Organic acid activation of persulfates

Abstract

The present invention is directed to a method of oxidizing an organic compound present in soil, groundwater, process water or wastewater comprising contacting such organic compound with a persulfate and an organic acid selected from the group consisting of ascorbic acid, formic acid, oxalic acid, lactic acid and citric acid, wherein the molar ratio of such organic acid to persulfate is between 1:100 and 3:1.

Claims

1. A method of oxidizing an organic contaminant present in soil, groundwater, process water or wastewater comprising contacting the organic contaminant present in the soil, groundwater, process water or wastewater with a persulfate solution and an organic acid solution selected from the group consisting of ascorbic acid, formic acid, oxalic acid, lactic acid and citric acid, to form an oxidizing solution at a molar ratio of organic acid to persulfate effective to activate the persulfate and oxidize the organic contaminant, wherein the molar ratio of such organic acid to persulfate is between 1:10 and 2:1, and wherein the pH of the oxidizing solution is acidic.

2. The method of claim 1 wherein the persulfate is a dipersulfate.

3. The method of claim 2 wherein the dipersulfate is sodium persulfate.

4. The method of claim 1 wherein the organic acid is ascorbic acid.

5. The method of claim 1 wherein the organic contaminant is selected from the group consisting of trichloroethylene (TCE), vinyl chloride, tetrachloroethylene (PCE), methylene chloride, 1,2-di chloroethane, 1,1,1-trichloroethane (TCA), carbon tetrachloride, chloroform, chlorobenzenes, benzene, toluene, xylene, ethyl benzene, ethylene dibromide, methyl tertiary butyl ether, polyaromatic hydrocarbons, polychlorobiphenyls, phthalates, 1,4-dioxane, nitrosodimethyl amine, and methyl tertbutyl ether.

6. The method of claim 1 wherein such method is performed in situ.

7. The method of claim 1 wherein such method is performed ex situ.

8. The method of claim 6 wherein the persulfate and organic acid are added simultaneously.

9. The method of claim 6 wherein the persulfate and organic acid are added sequentially.

10. The method of claim 1, wherein the contacting step comprises injection, blending, or mixing the persulfate and the organic acid with the soil, groundwater, process water or wastewater.

Description

EXAMPLES

Example 1

(1) Benzene and trichloroethylene were added to tap water to produce a test solution comprising 6.3 mg/L of benzene and 1.5 ppm of TCE. This test solution was poured into 40 mL vials and sodium dipersulfate (PS) added to a final concentration of 5.0 g/L. Ascorbic acid (AA) was added in solid form in those AA/PS ratios listed in Table 1 below. Control samples containing only the test solution; and containing only 5.0 g/L PS were also prepared. The samples were sealed without leaving any headspace. The samples were stored at 25° C. for one day.

(2) After such storage, the benzene and TCE concentrations present in each sample vial were determined using GC-MS (Shimadzu GCMS-QP2010) and a Purge & Trap sample concentrator (O.I. Analytical 4560), according to EPA methods 5030 and 8260. The results of such testing are summarized in Table 1.

(3) TABLE-US-00001 TABLE 1 Testing at 25° C. AA:PS Molar Benzene TCE Sample Ratio (ppm) (ppm) 1-A No PS or AA 6.26 1.45 1-B PS only 1.33 0.55 1-1 1:10 0 0 1-2 1:4 0 0 1-3 1:2 0 0 1-4 1:1 0 0

Example 2

(4) The procedure of Example 1 was repeated, except that the samples were stored at 2° C. The results of such testing are summarized in Table 2.

(5) TABLE-US-00002 TABLE 2 Testing at 2° C. AA:PS Molar Benzene TCE Sample Ratio (ppm) (ppm) 2-A No PS or AA 6.33 1.48 2-B PS only 6.26 1.43 2-1 1:10 0.22 021 2-2 1:4 0.14 0.15 2-3 1:2 0 0 2-4 1:1 0 0

(6) A comparison of Table 1 and Table 2 shows that the process of this invention is effective at lower temperatures of less than 20° C., and more typically of less than 10° C. at which most in situ environmental remediation must take place.

Example 3

(7) Benzene and trichloroethylene were added to tap water to produce a test solution comprising 32.7 mg/L of benzene and 18.3 ppm of TCE. The test solution was then divided into two parts, and sodium dipersulfate (PS) was added to one part to a final concentration of 5.0 g/L, and to the second part—to a final concentration of 1.0 g/L. These test solutions were poured into 40 mL vials, to which ascorbic acid (AA) was added in solid form in those AA/PS ratios listed in Table 3 below. Control samples containing only the test solution; and containing only 5.0 g/L PS and 1.0 g/L PS were also prepared. The samples were sealed without leaving any headspace. The samples were then divided into two parts. One part was stored at 25° C. for two days, and the second at 2° C. for two days.

(8) After such storage, the benzene and TCE concentrations present in each sample vial were determined using GC-MS (Shimadzu GCMS-QP2010) and a Purge & Trap sample concentrator (O.I. Analytical 4560), according to EPA methods 5030 and 8260. The results of such testing are summarized in Tables 3-6.

