Testing of activated carbon for water and non-volatile LNAPL quantitative determination in porous media under laboratory conditions

Abstract

Báťková K., Matula S., Miháliková M., Chala A.T., Moreira Barradas J.M., Mekonnen G.B. (2014): Testing of activated carbon for water and non-volatile LNAPL quantitative determination in porous media under laboratory conditions. Soil & Water Res., 9: 161-168.Activated carbon is a highly porous form of carbon, which has an exceptionally large surface area. Activated carbon material has been artificially processed as a set of plates, within which two different types of pores are present: micropores (< 2 nm) and transport pores (macropores > 50 nm and mesopores 2-50 nm). The transport pores bring molecules of different substances (organic compounds) into the micropores, which are basically the active centres where the adsorption takes place. Activated carbon, due to its high adsorption potential, is used in many applications such as air, water, wastewater or chemical purification. In this study, the pelletized activated carbon (Silcarbon SC40) was tested for water and non-volatile LNAPL (Light Non-Aqueous Phase Liquid; medicinal mineral oil used in this study) determination in a porous medium (silica sand). The experiments were carried out under controlled laboratory conditions. Three different sets of experiments were carried out: (i) the water or LNAPL adsorption from pure media (water or LNAPL liquids); (ii) the water or LNAPL adsorption from pure media (water or LNAPL vapours); (iii) water and/or LNAPL adsorption from the porous material at different sampling intervals. Furthermore, the water/LNAPL contents of the porous media were determined on the basis of the water/LNAPL contents of sampled Silcarbon SC40. The results confirmed the suitability of the Silcarbon SC40 for water/LNAPL sampling from the porous media under laboratory conditions. The method is suitable for detection of water and/or LNAPL in a liquid or gaseous phase and also for water and/or LNAPL quantitative determination. For the quantitative determination a calibration of this method would be required.Keywords: activated carbon; LNAPL; silica sand; Silcarbon SC40; sampling interval Organic contaminants are one of the most common substances contaminating the vadose and saturated zones of soil and rock environments. Light NonAqueous Phase Liquids (LNAPLs) represent a group of organic substances that are relatively insoluble in water and are less dense than water (US EPA 2012). The LNAPLs move through the vadose zone towards the ground water level; its lateral movement can start even before the LNAPL reaches the ground water level due to the capillary fringe and saturated conditions above the ground water level (Cohen & Mercer 1990). Quite a lot of effort has been invested in studies of LNAPL behaviour in homogeneous conditions (Lenhard et al. 1993;Ostendorf et al. 1993;Eckberg & Sunada 1984). However, LNAPL transport within heterogeneous media has not been investigated thoroughly and requires further research (Schroth et al. 1998). In the past, research was aimed at applications in the petroleum industry. Recently however preferences have ...

Evaluation of methods for water and non-volatile LNAPL content measurement in porous media

“…Medicinal grade white mineral oil commercially known as Marcol 82 (Lubstar a.s., Czech Republic) was used as LNAPL. Quality of the oil: inertness, immiscibility with water, higher boiling point and less dense compared to water were some of the considerations to select it for this experiment following Matula et al (2008) and Báťková et al (2014). Other liquids used in the experiment were drinking quality tap water and normal hexane (n-hexane; Penta s.r.o., Czech Republic).…”

“…SC40 is produced with average diameter 4 mm but varying length. For the whole experiment, ACP with narrow range both in diameter (around 4 mm) and length (8.5 to 10.5 mm) were used following the results from Báťková et al (2014) and Elsayed et al (2014). The size of the pellets was measured using a digital sliding gauge EXTOL ® Premium (Všestary, Czech Republic) with an accuracy of 0.01 mm.…”

“…The size of the pellets was measured using a digital sliding gauge EXTOL ® Premium (Všestary, Czech Republic) with an accuracy of 0.01 mm. The sampling of water and LNAPL was taken from the center of the sample column using oven-dried ACPs to a constant mass at 105°C for 24 h. ACP was placed to the sampling place using lab-built metal sampler and the detail of the sampling and analysis procedures used were based on Matula et al (2008) and Báťková et al (2014). Water was removed from the sampled liquid using oven-drying process and the remaining was assumed to be the mass of LNAPL and ACP.…”

“…Determination of both from a sample could be difficult if the oil could be lost with water at 105°C oven temperature. Matula et al (2008) and Báťková et al (2014) sampled both non-volatile LNAPL and water simultaneously from porous media and analyzed them using gravimetric analysis method. Due to its high porosity and high affinity for the environmental contaminants, activated carbon has been used in different treatments.…”