TECHNICAL FIELD

[0001] The present application relates to the field of oil adsorption, in general, and removing oil spills floating on a water surface of from soil, thereby cleaning an aqueous environment and soil.

BACKGROUND

[0002] Grinding used tires using rubber mills is a rather demanding and complex process. First, tires are pre-shredded or cmshed with rotor blades. Then, these pieces are processed with fine-grinding machines and yield rubber powder of desired sizes. Supplementary tire elements, such as metal and textile, are eventually separated from the output. To produce rubber powder, two methods of grinding are generally used: cold and ambient grinding.

[0003] Cold grinding utilises liquid nitrogen to effectively reduce the size of rubber using, for example jet mills. A disadvantage of the cold grinding is the rather high production cost, which is due to the fair amount liquid nitrogen needed. In contrast, ambient grinding takes place at ambient temperatures. Cracker mills lined up in a row grind up coarser granulates by means of slow-spinning mills to the desired sizes, leading into high quality rubber powder with large surface area.

[0004] The fine milling lines normally operate at ambient temperatures. A special distinctive feature of this equipment is that it is specifically designed to crush and grind up to about 5 cm wide truck tire tread peelings of a very high quality, which arise in the process of the truck tire re-treading. The resulted micronised rubber powder has a particle size of up to about 400 pm and a very large surface area. In the end of the process, this rubber powder becomes completely free from impurities, such as steel or textile, and corresponds to the highest quality standards.

[0005] It has been surprisingly found by the present inventors that this rubber powder is extremely efficient in adsorbing oil from soil or removing oil spills from water or any aqueous environment. SUMMARY

[0006] The present application describes embodiments of a method for purification of contaminated soil and aqueous environment or water having impurities in the form of suspended hydrophobic particles, organic colloidal particles or oil spills floating on the water surface or contaminating soil, comprising:

(1) Applying a micronised rubber powder to said water or contaminated aqueous environment or to said soil to adsorb the suspended hydrophobic particles, organic colloidal particles or oil spills floating on the water surface or from soil and,

(2) Upon completion of the adsorption process, removing particles of the rubber powder with the adsorbed suspended hydrophobic particles, organic colloidal particles or oils from said water or aqueous environment or from said soil, thereby purifying the soil and water or aqueous environment, characterised in that said micronised rubber powder is composed of crushed and grinded up to about 5 cm- wide truck tire tread peelings, and said rubber powder has a particle size of up to about 400 pm.

[0007] In a particular embodiment, the method of the present invention for removing oil spills from soil or oil spills floating on the water surface, wherein the method comprises applying said micronised rubber powder to said soil or water to adsorb said oil from the soil or from the water surface, and, upon completion of the adsorption process, removing the particles of the rubber powder with the adsorbed oil, thereby purifying the water or soil.

[0008] In another particular embodiment, the method of the present invention further comprises a step of washing the particles of the rubber powder with the adsorbed material after adsorption with suitable solvents to remove the adsorbed material and to recycle the micronised rubber powder and recover the adsorbed material.

[0009] In additional embodiment, the method of the present invention further comprises the step of fractionally distilling and refining the adsorbed material to produce hydrocarbon products, such as fuel gases, gasoline, naphtha, kerosene, jet fuel and diesel. [0010] Various embodiments may allow various benefits and may be used in conjunction with various applications. The details of one or more embodiments are set forth in the accompanying figures and the description below. Other features, objects and advantages of the described techniques will be apparent from the description and drawings and from the claims

DETAILED DESCRIPTION

[0011] In the following description, various aspects of the present application will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the present application. However, it will also be apparent to one skilled in the art that the present application may be practiced without the specific details presented herein. Furthermore, well-known features may be omitted or simplified in order not to obscure the present application.

[0012] The term "comprising", used in the claims, is "open ended" and means the elements recited, or their equivalent in structure or function, plus any other element or elements which are not recited. It should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a composition comprising x and z" should not be limited to compositions consisting only of components x and z. Also, the scope of the expression "a method comprising the steps x and z" should not be limited to methods consisting only of these steps.

[0013] Unless specifically stated, as used herein, the term "about" is understood as within a range of normal tolerance in the art, for example within two standard deviations of the mean. In one embodiment, the term "about" means within 10% of the reported numerical value of the number with which it is being used, preferably within 5% of the reported numerical value. For example, the term "about" can be immediately understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. In other embodiments, the term "about" can mean a higher tolerance of variation depending on for instance the experimental technique used. Said variations of a specified value are understood by the skilled person and are within the context of the present invention. As an illustration, a numerical range of "about 1 to about 5" should be interpreted to include not only the explicitly recited values of about 1 to about 5, but also include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values such as 2, 3, and 4 and sub-ranges, for example from 1-3, from 2-4, and from 3-5, as well as 1, 2, 3, 4, 5, or 6, individually. This same principle applies to ranges reciting only one numerical value as a minimum or a maximum. Unless otherwise clear from context, all numerical values provided herein are modified by the term "about". Other similar terms, such as "substantially", "generally", "up to" and the like are to be construed as modifying a term or value such that it is not an absolute. Such terms will be defined by the circumstances and the terms that they modify as those terms are understood by those of skilled in the art. This includes, at very least, the degree of expected experimental error, technical error and instrumental error for a given experiment, technique or an instrument used to measure a value.

