**4. Results**

Tab. 1 and 2 present data of the physical, chemical and mineralogical Brazilian soil and constituents of the gasoline type C studied.


\*Grain size data obtained by ultra-sound waves using a laser beam grain size analyser.

**Table 1.** Characteristics of the soil (Farias, 2003).

Tab. 2 presents the composition of the Brazilian type-C gasoline, according to Farias (2003).


**Table 2.** Brazilian Type C gasoline data.

**4. Results**

constituents of the gasoline type C studied.

644 Environmental Risk Assessment of Soil Contamination

Tab. 1 and 2 present data of the physical, chemical and mineralogical Brazilian soil and

**Atterberg Limits**

**Grain size distribution\***

**Chemical Parameters**

**Mineralogy**

\*Grain size data obtained by ultra-sound waves using a laser beam grain size analyser.

**Table 1.** Characteristics of the soil (Farias, 2003).

**Test Lateritic**

Liquid limit-WL (%) 41 Plastic limit-WP (%) 29 Plastic Index-IP (%) 12 Activity 0,18

Clay (%) 65 Silt (%) 34 Sand(%) 1

pH 5,70

Quartz (%) 30,2 Anatase (%) 1,57 Kaolinite(%) 24,6 Gibbsite (%) 25,5 Goethite (%) 4,6 Hematite (%) 7,5 Illite (%) 2,2 Vermiculite (%) 3,7

Degree of flocculation (%) 92 Degree of dispersion (%) 8

Organic Matter content (%) 0,41 CEC (mmolc/dm3) 6,4

Hydraulic Conductivity in water (cm/s) 3,7.E-07

Tab. 2 presents the composition of the Brazilian type-C gasoline, according to Farias (2003).

Fig. 4 presents the increase in hydraulic conductivity with an increase in the hydraulic gradient. At a gradient of approximately 210, conductivity becomes practically constant. Fig. 5 presents the intrinsic permeability, which considers the characteristics of the soil, but does not consider the chemical and physical properties of the fluid. Intrinsic permeability reaches values close to 10-13m2 . However, as the hydraulic gradient increases, stability reaches approximately 10-11m2 .

y = -3.3548x2 + 2.762x + 3.5475 R² = 0.9576

0.00 0.20 0.40 0.60 0.80 1.00 1.20

y = -3.3548x2 + 2.762x + 3.5475 R² = 0.9576

0.00 0.20 0.40 0.60 0.80 1.00 1.20

0.13 0.36 0.65 0.90 1.14

**Aromatics olefins Saturated Ethanol**

**Volume -Porous**

**Volume - Porous**

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

**Conductivity Hydraulic K.10-8**

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

0.00

0.20

0.40

0.60

0.80

**C/Co**

1.00

1.20

1.40

1.60

1.80

**Conductivity Hydraulic**

**K.10-8 (cm /s)**

**(cm /s)**

**Figure 4.** Behavior of hydraulic conductivity and hydraulic gradient of laterite soil on the gasoline flow. **Pore volume Hidraulic Gradient**

**Figure 5.** Behavior of the intrinsic permeability and hydraulic gradient of laterite soil on the gasoline flow.

Fig. 6 depicts the behavior of the hydraulic conductivity relative to the volume of pores while undergoing saturation in the test material with gasoline at a tension of **σ<sup>v</sup>** of 50 kPa. The saturation process takes place with the expulsion of the interstitial water accumulated in the pores due to optimal compacting moisture content (wopt = 26%) is the test material at normal Proctor energy. It may be observed that as the volume of pores in the gasoline flow increases, conductivity decreases from 4 to 2 x 10-8 cm.s-1. This suggests that the behavior of the reduction may be represented by a second-order equation.

**Figure 6.** Behavior of the lateritic soil saturated with gasoline at 50 kPa.

Fig. 7 presents the saturation process at a **σ<sup>v</sup>** tension of 50 kPa, based on the ratio between the concentration (C) of the gasoline hydrocarbons passing through the soil sample, and the initial concentration (**Co** ) added to the reservoir, in relative to the volume of pores. The hydrocarbons concentration data are from the Light Non-aqueous Liquid Phase (LNALP), after the flow through the soil sample in the hydraulic conductivity test.


\*Dry soil sample before the hydraulic conductivity test

\*\*Dry soil sample after the hydraulic conductivity test with the water flow

\*\*\* Dry Soil sample after the hydraulic conductivity test with the gasoline flow

**Table 3.** Result of the physical parameters of the test material.

10 110 210 310 410 510

y = -3.3548x2 + 2.762x + 3.5475 R² = 0.9576

0.00 0.20 0.40 0.60 0.80 1.00 1.20

**Pore volume**

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

**Conductivity Hydraulic K.10-8**

**(cm /s)**

The results in Tab. 3 present the physical parameters of the compacted test materials dried at room temperature before and after the hydraulic conductivity test. Highlights the volume of voids (**Vv**), which changes substantially when there is a flow of gasoline. The degree of saturation also decreases after the flow of gasoline. 1.E-08 **Hidraulic Gradient**

