Thermodynamics and kinetics parameters of co-combustion between sewage sludge and water hyacinth in CO2/O2 atmosphere as biomass to solid biofuel

•Thermochemical conversion of biomass waste was carried out in oxy-fuel atmosphere.•The performance sewage sludge combustion was improved by blending water hyacinth.•Thermodynamic parameters (△H, △S, △G) were calculated through TGA curves.•The lowest activation energy (Ea) of SW was obtained in CO2/O2=7/3 atmosphere. Thermodynamics and kinetics of sewage sludge (SS) and water hyacinth (WH) co-combustion as a blend fuel (SW) for bioenergy production were studied through thermogravimetric analysis. In CO2/O2 atmosphere, the combustion performance of SS added with 10–40wt.% WH was improved 1–1.97 times as revealed by the comprehensive combustion characteristic index (CCI). The conversion of SW in different atmospheres was identified and their thermodynamic parameters (ΔH,ΔS,ΔG) were obtained. As the oxygen concentration increased from 20% to 70%, the ignition temperature of SW decreased from 243.1°C to 240.3°C, and the maximum weight loss rate and CCI increased from 5.70%·min−1 to 7.26%·min−1 and from 4.913%2·K−3·min−2 to 6.327%2·K−3·min−2, respectively, which corresponded to the variation in ΔS and ΔG. The lowest activation energy (Ea) of SW was obtained in CO2/O2=7/3 atmosphere.