Deicing agents containing oxygen release compounds

Abstract

The present invention provides environmentally benign deicing compositions comprising deicers or anti-icing agents with oxygen release compounds for the mitigation of dissolved oxygen depletion in receiving waters due to the decomposition of organic deicers. The compositions also include additives for the effective release of oxygen from metal peroxides and for pH control as needed.

Claims

1. A deicer composition comprising (a) an organic deicer or a combination of organic deicer and inorganic deicer; (b) one or multiple oxygen release compounds (ORCs) added in the proportion of 0.5% to 30% by weight to the weight of organic deicers in the deicer composition for the purpose of mitigating oxygen depletion effects of organic deicers due to biodegradation in waters and soils.

2. An anti-icer composition comprising (a) an organic anti-icer or a combination of organic anti-icer and inorganic anti-icer; (b) one or multiple oxygen release compounds added in the proportion of 0.5% to 30% by weight to the weight of organic anti-icers in the anti-icer composition for the purpose of mitigating oxygen depletion effects of organic compounds that are present in anti-icer formulations.

3. A composition according to claim 1 to which one or more transition metal compounds are added to catalyze oxygen release from ORCs when such transition metal ions are not present in the soil or water.

4. A composition according to claim 2 to which one or more transition metal compounds are added to catalyze oxygen release from ORCs when such transition metal ions are not present in the soil or water.

5. A composition according to claim 1 to which acidic compounds are added when such acidic compounds are not present in the soil or water to neutralize the base released by the ORCs.

6. A composition according to claim 2 to which acidic compounds are added when such acidic compounds are not present in the soil or water to neutralize the base released by the ORCs.

7. A deicer composition according to claim 1 wherein the ORC is chosen from metal peroxides, metal percarbonates or combinations thereof.

8. A deicer composition according to claim 1 wherein the organic deicer is chosen from: (a) synthetic organic compounds including alkali carboxylates, alkaline earth carboxylates, or hydroxycarboxylic acid salts; (b) natural organic material including beet sugar processing wastes, whey permeates, corn steep water, or other agricultural and food processing waste byproducts; {c) combination synthetic and natural organic materials as described in (a) and (b).

9. A deicer composition according to claim 1 wherein the organic deicer or a combination of organic and inorganic deicer is in liquid, powder, granular, or solution form and is formulated with additives including corrosion inhibitors, inert materials, or other ingredients to improve traction.

10. An anti-icer composition according to claim 2 wherein the organic anti-icer or a combination of organic anti-icer and inorganic anti-icer is in liquid, powder, granular, or solution form and is formulated with additives including corrosion inhibitors, inert materials, or other ingredients to improve traction.

11. A deicer composition according to claim 1 wherein the ORC is in liquid, powder, granular, or solution form, or in encapsulated form.

12. An anti-icer composition according to claim 2 wherein the ORC is in liquid, powder, granular, or solution form, or in encapsulated form.

13. A deicer composition according to claim 1 wherein the organic deicer is alkali or alkaline earth metal salts of acetic acid or combinations thereof, and the ORC is calcium peroxide added in the proportion of 0.7% to 20% calcium peroxide by weight to the weight of acetate in the deicer.

14. A deicer composition of claim 1 wherein the organic deicer is alkali or alkaline earth metal salts of formic acid or combinations thereof, and the ORC is calcium peroxide added in the proportion of 0.5% to 10% calcium peroxide by weight to the weight of formate in the deicer.

15. A deicer composition of claim 1 wherein the organic deicer is acetate or formate salt of alkali or alkaline earth metals and combinations thereof, and calcium peroxide used as the metal peroxide is supplemented with iron as transition metal in the form of ferric chloride in the proportion of 2% to 5% of the weight of 100% calcium peroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) This invention discloses deicer and anti-icing compositions containing oxygen release compounds for roadway, airport runway, and aircraft deicing and anti-icing applications. The ORCs will counteract the oxygen depletion that can occur in receiving waters or soils due to the biodegradation of organic compounds present in deicers. The ORC may be organic or inorganic. However, as organic compounds will exert oxygen demand, this invention is primarily focused on inorganic ORCs. Alkali and alkaline earth metal peroxides and metal percarbonates can serve as ORCs. This invention focuses primarily on the use of calcium and magnesium peroxides singly or in combination as ORCs. However, this invention is not limited to these two compounds, and other compounds such as percarbonates or other metal peroxides can be used alone or added as additives to the aforementioned peroxides.

