Abstract:
A deicing salt composition, including: between 95 and 98 wt. % of a formate, between 1 and 3.5 wt. % of a silicate, between 0.05 and 0.5 wt. % of sodium metaaluminate, between 0.1 and 1 wt. % of sodium carbonate, and between 0.05 and 0.5 wt. % of a organophosphate containing a phosphoryl group. The formate is selected from the group consisting of sodium formate, potassium formate, or a mixture thereof. The silicate is selected from the group consisting of sodium disilicate, potassium disilicate, sodium metasilicate, potassium metasilicate, or a mixture thereof. The organophosphate containing the phosphoryl groups is selected from the group consisting of hydroxy ethyl disodium diphosphate, 2-phosphate butane-1, 2,4-tricarboxylic acid tetrasodium, α-hydroxy-phosphorus sodium acetate, or a mixture thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of International Patent Application No. PCT/CN2011/081957 with an international filing date of Nov. 8, 2011, designating the United States, now pending, and further claims priority benefits to Chinese Patent Application No. 201110270365.2 filed Sep. 9, 2011. The contents of all of the aforementioned applications, including any intervening amendments thereto, are incorporated herein by reference. Inquiries from the public to applicants or assignees concerning this document or the related applications should be directed to: Matthias Scholl P.C., Attn.: Dr. Matthias Scholl Esq., 14781 Memorial Drive, Suite 1319, Houston, Tex. 77079. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a deicing salt composition, and more particularly to an ecological deicing salt composition comprising formate as the main ingredient. 
     2. Description of the Related Art 
     Conventional chlorine deicers contain chlorine ions and thus are corrosive. Although rust inhibitors (slushing compounds) are always added into chlorine deicers to reduce the corrosiveness on metals and road construction materials, the corrosiveness is still prominent. Furthermore, chlorine ions have an impact on soils and vegetations, and do harm to the growth of plants. Biological deicers made from grain crops, waste water originated from paper-making, wine by-products, and lipolysaccharide products have low cost and no environmental pollution, however, the deicing effect is not so good. Urea deicers are apt to degrade into ammonia, and calcium nitrate and magnesium nitrate deicing salt contain nitrate radical, both of which may result in eutrophication. Alcohol deicing salts containing glycol or glycerin have a high COD (Chemical Oxygen Demand) value. 
     Formate salts are new organic deicing salts, with fast and effective deicing ability, easy degradation, low oxygen demand, and little impact on the environment. Thus, it is a mild deicing salt friendly to ecology and the environment. However, formate has certain corrosive effect on metals, particularly on light metals, and thus, rust inhibitors must be added to compromise the corrosiveness. In the prior art, inorganic phosphates are generally employed as rust inhibitors, which, however, will react with calcium ions in the water to form calcium carbonate. Thus, a scale inhibitor is needed. Furthermore, inorganic phosphates in the water stimulate the growth of algae and thus result in water eutrophication. 
     SUMMARY OF THE INVENTION 
     In view of the above-described problems, it is one objective of the invention to provide a deicing salt, which has a fast and effective deicing ability, low corrosiveness, and easy degradation. 
     To achieve the above objectives, in accordance with one embodiment of the invention, there is provided a deicing salt comprising between 95 and 98 wt. % of a formate, between 1 and 3.5 wt. % of a silicate, between 0.05 and 0.5 wt. % of sodium metaaluminate, between 0.1 and 1 wt. % of sodium carbonate, and between 0.05 and 0.5 wt. % of a organophosphate containing a phosphoryl group. The formate is selected from the group consisting of sodium formate, potassium formate, or a mixture thereof; the silicate is selected from the group consisting of sodium disilicate, potassium disilicate, sodium metasilicate, potassium metasilicate, or a mixture thereof; the organophosphate containing phosphoryl groups is selected from the group consisting of hydroxy ethyl disodium diphosphate (HEDPNa 2 ), 2-phosphate butane-1, 2,4-tricarboxylic acid tetrasodium (PBTCANa 4 ), α-hydroxy-phosphorus sodium acetate (HPAANa), or a mixture thereof. 
     In a class of this embodiment, a modulus of the silicate is between 1 and 3.5. 
     In accordance with another embodiment of the invention, there is provided a method of preparation of the deicing salt, comprising: grinding, mixing, stirring, and squeezing the formate, the silicate, the sodium metaaluminate, the sodium carbonate, and the organophosphate containing the phosphoryl group, to yield particles with diameters of between 2 and 6 mm, and drying the particles. 
     Advantages of the invention are summarized below:
         1) the deicing salt has a potent deicing ability;   2) the organophosphate containing the phosphoryl group [—PO(OH) 2 ] mixed with the silicate acts as an anti-corrosive agent, and a small amount of sodium metaaluminate and sodium carbonate are added, which improves the anti-corrosiveness of the anti-corrosive agent on the magnalium alloy, and the deicing salt has low corrosiveness on carbon steel and concrete; in particular, the deicing salt has such a low corrosiveness on magnalium alloy materials and aluminum alloy materials in airplanes that it meets the standard of environmental requirements to aerial materials in SAE-AMS-1431C of America;   3) the deicing salt can be biodegradable easily, and the biochemical oxygen demand (BOD) and the chemical oxygen demand during the biodegradation are very low, thus it has a good performance of environmental protection; and   4) the deicing salt has the ability of fast dissolution and high solubility at low temperature, and the particles of the deicing salt have strong hydroscopicity, they can rapidly absorb the water from the ambient air to form salt water at low temperature, penetrate into the earth surface, and spread outward to destroy the adhesion between the ice/snow and the freezing earth, to achieve the objective of deicing fast and effectively.       

