Patent Publication Number: US-2022228339-A1

Title: Sorbent-based oil skimmer and methods of use

Description:
RELATED APPLICATIONS 
     The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/140,179 filed Jan. 21, 2021 entitled “Sorbent-Based Oil Skimmer and Methods of Use” and U.S. Provisional Patent Application Ser. No. 63/234,066 filed Aug. 17, 2021 entitled “Sorbent-Based Oil Skimmer and Methods of Use,” the disclosures of which are hereby incorporated by reference as if fully set forth herein. 
    
    
     BACKGROUND 
     Due to the massive amount of exploration, storage, and transportation of oils and organic solvents in modern society, accidental oil and organic solvent spills in water remain a global challenge. While the yearly number of oil spills and the total amount of oil spillage have been reduced significantly in recent years, the technologies used to clean up these oil spills have remained the same with only incremental improvements over time. Oil spill cleanup crews use booms to corral or contain the spilled oil, skimmers to separate and extract the congregated oil slicks, sorbent materials to soak up any remaining thin oil sheen, and other less than ideal methods including in-situ burning, chemical dispersants, and manual labor. To extract oil from water, most oil skimmers require energy to move an often oleophilic media (belts, discs, drums, tube, rope, mop, etc.) through the oil layer and scrape off the attached oil above the surface into a container. These oil skimmers are typically heavy and difficult to deploy and scale-up, require an electric or pneumatic motor to separate the oil and water and are highly-inefficient for extracting thin oil layers from water. 
     In a real-world oil spill recovery, mechanical oil recovery is often needed when there are very thin layers of oil to alleviate the manual labor and solid waste required to use sorbent materials to clean up the remaining thin oil slicks. Notably, sorbent materials used in the field today are single-use materials that usually contribute to larger amounts of solid waste resulting from oil spills than liquid waste, with ratios as high as 400:1. Recently, sorbent materials researchers have been primarily focused on modifying the surface of substrates to improve the hydrophobic and oleophilic properties of the materials. Desired characteristics of state-of-the-art oil/water separation materials include high oil-sorption capacities, super-hydrophobicity, durability, reusability, low-cost, and facile fabrication. Additional features have been imparted on advanced sorbent materials including resistance to ultrahigh temperatures for in-situ oil burn-off from the sorbent, magnetism to facilitate sorbent recovery via magnets, stimuli-response such as resistive heating (Joule heating) and photothermal effects for crude oil absorption, and more. The most noteworthy and applicable of these advanced sorbent features includes Joule heating of a semi-conductive sorbent-material to lower the viscosity of crude oil and facilitate rapid absorption of the high viscosity pollutant. While this capability and others are impressive characteristics of novel sorbent materials, they have only been proven to be useful in the small counter-top-sized oil spill simulations. Very little work has been done to scale-up these sorbent materials by utilizing low-cost materials and facile fabrication methods. 
     The most promising sorbent-based technologies to reduce the amount of manual labor and solid waste required for oil spill cleanup include oil-collecting or oil-extraction devices. Instead of improving the sorption capacities of sorbent materials, the goal of these devices is to utilize sorbent materials to collect or extract the oil utilizing the material properties of the sorbent. The simplest of these devices includes placing a tube into the center of a sorbent member, such as an oleophilic and hydrophobic sponge, and pumping to extract the oil continuously as the sorbent continues to absorb and replace extracted oil. However, the rate of oil extraction is extremely slow using this technique and often results in some amount of water extracted through the sponge as well. Another method known as vessel-type oil collectors includes utilizing a sorbent material and gravity (or some external force) to fill a container with oil to later be removed. However, this method has not been demonstrated to be capable of extracting oil from the vessel during oil absorption in a sufficiently efficient, continuous, and automated process. It is to improving this system that the systems and methods of the present disclosure are directed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more implementations described herein and, together with the description, explain these implementations. The drawings are not intended to be drawn to scale, and certain features and certain views of the figures may be shown exaggerated, to scale or in schematic in the interest of clarity and conciseness. 
         FIG. 1  presents a side view of the sorbent-based oil skimmer base design. 