[0014] As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

[0015] The present application provides a method for purification of contaminated soil and aqueous environment or water having impurities in the form of suspended hydrophobic particles, organic colloidal particles or oil spills (such as crude oil), floating on the water surface or contaminating soil, comprising:

(1) Applying a micronised rubber powder to said water or contaminated aqueous environment or to said soil to adsorb the suspended hydrophobic particles, organic colloidal particles or oil spills floating on the water surface or from soil and,

(2) Upon completion of the adsorption process, removing particles of the rubber powder with the adsorbed suspended hydrophobic particles, organic colloidal particles or oils from said water or aqueous environment or from said soil, thereby purifying the soil and water or aqueous environment, characterised in that said micronised rubber powder is composed of crushed and grinded up to about 5 cm- wide truck tire tread peelings, and said rubber powder has a particle size of up to about 400 pm.

[0016] The rubber powder of the present invention is a micronised rubber powder having the particle size below about 400 pm. It is commercially available and produced from crushed and grinded up to about 5 cm-wide truck the tread peelings, most often from end-of-life tire material. One of the manufacturers of the rubber powder used in the present invention is Kurz Karkassenhandel GmbH (Landau, Germany). This micronised rubber powder is fine, dry, powdered or vulcanized elastomeric rubber in which a significant proportion of particles are less than 400 pm and free of foreign particulates, such as metal, fibre, etc. Metals and fibres found in this high-quality rubber powder is normally less than 0.1%. Therefore, this micronized rubber powder is defined in the present invention as being “essentially free of any metals and fibres”. The micronised particle size distributions typically range from about 380 pm to about 10 pm. Narrower distributions can be achieved depending on the classification technology.

[0017] The micronised powder particles of the present invention are black rubber powder particles capable of floating on water surface. Due to its micron size and special grinding and cutting, their surface area is enormously large, at least 2-3 m ² /gram, which results in high absorption ratio up to 1 part of the powder to 10 parts of contaminants. This micronised rubber powder is traditionally used in sealings, liquid and spray coatings, membranes, insulation systems, thermoplastic elastomer blends, automotive appliances, rubber-modified asphalt and in many other fields of civil engineering. However, the present inventors surprisingly and unexpectedly found that this rubber powder is also extremely efficient in adsorbing hydrocarbon oils, such as crude oil, or removing oil spills from soil and water or any aqueous environment.

[0018] Rubber powder GEC40B supplied by the present applicant was used in the experiments to prove the concept of the present invention. As mentioned above, it is custom-made from crushed and grinded up to about 5 cm-wide truck tire treads provided by Kurz Karkassenhandel GmbH (Landau, Germany), contains up to 80% natural rubber and is essentially free of any metals and fibres. In addition, the grinding technology implemented for this type of powder, is designed to produce a very large surface area (at least 2-3 m ² /gram) due to the special morphology and porosity of the powder particles. [0019] The advantages of the micronised rubber powder used in the present invention are:

1) High adsorption ratio up to 1 part of the powder to 10 parts of contaminants;

2) Short-contact time that enables an instant decontamination of aqueous environment or soil;

3) Safe for use, i.e., non-hazardous, non-flammable and non-toxic;

4) Capable of encapsulating contaminants, thereby preventing the leakage of toxic residues for generation to come;

5) Ease of use (simple application) based on the off-the-shelf conveying platforms; and

6) Extended shelf-life that allows storing the micronised rubber powder for years in wide environment conditions.

[0020] In fact, the method of the present invention can be carried out at any ambient conditions and in any environment condition at temperatures about -40° C to +60° C and at pH range of about 3.5 to 9.0. A wide range of contaminants can be adsorbed using the method of the present invention. Non-limiting examples of these contaminants are toxic metals, such as Hg, Zn, Pb, Cd, Cr, Ni, Se, As and Ba, and petroleum or hydrocarbon products, such as benzene, toluene, ethylbenzene and xylene (BTEX), polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs) and any mixture of hydrocarbons that are found in crude oil (TPH).

