AU601834B2 - Oil absorbent and method - Google Patents

Description

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COMMONWEALTH OF AUSTRALIA The Patents Act 1952-1969 ame of Applicant: GAMESEA PTY LTD ddress of Applicant: 238 Canterbury Road, Bayswater, in the State of Victoria, 3153, Commonwealth of Australia.

ctual Inventor: PERCY THOMAS HAINES ddress for Service: G.R. CULLEN COMPANY, Dalgety House, 79 Eagle Street, BRISBANE. Qld. 4000.

COMPLETE PATENT SPECIFICATION FOR THE INVENTION ENTITLED:- OIL ABSORBENT AND METHOD The following statement is a full description of the invention including the best method of performing it known to me: 4 1.

1, f THIS INVENTION relates to a product for absorbing liquids and is particularly concerned with a product for absorbing hydrophobic liquids such as oils, fuels and the like. The invention also relates to a method of absorbing such hydrophobic liquids.

The problem of pollution by petrochemicals such as hydrocarbons and other liquid pollutants is an ongoing and o 00 integral part of our modern existence. Petrochemicals are 0 generally immiscible with our most useful solvent, water, and o o0 i10 often must be rendered water miscible by the action of 0000 0 surface-active agents such as detergents and dispersants before water can be used as the bulk dispersal medium. The technology relating to the use of dispersants and detergents 0 0 0 is well advanced, with many improvements being made in the last twenty years since the weeks and months after the Torrey Canyon disaster of 1967 brought the problem home to England and the rest of the World.

In situations where oil decontamination of hard surfaces is required, the technology has generally revolved around the use of dispersants, detergents or saponifying chemicals, again to render the contaminants water-dispersable for disposal by volumetric flushing with water.

The obvious problems associated, with dispersant technology reside in its fundamental mode of operation. It does not remove the contaminant from the contaminated medium.

AltY .gh the capacity of the ocean to deal with the dispersed

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3 contaminant is remarkable, by the time the contaminant is degraded considerable economic and ecological damage may be done, particularly to filter feeding species such as shell fish, subsequent to the initial disruption to fish and birds.

The use of absorbents for removal of oily contaminants has been contemplated in the past, with several remedies proposed with varying degrees of success.

The use of oil-swellable polymer beads has been considered. However, the sheer volume of the more serious contamination incidents and the ongoing requirements of industries which generate large volumes of contaminants has in combination with the cost of the beads made the whole proposal unworkable from an economic view point.

Cheaper particulates, especially sawdust have been satisfactorily used for small scale removal of liquid contaminants such as oil from solid surfaces. However, the volumetric performance is extremely poor, and the performance in the aqueous environment is totally inadequate. Such products also have an inherently high water content, and the dried product rapidly absorbs atmospheric water resulting in storage, handling and safety problems including caking and especially spontaneous combustion due to exothermic decomposition. Furthermore, sawdust has an inherent tendency to desorb the contaminant when it becomes saturated with the contaminant and the concentration of surrounding contaminant has been reduced or eliminated.

4 It is therefore an object of the present invention to provide an absorbent for hydrophobic liquids which does not have the disadvantage of the aforementioned products.

According to one aspect of the present invention, there is provided a product for absorbing hydrophobic liquids, said product comprising the cones of coniferous trees which have been comminuted to provide a mixture of fibres and particulates.

Prior to comminution, it is preferred that the .0 cones be dried, either naturally or artificially, such as in a kiln, and deseeded. Cones of any species of conifer may be employed but the cones of pinus radiata are preferred because of their very good absorbing properties, and because of their abundance.

The bulk density of the product will be related to the nature of the hydrophobic liquid to be absorbed. For highly viscous liquids such as oils, the bulk density will usually be low whereas for low viscous liquids, it will be relatively high. Generally, however, the bulk density will preferably be within the range 0.1 to 0.5 Kg/l, most preferably about 0.2 Kg/l.

Preferably, less than 5% by weight of the product will comprise particles of a size less than 75 microns.

According to a further aspect of the present invention, there is provided a method of absorbing a hydrophobic liquid which comprises contacting said liquid i with an absorbent effective amount of a product as defined.

above.

The cones may be comminuted by milling in a preliminary hammer mill followed by final milling in a rod or ball mill. The product thus prepared is ready for immediate use. It may, however, be subject to subsequent processing by the addition of fire retardants, extenders, dyes, and the ao like.

Generally, the product will be packaged in a form 10 convenient to the desired end use. To this end, the 0o packaging itself may comprise a feature of absorbent system.

14.14 o o Thus it has been found that a cotton fabric container is 4 0 suitable in certain applications where the liquid to be absorbed passes through the container to the product.