         FIGS. 2 a -2 d    present various embodiments of the top sheet of the sorbent-based oil skimmer. 
         FIGS. 3 a -3 d    present various embodiments of the top sheet of the sorbent-based oil skimmer. 
         FIGS. 4 a -4 d    present various embodiments of the shell of the sorbent-based oil skimmer. 
         FIGS. 5 a -5 d    present various embodiments of the shell of the sorbent-based oil skimmer. 
         FIGS. 6 a -6 d    present various embodiments of the shell of the sorbent-based oil skimmer. 
         FIGS. 7 a -7 d    present various embodiments of the sorbent-based oil skimmer. 
         FIGS. 8 a -8 d    present various embodiments of the encasing of the sorbent-based oil skimmer. 
         FIGS. 9 a -9 d    present various embodiments of the encasing of the sorbent-based oil skimmer. 
         FIGS. 10 a -10 d    present various embodiments of the sorbent-based oil skimmer. 
         FIGS. 11 a -11 d    present various embodiments of the sorbent-based oil skimmer. 
         FIGS. 12 a -12 d    present various applications for the sorbent-based oil skimmer. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is directed to a floating vessel-type oil collector capable of continuous oil extraction from water via peristaltic pumping. The nanocomposite sorbent material used in the device is highly durable, reusable, and exhibits semi-conductivity for efficient Joule heating of the nanocomposite sponge to decrease viscosity of the spilled oil to more rapidly absorb and extract crude oil from the water surface. The separation of oil from water is encouraged by the hydrophobic and oleophilic properties of the funnel-shaped nanocomposite sponge and gravity. Thus, a key benefit of the sorbent-based oil skimmer  100  is the passive oil-water separation mechanism that is driven by gravity. In some embodiments, no applied energy to the system is needed to separate oil from water before evacuating the captured oil from the skimmer  100  with a suitable pump. The sorbent-based oil skimmer  100  is easily scalable to massive sizes via additive manufacturing or other manufacturing means. 
     Before describing various embodiments of the present disclosure in more detail by way of exemplary description, examples, and results, it is to be understood that the embodiments of the present disclosure are not limited in application to the details of methods and apparatus as set forth in the following description. The embodiments of the present disclosure are capable of other embodiments or of being practiced or carried out in various ways. As such, the language used herein is intended to be given the broadest possible scope and meaning; and the embodiments are meant to be exemplary, not exhaustive. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting unless otherwise indicated as so. Moreover, in the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the disclosure. However, it will be apparent to a person having ordinary skill in the art that certain embodiments of the present disclosure can be practiced without these specific details. In other instances, features which are well known to persons of ordinary skill in the art have not been described in detail to avoid unnecessary complication of the description. 
     Unless otherwise defined herein, scientific and technical terms used in connection with the embodiments of the present disclosure shall have the meanings that are commonly understood by those having ordinary skill in the art. Further, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular. 
     All patents, published patent applications, and non-patent publications mentioned in the specification are indicative of the level of skill of those skilled in the art to which embodiments of the present disclosure pertain. All patents, published patent applications, and non-patent publications referenced in any portion of this application are herein expressly incorporated by reference in their entirety to the same extent as if each individual patent or publication was specifically and individually indicated to be incorporated by reference. 
     While the methods and apparatus of the embodiments of the present disclosure have been described in terms of particular embodiments, it will be apparent to those of skill in the art that variations may be applied thereto and in the steps or in the sequence of steps of the methods described herein without departing from the spirit and scope of the inventive concepts. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit and scope of the systems as defined herein. 
     As utilized in accordance with the methods and apparatus of the embodiments of the present disclosure, the following terms, unless otherwise indicated, shall be understood to have the following meanings. 
     The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The use of the term “or” in the claims is used to mean “and/or” unless explicitly indicated to refer to alternatives only or when the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and/or.” The use of the term “at least one” will be understood to include one as well as any quantity more than one, including but not limited to, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 40, 50, 100, or any integer inclusive therein. The term “at least one” may extend up to 100 or 1000 or more, depending on the term to which it is attached; in addition, the quantities of 100/1000 are not to be considered limiting, as higher limits may also produce satisfactory results. In addition, the use of the term “at least one of X, Y and Z” will be understood to include X alone, Y alone, and Z alone, as well as any combination of X, Y and Z. 