[0021] Thus, the method of the present invention can be carried out either on water or any aqueous environment (the “water method”), or on soils (the “ground method”). In the water method, the micronised rubber powder is spread on the contaminated water source according to estimated amount of contaminants. On contact with the contaminants, the micronised rubber powder will quickly absorb them. The powder can adsorb up to about ten parts of the contaminants per one part of the powder. Since the micronised rubber powder is highly porous, light and hydrophobic, the obtained particles of the powder with the absorbed materials stay on the surface on the water. The micronised rubber particles can be further recovered by washing the particles of the rubber powder encapsulating the adsorbed material with suitable organic solvents to remove the adsorbed material. The removed adsorbed material can be further distilled and refined to produce hydrocarbon products, such as fuel gases, gasoline, naphtha, kerosene, jet fuel and diesel.

[0022] Table 1 show the tests conducted by Eurofins Laboratories (Quebec, Canada) in compliance with standard test procedures (MA.400-Hyd. 1.1 for C10-C50 hydrocarbon petroleum and MA.400-HAP 1.1 for hydrocarbon aromatic and polycyclic compounds) that clearly support the efficiency of the water method of the present invention:

Table 1: Experiments on the treatment of the contaminated water with the micronised rubber powder GEC40B with the tap water control.

[0023] As seen from the above tests, the quality of water achieved after treatment of the heavily contaminated water with the micronised rubber powder of the present invention is almost the same as pure tap water. [0024] In the above experiments, the amount of the rubber powder GEC40B required to purify water from petroleum oil spills was 158 kg for 1000 L (790 kg) of the petroleum oil at ambient temperature. Below 4° C, the amount of GEC40B required to purify cold water from petroleum oil spills was 198 kg for 1000 L of the petroleum oil.

[0025] In the ground method, polluted soil is collected, analysed and the amount of contaminants is measured accordingly. The soil is then mixed with the micronised rubber powder of the invention in the amount calculated based on the amount of contaminants. Water is added to the mixture and the mixture is centrifuged in a cement mixer. The obtained homogenously dispersed mixture is filtered through a regular sand filter, thereby leaving the rubber powder with the adsorbed contaminants on the filter.

[0026] In the experiments shown in Table 2 below, the micronized rubber powder used in the invention (GEC40B) was applied to soil heavily contaminated with TPH to remove the TPH from the soil. The amounts of GEC40B required to completely remove the TPH from the soil using the ground method described above are listed in the table:

Table 2: Experiments on complete removal of the TPH from the contaminated soil with the micronised rubber powder GEC40B.

[0027] The term “treatment of soil and water or aqueous environment” refers herein to the treatment of any soil and aqueous environment or of any material collected from soil or water collected from the aqueous environment and then treated. It means the micronised rubber powder of the present invention can be applied either directly to the soil and aqueous environment or to soil collected from ground or water collected from any source. In some embodiments, the contaminated aqueous environment is selected from an ocean, a sea, a river, a lake, a reservoir, a pond, a stream, groundwater, spring water, desalination feed water, surface water, or combinations thereof. The aqueous environment may contain hydrocarbon oil, such as crude oil, spills floating on the water surface, hydrophobic particles suspended in the bulk of the water or organic colloidal particles such as organic and bio contaminants and mixtures thereof.

[0028] The term “purification of soil or water” refers to the complete process of treating soil or treating water in aqueous environment or water collected from any source that entirely removes any hydrophobic impurities and contaminants from contaminated soil or water and also removes the portion of dissolved organic compounds that can be adsorbed on the micronised rubber particles. The result of this purification process is pure soil or water that complies with quality of soil and water standards. The term “quality of soil and water standards” refers to standards set by governments for soils in any urban, rural or agricultural areas, for drinking water and for ambient waters and differ from country to country and even in different geographical regions of the same country.

[0029] In desalination plants, performance of desalination reverse osmosis systems relies upon the production of high-quality pre-treated water. Removal or reduction of the undesirable materials in the sea water to acceptable levels before desalination protects the desalination facilities. In this context, the method of the present invention permits to carry out the purification of sea water from oil contaminants in one single step and in a short time.

[0030] In some embodiments, the method of the present invention further comprises a step of washing the rubber powder after adsorption with suitable solvents to remove the adsorbed material and to enable the rubber powder recycling and the adsorbed material recovery.

[0031] In other embodiments, the method of the present invention further comprises the step of fractionally distilling and refining the adsorbed material to produce fuel gases, gasoline, naphtha, kerosene, jet fuel and diesel.

[0032] The method of the present invention can be used for different applications, for example on roads, water, and any other industrial or environment surfaces. The method is eco-friendly. The micronised rubber powder is a 50% organic granulation absorbent, and can be recycled and reused almost indefinitely. It can withstand the harshest conditions and is approved by certified laboratory tests to be used in water and soil through a wide range of environment condition, in a temperature range between -40° C to +60° C and also at pH range of about 3.5 to 9.0. The last, but not the least, the micronised rubber powder is hassle-free for utilisation. It can be easily spread and picked back up through a wide range of tools thanks to its rugged powder form.

[0033] While certain features of the present application have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will be apparent to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the present application.