Experimental study and kinetics on CO2 mineral sequestration by the direct aqueous carbonation of pepper stalk ash

•Direct aqueous carbonation of pepper stalk ash under low-medium pressure conditions was investigated.•A new diffusion-controlled equation was proposed to evaluate the carbonation kinetics.•The effect of key operating parameters on the carbonation rate and efficiency was assessed.•1 t of PSA can produce more than 200 kg of potassium salts after carbonation.