fourteen years Afterof some use on military
F
. S . R0ST L ER
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. M . I( U N K E L , J R .
of dilution with water, the product penetrates to various depths in the soil and L sets up a cohesiveness much like that of naturally wind resistant soils. In the process it does not interfere with the soil’s porosity, and it is not Thus natural toxic. ground cover can move in. The genesis of this material was a meshing of two problems: a surplus of tacky petroleum residuals, and a lot of moving southern California topsoil. Substantial problems had to be solved in converting the residuals into a form which could be utilized, and much research had to be done into the nature of wind blown soils. The resulting product provides an excellent example of utilization research.
~1 -I-1
bases and other limited areas in California, one of the pioneering products for controlling wind erosion of soil will shortly 1 L move into full production for the civilian market. The product is a waterdilutable emulsion of petroleum residuals, manufactured by Golden Bear Oil Co. (a division of Witco Chemical) of Bakersfield, California. It is called Coherex, and it differs from most other erosion control chemicals in that it is not a surface sealant, and therefore does not act through forming a surface skin. Instead, this material acts as an adhesive which is preferentially adsorbed by mineral surfaces such as clay and silica. Depending on the amount
=I
‘
ST A B I LI Z AT I 0 N
Petroleum residua’-
-in be
modiJied to produce soil adhesives
VOL 56
NO. 4
APRIL 1964
27
M O D E S O F SO1 L T R A N S P O R T
The soil stabcier is a concentrated water emulsion of the resinous fractions of petroleum in the boiling range of lubricating oils. The particular fractions are best described as a mixture of unsaturated hydrocarbons and hydrocarbon derivatives. Unsaturation is shown by an iodine number which averages about 50 for most fractions, and by their typical response to sulfuric acid. The iodine number is too low for the category of drying oils, and reveals that the fractions are relatively stable under normal atmospheric conditions. This material represents the more chemically reactive portion of petroleum in this range. Although petroleum is today the most economical source of raw materials for the organic chemical industry, the chemical potential of its high boiling fractions has not been tapped. Commercial utilization of petroleum distillates in the lubricating oil range has been confined to isolating and relining mixtures of hydrocarbons which are relatively inert. These are used as lubricating oils, and technical and medicinal white oils. The reactive components, chemically unstable and physically characterized by a steep viscosity-temperature slope, are removed from the stable components. In the normal refining process, the bulk of these fractions are removed from lubricating oils in the form of solvent extracts. Additional auantities are removed as acid sludges from sulfuric acid treatment, while further resinous materials are adsorbed on acid clays or are found in distillation residues. I n the conditioner, Coherex, the resinous materials are held in an emulsion system containing a mixture of nonionic and anionic emulsifying agents added at between 1 and 1'/2% of the total aqueous emulsion.
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Wind Erosion
The fundamental principles of wind erosion are established and reported in the writings of three soil scientists, Bagnold (I), Stallings (IO), and Chepil (2-5). Erodible land lacks three things according to these investigators: cohesiveness (loose and dry soil), protective cover (smooth and bare ground), and shelter from wind (large wind-exposed areas). Wind disturbs the soil surface, causes persistent movement of soil particles, and eventually depletes the fines that cement the large particles and hold the soil surface together. Traffic, faulty cultivation practices, and negligence speed the process of soil movement, creating erosion damage to soils. Soil is transported bywind by three processes-saltation, surface creeo. and susDension. These are not independent of each other, and nearly always occur simultaneously. Together they are much l i e the motion of elastic balls on impact. Saltation (the bouncing, jump-
Fritz S. Rostln was Vice President in charge of Product Development, Golden Bear Oil Co., Bakngfeld, Calif., at the time that this article was written. He is MW Director of Research of the Matnials Research C3 Dcuelopment Division of Woodward-Clyde-Sherard C3 Associates, Oakland, Calif. W . M . Kunkel, Jr., is Assistant Editor with th Son Francisco ofice ef the ACS Applied Publications. AUTHOR
28
INDUSTRIAL AND ENGINEERING CHEMISTRY
Pmticle Frmtion
Diameter, M m .
W i d Suncpttbiltty
A B C D
6.4
Highly erodible Dficultly erodible Usually noncrodible Noncrodiblc
CLASSIFICATION BY ROSTLER Fration
Thamcticol Diomtn, Mm.
Siror Size
( 1 ) Dust grains (2) Fine grains
Passina 200 mesh Passing 60 mesh but retamed bv 200 mesh (3) Intermediate grains Pasing 30 mesh but retained by 60 mesh (4) Coarse grains Passing 10 mesh but retained by 30 mesh (5) Small clods or rocks Pasping 4 mesh but retained by 10 mesh (6) Lame clods or rocks Retained by 4 mesh TABLE II.