(9) TABLE-US-00003 TABLE 3 Testing at 25° C.; 5.0 g/L PS AA:PS Molar Benzene TCE Sample Ratio (ppm) (ppm) 3-A No PS or AA 32.5 18.1 3-B PS only 20.6 12.1 3-1 1:10 4.11 2.01 3-2 1:4 2.5 1.6 3-3 1:2 1.2 0.4 3-4 1:1 0.9 0.1 3-5 2:1 2.7 1.3 3-6 3:1 15.0 10.1 3-7 4:1 28.7 16.6 3-8 6:1 30.3 16.7 3-9 8:1 31.8 17.2

(10) TABLE-US-00004 TABLE 4 Testing at 25° C.; 1.0 g/L PS AA:PS Molar Benzene TCE Sample Ratio (ppm) (ppm) 4-A No PS or AA 32.6 18.2 4-B PS only 24.7 13.4 4-1 1:10 6.5 4.8 4-2 1:4 4.0 3.1 4-3 1:2 2.1 1.7 4-4 1:1 1.4 1.0 4-5 2:1 5.3 4.6 4-6 3:1 15.7 11.0 4-7 4:1 29.5 16.5 4-8 6:1 30.5 17.2 4-9 8:1 32.4 17.8

(11) TABLE-US-00005 TABLE 5 Testing at 2° C.; 5.0 g/L PS AA:PS Molar Benzene TCE Sample Ratio (ppm) (ppm) 5-A No PS or AA 32.6 18.3 5-B PS only 29.3 17.6 5-1 1:10 4.9 2.7 5-2 1:4 2.6 1.3 5-3 1:2 1.2 0.7 5-4 1:1 0.5 0.2 5-5 2:1 4.4 1.9 5-6 3:1 13.8 10.1 5-7 4:1 30.6 16.4 5-8 6:1 30.9 17.2 5-9 8:1 31.6 17.0

(12) TABLE-US-00006 TABLE 6 Testing at 2° C.; 1.0 g/L PS AA:PS Molar Benzene TCE Sample Ratio (ppm) (ppm) 6-A No PS or AA 32.7 18.3 6-B PS only 30.6 18.1 6-1 1:10 12.2 8.7 6-2 1:4 5.3 3.6 6-3 1:2 4.2 2.7 6-4 1:1 3.8 1.7 6-5 2:1 6.5 4.2 6-6 3:1 18.0 11.0 6-7 4:1 29.9 17.7 6-8 6:1 32.3 17.7 6-9 8:1 32.9 18.2

(13) The data in Tables 3 through 6 show that the process of this invention is effective at AA:PS molar ratios in the range of about 1:10 to about 3:1. The process is effective at lower temperatures (2° C.) which are frequently encountered in environmental remediation.

Example 4

(14) Benzene was added to tap water to produce a test solution comprising 9.1 mg/L of benzene. This test solution was poured into 40 mL vials and sodium dipersulfate (PS) added to a final concentration of 5.0 g/L. Those organic acids indicated were added in those Acid/PS ratios listed in Table 7 and Table 8 below. Control samples containing only the test solution; and containing only 5.0 g/L PS were also prepared. The samples were sealed without leaving any headspace. One part of the samples was stored at 25° C., and another part at 2° C. for one week. Samples were tested periodically for benzene concentration using GC-MS (Shimadzu GCMS-QP2010) and a Purge & Trap sample concentrator (O.I. Analytical 4560), according to EPA methods 5030 and 8260. The results of such testing are summarized Table 7 and Table 8.

(15) TABLE-US-00007 TABLE 7 Testing at 25° C. Acid:PS Molar Benzene (ppm) Sample Acid Ratio 1 Day 4 days 7-A — No PS or Acid 9.11 9.08 7-B — PS only 3.53 1.03 7-1 Oxalic 1:10 3.04 0.87 7-2 Oxalic 1:4 2.70 0.72 7-3 Oxalic 1:2 2.59 0.65 7-4 Citric 1:10 2.96 0.12 7-5 Citric 1:4 2.11 0.00 7-6 Citric 1:2 1.91 0.00 7-7 Formic 1:10 2.45 0.00 7-8 Formic 1:4 1.56 0.00 7-9 Formic 1:2 0.75 0.00 7-10 Lactic 1:10 2.86 0.45 7-11 Lactic 1:4 2.48 0.38 7-12 Lactic 1:2 2.28 0.30

(16) TABLE-US-00008 TABLE 8 Testing at 2° C. Acid:PS Benzene Molar (ppm) Sample Acid Ratio 1 day 4 days 8 days 8-A — No PS or Acid 9.14 9.12 9.13 8-B — PS only 8.58 6.60 3.71 8-1 Oxalic 1:10 7.99 6.22 3.09 8-2 Oxalic 1:4 6.82 5.77 2.78 8-3 Oxalic 1:2 5.99 4.68 2.15 8-4 Citric 1:10 6.11 3.94 2.01 8-5 Citric 1:4 5.49 3.53 1.44 8-6 Citric 1:2 4.82 3.10 0.87 8-7 Formic 1:10 5.95 3.89 1.93 8-8 Formic 1:4 5.19 3.13 1.26 8-9 Formic 1:2 4.52 2.84 0.72 8-10 Lactic 1:10 8.04 6.33 3.32 8-11 Lactic 1:4 7.22 5.42 2.85 8-12 Lactic 1:2 6.55 4.81 2.43

(17) The data in Tables 7 and 8 show that oxalic acid, citric acid, formic acid and lactic acid are all effective activators for PS, at both 2° C. and 25° C.