WATER VAPOR, SULFUR DIOXIDE AND AMMONIA ADSORPTION BY FIBROUS MATERIAL IMPREGNATED WITH CITRATE-MONOETHANOLAMINE BUFFER SOLUTIONS

The work is devoted to the study of adsorption of water vapor, sulfur dioxide and ammonia under static and dynamic conditions by citrate-monoethanolamine buffer systems impregnated onto a fibrous carrier at different molar ratios of monoethanolamine (MEA) : citric acid (H3Cit). It has been gravimetrically established that the water content in air and absolutely dry impregnated fibrous chemisorbents (IFCS) correlates with the MEA content in their composition. Most of the adsorption isotherms of H2O vapor by IFCS samples are classified as type V according to the IUPAC classification. Within the framework of the Brunauer-Emmett-Teller theory of polymolecular adsorption, the adsorption isotherms were analyzed, the values of monolayer capacity and the adsorption heats of water molecules in the first layer were determined, and the specific surface area of the adsorbate was estimated. Correlations were revealed between the structural and adsorption characteristics of IFCS samples and the MEA content. Characteristic sections of the water desorption curves that corresponding to negative hysteresis were noted. According to the classification of C.Giles, most of the SO2 adsorption isotherms at a relative humidity of P/Ps = 0,13 are classified as type S2; P/Ps = 0,23 and 0,50 – L2; P/Ps = 0,70 and 0,90 – C1-type. It has been shown that absolutely “dry” IFC samples are capable of absorb sulfur dioxide due to the presence of “free” water or the formation of a sulfamide N-S bond. The influence of the MEA content in the IFC composition and the relative humidity and physical adsorption of SO2 on them is revealed. Only at P/Ps = 0,90 a relationship between the SO2 chemically adsorbed by the IFCS samples and the MEA content on their surface was observed. Competing adsorption of H2O and SO2 confirmed by complex and different from each other dependencies α(SO2) = f(P/Ps) at different MEA:H3Cit molar ratios. This material (IFCS-2,94MEA-H3Cit) can be used in the manufacture of gas protection element for equipping personal respiratory protection equipment – lightweight gas-dust respirators.