CO2 capture performance of K2CO3-activated biochars derived from the textile dyeing sludge and corncob

The advancement of low-cost biochar derived from organic solid wastes is highly desirable, as it serves as an efficient and environmentally friendly absorbent for CO 2 abatement. Textile dyeing sludge (TDS) and corncob are two common types of carbonaceous solid wastes that are abundant and easily accessible. In this study, TDS and corncob were co-pyrolyzed to produce a series of CO 2 adsorption biochars (SCs). Results show that the synergetic and self-catalytic effects of the reaction between alkali/alkaline earth metals and the organic matters in TDS and corncob can increase biochar yield and enhance the ultra-micropore structure accounting for effective CO 2 adsorption. Moreover, the specific surface area of SC activated at 700 °C (SC700) was higher than corncob-based biochar. SC700 exhibited the highest CO 2 adsorption capacity (128.1 mg/g) among the SCs, which was more than double that of TDS biochar. This is primarily because SC700 had the highest specific surface area of ultra-micropores (544.38 m 2 /g) and ultra-micropore volume (0.16 cm 3 /g) among the SCs. After ten cycles tests, SC700 still showed good CO 2 adsorption-desorption performance, with a decrease of less than 1.5 %. The analysis of in situ DFIRT spectroscopy revealed that the CO 2 adsorption of SC700 involved both physical and chemical adsorption processes, with physical adsorption being dominant. This study provides an environmentally friendly and cost-effective method for the utilization of TDS and corncob to produce valuable biochar for CO 2 adsorption. • Synergistic mechanism is critical to improve ultra-micropore structure of biochar. • SC700 exhibits more than twice the adsorption capacity of the sludge biochar. • SC700 shows a high content of pyridine nitrogen enhancing CO 2 chemisorption. • Thermal stability and thermal-oxidation resistance of biochars were investigated. • SC700 behaves perfect cyclic regeneration performance as high as 98.73 % retention.