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4.760
RESULTS OF CONDITIONING SILTY SAND
1 I I
ing motion of soil grains close to the ground) is largely responsible for surface creep (the slow movement of the soil surface under the impact of saltating grains) and for suspension (the transport by wind of very small soil particles dislodged from the surface by saltating grains). These processes are illustrated on the opposite page. Most saltation takes place within a few inches of the ground. By force of impact, saltating grains can move individual grains that are two hundred times their own weight. The diameter of saltating grains is largely in the range of 0.05 to 0.5 mm.; particles moved by surface creep have diameten of 0.5 to 1 mm. Particles moved by suspension have diameters of less than 0.1 mm. It is rarely considered in air pollution control that dust is the largest contaminant in arid areas. Yet the amount of dust suspended in the atmosphere may be more than 100,000 tons per cubic mile of air. Chepil classified mineral soils by four fractions determined by sieve analysis. His classification is primarily one for agricultural soils. Six fractions have been TABLE 111.
RESULTS OFCONDITIONING DUNE SAND
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>4 4-10 l(t30 3o-w'6o-zw -drocarbonused as lubricating oils, technical and medicinal white oils, and the like. They are soft, sticky, resinous, reactilre: unstable, and have a steep temperature-viscosity curve. They are difficult to separate into fractions, characterize, or otheriiise work with (7-9). Thus, though they represent an economical raw material, they are largely untapped.
RESISTANCE OF SOIL T O G R I N D I N G
1
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4 Cycles
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TREATED WITH 1 TO 7 DILUTION OF CONDITIONER +4 mesh, 7c 4-10 mesh, yo 10-30 mesh, 70 30-60 mesh, %
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54.2 19.2 12.5 13.6 0.5 0.0 0.5 - 97 0.0 -100
TREATED WITH WATER $4 mesh, 7c 4-10 mesh, yc 10-30 mesh, % 30-60 mesh, Yo 60-200 mesh, yo Passes 200 mesh, 7o Total passing 60 mesh, % Change from original, Yo Total passing 200 mesh, 7c Change from original, 70 a
30
14.2 16.5 18.4 20.7 18.3 11.9
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42.4 +168 14.0 +137
Sieve analysis of ball-milled specimens which have besn dried after 7epeat.d treatments with Coherex or u,ater. INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
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14.0 13.8 6.7 4.5 35.5 25.5 61 . 0 $286 25.5 +332
14.0 13.2 5.0 1.9 21.7 44.2 65.9 +317 44.2 tG49
Figure 2. Ease of handlin,< and e use 0 1 dilution were achieved by development of an emulsion of the petroleum resins
Figure 3. Effect on soil particles. Photomicrograph shows qrains held together by the soil adhesive
Figure 4. Eject on plant growth. A j a t seeded with cotton, rye gras.r, and radishes was sprayed. Because qf the organic nitrogen bases present in the emulsaon, germination of the plants was speeded by 24 hours. The plants are shown 72 duys after planting
Figure 5. Efect on wind erosion. Resistance to wind was tested in a miniature wind machine. These samples oj dune sand were treated with jive dayerent amounts of conditionel and exposed to winds of 50 miles per hour. The untreated sample is at the left
One way to remove these fractions from lube oils is to adsorb them on clays and silica. This makes them extremely likely as soil adhesives. A utilization program was therefore carried out, which involved studying the underlying principles of wind erosion, designing lab test equipment, and adapting petroleum residuals to the use. Soil conditioners had been previously designed to improve horticultural properties, for instance to increase soil porosity or water holding capacity. But a product had not bem used before to impart permanent cohesiveness to soils. Testing of a petroleum oil for similar purposes has been reported (I&EC, August 1963, page 9). Improving Handling Characferistics
The physical properties of the resinous fractions which make them desirable raw materials for an adhesive also make them difficult to handle conveniently. Without
eliminating the rheological characteristics of the resins during application they could not be tested as to reproducibility of performance or effectiveness of various dosages. Ways had to be found to convert these sticky, resinous materials into products which are free-flowing at ordinary temperatures. Changing the handling properties without impairing the physical and chemical characteristics of the resins was obviously to be best accomplished by temporary reduction of the viscosity during application Heating was not practical because resins cool rapidly on contact with the soil. Dilution with solvents had the disadvantages of increased cost, fire hazard, and toxicity to the soil. The most promising approach was emulsification. Testing a number of emulsification systems and procedures led to a combination fulfilling all the requireinents of a stable, VOL. 5 6
NO. 4 A P R I L 1 9 6 4
31
frc=e-flo\vingeinulsion uith good penetrating po\j.er into soils (Figures 2 and 3). Thcn systematic resting could b e initiated. This testing included determining the action of the various resinous fractions on soils-not just effect on cohesiveness and resistance to erosion and traffic, but their eflect on soil fertility, porosity, and other agronomic requirements. Then the researchers could select the most suitable fractions and go into field trials. One of the first tests for influence of resin composition on vegetation was on a flat seeded with cotton, rye grass, and radishes. The test proved that the emulsion residue was not harmful to germination (Figure 4). Improvement of resistance to wind was tested in a miniature wind machine, Figure 5. Increase i n angle of repose was measured on a tilting plane, and other laborator)- tests of cohesiveness were devised. That resistance of the soil to dry grinding was greatly improved by stabilization is shown clearly in Table I V . large-Scale Testing
The first test on barren land was carried out in February 1950. -420-acre area which was located in Kern County, California, approximately 5 miles south of Lost Hills was treated at the rate of I / % gal./sq. yd. with Coherex, diluted 1 :7 with water. T h i s location was chosen to test Lvhether or not treatment of a barren area at the edge of an area of natural vegetation could make it receptive to natural seeding. The area was covered with vegetation two years later, and still is today. Following this, the product went into its first, largescale use at Edwards Air Force Base, California. For effective erosion control at Edwards, a combination of measures was required. Personnel at Edwards first established a perimeter for the area to be protected from 32
I N D U S T R I A L AND E N G I N E E R I N G CHEMISTRY
Figure 9. Apblication of Coherex from a spray truck equipped f o r traveling in the dune area Figure 70. A sand d m e , located in the coartal dune area at Vandenberg Air Force Base in Lompoc, Calif, The dune has been treated with I/Q gal. per sq. y d . of a 7 to 7 dilution of conditioner in water
Figures 6, 7, and 8. The picture on the left shows treatment of a nezoly seeded area with sot1 conditioner. During a heavy wind storm, the area is almost dust-free, as shown i n the center picture. The picture on the right is of an adjacent untreated area, showing the effect of the same wind storm
i
5.
