[Elimination of nitrogen dioxide and nitric oxide by soda lime and its components]

To investigated the efficacy of soda lime and its components in absorbing NO2 and NO.

VIP BIRD ventilator was connected with Siemens test lung. While the concentration of inhaled NO was 80 mg/L, the inspired gas passed through soda lime or its component. NO and NO2 were measured before and after testing materials in the circuit. Test 1, the soda lime canister sequentially was filled with smaller particle soda lime 500, 250, 125, 62.5, 39, 20, 10 and 0 g, to determine weight-efficacy relationship of the soda lime. Test 2, the canister sequentially was filled with bigger particle soda lime 500, 62.5, 30, 20 and 10 g, for comparing effective absorption of NO and NO2 between the two types of soda lime Test 3, 1.0 g methyl orange was added to smaller particle soda lime 10 g and 20 g respectively to observe its effect on eliminating NO and NO2. Test 4, silica gel tube was filled with smaller particle soda lime 10 g, KOH 10 g, NaOH 10 g, Ca(OH)2 2.5 g, and methly orange 0.5 g respectively for observing their ability of eliminating NO and NO2.

The two types soda lime had the ability to eliminating NO and NO2 from inspired gas with a positive relationship with its weight. Both KOH and NaOH did not eliminate NO and NO2 Ca(OH)2 and methyl orange had a week ability. Methyl orange did not affect the ability of soda lime to eliminate NO2, but decreased its ability to eliminate NO. During 240 min, the eliminating NO2 ability of soda lime did not change, but the eliminating NO ability was reduced from 30% to 19% after 60 min.

The effective components to eliminate NO and NO2 in soda lime are Ca(OH)2 and NaOH. Their ability to eliminate NO and NO2 increases with increase in their weight. The ability to eliminate NO decreases with increase in the contacting time with NO.