     As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. 
     The term “or combinations thereof” as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof” is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AAB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context. 
     Throughout this application, the terms “about” or “approximately” are used to indicate that a value includes the inherent variation of error. Further, in this detailed description, each numerical value (e.g., time or frequency) should be read once as modified by the term “about” (unless already expressly so modified), and then read again as not so modified unless otherwise indicated in context. The use of the term “about” or “approximately” may mean a range including ±0.5%, or ±1%, ±2%, or ±3%, or ±4%, or ±5%, ±6%, or ±7%, or ±8%, or ±9%, or ±10%, or ±11%, or ±12%, or ±13%, or ±14%, or ±15%, or ±25% of the subsequent number unless otherwise stated. 
     As used herein, the term “substantially” means that the subsequently described event or circumstance completely occurs or that the subsequently described event or circumstance occurs to a great extent or degree. For example, the term “substantially” means that the subsequently described event or circumstance occurs at least 80% of the time, or at least 90% of the time, or at least 95% of the time, or at least 98% of the time. 
     Features of any of the embodiments described herein may be combined with any of the other embodiments to create a new embodiment. As used herein any reference to “one embodiment” or “an embodiment” means that a particular element, feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. 
     As used herein, all numerical values or ranges include fractions of the values and integers within such ranges and fractions of the integers within such ranges unless the context clearly indicates otherwise. Thus, to illustrate, reference to a numerical range, such as 1-10 includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, as well as 1.1, 1.2, 1.3, 1.4, 1.5, etc., and so forth. Reference to a range of 1-50 therefore includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc., up to and including 50. Similarly, fractional amounts between any two consecutive integers are intended to be included herein, such as, but not limited to, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, .65, 0.7, 0.75, 0.8, 0.85, 0.9, and 0.95. For example, the range 3 to 4 includes, but is not limited to, 3.05, 3.1, 3.15, 3.2, 3.25, 3.3, 3.35, 3.4, 3.45, 3.5, 3.55, 3.6, 3.65, 3.7, 3.75, 3.8, 3.85, 3.9, and 3.95. Thus, even if specific data points within the range, or even no data points within the range, are explicitly identified or specifically referred to, it is to be understood that any data points within the range are to be considered to have been specified, and that the inventors possessed knowledge of the entire range and the points within the range. 
     Reference to a series of ranges includes ranges which combine the values of the boundaries of different ranges within the series. For example, “a range from 1 to 10” is to be read as indicating each possible number, particularly integers, along the continuum between about 1 and about 10. Thus, even if specific data points within the range, or even no data points within the range, are explicitly identified or specifically referred to, it is to be understood that any data points within the range are to be considered to have been specified, and that the inventors possessed knowledge of the entire range and the points within the range. 
     Thus, to further illustrate reference to a series of ranges, for example, a range of 1-1,000 includes, for example, 1-10, 10-20, 20-30, 30-40, 40-50, 50-60, 60-75, 75-100, 100-150, 150-200, 200-250, 250-300, 300-400, 400-500, 500-750, 750-1,000, and includes ranges of 1-20, 10-50, 50-100, 100-500, and 500-1,000. The range 100 units to 2000 units therefore refers to and includes all values or ranges of values of the units, and fractions of the values of the units and integers within said range, including for example, but not limited to 100 units to 1000 units, 100 units to 500 units, 200 units to 1000 units, 300 units to 1500 units, 400 units to 2000 units, 500 units to 2000 units, 500 units to 1000 units, 250 units to 1750 units, 250 units to 1200 units, 750 units to 2000 units, 150 units to 1500 units, 100 units to 1250 units, and 800 units to 1200 units. Any two values within the range of about 100 units to about 2000 units therefore can be used to set the lower and upper boundaries of a range in accordance with the embodiments of the present disclosure. 
