Investigation of volatile organic compound absorption in water

Abstract

Absorption is one of the most widely applied methods for capturing gaseous air pollutants. The efficiency of the process depends upon the solubility of the gas phase in an absorbent, i.e. in a liquid of a different character. Water is the most common absorbent which besides being an excellent solvent is also cheap. Volatile organic compounds (VOC) – acetone, buthylacetate, butanol, propanol, toluene, toluene, etc – are substances usually used in technological processes. A high volatility of these liquids conditions their great concentration in the ambient air of a workplace. For investigating the absorption process of acetone, butanol, and propanol under laboratory conditions, it was necessary to tailor the experiment equipment, adopt the chromatographic methodology for the study of these organic compounds, and design calibration curves for determining control concentrations. The investigation results might be used in the development of absorption methods for air cleaning from volatile organic compounds and in setting of maintenance regimes. In the first stage of the work, the equilibrium curves of acetone, butanol and propanol vapour transference from a gaseous to liquid state under static conditions were developed. The investigation was carried out at a temperature of 15, 20 and 25 °C. VOC concentrations in the air and water were determined with the help of the gas chromatography method. A biological air-cleaning filter was used during the investigation of dynamic absorption. It was determined that the general character of water solubility for individual substances under dynamic conditions was similar to that under static conditions, i.e. the dissolved amount of butanol was much smaller and its concentration in water was increasing much slower than that of acetone or propanol. The aim of the investigation was to determine experimentally the regularities of static and dynamic absorption of certain volatile organic compounds in water.

Absorbcija yra vienas iš plačiausiai taikomų dujinių teršalų gaudymo metodų. Proceso efektyvumą lemia dujinės fazės teršalų tirpumas absorbente - įvairios kilmės skystyje. Paprasčiausias absorbentas yra vanduo, jis ne tik puikus tirpiklis, bet ir yra pigus. Technologiniuose procesuose dažnai naudojama lakieji organiniai junginiai - acetonas, butilacetatas, butanolis, propanolis, ksilenas, toluenas ir kiti. Dėl didelio šių skysčių lakumo susidaro didelės teršalų koncentracijos darbo aplinkos ore. Tyrimų tikslas - eksperimentiškai nustatyti lakiųjų organinių junginių absorbcijos vandenyje statinėmis ir dinaminėmis sąlygomis dėsningumus. Tyrimų rezultatai panaudojami kuriant absorbcinius lakiųjų organinių junginių valymo iš oro filtrus, nustatant jų eksploatacinius režimus. Gauti duomenys taip pat svarbūs biologinio oro valymo, naudojant aktyvųjį dumblą, procesui nagrinėti. Aktyvusis dumblas - vandens ir mikroorganizmų mišinynys, kuris recirkuliacijos įrenginyje metu sugeria ir suskaido organinius teršalus. Svarbiausia prielaida, kad biologinis filtras veiktų efektyviai - dujinis teršalas turi būti gerai absorbuojamas vandenyje.