1.E-06

1.E-05

Fig. 6 depicts the behavior of the hydraulic conductivity relative to the volume of pores while

saturation process takes place with the expulsion of the interstitial water accumulated in the pores due to optimal compacting moisture content (wopt = 26%) is the test material at normal Proctor energy. It may be observed that as the volume of pores in the gasoline flow increases,

of 50 kPa. The

. This suggests that the behavior of the reduction

y = -3.3548x2 + 2.762x + 3.5475 R² = 0.9576

0.00 0.50 1.00 1.50

) added to the reservoir, in relative to the volume of pores. The hydrocarbons

**(kN.m-3) <sup>e</sup> <sup>n</sup> S r**

**(%)**

**Vv cm3**

**γs**

**Pore Volume**

Fig. 7 presents the saturation process at a **σ<sup>v</sup>** tension of 50 kPa, based on the ratio between the concentration (C) of the gasoline hydrocarbons passing through the soil sample, and the initial

concentration data are from the Light Non-aqueous Liquid Phase (LNALP), after the flow

lateritic\* 1,7 17,7 17,4 27,5 0,58 0,4 8,1 134,3 lateritic\*\* 1,7 15,8 15,6 27,5 0,77 0,4 6,2 178,5 lateritic\*\*\* 1,8 14,7 14,5 27,5 0,90 0,5 5,3 210,0

**γdmax (kN.m-3)**

undergoing saturation in the test material with gasoline at a tension of **σ<sup>v</sup>**

cm.s-1

conductivity decreases from 4 to 2 x 10-8

646 Environmental Risk Assessment of Soil Contamination

**Hydraulic Conductivity** 

concentration (**Co**

**Sample <sup>w</sup>**

**(%)**

\*Dry soil sample before the hydraulic conductivity test

**Table 3.** Result of the physical parameters of the test material.

**K.10-8 (cm /s)**

may be represented by a second-order equation.

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5

**Figure 6.** Behavior of the lateritic soil saturated with gasoline at 50 kPa.

through the soil sample in the hydraulic conductivity test.

**γ (kN.m-3)**

\*\*Dry soil sample after the hydraulic conductivity test with the water flow \*\*\* Dry Soil sample after the hydraulic conductivity test with the gasoline flow

**Figure 7.** Light non-aqueous liquid phase ratio of the gasoline relative to the volume of pores of the lateritic soil in a saturation process at 50 kPa.

The micromorphology of the three compacted soil samples was important in order to visualize the behavior of the test material before the hydraulic flow (Fig. 8), after the hydraulic flow with water, and after the flow with gasoline. It must be noted that the grains of quartz make up approximately 40% of the total solid material; variable in size, 0.12 mm on average; and overall, are sub-rounded to angular. They are highly fractured, without orientation and their contours present corrosion. In spite of the compacting, the structure of this soil is not totally dispersed, for microaggregations of oxyhydroxides of Fe and Al remain, forming micropores. The compacted soil sample submitted to percolation in water showed a single micro-structural difference relative to the one performed on the LT of the compacted soil sample. Actually, there was an increase in small canal-type voids, generated by the flow of water (Fig. 9). The micromorphology regarding the LT of the compacted soil submitted to the flow of gasoline also showed only a quantitative increase in canal-type voids (Fig. 10). However, this variation was greater than that registered in the previous sample with the water flow.

**Figure 8.** Photomicrography of the porfirosquelic APE, aggregates, and quartz grains of the compacted lateritic soil. Parallel nichols (N//).

**Figure 9.** Photomicrography showing the nodules and canal- and chamber-type voids of the compacted lateritic soil submitted to percolation with water. Parallel nichols (N//).

Chemical and Hydraulic Behavior of a Tropical Soil Compacted Submitted to the Flow of Gasoline Hydrocarbons http://dx.doi.org/10.5772/57234 649

**Figure 10.** Photomicrography showing the canal-type voids of the compacted lateritic soil submitted to percolation with gasoline. Parallel nichols (N//).

**Figure 8.** Photomicrography of the porfirosquelic APE, aggregates, and quartz grains of the compacted lateritic soil.

**Figure 9.** Photomicrography showing the nodules and canal- and chamber-type voids of the compacted lateritic soil

submitted to percolation with water. Parallel nichols (N//).

Parallel nichols (N//).

648 Environmental Risk Assessment of Soil Contamination

Fig. 11 presents the results of the adsorption of the ethanol and aromatic substances in the samples with and without the extraction of organic matter with the use of hydrogen peroxide. Note that the samples treated with extractor presented low adsorption. Aromatic compounds showed no adsorption after extraction of organic matter contained in the soil.

**Figure 11.** Results of the adsorption of the gasoline hydrocarbons in the soils with and without the extraction of the soil organic matter.

Gasoline ethanol can be adsorbed on the sites of hydroxyls of the octahedron of Al, exposed by fractures, Scrubs or crystalline lattice imperfections, or by interactions with the Fe oxides and hydroxides and Al amorphous. This occurs from adsorption of hydrogen bonds, which can also occur with water strongly adsorbed on the surface of the clay minerals (Fig. 12).

**Figure 12.** Coordination of interaction of hydrogen and hydroxyl ethanol exposed in the clay mineral (1:1).