     The present disclosure will now be discussed in terms of several specific, non-limiting, examples, and embodiments. The examples described below, which include particular embodiments, will serve to illustrate the practice of the present disclosure, it being understood that the particulars shown are by way of example and for purposes of illustrative discussion of particular embodiments and are presented in the cause of providing what is believed to be a useful and readily understood description of procedures as well as of the principles and conceptual aspects of the present disclosure. 
     With reference to  FIG. 1 , the sorbent-based oil skimmer  100  generally includes a sorbent-based sponge  102  contained within a housing or “encasing”  104 . The sponge  102  includes a top sheet  106  and a shell (or funnel)  108  that can be contained within the encasing  104 . The sponge  102  can include a drain  110 , a vent  112  and a central chamber  114 , which cooperate to pass oil absorbed by the top sheet  106  from an oil layer  200  into the encasing  104  through the shell  108  and drain  110 . It will be appreciated that the oil layer  200  may include a crude oil or other petroleum-based liquids suspended on top of a water-based liquid, such as seawater, brine, or freshwater. The oil layer  200  may include water and other components that present as immiscible or miscible mixtures, including emulsions. In this way, the oil skimmer  100  can be configured to capture an oil-containing first liquid (oil layer  200 ) from the top of a second liquid (a water-based layer). 
     The skimmer  100  can be configured with an appropriate amount of buoyancy that the top sheet  106  is partially immersed in the oil layer  200 , but without submerging the drain  112  below the surface of the oil-water mixture. Oil is pulled out of the sponge  102  into the interior of the encasing  104 , where it can be stored for bulk removal when the skimmer  100  is full, or evacuated on a continuous or periodic basis by a pump  202 . In some embodiments, the pump  202  is a peristaltic pump that moves the collected oil from the encasing to an external storage vessel  204  located on a boat, platform or other suitable onshore or offshore facility. 
     Before addressing the various configurations and applications for the sorbent-based oil skimmer  100 , a brief description of the sponge  102  is provided. In exemplary embodiments, the sponge  102  is manufactured from a sorbent material that is oleophilic, hydrophobic or oleophilic and hydrophobic. In some embodiments, the sponge  102  is manufactured from a silicone polymer impregnated with carbonaceous material. For example, the sponge  102  can be constructed from polydimethylsiloxane (PDMS) impregnated with carbon black (CB) to create a nanocomposite polymer (CB/PDMS). In one example, a two-part PDMS kit is mixed with 5 wt %, 10 wt %, 15 wt %, 20 wt %, and 25 wt % CB via centrifugal mixing with a Thinky mixer (AR-100) to create the nanocomposite prepolymer (CB/PDMS). The CB/PDMS can be mixed with salt at a 4:1, 5.7:1, and 9:1 salt:CB/PDMS ratios (80 wt %, 85 wt %, and 90 wt %) to create an uncured mixture (PCS) that is easily moldable into various shapes for the sponge  102 . The PCS can be molded into cubes (1×1×1 cm=1 cm 3  and 5×5×5 cm=125 cm 3 ) with 3D printed templates and cured in an oven. The salt porogen can be removed via sonication and mechanically squeezing in running warm water. 
     In other embodiments, the sponge  102  is manufactured from materials that require an open-cell network of porosity to allow the oil to flow through the microstructure of the sorbent-based sponge  102  and into the encasing  104 . Suitable porous materials include sponges, fabrics, woven fibers, natural microstructures, foams, meshes, and membranes. The materials that may be used independently or in conjunction with other material(s) to fabricate the sorbent material used in the sponge  102  include, but are not limited to polymers, elastomers, silicone rubber, polydimethylsiloxane (PDMS), platinum-catalyzed silicone polymers, melamine, polylactic acid (PLA), polyurethane, polyethylene terephthalate (PET), polypropylene, functional polymers, polyethylene, and aerogels, whether silica-based or aeroclays. 
     The sponge  102  can also be manufactured with particles or polymer fillers, including the carbonaceous nanoparticles, carbon black, carbon nanotubes, carbon nanowires, graphene, carbon-based sponges, magnetic iron(III) oxide (Fe 2 O 3 ), and nanowire meshes. The sponge  102  can also be manufactured with composites and nanocomposites, including carbon-based nanocomposites, Fe 2 O 3 -based nanocomposites, and carbon fiber sponges. 
