1
2
LABORATORY AND FIELD EVALUATION OF SODIUM PROPIONATE 3
FOR SNOW AND ICE CONTROL 4
5
6
7
Submitted by: 8
9
10
Naoto Takahashi, Ph.D., P.E. 11
Deputy Team Leader 12
Traffic Engineering Research Team, 13
Civil Engineering Research Institute for Cold Region 14
1-3 Hiragishi, Toyohira-ku, Sapporo, 062-8602, Japan 15
Tel: +81-11-841-1738 16
Fax: +81-11-841-9747 17
E-mail: [email protected] 18
19
Kenji Sato, 20
Researcher 21
Traffic Engineering Research Team, 22
Civil Engineering Research Institute for Cold Region 23
1-3 Hiragishi, Toyohira-ku, Sapporo, 062-8602, Japan 24
Tel: +81-11-841-1738 25
Fax: +81-11-841-9747 26
E-mail: [email protected] 27
28
Roberto A. Tokunaga, Ph.D. 29
Senior Researcher 30
Traffic Engineering Research Team, 31
Civil Engineering Research Institute for Cold Region 32
1-3 Hiragishi, Toyohira-ku, Sapporo, 062-8602, Japan 33
Tel: +81-11-841-1738 34
Fax: +81-11-841-9747 35
E-mail: [email protected] 36
37
Noriyuki Nakajima, Ph.D. 38
Professor 39
Biotechnology Research Center and Department of Biotechnology, 40
Toyama Prefectural University 41
Kurokawa 5180, Izumi, Toyama, 939-0398, Japan 42
Tel: +81-766-56-7500 43
Fax: +81-766-56-2498 44
E-mail: [email protected] 45
46
47
2
Takahashi et al.
Shugo Kasamatsu 1
Research Officer, Road Planning Division 2
Construction Department, Hokkaido Regional Development Bureau 3
Kita 8 Nishi 2, Kita-ku, Sapporo, Hokkaido, 060-8511, Japan 4
Tel: +81-11-709-2311(ext. 5357) 5
Fax: +81-11-757-3270 6
E-mail: [email protected] 7
8
9
10
Word count: 4,154 words text + 12 tables/figures x 250 words (each) = 7,154 words 11
12
Revision Date : November 15, 2016 13
Submission Date: August 1, 2016 14
3
Takahashi et al.
ABSTRACT 1
To provide the driving public with a safe road surface during winter, large amounts of anti-2
icing and deicing chemicals (deicers) are used. Since there are growing concerns about the 3
impact of chloride-based deicers on motor vehicles, highway infrastructures, maintenance 4
equipment and the environment, the development of alternative deicers and additives serves 5
the public interest. 6
To find a material that can be feasibly used as a deicer, the performance of sodium 7
propionate (SP), which is commonly used as a food additive, was evaluated through a series of 8
laboratory and field tests. Freezing point, metal corrosion, ice melting performance, toxic 9
constituents, and damage to plants were tested in the laboratory, and a field test was conducted 10
to evaluate SP’s deicing performance. 11
SP was found to conform to the standard for toxic substances of deicer in Japan, to achieve 12
more rapid deicing than sodium chloride (NaCl), and to cause almost no corrosion of metal. To 13
reduce costs while taking advantage of SP, the mixing of NaCl and SP, which exhibits 14
performances intermediate between those of NaCl and SP, is considered to be a solution. A 15
mixture of 80% NaCl and 20% SP shows freezing point and ice melting performance equivalent 16
to those of NaCl, mitigates the concentration of chloride ions and the inhibitory effects of NaCl 17
on plants, and is still 80% less corrosive to metal than NaCl is. Considering SP’s high solubility 18
in water and the field test results, it is recommended that SP be used as a pre-wetting material. 19
20
Keywords: Snow and ice control, Sodium propionate, Metal corrosion 21
22
4
Takahashi et al.
INTRODUCTION 1
In cold regions, winter weather poses a significant hazard to road transportation. Snow and ice 2
reduce pavement friction, and this can cause traffic delays and increase the risk of traffic 3
accidents (e.g., (1), (2), (3), (4)). To prevent the formation or development of ice, and to break 4
the bond of already-bonded snow and ice, anti-icing and deicing operations have been 5
commonly conducted as a primary snow and ice control strategy (5). 6
As anti-icing and deicing chemicals (hereinafter: “deicers”), chloride-based deicers, such 7
as sodium chloride (NaCl), magnesium chloride, (MgCl2) and calcium chloride (CaCl2) are 8
frequently used (6), (7). To provide a safe road surface for the driving public, large amounts of 9
chloride-based deicers have been applied on winter highways (7), (8), (9), and such use can 10
adversely affect motor vehicles, highway infrastructure, maintenance equipment and the 11
environment (e.g., (9), (10), (11), (12)). 12
Therefore, alternative deicers and additives those promise to be less harmful to highway 13
facilities, motor vehicles and the natural environment have been sought and tested by road 14
agencies and researchers. These include agriculturally derived products (also known as agro-15
based products) (e.g., (13), (14), (15)), compositions formed from organic acids (e.g., (16), (17), 16
(18)), complex chlorides/minerals (CCM) (e.g., (19), (20), (21)), and other deicers (nitrogen 17
products, etc.) (e.g., (22), (23), (24)). Although a considerable amount of research has been 18
carried out and various products are commercially available, chloride-based deicers are still 19
widely used due to their availability, low costs and effectiveness at subfreezing temperatures. 20
Thus, the development of alternative deicers and additives still serves the public interest. 21
This study aims to seek a chemical substance that will be suitable for use as a deicer in 22
terms of cost, corrosion, environmental effect, availability, ease of handling. Most importantly, 23
since the metallic corrosion of motor vehicles, maintenance equipment and infrastructure 24
imposes a lot of costs on both motor vehicle users and highway agencies (25), (26), the 25
substance is required to be much less corrosive to metal than chloride-based deicers are. 26
27
28
METHODOLOGY 29
Selection of the Test Material 30
Chloride-based deicers are known to be highly corrosive to metal because chloride ions (Cl⁻) 31
induce the breakdown of the passive film on iron (27). Compositions formed from organic 32
acids, represented by calcium magnesium acetate (CMA), potassium acetate (KAc) and 33
potassium formate (also known as “acetate/formate-based deicers”) were found to be less 34
corrosive to metal than sodium chloride (16), (17), (18), and even a mixture of acetate and 35
sodium chloride was found to reduce the corrosion of metal relative to sodium chloride (28). 36
However, acetate/formate-based deicers are not frequently used due to cost considerations (6), 37
(29). 38
To find a material that can be feasibly used as a deicer, odorless salts of common organic 39
acid were investigated. First, aqueous solutions of each candidate material were prepared, and 40
the freezing point of each solution was determined. The candidate materials, their freezing 41
points and odor in solution are summarized in TABLE 1. 42
43
44
5
Takahashi et al.
