Adsorption of acetic acid and hydrogen sulfide using NaOH impregnated activated carbon for indoor air purification

Abstract

Excessive exposure to hydrogen sulfide (H2S) and acetic acid (CH3COOH) gases is extremely dangerous in a confined space. An effective indoor air pollutant removal porous carbon filter was developed using NaOH impregnated on activated carbon (NaOH/AC) for the adsorption of H2S and CH3COOH. Activated carbon (NaOH/AC) filter was characterized using various methods, indicating good physical and chemical properties (especially -OH functional groups) for the adsorption of air pollutants. The prepared NaOH/AC filter was cured at different curing temperatures and residence times to understand the effect of the curing conditions on the adsorption performance. The best results were obtained with NaOH/AC filter cured at 100°C for 20 minutes as it eliminated the initial concentration of 400 ppm of CH3COOH in 15 minutes and H2S in 30 minutes at 20°C and 60% relative humidity. Isotherm and kinetic models were used to analyze the adsorption process. Langmuir isotherm and pseudo-second order kinetic models provided the best fit to the adsorption of CH3COOH and H2S on NaOH/AC filter. The adsorption mechanism was controlled by the intraparticle diffusion combined with film diffusion. The maximum adsorption capacity of NaOH/AC filter was 473 mg/g for H2S adsorption, and 550 mg/g for CH3COOH adsorption. In addition, the spent NaOH/AC filter was regenerated for reuse. This study is expected to develop low-cost and effective porous carbon filter using NaOH-modified activated carbon for indoor air purification.