(2) As noted, the rate at which oxygen is released for a given environmental conditions is a function of the ORC chosen and the solubility of the compound. CaO.sub.2 releases oxygen at a faster rate than MgO.sub.2 due to its higher solubility. The rate of oxygen release can be slowed if need by using a mix of CaO.sub.2 and MgO.sub.2. The rate of oxygen release can also be slowed by encapsulating the peroxide in bentonite or other phyllosilicate materials.

(3) The oxygen release rate is also a function of whether the H.sub.2O.sub.2 produced from the decomposition of metal peroxide is stable or decomposes to O.sub.2. In natural waters transition metal ions such as Fe, Mn, may be present in sufficient quantities to catalyze the decomposition of H.sub.2O.sub.2. The laboratory data shown in Tables 1 and 2 indicate that CaO.sub.2 decomposition can generate stable H.sub.2O.sub.2 which may be further decomposed by iron compound such as ferric chloride. In this example, 20 mg of powder containing 75% CaO.sub.2 was added to tap water at 20° C. in a 300 mL BOD bottle and the DO was monitored over a period of five days. After five days, 0.1 mL of 0.1 molar solution of ferric chloride (FeCl.sub.3) was added and the DO was monitored. The data indicate that additional oxygen is released with the addition of FeCl.sub.3. As noted previously, the amount of hydrogen peroxide and oxygen generated from the decomposition of metal peroxides is a function of their solubilities, pH, and temperature. Depending on the field site conditions and the environment, addition of transition metal ions would be useful in the full decomposition of CaO.sub.2 to obtain the maximum amount of oxygen. Accordingly, this invention also includes deicer compositions containing transition metal ions, in particular, iron compounds.

(4) TABLE-US-00001 TABLE 1 DO from calcium peroxide decomposition without FeCl.sub.3 Time, hr 0 1 3 5 7 24 48 72 96 120 DO, 9. 9. 10. 10. 10. 11. 11. 11. 11. 11. mg/ 47 90 26 49 64 46 42 23 17 17 L

(5) TABLE-US-00002 TABLE 2 DO from calcium peroxide decomposition after FeCl.sub.3 addition Time, hr 0 1 2 24 48 72 DO, mg/L 11.17 11.40 11.46 12.19 12.79 12.69

(6) The oxygen demand of organic matter from the degradation by microorganisms is measured using the standard biochemical oxygen demand (BOD) test. The test method is available in the Standard Methods for the Examination of Water and Wastewater, 23.sup.rd Edition (American Water Works Association, 2017). Standard BUD tests require the preparation of dilution water that contains nutrients conducive to the growth of microorganisms, aeration of this water and the addition of bacterial seed for biodegradation. In examples listed below, 6 L of dilution water was prepared using deionized water by adding 0.135 g MgSO.sub.4.Math.7H.sub.2O, 0.165 g CaCl.sub.2, 0.003 g FeCl.sub.3, 0.186 g KH.sub.2PO.sub.4, 0.131 g K.sub.2HPO.sub.4, 0.2004 g Na.sub.2HPO.sub.4, and 0.0102 g NH.sub.4Cl. This composition provides additional 0.135 g KH.sub.2PO.sub.4 for base neutralization from CaO.sub.2 decomposition, and 0.0015 g additional FeCl.sub.3 to catalyze H.sub.2O.sub.2 decomposition.

EXAMPLE 1

Effect of Calcium Peroxide on Dissolved Oxygen with CMA Biodegradation

(7) BOD tests were conducted using aerated dilution water as noted above in 300 mL BOD bottles. Tests were conducted in duplicate and average results are reported here. Each BOD bottle was prepared with the prescribed amount of CMA solution, calcium peroxide, and 3 mL of influent wastewater obtained from the City of Manhattan, Kans. wastewater treatment plant as bacterial seed. The initial CMA concentration in each BOD bottle was 10 mg/L. The CMA had calcium to magnesium mole ratio of 4 to 6. The CaO.sub.2 as supplied contained 75% CaO.sub.2. A 5 mg CaO.sub.2 dose to the 300 mL BOD bottle corresponds to 12.5 mg/L 100% CaO.sub.2. The 10 mg dose corresponds to 25 mg/l 100% CaO.sub.2. The BOD bottles were placed in an incubator set at 20° C. Initial DO was measured, and the DO was monitored over the course of 11 days. Initial and final pH values were monitored.

