Modification and adsorption properties on NH₃ of humus soil

Ammonia (NH₃) is a colorless, pungent, alkaline gas, which is not only injurious to human and animal health, but also causes air pollution. Humus soil has porous, loose, carboxyl (-COOH), and hydroxyl (-OH) radicals. In this study, humus soil was modified by different chemical substances (acids, alkalis, and salts) to expand its specific surface area and pore size, which can improve the soil's ability to adsorb gaseous ammonia. The conditions of modification were as follows: H₂SO₄ solution concentration was 17%, the solid-liquid ratio was 1:8 the temperature was 60℃, the modification time was 8 hours, and the modified humus soil was dried at 105℃. The results show that the BET surface area of the modified humus soil increased from 12 to 46 m²·g^-1, indicating a 3.83 times increase. The adsorbent was made by modified humus soil and methyl cellulose (1%), which was then calcined at 200℃ for 2 hours. The penetration time of ammonia increased by a factor of 8, from 10 min to 90 min. The NH₃ breakthrough capacity was improved by a factor of 26, from 0.085 to 2.3 mg·g^-1.