     In some embodiments, the sponge  102  is manufactured from naturally occurring or naturally-derived components, including peat moss, straw, hay, sawdust, ground corncobs, feathers, cellulose-based materials, kapok/milkweed seed, hair, clay, perlite, vermiculite, glass wool, sand, volcanic ash, cotton, rice husks, rice hulls, filter paper, wood, tree bark, bamboo, fruits, vegetables, and other readily available carbon-based products. In yet other embodiments, the sponge  102  is manufactured with man-made materials including cat litter, bio-based materials, and absorbent pads. It will be appreciated that the sponge  102  can be manufactured from any number of combinations of the materials set forth herein. 
     Turning to  FIGS. 2-7 , shown therein are various configurations of the sponge  102 . The top sheet  106  may be any common geometric shape including circular ( FIG. 2A ), rectangular ( FIG. 2B ), triangular ( FIG. 2C ), hexagonal/octagonal ( FIG. 2D ), ‘X’-shaped or cross-shaped ( FIG. 3A ), crescent-shaped ( FIG. 3B ), flower or star shape ( FIG. 3C ), any unique shape with the aim to maximize sheet surface area in contact with oil for faster extraction rates (e.g.,  FIG. 3D ), and uncommon shapes such as asymmetrical, freeform, or abstract shapes. The sorbent shell  108  can include the central chamber  114  and may be an extended cone ( FIG. 4A ), cone ( FIG. 4B ), extended semi-spherical ( FIG. 4C ), semi-spherical ( FIG. 4D ), cylindrical ( FIG. 5A ), open-ended cylindrical with the vent  112  ( FIG. 5B ), and open-ended cylindrical without the vent  112  ( FIG. 5C ). 
     The sponge  102  may also include stalactite-like extensions  116  on the underside of the top sheet  106 , which can be configured to drip oil down (due to gravity). The skimmer  100  may include one extension  116  without the vent  112  ( FIG. 5D ), several extensions  116  without vent holes  112  ( FIG. 6A ), a single extension  116  that includes the vent  112  ( FIG. 6B ), and several extensions  116  with multiple vents  112  ( FIG. 6C ). The sorbent-based sponge  102  (both top sheet  106  and shell  108 ) may be 3D-printed into any shape necessary to meet the geometric requirements of the particular embodiment of the skimmer  100  or as required for specific applications. 
     In some applications, it may be desirable to use the top sheet  106  alone without the shell  108 , but with an oleophilic layer  118  on the interior surface of the encasing  104 , such that the top sheet  106  is configured to drip oil along the inside of the encasing  104 . In these embodiments, the top sheet  106  may be approximately the same diameter as the encasing  104  ( FIG. 6D ) or larger than the diameter of the encasing  104  ( FIG. 7A ). 
     In other variations, a single oleophilic object  120  (e.g., a rod, pipe, or other object) can be extended through the top sheet  106  to drip oil down into the encasing  104  due to gravity (FIG.  7 B). In other embodiments, a plurality of oleophilic objects  120  can be extended through the top sheet  106  ( FIG. 7C ). In yet other variations, the top sheet  106  is omitted, leaving only the hollow shell  108  within the encasing  104  ( FIG. 7D ). 
     The encasing  104  of the sorbent-based oil skimmer  100  may be manufactured from a polymer or other rigid material, including through additive manufacturing techniques. The encasing  104  includes the hard shell around the sorbent-based sponge  102 , including the main body (encases the hollow shell  108  of the sponge  102 ), the lid and vent, and potentially necessary lid extensions to secure the sponge  102  firmly to the encasing  104 . The encasing  104  may be made from any hard material that does not dissolve in water, oil, and preferably organic solvents. The encasing may be made up entirely by one, or any potential combination of the following list of materials including but are not limited to metals such as aluminum, steel, copper, iron, nickel, titanium, magnesium, zinc, silicon, metal alloys, polymers such as thermoplastics, polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), polyethylene (low-density (LDPE) and high-density (HDPE)), acrylic, nylon, polycarbonate, polypropylene, polystyrene, elastomers, thermosets including epoxies, phenolics, bismaleimide, fluoropolymers, melamine, and elastomers, and composites including fiber-reinforced composites, matrix materials, continuous or chopped fiber products, carbon fiber, glass fiber, Kevlar fiber, hybrid polymers, other fillers including microparticles, nanoparticles, and rheology modifiers. In some embodiments, the encasing  104  is manufactured from naturally-occurring substances including wood, ceramic, concrete, glass and clay. 
