Unlocking potential of blast furnace slag: CO2 adsorption performance and mechanism of slag-derived zeolite.

For meeting requirements of "green steel" and "circular economy", there was great potential and value to synthesize CO2 adsorbent with low price and excellent performance by using multiple solid wastes. In this study, a novel method was proposed to synthesize zeolite by blast furnace slag. CO2 adsorption isotherm, thermodynamic and kinetic were investigated comprehensively. Zeolite exhibited favorable physical and chemical structure. Sips model was more suitable to describe isotherm of CO2 adsorption. CO2 adsorption process of zeolite was a spontaneous adsorption process without additional energy need, which could be determined as physisorption process. Four kinetic models were used to fit experimental data. CO2 adsorption by slag-derived zeolite was complicated multi-path adsorption involving adsorption sites and activity. Film diffusion and intraparticle diffusion were rate-limiting steps for CO2 adsorption by slag-derived zeolite. Generally, it was economically and environmentally beneficial to synthesize zeolite from blast furnace slag to achieve CO2 adsorption.