WO2012007927A1

WO2012007927A1 - Treatment of oil

Info

Publication number: WO2012007927A1
Application number: PCT/IB2011/053165
Authority: WO
Inventors: Thomas Brian Ferguson
Original assignee: Thomas Brian Ferguson
Priority date: 2010-07-15
Filing date: 2011-07-15
Publication date: 2012-01-19

Abstract

The invention provides for a method of treating oil. According to the method, polystyrene particles are distributed over oil that is to be treated. The polystyrene particles are then allowed to absorb oil, thereby obtaining oil- drenched polystyrene particles and hence treating the oil.

Description

TREATMENT OF OIL

THIS INVENTION relates, broadly, to the treatment of oil. More particularly, the invention relates to the treatment of oil spills, thereby to clean up and recover oil from oil spills. Still more particularly, the invention provides a method of treating oil, and an oil treatment kit.

Thus, in accordance with a first aspect of the invention, there is provided a method of treating oil, which method includes

distributing polystyrene particles over oil to be treated; and

allowing the polystyrene particles to absorb oil, thereby obtaining oil- drenched polystyrene particles and hence treating the oil. The oil to be treated may, in particular, be spilt oil. In other words, the oil to be treated may be oil forming part of an oil spill, i.e. oil which has spilt into or onto a body of water, e.g. at sea, or onto a tract of land. The invention is, of course, not limited to treatment of such spilt oil and it is envisaged that other sources of oil can also be treated in accordance with the invention, e.g. a catch pit of a vehicle service station which catches oil washed from a driveway of the service station using water, with the catch pit thus containing a mixture of oil and water and with it being desired to recover or separate the oil from the water. The polystyrene particles may be particles of expanded polystyrene. Preferably, the polystyrene is waste expanded polystyrene. By 'waste expanded polystyrene', there is meant polystyrene having been recycled from prior use thereof. It is to be appreciated that waste expanded polystyrene may, typically, for the purposes of the prior use thereof, have been rendered or moulded into a shaped artefact, dictated by its prior use. In such a case, the method may include, in a pretreatment step, rendering artefacts of waste expanded polystyrene into particulate, preferably coarse particulate, form by shredding the artefacts, thus prior to distributing the waste polystyrene over the oil. It is to be noted that, as indicated above, it is desirable for the waste polystyrene from which the shredded polystyrene is obtained to have a coarse polystyrene pebble structure rather than a fine polystyrene pebble structure. Thus, it is preferred that the polystyrene is not virgin polystyrene beads, although the use of such beads is envisaged as a possible, albeit non-desirable, embodiment of the invention.

The polystyrene particles may be left in contact with the oil for a period of time to allow maximum drenching or absorption of the oil into the polystyrene particles. It is expected that the length of this contact period will depend on the viscosity of the oil as well as on the volume of oil to be recovered. Thus, for low viscosity oils such as diesel oil and paraffin, the contact period may typically be no more than a few minutes, more particularly typically from about 1 minute to about 2 minutes. In contrast, for high viscosity oils such as gear oil and oxidized crude oil, the contact period may be a few hours, typically from about 6 to about 12 hours. It will therefore be appreciated that the polystyrene particles may be left in contact with the oil for a time period from about 1 minute to about 12 hours, in order to become drenched with oil. The method may further include

recovering or collecting at least some of the oil-drenched polystyrene particles;

treating the recovered oil-drenched polystyrene with a solvent for polystyrene, thereby dissolving the polystyrene and obtaining a mixture of a polystyrene phase and an oil phase; and

separating the polystyrene phase and the oil phase.

Treating the oil-drenched polystyrene may be conducted in a closed environment, e.g. in a closed container, so as to minimize the loss of solvent by evaporation, particularly if the solvent is volatile. In such a case, the method may include collecting and recovering evaporated solvent.

Treating the oil-drenched polystyrene may also be conducted in a heated environment and may thus include applying heat to the mixture of polystyrene phase and oil phase. The solvent may also be heated prior to contacting it with the oil-drenched polystyrene.

Recovering or collecting the oil-drenched polystyrene may be effected by collection means, the nature of which may be dictated by the nature of the surface over or on which the oil that is to be treated is dispersed. As has been alluded to hereinbefore, the oil may, typically, have been dispersed or spilt onto or into a body of water, such as at sea, or on a tract of land. When the oil to be treated is dispersed on water, it will be appreciated that the oil-drenched polystyrene will, after having been distributed over the oil and having been allowed to absorb at least some of the oil, typically float on the water surface due to the polystyrene, even when drenched with oil, having a lower density than water. In such a case, recovering or collecting the oil- drenched polystyrene may be carried out by means of straining or screening the polystyrene from the water surface, e.g. by means of a net or the like, allowing water to pass through the collection means whilst collecting the drenched polystyrene with the collection means. When the oil to be treated is dispersed on land, recovering the oil-drenched polystyrene may include sweeping or scooping up the oil-drenched polystyrene by any suitable equipment, i.e. by means of any suitable equipment for collecting solid material on land, such as, in simple terms, a broom and a bucket.

