline paper mill waste (APMW) can be used to remove CO2 from coal-fired power plants. In this work, the prolonged adsorption duration treatment was used to modify CO2 capture behavior of the raw and the prewashed APMW in the multiple adsorption/desorption cycles. The effects of increased duration of adsorption and CO2 partial pressure in the first cycle on the fractional adsorption of CO2 and adsorption rate were investigated, when the raw and the prewashed APMW are employed as the sorbents. The cyclic CO2 capture behavior of APMW after the repeated prolonged adsorption in different cycles was also studied. For the raw and the prewashed APMW as the sorbents, 9-12 h adsorption of CO2 just in the 1st cycle enhances the cyclic fractional adsorption of CO2 and adsorption rate of CO2 in the 1st cycle and the subsequent cycles. The repeated prolonged adsorptions in the various cycles are more effective to increase the cyclic CO2 capture capacity of APMW than only in the 1st cycle. The longer adsorption duration results in larger area and volume of pores in 10-100 nm in diameter for CaO derived from APMW after the next cycles, which are helpful to cyclic CO2 capture of APMW. The raw and the prewashed APMW can retain high CO2 adsorption reactivity by the prolonged adsorption duration treatment in the multiple adsorption/desorption cycles.