TABLE 1 Candidate materials, their freezing points and odor in solution 1
2 3
Among the odorless materials, sodium formate and sodium propionate show freezing 4
points equivalent to that of sodium chloride. Sodium formate is hygroscopic and, accordingly, 5
can absorb moisture while in storage. Since this can cause caking and agglomeration, sodium 6
formate was ruled out for this study. Eventually, sodium propionate was chosen as a test 7
material. 8
Compound
classificationMaterial
Concentration of
solution (wt%)
Freezing
point (˚C)Odor
10 -6.00
15 -10.50
20 -22.00
25 -38.90
5 -1.50
10 -8.30
15 -13.50
20 -19.80
20 -14.50
30 -14.40
20 -13.80
30 -23.70
20 -8.00
30 -16.10
40 -21.20
Ammonium carbonate 20 -4.90 Ammonia odor
20 -16.20
30 -24.50
Ammonium formate 20 -15.70 Odorless
Sodium acetate 20 -19.20 Acetic acid odor
Ammonium acetate 20 -16.10 Acetic acid odor
potassium acetate 20 -15.10 Acetic acid odor
Calcium acetate 20 -10.50 Acetic acid odor
Magnesium acetate 20 -8.55 Acetic acid odor
Propionic acid Sodium propionate 20 -17.00Odorless or faint acetic-
butyric acid odor
Butyric acid Sodium butyrate 20 -15.20 Butyric acid odor
Oxalic acidPotassium oxalate
monohydrate20 -6.90 Odorless
20 -10.30
30 -27.10
Disodium succinate 20 -11.60 Odorless
20 -10.60
30 -21.00
Potassium succinate
trihydrate20 -6.30 Odorless
Sodium succinate
hexahydrate20 -5.90 Odorless
20 -6.60
30 -11.20
40 -21.40
Tripotassium citrate
monohydrate20 -5.10 Odorless
Trisodium citrate dihydrate 20 -4.90 Odorless
Diammonium hydrogen citrate 20 -4.50 Odorless
Dipotassium hydrogen citrate 20 -4.00 Odorless
Ammonium dihydrogen citrate 20 -3.80 Odorless
Citric acid 20 -3.20 Odorless
20 -7.50
30 -14.60
40 -27.20
Lactic acid Sodium lactate 20 -5.10 Odorless
Potassium gluconate 20 -3.70 Odorless
Sodium gluconate 20 -3.90 Odorless
Maleic acid Disodium Maleate Odorless
Gluconic acid
Succinic Acid
Diammonium succinate Odorless
Citric acid
Triammonium citrate Odorless
Formic acidSodium formate Odorless
Acetic acid
Malonic acid Disodium malonate Odorless
Ammonium salt
Ammonium carbamate Odorless
Ammonium nitrate Odorless
Chloride
Calcium chloride Odorless
Sodium chloride Odorless
Ammonium chloride Odorless
6
Takahashi et al.