The solvent may be any solvent which is capable of dissolving polystyrene. Preferably, the solvent is any solvent, typically an organic solvent, which favours dissolution of polystyrene over dissolution of oil, more preferably a solvent which dissolves polystyrene but does not dissolve oil to an appreciable extent. Alternatively, the solvent may be solvent for both polystyrene and oil. The solvent may include high and low aromatic hydrocarbons and well aliphatic hydrocarbons, typically being selected from solvents including in their molecular structure a similar molecular structure to that of the styrene monomer. Typically, the solvent may be a crude-oil or petroleum-based solvent, preferably gasoline or petrol. The solvent may also be selected from xylene, lemon oil, turpentine and camphor oil.

The solvent may, in particular, be of such a nature that dissolution of the polystyrene therein results in the formation of a polystyrene phase that is of different density and viscosity than the oil phase, such that the polystyrene phase is thus readily separable from the oil phase. When the solvent is petrol, for instance, the polystyrene phase may typically be in the form of a highly viscous, high-density gel-like substance, which is of a significantly higher density and higher viscosity than the oil phase. Thus, the mixture of the polystyrene phase and the oil phase may typically comprise at least two phases, i.e. the polystyrene phase and the oil phase.

Separation of the oil phase from the polystyrene phase may be carried out on the basis of their differing densities and viscosities, typically being achieved by way of any one or more or gravity separation, decantation, screening and filtration, or by drawing the oil phase from the polystyrene phase when the solvent is also a solvent for oil and the oil phase is thus contained in the polystyrene phase.

It will be appreciated that dissolution of the polystyrene by the solvent to obtain the polystyrene phase, regardless of whether the solvent also dissolves the oil or not, may thus result in liberation of the oil from the polystyrene, considering that the oil does not dissolve or chemically react with the polystyrene to an appreciable extent. The oil phase is thus obtained in admixture with the polystyrene phase, with the oil phase comprising a mixture of oil and, possibly, some solvent.

The method may also include recovering polystyrene from the polystyrene phase. In this regard, it is worth noting that depending on the solvent employed, no chemical reaction may occur between the solvent and the polystyrene, thus resulting in the solvent being readily separable from the polystyrene. In such a case, recovering the polystyrene may include drawing solvent from the polystyrene phase. This may be carried out by applying pressure to the polystyrene phase and/or by merely allowing the solvent to seep out of the polystyrene phase. Preferably, separating the solvent from the polystyrene phase may continue until the solvent content of the polystyrene phase has been virtually depleted and the polystyrene phase is in the form of a virtually dry, solid polystyrene residue.

If the solvent is a solvent for oil as well, the solvent separated from the polystyrene phase may therefore include at least some oil which may then be recovered to the oil phase. It is to be appreciated that, in such a case, it is possible that the oil phase may, when the solvent is also a solvent for oil, be contained in the polystyrene phase, thus being separated from the polystyrene phase along with the solvent.

If the solvent is also a solvent for oil, the oil phase may thus comprise a solution of the oil in the solvent, with the solvent effectively having leached the oil from the polystyrene. Thus, the method may include recovering oil from the oil phase. Typically, recovering oil from the oil phase may be carried out by any one or more of gravity separation, decantation and distillation.

When the oil is recovered from a water surface, some water, which may have been absorbed by or may have adhered to the oil-drenched polystyrene, may also be dispersed in the oil phase in the form of a water phase. The method may thus include, if applicable, separating the water dispersed through the oil phase from the oil phase, typically through gravity separation and decantation. In accordance with a second aspect of the invention, there is provided an oil treatment kit, the kit including

at least one polystyrene pack containing a quantity of polystyrene particles capable of absorbing oil and hence of becoming oil-drenched; oil-drenched polystyrene recovery or collection means for recovering or collecting oil-drenched polystyrene particles;

an oil-recovery container for recovering oil from the oil-drenched polystyrene; and

a solvent for dissolving the oil-drenched polystyrene in the oil-recovery container, thereby to form separate oil and polystyrene phases.

The polystyrene particles and the solvent may be as hereinbefore described.

The oil-drenched polystyrene recovery means may be in the form of a net, sieve or strainer, particularly when the kit is used to treat an oil spill which has occurred on or in water, e.g. at sea. Alternatively, e.g. when the kit is used to treat an oil spill that has occurred on land, the recovery means may be in the form of any suitable equipment for collecting solid material on land, as exemplified hereinbefore.