    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     To further illustrate the invention, experiments detailing a deicing salt and a method for preparing the same are described below. It should be noted that the following examples are intended to describe and not to limit the invention. 
     Examples 1-4 
     Components of deicing salts of 4 examples of the invention are given below in Table 1 (data hereinbelow mean weight percents of each component in the total of a deicing salt): 
     
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Components of deicing salts of Examples 1-4 
               
             
          
           
               
                 Component 
                 Example 1 
                 Example 2 
                 Example 3 
                 Example 4 
               
               
                   
               
             
          
           
               
                 Sodium formate 
                 96 
                 98 
                 97.5 
                 97.2 
               
               
                 Sodium carbonate 
                 0.5 
                 0.2 
                 0.5 
                 0.3 
               
               
                 Sodium disilicate 
                 3.25 
                 1.58 
                 1.75 
                 2.3 
               
               
                 Sodium metaaluminate 
                 0.1 
                 0.1 
                 0.1 
                 0.1 
               
               
                 HEDPNa 2   
                 0.15 
                 0 
                 0 
                 0 
               
               
                 PBTCANa 4   
                 0 
                 0.12 
                 0.15 
                 0 
               
               
                 HPAANa 
                 0 
                 0 
                 0 
                 0.1 
               
               
                   
               
             
          
         
       
     
     The modulus of silicate is 2. 
     A method for preparing the deicing salts of Examples 1-4 is given below: each component was collected by weight percent, ground, mixed, and stirred uniformly, then the resulting mixture was squeezed into particles between 2 and 6 mm in diameter, and finally oven-dried to yield the deicing salts. 
     Example 5 
     Test of Deicing Ability of Deicing Salts of Examples 1-4 
     In accordance with GB/T23851-2009 (Road deicing agent), deicing ability of the deicing salts of Examples 1-4 has been tested, and the testing method was as follows: 
     100 mL of water was added into a ceramic crucible, which was then put in a low-temperature calorstat at a temperature of −10° C. After the water was frozen into ice, the ceramic crucible was taken out. Then the water and the ice on the outer surface of the ceramic crucible were wiped away, and the ceramic crucible was weighed, readings of which were accurate to 0.1 g. 
     Each of the deicing salts of Examples 1-4 was diluted with water to yield a water solution with a concentration of 0.2 g/mL 25 mL of the water solution was added into the ceramic crucible. The ceramic crucible was then put in the low-temperature calorstat at the temperature of −10° C. for 30 minutes, thereafter, the liquid in the ceramic crucible was poured out, and the ceramic crucible with remnant ice was quickly weighed. 
     A sodium chloride deicing salt was tested under the same conditions as above, and a deicing ability ratio of the deicing salt of the invention to the sodium chloride deicing salt was calculated according to the formula: K=(m0−m1)×100/(m01−m11), m0 and the m1 represent the total weight (g) of the ice and ceramic crucible before and after adding the deicing salt of this invention, respectively, and m01 and m11 represent the total weight (g) of the ice and ceramic crucible before and after adding the sodium chloride deicing salt, respectively. Results of the testing are given below in Table 2. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Deicing ability of  
               
               
                 deicing salts of the invention 
               
             
          
           
               
                 No. 
                 Example 
                 Deicing ability ratio K (%) 
               
               
                   
               
               
                 1 
                 1 
                 108 
               
               
                 2 
                 2 
                 123 
               
               
                 3 
                 3 
                 121 
               
               
                 4 
                 4 
                 116 
               
               
                   
               
             
          
         
       
     