Suitably, the cotton fabric container will have a cylindrical shape and be tied at one or both ends once the product of the invention has been placed therein. This provides a convenient, readily manageable method of handling the product. One particularly preferred embodiment comprises approximately two litres of the product in a cotton hose fabric measuring approximately 1 metre in length and having an average diameter of about 75 mm.

A preferred product according to the present invention has the following physical parameters: APPEARANCE: A dry of fibres and particulates 4* 6

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HAZARD POTENTIAL: Not normally subject to spontaneous combustion Not combustible without addition of volatiles Complies with ASTM C-739, 1984 No known explosive tendency.

HUMAN CONTACT: No knowa effects upon ingestion, inhalation or skin contact REACTIVITY: No known reactions. Stable but biodegradable.

A chemical analysis of a typical product in accordance with the present invention gave the following results: Organic Matter 83.1 Acid Extractable Chromium as Cr, mg/kg 0.7 Acid Extractable Copper as Cu,mg/kg 1.3 Moisture (8 hours at 105 0

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w/w 13.4 Ash (24 hours at 600 0

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w/w Specific Gravity 1.24 Particle Size Less than microns 3.52 r r 2

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7 Less than microns 0.012 The preferred apparatus for generating the crushed cone product comprises conveyor means to carry mature deseeded cones from storage to a hammer mill. The hammer mill is a primary crusher which breaks the cones down to individual fractured pieces, and feeds these pieces to a rod or ball mill. The rod or ball mill reduces the cones to the desired particle size, whereupon they can be removed to a storage bin by fluidization with compressed air. The material may then be dispensed, either in bulk or to a packaging plant.

In use, the present product need only be in contact with the hydrophobic liquid for the product to exhibit its selective lipophilic absorption. The product may be dispersed freely over a contaminated area, or contained in nets or containers to make retrieval of the spent product easier.

The invention will be further described with 20 reference to the following examples.

Example 1 illustrates the performance testing and results of the present product when used for absorbing various oil contaminants on water.

Examples 2 to 4 illustrate the protocols of use of the present product for removal of contaminants from a variety of surfaces.

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llur" 8 Example 1 Method It r t If Ii I ii II I I I I

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The absorption properties of the present composition were ascertained by measuring the increase in weight of 10 gram portions of the product placed on a 1.0 cm layer of oil floating over 10 cm of water at a temperature of 0 C. The surface area over which the product was spread was cm 2 (this resulted in a layer depth of approximately 0.4 cm). These quantities represented a large excess of oil.

0 Absorption of oil at 2 minutes and 5 minutes was measured after removal of the oil soaked material. Excess oil adhering to the surface of the particles was removed by gentle pressing between filter pads. The following hydrocarbons were used: 5 Hydrocarbon Measured Specific 0 Unleaded Petrol Diesel Distillate Lubricating Oil (Rotella) Gear Oil (Spirax HD80W90) Hydraulic Oil (Tellus 46) Industrial Gear Oil (Omala 100) Results Gravity 0.73 0.84 0.88 0.89 0.87 0.88 The table below gives the mean weight of oil absorbed by the product after two minutes and five minutes.

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r.i. lr. Hydrocarbon Unleaded Petrol Diesel Distillate Lubricating Oil (Rotella) Gear Oil (Spirax) Hydraulic Oil 0 (Tellus) Industrial Gear 2 Minute Absorption %W/W %V/V 67 17 74 22 5 Minute Absorption %W/W %V/V 77 79 23 t( 14

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o 0 0400 o O Q 4 0 60 a 0 o 0 BO o *1 Oil (Omala) 74 23 77 24 Mean 69 20 86 26 For the purpose of measuring absorption capacity on "15 volume to volume basis the specific gravity of oils and the density of the product was also measured. The mean density of the product was 0.35 kg/litre.

Additionally, it was determined that the product would absorb a considerable amount of water if a layer of oil 0 was not present on the surface of the water prior to 0 spreading of the product. Ten grams of product absorbed 9.4 gms. of water within 2 minutes in quiescent conditions. The speed of absorption increased with agitation. The peak absorption of water was reached after 10 minutes and at this time some 13.6 gms. of water had been absorbed. As the particles became wetted they suilk to the bottom of the test -LU. container.

Discussion Observations made during these tests showed that with lighter fractions and less viscous hydrocarbons such as petrol or diesel fuel, absorption was almost immediate (5 to seconds) and there was little difference in the measured absorption capacity between 2 minutes and 5 minutes. On addition of the composition to these hydrocarbons, it quickly sank to the water hydrocarbon interface but did not sink into the water.

h With the more viscous oils such as gear oil or hydraulic oil the product tends to stay on or near the surface of the oil for the first few minutes under quiescent conditions. Up to 5 minutes elapsed before a 5 mm layer of the product over these oils was completely wetted. When this occurred the whole mass of oil soaked product then sin.r_ to the oil-water interface as it is no longer buoyed up by air within the fibres.