Material of Interest 1
Sodium propionate (C3H5NaO2) is the sodium salt of propionic acid. It occurs as colorless, 2
transparent crystals or a granular crystalline powder. It is odorless, or it has a faint acetic-3
butyric acid odor, and it is highly soluble in water (TABLE 2). Since the ingredients meet the 4
specifications of the food chemicals, sodium propionate is used as a food additive in many 5
countries (e.g., (30), (31), (32)). In Japan, the annual consumption of sodium propionate is 6
around 40 tons. 7
8
TABLE 2 General information and properties of sodium propionate (33), (34), (35) 9
10 11
The price of sodium propionate as a food additive is US$2.3/kg for purchases of 10 tons at a 12
time. This is about 10 times as expensive as sodium chloride for deicer in Japan. To reduce the 13
cost but still benefit from the positive effects of sodium propionate, mixtures of sodium 14
propionate and sodium chloride were also tested in this study. 15
16
17
Description of laboratory tests 18
Freezing point 19
A test tube that contains specimen (solution of the test material) is put into acetone which is 20
kept at 0°C in a stainless steel dewar bottle. Then, the specimen was gradually cooled. The 21
temperature decrease was set to be approximately 1°C/min. The temperature of the specimen 22
is measured and recorded periodically. Measurement was conducted three times, and the 23
average value was adopted in this study. The freezing point is taken as the intersection of 24
projections of the cooling curve and the freezing curve. If the solution supercools, the freezing 25
point is the maximum temperature reached after supercooling. 26
Since the freezing points of sodium chloride (hereinafter: “NaCl”) and sodium propionate 27
(hereinafter: “SP”) are already known, a mixture of sodium chloride and sodium propionate 28
(hereinafter: “NaCl/SP mixture”) are additionally tested. 29
30
31
32
Appearance
Chemical Formula
C3H5NaO2
CAS* Registry Number 137-40-6
Molar Mass 96.060 g/mol
Solubility in Water 995 kg/m3 (20 ˚C)
Potential of hydrogen (pH) 8 - 9.5
Food Additive Price** (USD/Kg) 2.3
* CAS: Chemical Abstracts Service issued by American Chemical Society
** For purchase of 10 tons at a time. 1USD = 110JPN
o
o-+NaH3C
7
Takahashi et al.
Corrosion of metal 1
The corrosiveness of test material on metal was evaluated by the procedures below: 2
3
Preparation of test solutions: 3.0 g of test material is dissolved in 100 cc of distilled water. 4
The test materials are NaCl, calcium chloride (hereinafter: “CaCl2”), SP, and NaCl/SP mixtures. 5
6
Preparation of test specimen: A steel sheet used as the cathode panel for the Hull Cell Test 7
(36) is cut into strips (67 mm x 50 mm x 0.3 mm). Zinc film is stripped off and the weight of 8
each specimen is measured. 9
10
Immersion and aeration of test specimen: Test specimens are immersed in the solutions 11
for 24 hours, and then the specimens are taken out from the solutions and aerated for 24 hours. 12
This immersion-aeration cycle is repeated for 7 days. That means the specimen is immersed in 13
the solution 4 times and aerated 3 times. The immersion-aeration cycle for distilled water is 14
also conducted as the control. 15
16
Calculation of corrosive effect for each solution: After the immersion-aeration cycle 17
described above, the test specimen was immersed in a cleaning solution of hydrochloric acid 18
(HCl) at 5.0 wt% containing propargyl alcohol (1.0 wt% to the HCl). Propargyl alcohol was 19
added to the HCl to stop further oxidization once the resulting rust was removed. Then, the test 20
specimen was removed from the cleaning solution and rinsed with ethanol. The corrosion rate 21
(Cr) is determined by the following equation. 22
23
𝐶𝑟 = (𝑊𝑖 − 𝑊𝑓)
𝐴 × 𝐷 (1) 24
25
where 26
Wi = initial weight of the test specimen (mg), 27
Wf = final weight of the test specimen (mg), 28
A = surface area of the test specimen (dm2), and 29
D = duration of immersion-aeration cycle (day) 30
31
32
Ice melting performance 33
The test method in this study was modeled after the “Ice Melting Test (SHRP H-205.1 and 34
H-205.2)” (37). The test was conducted in a temperature-controlled chamber. TABLE 3 shows 35
the test conditions. 36
First, 200 ml of water is frozen in a stainless steel tray of 185 mm in width, 140 mm in 37
depth and 27 mm in height. After the initial weight of the test specimen was measured, 5 g of 38
test material (grain size: 0.3 - 1.0 mm) was evenly applied over the specimen. 5, 10, 20, 30, 60, 39
120, 180 and 360 minutes after application, the liquid and undissolved test material were 40
completely removed, and then, the weight of the test specimen was measured. The weight of 41
ice melted can be determined by measuring the change in the weight of test specimen. The test 42
was conducted at -2°C, -5°C, -8°C, and -15°C, with triplicate samples tested for each 43
combination of test material, time and temperature. 44
45
8
Takahashi et al.
TABLE 3 Conditions of the ice-melting test 1
2 3
4
Toxic constituents 5
Since large amounts of deicers are used, deicer must not contain toxic substances. In Japan, 6
deicer must conform to the standard for toxic substances of deicer (TABLE 4). This standard 7
was defined by referring to the industrial effluent standards in Japan, based on the idea that 8
substantial amounts of deicer can be finally discharged from the road by surface runoff, 9
infiltration, and outflow from the drainage system. 10
As shown in TABLE 4, 16 items and their standard values (i.e., maximum allowances) 11
are defined. Since deicer may accumulate in drainage basins, the content of each item in a 12
saturated solution is evaluated. Although SP is used as a food additive and its properties are 13
shown in Material Safety Data Sheets (MSDS), the toxic constituent test was conducted to 14
determine whether SP conforms to the standards. 15
16
TABLE 4 Standard for toxic constituents of deicer 17
18 19
20
21
NaCl
SP
NaCl/SP mixture （weght ratio 8:2）
Test temperature (°C) -2, -5, -8, -15
Measurement time (min) 5, 10, 20, 30, 60, 120, 180, 360
Test material
(A)* (B)**
mg/L ≤ 0.03 ≤ 0.01
mg/L ≤ 1 Not detectable***
mg/L ≤ 1 Not detectable***
mg/L ≤ 0.1 N/A
mg/L ≤ 0.5 ≤ 0.05
mg/L ≤ 0.1 ≤ 0.05
mg/L ≤ 0.005 ≤ 0.0005
mg/L Not detectable*** N/A
mg/L ≤ 0.003 N/A
mg/L ≤ 0.06 N/A
mg/L ≤ 0.03 N/A
mg/L ≤ 0.2 N/A
mg/L ≤ 0.1 N/A
mg/L ≤ 10 N/A
mg/L ≤ 8 N/A
mg/L ≤ 100 N/A
Note:
* ***** "Not detectable " means that the amount of the substance is less than the limit of detection.