     As shown in the above table, the deicing ability of the deicing salts of this invention is stronger than that of the sodium chloride deicing salt. 
     Example 6 
     Test of Corrosiveness of Deicing Salts of Examples 1-4 on Carbon Steel 
     According to Chinese national standard GB/T10124-1988, the corrosiveness of the deicing salts of Examples 1-4 on carbon steel has been tested, and the method is summarized as follows: 
     1) 5 carbon steel sheets with a dimension of 50×25×2 mm 3 , each having a hole of 3 mm in diameter in the center, were separately immersed in a 5% sulfuric acid solution for 5 minutes, and then washed with water, alcohol, and acetone in turn. After dried with nitrogen, the sheets were put in a dry cabinet, numbered, measured, and weighed; 
     2) To each of 5 beakers with a capacity of 200 mL, 1,000 mL of purified water was added. 200 g of sodium chloride was then added in one of the beakers, and 200 g of deicing salts of Examples 1-4 of the invention was separately added in the other four beakers; 
     3) Each carbon steel sheet was hung to one end of a nylon cord, respectively, and the other end of the nylon cord was attached to a glass rod disposed on the edge of the beaker, to make sure the carbon steel sheet be in a center or a lower position of the solution; 
     4) After being immersed in the solutions for 48 hours, the 5 carbon steel sheets were treated with a 3% chlorhydric acid for another 10 minutes, then taken out with rusts cleaned off with brushes, further washed with water and alcohol in turn, thereafter, dried with nitrogen, put in a dry cabinet, and finally weighed; 
     5) Assessment of the corrosive effect, and the results are given below in Table 3. 
     
       
         
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Results of corrosive effect on carbon steel metal sheets 
               
             
          
           
               
                   
                   
                   
                 Weight  
                 Weight  
                   
                   
               
               
                   
                   
                 Original 
                 after 
                 loss of  
                 Corrosion 
                 Corrosion 
               
               
                   
                   
                 weight 
                 corrosion 
                 corrosion 
                 rate 
                 ratio 
               
               
                 No. 
                 Example 
                 M (g) 
                 M 1  (g) 
                 (g) 
                 R (mm/a) 
                 (%) * 
               
               
                   
               
               
                 1 
                 Sodium  
                 19.1841 
                 19.1278 
                 0.0563 
                 0.4675 
                   
               
               
                   
                 chloride 
                   
                   
                   
                   
                   
               
               
                 2 
                 Example 1 
                 19.2939 
                 19.2891 
                 0.0048 
                 0.0399 
                 8.53 
               
               
                 3 
                 Example 2 
                 19.6620 
                 19.6599 
                 0.0021 
                 0.0174 
                 3.73 
               
               
                 4 
                 Example 3 
                 20.0181 
                 20.0154 
                 0.0027 
                 0.0224 
                 4.79 
               
               
                 5 
                 Example 4 
                 19.1117 
                 19.1102 
                 0.0015 
                 0.0125 
                 2.66 
               
               
                   
               
             
          
         
       
     
     *Corrosion rate (%) is calculated on the premise that the corrosion rate of the sodium chloride is 100%.
 
Corrosion rate  R =[8760×( M−M   1 )]÷ STD× 10
 
     In the formula, S represents the area of the testing carbon steel sheet, and the standard value is 28 m 2 ; T represents the time of immersion, the value is 48 hours; D represents the density of the carbon steel sheet, and the value is 7.85 g/cm 3 ; 8760 represents the number of hours in one year; and 10 is a unit conversion coefficient. 
     As shown in the above table, the corrosive effects on the carbon steel sheets of the deicing salts of this invention are obviously lower than that of sodium chloride. 
     Example 7 
     Test of Corrosiveness of Deicing Salts of Examples 1-4 on Concrete 
     According to the method of ASTM designation C672-84, the corrosiveness of the deicing salts of Examples 1-4 on concrete has been tested, and the testing method is summarized below: 
     A concrete block with a dimension of 100×100×100 mm 3  was first immersed in a 3% deicing salt solution at a freezing temperature of −20° C. for 16 hours, and then defrozen at room temperature for 8 hours. The above freezing and defreezing processes were repeated for 50 days, once per week, and the deicing salt was renewed and the concrete block was weighed. The corrosion rate of concrete was calculated based on the weight loss, and the corrosion ratio was calculated based on comparison to the sodium chloride. Results of the testing are given below in Table 4. 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Corrosive effects of deicing salts of Examples 1-4 on concrete 
               
             
          
           
               
                   
                   
                   
                 Concrete 
                   
               
               
                   
                 No. 
                 Example 
                 corrosion rate (%) 
                 Corrosion ratio (%) * 
               
               
                   
                   
               
               
                   
                 1 
                 Sodium chloride 
                 4.98 
                   
               
               
                   
                 2 
                 Example 1 
                 0.30 
                 6.02 
               
               
                   
                 3 
                 Example 2 
                 0.23 
                 4.62 
               
               
                   
                 4 
                 Example 3 
                 0.17 
                 3.41 
               
               
                   
                 5 
                 Example 4 
                 0.14 
                 2.81 
               
               
                   
                   
               
               
                   
                 * Corrosion ratio (%) is calculated on the premise that the corrosion rate of sodium chloride is 100%. 
               
