Removal of CO2 and H2S from raw biogas using activated natural zeolite

Abstract

This paper presents raw biogas purification method through a membrane porous. Biogas purification is required as biogas produced from anaerobic digestion process contains some traces such as carbon dioxide (CO2) and hydrogen sulfide (H2S) which lowered the calorific value. The raw biogas is produced from an anaerobic process of cow dung. The membrane porous was originated from natural zeolite and was activated by various concentrations of sodium hydroxide (NaOH). The effect of different sodium hydroxide concentrations addition in order to adsorb impurities gases in raw biogas was studied. The results show that the addition of 5% NaOH resulted in the methane (CH4) in biogas reached the highest concentration compared to those of 0 and 15% NaOH respectively. The advantage was obtained due to the superiority of zeolite micropores resulted in the adsorption process and selectivity in membrane porous improved. This also was supported by the morphology structure of the membrane which showing a decrease in crystal size. The bigger cave or porosity created in 5% NaOH allowed more CO2 and H2S was trapped and thus increasing CH4 concentration in purified biogas. It was recorded that CH4 in purified biogas was 95% and maintained in longer duration in 5% NaOH compared to those of 0 and 15%.