UnitStandard values
Item
Cadmium
Total cyanide
Organic phosphorus
Lead
Hexavalent chromium
(B): Stringent standard applied to vulnerable area designated by ordinance
Ammonia, Ammonia compound,
Nitrous acid compound and Nitric
acid compound
(A): National uniform standard
Thiobencarb
Selenium
Boron
Fluorine
Arsenic
Total mercury
Alkyl mercury
PCB
Thiram
Simazine
9
Takahashi et al.
Damage to plants 1
The test method in this study is modeled after a test method determined by the Ministry of 2
Agriculture, Forestry and Fisheries of Japan (38). FIGURE 1 summarizes the basic steps of the 3
test and the test conditions. 4
- 500 ml of sieved air-dried soil is filled in a Neubauer pot (113 mm inside diameter x 65 5
mm height) and a defined quantity of water is added. 6
- 0, 1, 2, 4, and 8 g of test material is applied over the soil, with duplicate samples for each 7
dosage. 0 g is the control. 8
- 20 seeds of the test plant are placed in a pot to allow them to germinate. 9
- The test plants are cultivated in a temperature-controlled chamber for 21 days. 10
11
12 FIGURE 1 Basic steps of the test and the test conditions 13
14
15
Description of field test 16
A field test was conducted to evaluate the deicing performance of the test materials. The test 17
was conducted at a test track of our institute. The test track is 2,700 meters in circumference, 18
and the straightway of the test track paved with dense-graded asphalt was used. 19
The test track layout, the application method, and the basic steps of the test are 20
summarized in FIGURE 2. Section 1 was set to serve as the control section (i.e., no treatment 21
was performed) to compare the differences in friction values to the treated sections (sections 22
No. 2 - No. 5). In between the treated sections, dry-surface sections were set to prevent the 23
vehicles from dragging the test material to the next test section. 24
Since the granularity of salt is known to affect its deicing performance (39), molded 25
granules of SP were prepared such as to have the same granularity of NaCl used as deicer. 26
27
The basic steps of the field test are listed below. 28
- Icy surfaces were artificially created by applying water to the dry surface with a road 29
sprinkler when the surface temperature was below 0 °C. 30
- Test materials were spread on the icy surfaces (test sections No. 2 - No. 5). 31
- Friction values were measured immediately after test material spreading. 32
(a) Basic steps of the test
Growth of test plant
MeasurementCultivation
Seeding
(b) Test conditions
NaCl
SP
NaCl/SP mixture （weght ratio 8:2）
Dosage (g) 0 (no application), 1.0, 2.0, 4.0, 8.0
Test plant Brassica rapa var. perviridis
Germination rate (%)
Length of test plant (mm)
Weight of test plant (g)
Growth condition (leaf scorch etc.)
Potential of hydrogen (pH)
Chloride ion (Clˉ) concentration (mg/mg)
Test material
Measurement item
for test plant
Measurement item
for soil
10
Takahashi et al.
- Vehicles ran on these surfaces to duplicate traffic flow. 1
- Friction values were measured after 50, 100, 150, 200, 250 and 300 vehicle passes. 2
3
Friction values were measured using a RT3 (Halliday Technologies Inc., RT3 GRIP) (40). 4
A friction value determined by the RT3 is referred to as a Halliday friction number (HFN), and 5
HFN values can be converted to coefficient of friction (μ) (41). 6
7
8 FIGURE 2 Test track layout, the application method and the basic steps of the field test 9
10
11
TEST RESULTS 12
Results of laboratory tests 13
Freezing point 14
TABLE 5 shows the freezing points of the test materials. The freezing point of SP is 2.8°C 15
higher than that of NaCl. Mixing NaCl and SP gives the mixture a freezing point intermediate 16
between those of NaC and SP. The freezing point of a NaCl/SP mixture (weight ratio 8:2) is -17
18.9°C. This means the mixture is expected to have a low-temperature performance 18
comparable to that of NaCl. 19
20
TABLE 5 Freezing points of the test materials. 21
22 23
24
SpreadingWatering Vehicle running Measurement
Dry surface
100m 50m 50m 50m 50m 50m 50m 50m
Icy surface
1 2 3 4 5
(a) Basic steps of the test
(b) Application method and application rate for each test section
(c) Basic steps of the test
Section No.Type of spreading
operationApplication rate
1 - No treatment (control section)
2 Dry NaCl (solid) 20g/m2
3 Dry NaCl (solid) 16g/m2 + SP (molded granule) 4g/m2
4 Pre-wetted NaCl (solid) 18g/m2 + 30wt% SP solution 2g/m2
5 Pre-wetted NaCl (solid) 18g/m2 + 30wt% CaCl2 solution 2g/m2
Specimen (20 wt% aqueous solution) Freezing point ( ˚C)
NaCl -19.8
SP -17.0
NaCl/SP mixture (weight ratio 8:2) -18.9
11
Takahashi et al.