In a particular embodiment of the invention, and particularly when the kit is for use in treating oil which gathers, together with wash water, in a catch pit of a service station driveway, the kit may include a plurality of vacuum-packed polystyrene packs, each pack containing about 1 .2 kg of shredded waste expanded polystyrene. Preferably, the kit includes three or four such polystyrene packs. The container may then preferably be in the form of a 50 litre plastic container. The kit may also include a funnel for facilitating feeding solvent and, possibly, drenched polystyrene, into the container. The oil- drenched polystyrene recovery means may then comprise a hand-held net for scooping drenched polystyrene particles from the catch pit.

In one embodiment of the invention, the container may comprise a recovery assembly, including a 50 litre plastic container, having a threaded neck which defines an opening which is closed by a lid which is screwed onto the neck, as well as a feeding funnel being adapted to be screwed onto the neck after the lid has been unscrewed therefrom. The container may be provided with a handle which facilitates displacement thereof. In such an embodiment, treatment of the oil-drenched polystyrene with the solvent may typically be carried out in the feeding funnel, with the polystyrene phase thus being formed in the funnel. In such a case, the funnel may be provided with a screen which retains the polystyrene phase in the feeding funnel and allows passage into the container only for the oil phase containing the oil which has been liberated from the oil-drenched polystyrene. The container may be provided with an outlet adjacent a base thereof, such that, once the oil phase which has been collected in the container has settled into phases thereof, the denser phase, typically being water, may be withdrawn along the outlet, whereafter the oil, which may contain some solvent, may be withdrawn.

It is envisaged that the kit will include a manual for guiding a user in carrying out the method of the invention by using the kit.

The invention will now be described in more detail by way of example only with reference to the following example:

EXAMPLE:

Recovery of crude oil

A volume of 200ml crude oil was discharged over a water body defining a surface area of approximately 0.78m².

Two batches of shredded waste expanded polystyrene of 30g each were distributed over the discharged oil.

The distributed polystyrene was allowed to absorb oil from the water surface over an absorbance period of approximately 5 minutes, resulting in most of the polystyrene becoming drenched with the crude oil and virtually all of the oil being absorbed by the polystyrene. It is expected that an extended absorbance period would increase the quantity of oil which is absorbed, particularly in view thereof that some of the discharged oil was observed to have gone into suspension in the water. An extended absorbance period would therefore allow for the oil in suspension to rise to the surface and be absorbed by the polystyrene.

Throughout the absorption period, the polystyrene remained floating on the surface, regardless of the quantity of oil which had been absorbed. From time to time the water was stirred whilst the polystyrene was floating thereon, thereby to maximise contact of the polystyrene with the oil.

After absorbance period had elapsed, the oil-drenched polystyrene was recovered from the water volume by means of a sieve and was transferred to an oil recovery container in the form of a shallow dish. The oil-drenched polystyrene included at least some water, whether due to absorbance into the polystyrene and/or water which adhered to the sieve and/or to the polystyrene. In the dish, the oil-drenched polystyrene was treated with a polystyrene solvent in the form of petrol, which is also a solvent for crude oil. More particularly, a volume of 150ml of petrol was poured onto the oil- drenched polystyrene. It is envisaged that the solvent may, alternatively, be sprayed onto the oil-drenched polystyrene so as to maximise contact of the solvent with the oil-drenched polystyrene.

The petrol was allowed to dissolve the polystyrene over a period of approximately 15 to 25 minutes, resulting in a mixture of polystyrene phase and oil phase being obtained, the oil phase comprising a solution of crude oil in petrol with the crude oil having been liberated from the polystyrene due to the dissolution of the polystyrene in the petrol.

No external heating was applied during the experiment, although it is envisaged that the application of external heating would increase the polystyrene dissolution rate and thus decrease the reaction period. From time to time the mixture of oil-drenched polystyrene and oil phase was stirred by means of a stirring rod. The polystyrene solution/phase and the oil phase were separated from each other by straining the mixture by means of the sieve, with the polystyrene phase thus being collected on the sieve surface. The polystyrene phase was then returned to the dish. The separated polystyrene phase was in the form of a highly viscous high-density gel-like substance which was clearly distinguishable and easily separable from the oil-phase. Dissolution of the polystyrene in the petrol did not appear to involve a chemical reaction and the polystyrene phase appeared to comprise the polystyrene and some of the solvent, with the solvent being easily separable from the polystyrene. Solvent continuously seeped out of the polystyrene phase and was added to the already recovered oil phase. The solvent seeping out of the polystyrene phase of course also contained some oil dissolved therein. Pressure was applied to the polystyrene phase from time to time to stimulate release of solvent therefrom and to maximise the recovery of solvent to the oil phase.

