Efect of Potassium Hydroxide Concentration and Activation Time on Rice Husk-Activated Carbon for Water Vapor Adsorption

Rice husk carbon by-product from the industrial combustion is a promising source to produce a vast amount of activated carbon adsorbent. This research prepared rice husk-activated carbon adsorbent by varying the concentration of potassium hydroxide solution (۵, ۱۰, ۱۵, ۲۰ % w/v) and activation time (۲, ۴, ۶, ۸ hours). Fourier-transform infrared spectral characterization (FTIR) indicated a significant effect before and after activation, especially the presence of hydroxyl groups. Based on the iodine adsorption, the specific surface area of the produced-activated carbon was approximately ۶۱۵ m۲/g. Experimental results showed that increasing potassium hydroxide concentration and activation time increases the water vapor adsorption capacity of the activated carbon. Compared with the rice husk carbon, the KOH-activated carbon enhanced the water vapor adsorption capacity to ۹۳۱%. In the adsorption observation, changing the temperature from ۱۵ to ۲۷ ℃ caused a higher water vapor uptake onto the activated carbon. Two adsorption kinetics (pseudo-first- and pseudo-second-order models) were used to evaluate the adsorption mechanism. This research found that rice husk-activated carbon performed a higher water vapor adsorption capacity than other adsorbents (silica gel, zeolite, and commercially activated carbon).

Keywords:

activated carbon , adsorption kinetics , desiccant , rice husk , water vapor adsorption