Metal corrosion 1
FIGURE 3 shows the metal corrosion test results for distilled water and the test materials. SP 2
aqueous solution is found to cause almost no corrosion. And the aqueous solution of NaCl/SP 3
mixture (weight ratio 8:2) is found to be 49% less corrosive to metal than distilled water and 4
80% less corrosive than NaCl. Even the aqueous solution of NaCl/SP mixture (weight ratio 5
9:1) is able to reduce metal corrosion by 45% relative to the NaCl aqueous solution. SP 6
demonstrates significant corrosion-inhibiting performance. 7
8
9 FIGURE 3 Metal corrosion rates of distilled water and the test materials 10
11
12
Ice melting performance 13
Figure 4 shows the amount of ice melted (g) over time at each test temperature. 14
15
16 FIGURE 4 Results of ice melting test for NaCl, SP and NaCl/SP mixture 17
Co
rro
sio
nra
te(C
r)
NaCl/SPmixture(19:1)
Distilled water
NaCl CaCl2 SPNaCl/SP mixture
(8:2)
NaCl/SPmixture
(9:1)
25
20
15
10
0
30
5
8.6
22.5
27.5
0.3
4.4
12.5
14.6
(a) Test temp.: -2 ºC (b) Test temp.: -5 ºC
(c) Test temp.: -8 ºC (d) Test temp.: -15 ºC
0
20
40
60
80
100
0 60 120 180 240 300 360
Ice m
elted (
g)
Time (minutes)
0
20
40
60
80
100
0 60 120 180 240 300 360
Ice m
elted (
g)
Time (minutes)
0
20
40
60
80
100
0 60 120 180 240 300 360
Ice m
elted (
g)
Time (minutes)
0
20
40
60
80
100
0 60 120 180 240 300 360
Ice m
elted (
g)
Time (minutes)
0
100
0 360
Ice
me
lte
d (
g)
Time (minutes)
NaCl
SP
NaCl+SP
NaCl
SP
NaCl/SP mixture
0
100
0 360
Ice
me
lte
d (
g)
Time (minutes)
NaCl
SP
NaCl+SP
NaCl
SP
NaCl/SP mixture
0
100
0 360
Ice
me
lte
d (
g)
Time (minutes)
NaCl
SP
NaCl+SP
NaCl
SP
NaCl/SP mixture
0
100
0 360
Ice
me
lte
d (
g)
Time (minutes)
NaCl
SP
NaCl+SP
NaCl
SP
NaCl/SP mixture
12
Takahashi et al.
At the test temperatures of -2°C and -5°C, SP melts more ice in the first 45 minutes than NaCl 1
and the NaCl/SP mixture (weight ratio 8:2) do. After 60 minutes, NaCl exhibits the highest ice 2
melting performance. Although SP is able to melt less ice than NaCl, the NaCl/SP mixture 3
(weight ratio 8:2) demonstrates almost the same ice melting performance as NaCl. 4
At the test temperature of -8°C or below, there are no large differences in the amount of 5
ice melted. 6
7
8
Toxic constituents 9
TABLE 6 shows the results of the toxic constituents test for sodium propionate. It is 10
confirmed that SP conforms to the standard for toxic substances of deicer in Japan. Since 11
organic compounds in general have been found to elevate biological oxygen demand (BOD) in 12
adjacent waterways (42), further study on the toxicity of the effluents is required. 13
14
TABLE 6 Results of toxic constituents test for sodium propionate 15
16 17
18
Damage to plants 19
FIGURE 5 summarizes the test results. Although almost all of the seeds germinate when 2.0 g 20
of NaCl is applied, growth inhibition and leaf scorching of the test plant are observed. No seed 21
is able to germinate when 4.0 g or more of NaCl is applied. The test plants show better growth 22
when 1.0 g of SP is applied than when 1.0 g of NaCl is applied. However, no germination is 23
observed when 2.0 g or more of SP is applied. 24
When the NaCl/SP mixture is applied, the test plant exhibits good growth relative to that 25
when NaCl is applied: Even 10% of the seeds germinate when 4.0 g of the mixture is applied. 26
We cannot conclusively determine the impact of SP on plants due to diversity of vegetation 27
and soil conditions, but the NaCl/SP mixture is found to mitigate the inhibitory effects of NaCl 28
on the germination and growth of Brassica rapa var. perviridis. Considering the diversity of 29
the vegetation and soil conditions, further laboratory and field studies on the impacts on plants 30
are required. 31
32
(A)* (B)**
mg/L ≤ 0.03 ≤ 0.01 Not detected
mg/L ≤ 1 Not detectable*** Not detected
mg/L ≤ 1 Not detectable*** < 0.02
mg/L ≤ 0.1 N/A Not detected
mg/L ≤ 0.5 ≤ 0.05 < 0.05
mg/L ≤ 0.1 ≤ 0.05 Not detected
mg/L ≤ 0.005 ≤ 0.0005 Not detected
mg/L Not detectable*** N/A Not detected
mg/L ≤ 0.003 N/A Not detected
mg/L ≤ 0.06 N/A < 0.001
mg/L ≤ 0.03 N/A < 0.001
mg/L ≤ 0.2 N/A Not detected
mg/L ≤ 0.1 N/A Not detected
mg/L ≤ 10 N/A 0.22
mg/L ≤ 8 N/A 0.5
mg/L ≤ 100 N/A 0.18
Note:
* ***** "Not detectable " means that the amount of the substance is less than the limit of detection.