             
          
         
       
     
     *Corrosion ratio (%) is calculated on the premise that the corrosion rate of sodium chloride is 100%. 
     As shown in the above table, the corrosive effect of the deicing salt of this invention on concrete is prominently lower than that of the sodium chloride. 
     Example 8 
     Test of Biodegradation Ability and Appearance of Deicing Salts of Examples 1-4 
     According to APAH standard methods for examination of water and waste water, the biodegradation ability of deicing salts of Examples 1-4 has been tested. The testing method is summarized below. 
     The deicing salt was diluted with water to yield a 15% water solution, and then incubated at a constant temperature of 20° C. for 15 days. Testing results are given below in Table 5: 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Results of biodegradation ability of deicing salts 
               
             
          
           
               
                   
                   
                 15 days&#39; 
                 15 days&#39; 
                 Biodegradation 
               
               
                   
                   
                 BOD 
                 COD 
                 ratio after  
               
               
                   
                   
                 (O 2 /kg of 
                 (O 2 /kg of 
                 15 days 
               
               
                 Sample 
                 Odor 
                 sample) 
                 sample) 
                 (%) 
               
               
                   
               
               
                 Example 1 
                 Odorless 
                 0.22 
                 0.28 
                 92 
               
               
                 Example 2 
                 Odorless 
                 0.20 
                 0.32 
                 95 
               
               
                 Example 3 
                 Odorless 
                 0.09 
                 0.19 
                 90 
               
               
                 Example 4 
                 Odorless 
                 0.25 
                 0.27 
                 91 
               
               
                 Sodium acetate 
                 Slightly 
                 0.54 
                 0.86 
                 58 
               
               
                 deicing salt 
                 acidic 
                   
                   
                   
               
               
                 Urea deicing salt 
                   
                 3.44 
                 2.95 
                 34 
               
               
                   
               
             
          
         
       
     
     As shown in the above table, compared with the sodium acetate deicing salt or the urea deicing salt, the deicing salt of the invention is easier to be biodegraded, and the BOD and the COD of the deicing salt of the invention are both lower than those of the sodium acetate deicing salt or the urea deicing salt, thus the deicing salt of the invention has a better performance of environmental protection. 
     Example 9 
     Total Immersion Corrosion Test 
     According to the standard practice for total immersion corrosion test of ASTMF 483 in SAE AMS 1431C-Compound, Solid Deicing/Anti-Icing Runways and Taxiways, total immersion corrosion test of Examples 1-4 of the invention has been carried out: 
     The standard practice of ASTMF 483 comprises steps of below: a metal sheet in a dimension of 50.8×25.4×1.6 mm 3  was totally immersed in a 15% deicing salt solution at a constant temperature of 38±3° C. under one standard atmospheric pressure for 24 hours, during which weight change and color change of the corrosion appearance were recorded. The unit of the weight change before and after the immersion is mg/cm 2 ·24 hours. 
     Results of the total immersion corrosion test on the metal sheet are given below in Table 6: 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 Results of the total immersion corrosion test on metal sheet 
               
             
          
           
               
                   
                 Allowable value 
                 Weight change (mg/cm 2  · 24 hours)  
               
               
                 Specifications 
                 of the standard 
                 and appearance change 
               
             
          
           
               
                 of metal 
                 (weight change 
                 Exam- 
                 Exam- 
                 Exam- 
                 Exam- 
               
               
                 sheets 
                 and appearance) 
                 ple 1 
                 ple 2 
                 ple 3 
                 ple 4 
               
               
                   
               
               
                 Aluminum 
                 ≦0.3 
                 0.06 
                 0.01  
                 0.005 
                 0.005 
               
               
                 alloy of AMS 
                 no visible 
                 no 
                 no 
                 no 
                 no 
               
               
                 4037 treated 
                 corrosion (such 
                 discolor- 
                 discolor- 
                 discolor- 
                 discolor- 
               
               
                 with the 
                 as discoloration, 
                 ation 
                 ation 
                 ation 
                 ation 
               