dust and inblowing sand by sand fences, trees and shrubs. Only then could the area inside this perimeter be SUCcessfully treated. At Edwards vegetation has become established, the base has been converted into a dust-free community located in the middle of a desert notorious for dust and sand storms. Figures 6 , 7 , and 8 are of this base. Another job has been done at Vandenberg Air Force Base at Lompoc, California. Here more than 500 acres, including 350 acres of active sand dune area, have been treated. The picture on page 27 shows such a dune, three years after it was seeded and treated with Coherex. Other military installations treated are Holloman Air Force Base in New Mexico, Minot Air Force Base, North Dakota, and Malmstrom Air Force Base in Montana, Ellsworth Air Force Base in South Dakota, and Elmendorf Air Force Base in Alaska. In all, approximately seven million gallons have been used, mostly at military installations, since the product was first produced. Among other tests, a project involving the treatment of 105 acres of desert is scheduled for this spring at Nellis Air Force Base, Nevada. Civilian uses have been limited to a few near-by areas of Bakersfield including city school grounds, civilian airports, workyards, chicken and turkey pens, summer camps, road embankments, and gravel roads. The use of Coherex for the stabilization of sand dunes has been described in a detailed report by the U. S. Army Corps of Engineers ( I I ) . A paper describing experiments carried out a t the Kansas Agricultural Experiment Station comparing the product with other materials used for mulching has been published (5). The demand of the military was large enough to keep the production of the Bakersfield manufacturing plant in full operation. Now, since the product has been
proven and the methods of application extensively tested, Witco is increasing manufacturing facilities and planning additional facilities throughout the country. The product and the process will be made available both here and abroad . Future Applications
The development efforts described here were originally aimed at developing new means of soil stabilization. Although this is still the most important and largest potential application, Coherex can be used for the agglomeration of fines in any material which is not water soluble. Some of these applications tested and proven useful are treatment of ores and dustproofing of coal. Tests have shown that coal can be made completely dust-free by treatment with 7 gallons of a 1 :15 dilution per ton of coal. Other applications of this new adhesive, which is low in cost and available in large quantities, are possible; some are in the development stage.
LITERATURE CITED (1) Bagnold, R. A,, “The Physics of Blown Sand and Desert Dunes,” Methuen and Co. Ltd., London, 1954. (2) Chepil, W. S., A m . J.Sci. 225,12-52 (1957). (3) Chepil, W. S., Sod Sci. 69, 149-162 (1950); Ibid., 75, 387-401 (1951); Zbid. 473-483 (1953). (4) Chepil, W. S., U . S.DcpI. Agr. Tech. Bull. 1185, 1958. (5) Chepil, W. S., Woodruff, N. P., Siddoway, F. H., Ambrust, D. V., U . S. Depi. Agr. ARS 41-84, July 1963. (6) Rostler, F. S., Pardew, M. B., Rubber Age 63, 317-326 (1948). (7) Rostler, F. S., Sternberg, W., I N D . END.CHEM.41, 598-608 (1949). (8) Rostler, F. S. Vallerga, B. A. “A Manual on Control of Dust and Wind Erosion,” Goldeh Bear Oil C o . , Baiersfield, Calif., 1960. ( 9 ) Rostler, F. S., White, R. M.. Rubber Age 70,735-747 (1952). (10) Stallings, J. H., “Soil Conservation,” Prentice-Hall, 1957. (11) U. S.Army Corps of Engineers, Los Angeles, Calif., “Report on Wind Erosion Control for G/M Training Facility 75-1, Vandenberg Air Force Base, Lompoc, Calif.,” Sept. 1960.
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