UnitStandard values
Item
Cadmium
Total cyanide
Organic phosphorus
Lead
Hexavalent chromium
(B): Stringent standard applied to vulnerable area designated by ordinance
Ammonia, Ammonia compound,
Nitrous acid compound and Nitric
acid compound
(A): National uniform standard
Results
Thiobencarb
Selenium
Boron
Fluorine
Arsenic
Total mercury
Alkyl mercury
PCB
Thiram
Simazine
13
Takahashi et al.
1 FIGURE 5 Growth conditions of the test plants, and the measurement results 2
3
4
Field test results 5
FIGURE 6 shows the changes in the coefficient of friction (μ) as a function of the number of 6
vehicle passes. The μ value remains low on section No.1 (no treatment). On section No.2 (solid 7
NaCl applied), the μ value gradually increases with increases in the number of vehicle passes, 8
finally reaching around 0.7. On section No.3 (solid NaCl/SP mixture applied), although the μ 9
value rapidly increases, it gradually decreases with increases in the number of vehicle passes 10
after 150 vehicle passes. On section No.4 (solid NaCl pre-wetted with SP solution applied), the 11
μ value gradually increases even after 150 vehicle passes, finally approaching 0.7 at 300 vehicle 12
passes. On section No.5 (solid NaCl with pre-wetted CaCl2 solution applied), although the μ 13
value is the highest at 100 vehicle passes, it levels off after that. 14
Although the friction patterns may change when tested under different environmental 15
parameters, the field test suggests that application of the NaCl/SP mixture is as effective as 16
conventional application methods. Considering its high solubility in water, it is recommended 17
to use SP as a pre-wetting material. 18
19
(a) NaCl
0 g
1.0 g 2.0 g 4.0 g 8.0 g
(b) SP
0 g
1.0 g 2.0 g 4.0 g 8.0 g
(c) NaCl/SP
mixture0 g
1.0 g 2.0 g 4.0 g 8.0 g
Dosage (g)
0.0 1.0 2.0 4.0 8.0
Germinaton rate (%) 100 100 97.5 0 0
Lengt of test plant* (mm) 128.0 96.6 53.0 0 0
Weight of test plant* (g) 7.73 6.29 1.13 0 0
Potential of hydrogen (pH) 5.2 5.1 5.3 5.5 5.3
Clˉ concentration (mg/mg) 16 800 1900 4400 9200
NOTE: * Germinated test plants were measured and averaged
Dosage (g)
0.0 1.0 2.0 4.0 8.0
Germinaton rate (%) 100 100 0 0 0
Lengt of test plant* (mm) 128.0 122.0 0 0 0
Weight of test plant* (g) 7.73 7.87 0 0 0
Potential of hydrogen (pH) 5.2 6.4 7.7 8.6 9.3
Clˉ concentration (mg/mg) 16 17 34 39 26
NOTE: * Germinated test plants were measured and averaged
Dosage (g)
0.0 1.0 2.0 4.0 8.0
Germinaton rate (%) 100 100 100 10 0
Lengt of test plant* (mm) 128.0 105.0 84.8 8.5 0
Weight of test plant* (g) 7.73 5.42 4.52 0.26 0
Potential of hydrogen (pH) 5.2 5.3 5.5 6.1 6.5
Clˉ concentration (mg/mg) 16 860 1700 4200 6900
NOTE: * Germinated test plants were measured and averaged
14
Takahashi et al.
1 FIGURE 6 Changes in μ as a function of the number of vehicle passes 2
3
4
CONCLUSIONS 5
In this study, a series of laboratory and field tests were conducted to investigate the performance 6
of SP as a deicer. SP was found to conform to the standard for toxic substances of deicer in 7
Japan, to achieve more rapid deicing than NaCl, and to cause almost no corrosion of metal. To 8
reduce costs while taking advantage of SP, the mixing of NaCl and SP, which exhibits 9
performances intermediate between those of NaCl and SP, is considered to be a solution. A 10
mixture of 80% NaCl and 20% SP shows freezing point and ice melting performance equivalent 11
to those of NaCl, mitigates the concentration of chloride ions and the inhibitory effects of NaCl 12
on plant germination and growth, and is still 80% less corrosive to metal than NaCl is. 13
Considering SP’s high solubility in water and the field test results, it is recommended that SP 14
be used as a pre-wetting material. This application method is as effective as conventional 15
application methods, and it can be applied using existing facilities and equipment. 16
In order to add SP as a choice of snow and ice control materials, quantitative field 17
observations regarding deicing performance, impact on environmental systems, and impact on 18
highway infrastructures and maintenance facilities are required. 19
20
21
22
No.1: No treatment
No.2: NaCl (solid) 20g/m2
No.3: NaCl (solid) 16g/m2 + SP (molded granule) 4g/m2
No.4: NaCl (solid) 18g/m2 + 30wt% SP solution 2g/m2
No.5: NaCl (solid) 18g/m2 + 30wt% CaCl2 solution 2g/m2
Air temp. (ºC) Surface temp. (ºC)
-16.0
-14.0
-12.0
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 50 100 150 200 250 300
Air &
su
rfa
ce
te
mp
era
ture
(▫C
)
Co
eff
ien
t o
f fr
ictio
n
Number of vehicle passes
15
Takahashi et al.