Due to time constraints, virtual complete recovery of solvent from the polystyrene phase to the oil phase, keeping in mind loss of solvent to evaporation, could not be achieved, although such recovery was achieved in other similar undocumented experiments. In these undocumented experiments, the resulting polystyrene phase was in the form of a polystyrene residue in the form of a hard solid substance which had a volume significantly less than the volume of the waste polystyrene and was easily handled was obtained.

The recovered oil phase was left to separate, under gravity, into a water phase and a combined oil and petrol or diluted oil phase. The combined oil and petrol phase was decanted and measured and comprised a volume of approximately 300ml of the original combined volume of 350ml oil and petrol which were employed, constituting a recovery of approximately 85%. The reduced volume of recovered oil phase may be attributed to solvent evaporation losses and to the fact that not all of the oil and solvent was recovered from the polystyrene phase, from which oil phase continuously seeped whilst the oil phase separated into the water and combined oil and petrol phase. It is expected, based on results obtained from other undocumented experiments that an oil phase recovery of between 90 and 95% may be obtained, with virtually all of the oil being recovered to the oil phase.

The abovementioned experiment was repeated, albeit not documented, for foam filter oil, waste engine oil, disk brake fluid, automatic transmission fluid, diesel oil, and burned petrol residue. In each case, the same quantities of oil and solvent were used. The absorption periods required for absorption of these substances were different for that of crude oil and particularly in the case of foam filter oil, which is highly viscous, the absorption period was found to be significant longer than for the other oils, spanning a few hours. In each case, the volume of recovered oil phase, when separated from the water contained therein, was found to comprise between 90 and 95% of the original combined volume of oil and solvent.

The Applicant believes that the invention, as described, provides a viable and cost-effective method for recovering oil from an oil spill, particularly where the oil has been spilt on or in water, such as at sea, e.g. due to the rupture of the hull of an oil tanker.

The Applicant further believes that the invention advantageously provides a viable use for waste polystyrene, which would normally be disposed of in a landfill site if it is not recycled. Polystyrene is a non- biodegradable substance disposal thereof in a landfill site is therefore undesirable and, in some cases, unlawful. Recycling processes are also expensive and cumbersome and requires chemical breakdown of the waste polystyrene before. The handling of waste polystyrene is also cumbersome, particularly in view of the voluminous nature thereof. Through the present invention, waste polystyrene is reduced to the solid polystyrene residue having a greatly reduced volume than the original volume of waste polystyrene used and being solid and easy to handle. The polystyrene residue has also, at least to some extent, been chemically broken down and is therefore readily usable as a raw material in a polystyrene recycling operation.

Claims

CLAIMS:

1 . A method of treating oil, which method includes

distributing polystyrene particles over oil to be treated; and

allowing the polystyrene particles to absorb oil, thereby obtaining oil- drenched polystyrene particles and hence treating the oil.

2. The method according to Claim 1 , wherein the polystyrene particles are particles of expanded polystyrene.

3. The method according to Claim 2, wherein the expanded polystyrene is waste expanded polystyrene.

4. The method according to Claim 3, which includes, in a pretreatment step, rendering artefacts of waste expanded polystyrene into particulate form by shredding the artefacts.

5. The method according to any of claims 1 to 4 inclusive, wherein the polystyrene particles are left in contact with the oil for a time period of from about 1 minute to about 12 hours, in order to become drenched in oil.

6. The method according to any of claims 1 to 5 inclusive, which further includes

recovering at least some of the oil-drenched polystyrene particles; treating the recovered oil-drenched polystyrene particles with a solvent for polystyrene, thereby dissolving the polystyrene and obtaining a mixture of a polystyrene phase and an oil phase; and

separating the polystyrene phase from the oil phase.

7. The method according to Claim 6, wherein the solvent is an organic solvent, being selected from organic solvents including in their molecular structure a similar molecular structure to that of the styrene monomer, gasoline, xylene, lemon oil, turpentine and camphor oil.

8. The method according to Claim 6 or Claim 7, wherein the separation of the polystyrene phase from the oil phase is carried out by any one or more of gravity separation, decantation, screening, filtration, and drawing the oil phase from the polystyrene phase.

9. The method according to any of claims 6 to 8 inclusive, which includes recovering polystyrene from the polystyrene phase.

10. The method according to Claim 9, wherein the recovering of polystyrene from the polystyrene phase includes drawing solvent from the polystyrene phase.

1 1 . The method according to any of claims 6 to 10 inclusive, which includes recovering oil from the oil phase.

12. The method according to Claim 1 1 , wherein the recovering of oil from the oil phase is carried out by any one or more of gravity separation, decantation and distillation.

13. An oil treatment kit, which includes

at least one polystyrene pack containing a quantity of particulate polystyrene capable of absorbing oil and hence of becoming oil-drenched; oil-drenched polystyrene recovery or collection means for recovering or collecting oil-drenched polystyrene particles;