(8) Table 3 shows that without the addition of CaO.sub.2 the biodegradation of CMA results in the depletion of 8.4 mg/L of dissolved oxygen in five days and the DO concentration is 1.1 mg/L at the end of five days. When 5 mg of 75% CaO.sub.2 is added, the DO is 3.47 mg/L after five days and 2.62 mg/L after 11 days. With the addition of 10 mg of 75% CaO.sub.2 the DO is 4.4 mg/L after five days, and 4.3 mg/L after 11 days. These data show that the addition of ORCs can help mitigate the adverse effects of DO depletion from the biodegradation of organic deicers. In field applications, the amount of CaO.sub.2 required will vary depending on the local conditions. In most cases, the temperature may be close to around 0° C. to 10° C., and the DO levels will be high. Hence the amount of CaO.sub.2 required will be less to assure desired DO levels to protect aquatic organisms in the receiving waters. The amount of CaO.sub.2 required will also be a function of the proximity of the waters to be protected are from the point of application. If water bodies to be protected are adjacent to roadways or airports, the dispersion effects will be low and hence higher ORC doses may be required.

(9) TABLE-US-00003 TABLE 3 Biodegradation of 10 mg/L CMA and the effect of CaO.sub.2 on dissolved oxygen DO, mg/L DO, mg/L DO, mg/L Time, days 0 mg CaO.sub.2 5 mg CaO.sub.2 10 mg CaO.sub.2 0 9.51 9.76 9.90 1 4.09 7.23 9.58 2 2.32 4.87 6.19 3 1.58 4.10 5.35 5 1.10 3.47 4.40 9 1.02 3.17 4.25 11 0.99 2.62 4.30

EXAMPLE 2

Effect of CaO.SUB.2 .on Dissolved Oxygen with Formate Biodegradation

(10) Sodium formate or potassium formate is typically used at airports for runway deicing and aircraft anti-icing applications. This is due to the fact that BODs of formates are lower than that of acetates. The depletion of oxygen from biodegradation of sodium formate was tested using the standard BOD test. The sodium formate concentration tested was 10 mg/L. The procedure used was identical to that used for Example 1. The results from tests are shown in Table 4.

(11) In the absence of CaO.sub.2 the DO decreased by 6.27 mg/L to 3.26 mg/L in 11 days. When 5 mg/L of 75% CaO.sub.2 is present, the DO is 7.66 mg/L after 11 days. In the case of 10 mg of 75% CaO.sub.2 addition, the DO is higher than the initial value due to unused oxygen from the decomposition of CaO.sub.2. The requirement for CaO.sub.2 for field applications will depend on the site conditions and weather during the time of application and thereafter.

(12) TABLE-US-00004 TABLE 4 Biodegradation of 10 mg/L sodium formate and the effect of CaO.sub.2 on dissolved oxygen DO, mg/L DO, mg/L DO, mg/L Time, days 0 mg CaO.sub.2 5 mg CaO.sub.2 10 mg CaO.sub.2 0 9.53 9.80 10.01 1 8.64 10.53 11.06 2 7.82 10.24 11.29 3 7.33 9.85 11.14 5 6.42 9.37 11.00 9 4.62 7.99 10.90 11 3.26 7.66 10.72

(13) The above examples indicate the addition of ORCs can mitigate the effects of oxygen depletion in rivers, lakes, and groundwaters due to the biodegradation of organic deicers and anti-icing agents applied for snow and ice control on roads and bridges, at airports, and on sidewalks and driveways. The fate and transport of road deicing chemicals after their application is a complex process. CMA application rates vary according to climate and maintenance practices and range from 250 to 400 lbs/lane mile. Due to dispersion, absorption in soils, and aerobic and anoxic decompositions, only a fraction of the original amount applied will reach surface and ground waters (Ramakrishna and Viraraghavan, 2005). The dilution of deicers from roadways to nearby streams is estimated to range from 100 to 500-fold (Fischel, 2021). Less than 10% of acetate applied to field plots appeared in runoff or groundwater. The concentration of CMA in the runoff from highways is estimated to be between 10 mg/L to 100 mg/L (Horner, 1988). Thus, the ORC amount that needs to be added to the deicer will vary greatly depending on weather and local site conditions.

(14) This invention intends to use an ORC percentage of 1% to 30% of the total weight of organic deicer to provide the necessary oxygen to mitigate oxygen depletion effects. A more preferred range would be 1% to 10% of the weight of the organic deicer. The actual percentage to be used will depend on the organic deicer being used, the weather conditions including temperatures anticipated, proximity of the application point to receiving waters, and other local factors. The deicer composition of this invention will also include iron compounds or transition metal ion compounds to promote the decomposition of hydrogen peroxide to provide maximum oxygen release from ORCs. The deicer composition of this invention will also include acidic compounds such as metal bicarbonates or metal phosphates for pH control.