IRON-COMPRISING CONCENTRATE FOR PREPARATION OF IN SITU REMEDIATION SOLUTION

Abstract

A liquid concentrate composition for remediation of groundwater, said composition consisting of powdered iron in the amount of 30 to 70% zero-valent iron powder, such as 40 wt, 1 to 15 wt % of water, 0.1 to 1.5% of surfactant and 40 to 70 wt % of the organic carrier, wherein the organic carrier is added to the 100 wt % and optionally, organic electron donor solution and/or remediation chemical, wherein organic electron donor solution and/or remediation chemical is not exceeding 10 wt % of the liquid concentrate.

Claims

1. A liquid concentrate composition for remediation of groundwater, said composition consisting of: 30 to 50 wt % of zero-valent iron powder; 1 to 15 wt % of water; 0.1 to 1.5 wt % of a surfactant and 40 to less than 70 wt % of an organic carrier and optionally, n organic electron donor solution and/or remediation chemical, wherein the organic electron donor solution and/or remediation chemical is not exceeding 10 wt % of the liquid concentrate.

2. The liquid concentrate according to claim 1, wherein the surfactant is anionic or nonionic surfactant.

3. The liquid concentrate according to claim 2, wherein the anionic surfactant is an alkali metal salt of a long-chain carboxyl or sulfonic acids.

4. The liquid concentrate according to claim 2, wherein the non-ionic surfactant is a sorbitan ethoxylate.

5. The liquid concentrate according to claim 1, wherein the organic carrier is selected from propylene glycol or glycerol.

6. The liquid concentrate according to claim 1, wherein the viscosity of the composition is between 2000 and 5000 cp as measured at 6 RPM with a Brookfield DV1 viscometer (spindle #2) at a temperature of 20 degrees C.

7. The liquid concentrate according to claim 1, wherein the gravity is about 1.8 fas determined by using a 83.2 mL BYK-Gardner PV-9654 specific gravity cup with 0.5% tolerance.

8. The liquid concentrate according to claim 1, wherein the iron particles in the dispersion have average diameter between 1 and 10 microns as measured by laser light scattering methods.

9. A method for preparation of a ready-to-use solution for injecting into the ground water with the purpose of remediation, said method comprising: providing the liquid concentrate according to claim 1, diluting with water such that the final concentration of iron in the solution is between 0.1 wt % and 5 wt %.

Description

FIGURE LEGENDS

[0030] FIG. 1. Maximum injection pressure of each column (Column 1, Column 2 and Column 3) as disclosed below.

[0031] FIG. 2. Iron distribution by magnetic susceptibility measurement. Comparison of the control (black bars) with the invention (dotted bars).

EXAMPLE COLUMNS

[0032] (1) Column 1: iron powder in water, —Comparative Sample 1 [0033] (2) Column 2: Invention, —Sample 2 According to the invention [0034] (3) Column 3: iron powder in glycerol and water, Comparative Sample 3

Example 1

[0035] Three plastic columns (4′ long by 2″ inner diameter) were loaded with water-saturated sand, taking precaution to avoid entrainment of air. Using a peristaltic pump, water was then flowed through each column at a flowrate of 260 mL/min, maintaining approximately 5 psi of pressure. For each test condition, the feed was then switched from water to the test sample while keeping the pumping rate constant. The test sample for Column 1 (Control) was a simple iron slurry consisting of 0.87% w/w iron powder in water. In Column 2, the present invention was tested at the same iron loading. In Column 3, a mixture of glycerol (1.3 wt %), water (97.83 wt %), and iron powder (0.87 wt %) was tested as a control for the presence of glycerol.

[0036] Pumping was continued for each sample for 10 minutes. While the injection pressure in Column 2 was consistent at approximately 5 psi, the pressure in the control column rose to near 35 psi, shown in FIG. 1, indicating some clogging by the simple iron slurry. Each feed was then switched back to water, and pumping continued for another 10 minutes. The columns were then sealed for further analysis. The collected eluents from the control Columns 1 and 3 were clear with no apparent presence of iron. Eluent from Column 2 was a dark-colored suspension, indicating the elution of iron particles.

[0037] Magnetic susceptibility measurements were made along the length of each column to determine the relative concentration of iron metal particles in the saturated sand. The magnetic susceptibility was measured using a Barrington MS2/MSC magnetic susceptibility meter. The measurements were taken at 1 inch intervals along the entire length of the column. The data, summarized in FIG. 2, indicate that the control sample deposited more iron in the first two feet of the column, while the invention transported significantly more iron particles to the 2-4 foot section of the column.

[0038] Further analysis of the magnetic susceptibility data was performed to evaluate the relative amount of iron distributed beyond two feet for each test sample. The results, normalized to the amount of iron distributed by the control sample, are shown in Table 1.

TABLE-US-00001 TABLE 1 Relative amount of iron distributed further than 2 feet, normalized to control. Average MS reading in Relative % Fe in Sample 2-4 foot section (SI) 2-4 foot section Column 1 (Control) 1.05 × 10.sup.−3 100% Column 2 (Invention) 3.33 × 10.sup.−3 316% Column 3 (Control + 8.66 × 10.sup.−4  82% glycerol)