REFERENCES 1
1. FHWA. Snow and Ice, 2
http://www.ops.fhwa.dot.gov/weather/weather_events/snow_ice.htm. Accessed May 1, 3
2016. 4
2. Norrman, J., Eriksson, M. and Lindqvist, S. Relationships between road slipperiness, 5
traffic accident risk and winter road maintenance activity, Climate Research, vol. 15, pp. 6
185-193, published Sep. 5, 2000, http://www.int-res.com/articles/cr/15/c015p185.pdf. 7
Accessed June 20, 2016. 8
3. Eisenberg, D. and Warner, K. E. Effects of Snowfalls on Motor Vehicle Collisions, 9
Injuries, and Fatalities, American Journal of Public Health, Volume 95, pp. 120-123, 10
2005. 11
4. Andrey, J. Long-term trends in weather-related crash risks, Journal of Transport 12
Geography, Volume 18, pp. 247-258, 2010. 13
5. FHWA. Manual of Practice for an Effective Anti-icing Program: A Guide for Highway 14
Winter Maintenance Personnel, 15
http://www.fhwa.dot.gov/reports/mopeap/mop0296a.htm#eap23. Accessed June 22, 16
2016. 17
6. Fay, L., Volkening, K., Gallaway, C. and Shi, X. Performance and Impacts of Current 18
Deicing and Anti-icing Products: User Perspective Versus Experimental Data, TRB 19
87thd Annual Meeting Paper #08-1382, TRB, 2008. 20
7. World Road Association (PIARC) Technical Committee 2.4 Winter Service. Snow and 21
Ice Databook 2014, 2015. 22
8. Environment Canada. Best Management Practices for Salt Use on Private Roads, Parking 23
Lots and Sidewalks. 2004. 24
9. Jungwirth, S., Shi, X., Seeley, N. and Fang, Y. Proactive Approaches to Protecting 25
Maintenance Equipment against Chloride Roadway Deicers, Journal of Cold Regions 26
Engineering, Volume: 30, 2016. 27
10. Fay, L. and Shi, X. Environmental impact of Chemicals for Snow and Ice Control: State 28
of the Knowledge, Water Air and Soil Pollution, Vol. 223, pp. 2751-2770, 2012. 29
11. Shi, X., Fay, L., Yang, Z., Nguyen, T.A. and Liu, Y. Corrosion of Deicers to Metal in 30
Transportation Infrastructure: Introduction and Recent Developments, Corrosion 31
Reviews, Vol. 27, No. 1-2, pp. 23-52, 2009. 32
12. Mahoney, J., Jackson, E., Larsen, D., Vadas, T., Wille, K. and Zinke, S. Winter Highway 33
Maintenance Operations: Connecticut, A Report by the Connecticut Academy of Science 34
and Engineering for the Connecticut Department of Transportation, 35
http://www.ctcase.org/reports/WinterHighway2015/winter-highway-2015.pdf. Accessed 36
June 20, 2016. 37
13. Jungwirth, S., Cao, L. and Shi, X. Developing Locally Sourced Brine Additive, 38
INE/AUTC 14.09, 2014. http://www.dot.state.ak.us/stwddes/research/assets/pdf/4000-39
104.pdf. Accessed June 20, 2016. 40
14. Hosseini, F., Hossain, S M K., Fu, L., San Gabriel, P. and Van Seters, T. Field 41
Evaluation of Organic Materials for Winter Snow and Ice Control, TRB 94th Annual 42
Meeting Paper #15-4555, TRB, 2015. 43
15. Muthumani, A., Fay, L., Bergner, D. and Shi, X. Understanding the Effectiveness of 44
Non-Chloride Liquid Agricultural By-Products and Solid Complex Chloride/Mineral 45
Products, Clear Roads 13-02, Contract No. 99006, http://clearroads.org/wp-46
content/uploads/dlm_uploads/FR_CR-13-02_Revised.pdf. Accessed June 1, 2016. 47
16. Chollar, B. H. FHWA Research on Calcium Magnesium Acetate - An Alternative 48
Deicer, Public Roads Volume: 47, pp.113-118, 1984. 49
16
Takahashi et al.
