SIMPLE METHOD FOR DETERMINATION OF CARBONATE ADSORPTION AT ELEVATED CARBON DIOXIDE CONCENTRAT

Abstract

We developed a simple method to measure carbonate adsorption by soils and clays at equilibrium with the air having elevated carbon dioxide concentrations. The method uses bags made of laminated polyamide-polyethylene film as experimental container. Soil or clay sample is put in the bag and sealed up. Addition of equilibrating solution and air containing CO² and sampling of the air and solution are all made through a three-way stopcock attached to the bag. The equilibrium pH is measured with a fow-through glass electrode attached also to the stopcock.
The carbonate adsorption by specimen boehmite was measured with the proposed method under equilibrium CO² concentration of 3 to 3.9% and pH of 4.4 to 7.6. The carbonate adsorption increased as the pH increased, reached maximum at around pH 7.4 and then decreased. The coefficient of variation of the measured values ranged 2.0 to 4.3%, which were significantly lower than those from measurements with conventional methods.