               
                 method of 
                 etching spots, 
                   
                   
                   
                   
               
               
                 AMS 2470 
                 and imprints) 
                   
                   
                   
                   
               
               
                 Aluminum 
                 ≦0.3 
                 0.06 
                 0.04  
                 0.010 
                 0.005 
               
               
                 alloy of AMS 
                 no visible 
                 no 
                 no 
                 no 
                 no 
               
               
                 4041 
                 corrosion (such 
                 discolor- 
                 discolor- 
                 discolor- 
                 discolor- 
               
               
                   
                 as discoloration, 
                 ation 
                 ation 
                 ation 
                 ation 
               
               
                   
                 etching spots, 
                   
                   
                   
                   
               
               
                   
                 and imprints) 
                   
                   
                   
                   
               
               
                 Aluminum 
                 ≦0.3 
                 0.09 
                 0.006 
                 0.008 
                 0.001 
               
               
                 alloy of AMS 
                 no visible 
                 no 
                 no 
                 no 
                 no 
               
               
                 4049 
                 corrosion (such 
                 discolor- 
                 discolor- 
                 discolor- 
                 discolor- 
               
               
                   
                 as discoloration, 
                 ation 
                 ation 
                 ation 
                 ation 
               
               
                   
                 etching spots, 
                   
                   
                   
                   
               
               
                   
                 and imprints) 
                   
                   
                   
                   
               
               
                 Magnesium 
                 ≦0.2 
                 0.08 
                 0.070 
                 0.001 
                  0.0006 
               
               
                 alloy of AMS 
                 no visible 
                 no 
                 no 
                 no 
                 no 
               
               
                 4376 treated 
                 corrosion (such 
                 discolor- 
                 discolor- 
                 discolor- 
                 discolor- 
               
               
                 with the 
                 as discoloration, 
                 ation 
                 ation 
                 ation 
                 ation 
               
               
                 dichromate 
                 etching spots, 
                   
                   
                   
                   
               
               
                 method of 
                 and imprints) 
                   
                   
                   
                   
               
               
                 AMS 2475 
               
               
                   
               
             
          
         
       
     
     As shown in the above table, the corrosion test of magaluma, aluminum, and other light metal materials indicates that the deicing salt of the invention has meet the standard of total immersion corrosion test of SAE AMS 1431C. 
     The above examples have exemplified components and their weight percents of four deicing salts. To further illustrate the invention, examples of the deicing salt are provided hereinbelow. 
     Example 10 
     A deicing salt comprises 95 wt. % of a formate, 3.5 wt. % of a sodium disilicate, 0.5 wt. % of sodium metaaluminate, 0.5 wt. % of sodium carbonate, and 0.5 wt. % of PBTCANa 4 . 
     The modulus of the silicate is 1. 
     The method for preparing the deicing method is as follows: 
     each component was collected by weight percent, ground, mixed, and stirred uniformly, then the resulting mixture was squeezed into particles between 2 and 6 mm in diameter, and finally oven-dried to yield the deicing salt. 
     Example 11 
     A deicing salt comprises 97.9 wt. % of a formate, 1 wt. % of a sodium disilicate, 0.05 wt. % of sodium metaaluminate, 1 wt. % of sodium carbonate, and 0.05 wt. % of HPAANa. 
     The modulus of the silicate is 3.5. 
     The method for preparing the deicing salt is the same as that in Example 10. 
     Example 12 
     A deicing salt comprises 96.35 wt. % of a formate, 3 wt. % of a sodium disilicate, 0.05 wt. % of sodium metaaluminate, 0.1 wt. % of sodium carbonate, and 0.5 wt. % of HPAANa. 
     The modulus of the silicate is 2. 
     The use dosage of the deicing salt of the invention can be referred to Table 7 hereinbelow: 
     
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE 7 
               
             
             
               
                   
               
               
                 Usage amount of deicing salt of the invention 
               
             
          
           
               
                 Atmospheric  
                 Usage amount for 
                 Usage amount for 
               
               
                 temperature 
                 prevention (g/m 2 ) 
                 deicing (g/m 2 ) 
               
               
                   
               
             
          
           
               
                    0-−5° C. 
                 30 
                 50 
               
               
                  −5-−10° C. 
                 50 
                 80 
               
               
                 −10-−15° C. 
                 80 
                 120 
               
               
                   
               
             
          
         
       
     
     The deicing salt of the invention is mainly used to remove and prevent the accumulation of frost, ice, and snow, in airport runways or in streets, roads, bicycle routes, sidewalks, bridges, courtyards, parking lots, playgrounds, and other traffic areas. 
     While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.