17. Chauhan, S. P., Roshon, M. S., Conkle, H. N., Samuels, W. D. and Berman, E. M. 1
Development of Environmentally Benign and Reduced Corrosion Runway Deicing 2
Fluid, Strategic Environmental Research and Development Program project SI-1535, 3
2009. http://www.dtic.mil/cgi-4
bin/GetTRDoc?AD=ADA512786&Location=U2&doc=GetTRDoc.pdf. Accessed Jun 20, 5
2016. 6
18. Palmer, D. A. Formates as Alternative Deicers, Transportation Research Record 1127, 7
TRB, pp. 34-36, 1987. 8
19. Goyal, G., Lin, J. and McCarthy, J. L. Time, Temperature, and Relative Humidity in 9
Deicing of Highways Using Sodium Chloride or Magnesium Chloride with A Metal 10
Corrosion Inhibitor, Transportation Research Record 1246, TRB, pp. 9-17, 1989. 11
20. Fischel, M. Evaluation of Selected Deicers Based on A Review of the Literature, CDOT-12
DTD-R-2001-15, 2001. 13
21. Muthumani, A. and Shi, X. Effectiveness of Liquid Agricultural By-Products and Solid 14
Complex Chlorides for Snow and Ice Control, TRB 94th Annual Meeting Paper #15-15
5815, TRB, 2015. 16
22. Lewis, W. M. Preliminary Environmental Evaluation of Caliber M1000 Deicer for Use in 17
Colorado, CDOT-DTD-R-2000-12, 2000. 18
http://ntl.bts.gov/lib/18000/18700/18724/PB2002101701.pdf. Accessed June 1, 2016. 19
23. Laurinavicius, A., Mazeika, R., Vaiskunaite, R., Brimas, G. and Milasius, S. Possibilities 20
for the Use of Chemicals Materials Alternative to Chlorides for Decreasing Road 21
Slipperiness in Winter, Baltic Journal of Road and Bridge Engineering Volume: 6, pp. 22
274-282, 2011. 23
24. Koefod, S. Eutectic Depressants: Relationship of Eutectic, Freezing Point, and Ice Melting 24
Capacity in Liquid Deicers, Proceedings of Sixth International Symposium on Snow 25
Removal and Ice Control Technology, Transportation Research Circular Number E-C063, 26
pp. 73-84, 2008. http://onlinepubs.trb.org/onlinepubs/circulars/ec063.pdf. Accessed June1, 27
2016. 28
25. Nixon, W.A. and Xiong, J. Investigation of Materials for the Reduction and Prevention 29
of Corrosion on Highway Maintenance Equipment, IHRB Project TR-472, 2009. 30
http://ntl.bts.gov/lib/31000/31100/31183/TR-472_Final_Report.pdf. Accessed June1, 31
2016. 32
26. Koch, G.H., Brongers, M.P.H., Thompson, N.G., Virmani, Y.P. and Payer, J.H. 33
Corrosion Cost and Preventive Strategies in The United States, FHWA-RD-01-156, 34
2002. http://isddc.dot.gov/OLPFiles/FHWA/011536.pdf. Accessed June 20, 2016. 35
27. Nishimura, R., Araki, M. and Kudo, K. Breakdown of Passive Film on Iron, 36
CORROSION, Volume 40, Issue 9, pp.465-470, 1984. 37
28. Ihs, A., Gustafson, K. and Persson, K. Evaluation of a CMA/NaCl-mixture. Effect on 38
road condition/friction, ice melting capacity, corrosion and impact on concrete, Swedish 39
National Road and Transport Research Institute (VTI), 1996. 40
29. NCHRP. Guidelines for the Selection of Snow and Ice Control Materials to Mitigate 41
Environmental Impacts, NCHRP Report 577, 2007. 42
http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_577.pdf. Accessed June 1, 2016. 43
30. U.S. Food and Drug Administration. Food Additive Status List, 44
http://www.fda.gov/food/ingredientspackaginglabeling/foodadditivesingredients/ucm09145
048.htm#ftnS. Accessed June 27, 2016. 46
31. Food Standards Agency. Current EU approved additives and their E Numbers, 47
http://www.food.gov.uk/science/additives/enumberlist. Accessed June 27, 2016. 48
17
Takahashi et al.
32. Australian Government. Federal Register of Legislation, Australia New Zealand Food 1
Standards Code - Standard 1.2.4 - Labelling of Ingredients, 2
https://www.legislation.gov.au/Details/F2011C00827. Accessed June 27, 2016. 3
33. U.S. Food and Drug Administration (FDA). Code of Federal Regulations Title 21, Sec. 4
184.1784 Sodium propionate, 5
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=184.1784. 6
Accessed June 1, 2016. 7
34. Chemical Entities of Biological Interest (ChEBI). CHEBI:132106 - sodium propionate, 8
https://www.ebi.ac.uk/chebi/searchId.do?chebiId=CHEBI:132106. Accessed June 1, 9
2016. 10
35. Niacet. Safety data sheet, Sodium Propionate, http://www.niacet.com/wp-11
content/uploads/Niacet-Sodium-Propionate-EU-EN-12
NEW.pdf#search='msds+sodium+propionate', Accessed June 1, 2016. 13
36. Nohse, W. The Investigation of Electroplating and Related Solutions with the Aid of the 14
Hull Cell (no.9), Teddington (Mddx.), Draper, 1966. 15
37. Chappelow, C. C., McElroy, A. D., Blackburn, R. R., Darwin, D., de Noyelles, F. G. and 16
Locke, C. E. Handbook of Test Methods for Evaluating Chemical Deicers, SHRP, 17
National Research Council, 1992. http://onlinepubs.trb.org/onlinepubs/shrp/SHRP-H-18
332.pdf. Accessed June 20, 2016. 19
38. Ministry of Agriculture, Forestry and Fisheries of Japan, Test Method for Determining 20
Inhibitory Effects of Fertilizer on Plant Growth (summary), 1984. 21
http://www.maff.go.jp/j/kokuji_tuti/tuti/pdf/t0000056_p001.pdf. Accessed June 1, 2016. 22
39. Hosseini, F., Hossain, S. M. K., Fu, L. and Li, S. D. Effect of Granularity of Salt and 23
Pretreatment on Deicing Performance, TRB 95th Annual Meeting Paper #16-3948, TRB, 24
2016. 25
40. Halliday Technologies Inc. http://www.hallidaytech.com/rt3grip.html. Accessed June1, 26
2016. 27
41. Kiriishi, M., Tokunaga, R., Takahashi, N. Comparative Testing of Evaluation Method of 28
Winter Road Surface Condition, Civil Engineering Research Institute for Cold Region 29
Monthly Report No. 702, pp.50-55, 2011. 30
42. Fay, L., Jungwirth, S., Li, Y. and Shi, X. Toxicological Effects of Chloride-Based 31
Deicers in the Natural Environment: Synthesis of Existing Research, TRB 93th Annual 32
Meeting Paper #14-4017, TRB, 2014. 33