During the separation of the oil soaked product 'o 0 from the excess oil and water it was noted that even strong mixing would not cause the material to sink into or mix with the water layer to any degree. The oil soaked material was not found to contain any water throughout all tests due to a preferred affinity for oil.

It was further found that once the product is coated with even a thin layer of oil over water it becomes 11 very resistant to water absorption. Further experiment showed that a 1 mm thick oil film with 10 mm of the product placed over it resulted in no more than 1% of the product sinking below the oil-water interface.

The test results for absorption capacity do not show very large differences in the absorption capacity of different oils at either the 2 minute or 5 minute absorption times, although hydraulic oil tended to absorb more slowly than other oils and required a full five minutes to achieve its maximum absorption capacity. The difficulty in removing excess clinging hydraulic oil from the product mass may partly explain the apparently high 5 minute absorption capacity of this oil. Overall it was found that on average the product would absorb 69% of its weight (20% by volume) of oil within 2 minutes and 86% of its weight (26 by volume) of oil within 5 minutes. Where the thickness of the product used is greater than 1 cm then some surface agitation may be necessary if a fast absorption time is required.

For practical purposes the variation in test i0 results between different oils is not high enough to justify significant differences in procedures during a cleanup operation.

It is calculated from the results that for each 1 mm of oil on a surface some 4--5 mm of the product will be needed for complete absorption. Screens with a steel mesa with spacing about 2 mm was found to be the most efficient i 12 Summary 1. The product will absorb thin oils almost immediately and more viscous oils within 5 minutes.

2. The product can absorb about 69% of its weight of oil (20% by volume) within 2 minutes, to an ultimate capacity of 86% of its weight (26% by volume) within minutes.

S3. Approximately 4 to 5 mm of the product is needed per 1 mm of oil film thickness for complete Iabsorption.

4. The product placed in water without an oil layer will quickly absorb water and sink.

Once the product has come in contact with any oil it will no longer absorb water and sink, even under I strong agitation.

Example 2 On still water, an oil film of approximately 2 mm thickness was laid down. The spill area was covered with a layer of the present product at an average thickness of 13 mm.

m After three minutes the cohesive mat of oil laden product was removed from the water surface using steel mesh nets of 2 mm pore size.

The surface of the pond showed only the occasional patch where interference patterns were observed, the fine L 13 films causing this effect not constituting a significant oil residue.

Example 3 Oil contaminant was placed in a running stream in sufficient quantity to form a noticeable running slick. The present product was employed downstream of the slick, contained in a nylon mesh holding net disposed at the surface of the stream in the path of the slick. As the net caused the slick to pond against its upstream side, the resulting stationary slick was treated as in Example 2.

Example 4 A 2 mm film of heavy oil was placed on a concrete surface. 13 mm of the present product was spread over the spill and allowed to stand for approximately four minutes, whereupon the contaminated product was swept up for disposal.

A slight residual stain left on the concrete was raised by saturating the area with light hydrocarbon solvent, followed by a repeat treatment with the present product. The light solvent and the stain were lifted in approximately one minute.

Disposal of the contaminated product may be effected in any manner consistent with good ecological management, with it being especially preferred to dispose of the product by forced air incineration or as landfill either before or after oil recovery, depending on the contaminant.

Whilst the above has been given by way of 14 illustrative example of the invention, many modifications and variations may be made thereto by persons skilled in the art without departing from the broad scope and ambit of the invention as herein set forth in the following claims.

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Claims (8)

1. A product for absorbing hydrophobic liquids comprising the cones of coniferous trees, said cones being comminuted to provide a mixture of fibres and particulates.

2. A product as claimed in Claim 1 wherein said cones are the cones of pinus radiata.

3. A product as claimed in Claim 1 or Claim 2 and having a bulk density of between 0.1 and 0.5 Kg/l.

4. A product as claimed in Claim 3 wherein t bulk .0 density is about 0.2 Kg/l.

5. A product as claimed in any one of the preceding claims wherein less than 5% by weight of the product comprises particles of size less than 75 microns.

6. A product as claimed in any one of the preceding claims wherein the cones are deseeded prior to comminution.

7. A method of absorbing a hydrophobic liquid which comprises contacting said liquid with an effective amount of a product as claimed in any one of the preceding claims.

8. A method as claimed in Claim 7 wherein the i0 hydrophobic liquid is a petrochemical. A product fr abzcrbing hydrophbi li uids=- substantially as hereinbefore specifical c-ribed. A method sorbing a hydrophobic liquid substantially as herinbefore spcifically described. DATED this 12th day of April, 1988. GAMESEA PTY LTD By their Patent Attorneys G.R. CULLEN CO.