     The encasing  104  or vessel that covers the sorbent shell  108  can be pressed into firm contact with the top sheet  106  to prevent water from leaking into the vessel  104 , and can be designed and fabricated into many different shapes and sizes. The primary function of the encasing  104  is to provide an isolated environment where oil will be separated from the water and subsequently extracted via pumping. The secondary function is to bring the oil to one extraction point; thus, the encasing  104  will ideally be shaped to facilitate gravity pulling the oil toward the extraction point. In other embodiments, multiple extraction points are used, with multiple pumps or manifolds to extract oil from the encasing  104 . 
     In some embodiments, the encasing  104  is constructed according to the following forms: cylindrical ( FIG. 8A ), conical ( FIG. 8B ), extended cone ( FIG. 8C ), semi-spherical or bowl-shaped ( FIG. 8D ), extended bowl ( FIG. 9A ), spherical ( FIG. 9B ), cube or rectangular prism ( FIG. 9C ), and pyramid ( FIG. 9D ). 
     Having described the general form and variations of the sponge  102  and encasing  104 , attention is drawn to the various designs and applications for the skimmer  100  depicted in  FIGS. 10-12 . In some embodiments, the sorbent-based oil skimmer  100  includes a counterweight  122  attached to the encasing  104  to help maintain a vertical floating orientation ( FIG. 10A ). The counterweight  122  may be constructed using weights (as shown in  FIG. 10A ), or by integrating weights or a weighted portion into the encasing  104 . The counterweights  122  are selected so that the skimmer  100  maintains a proper buoyancy and level within the oil layer  200 . 
     In another embodiment, the sorbent-based oil skimmer  100  can include a ballast tank  124  surrounding the encasing  104 . The ballast tank  124  is optionally provided with a buoyancy adjustment system  126  to maintain a desired buoyancy in the water to ensure proper placement of the sponge  102  within the oil layer  200 . The buoyancy adjustment system  126  can include a displacement vent  128  and low-pressure blower  130  to feed atmospheric air into the ballast tank  124  to control the buoyancy of the skimmer  100  ( FIG. 10B ). As the skimmer  100  collects more oil within the encasing  104 , the blower  130  can be used to displace water from the ballast tank  124  to increase the buoyancy to counteract the increased weight of oil within the encasing  104 . In other embodiments, the skimmer  100  includes a combination of counterweights  122  and the ballast tank  124  ( FIG. 10C ). 
     In yet another embodiment, the buoyancy adjustment system  126  is provided with an onboard control system  132  that is configured to cooperate with the buoyancy adjustment system  126  to adjust the orientation and buoyancy of the skimmer  100  in response to measurements made by one or more sensors  134 , which can be configured to determine the level and position of the skimmer  100  in the water. The onboard control system  132  and buoyancy adjustment system  126  cooperate to detect the position and orientation of the skimmer  100  and adjust the buoyancy of the skimmer  100  to automatically maintain the vertical floating orientation of the skimmer  100  for a self-balancing sorbent-based oil skimmer  100  ( FIG. 10D ). 
     In another embodiment, the sorbent-based oil skimmer  100  mimics the design of conventional weir-type oil skimmers, but with the sorbent-based sponge  102  used to facilitate the efficient and effective separation of oil from water ( FIG. 11A ). In this embodiment, the skimmer  100  includes one or more external ballast tanks  124  that cooperate to maintain the orientation and level of the sponge  102  within the oil layer  200 . In yet another embodiment, the skimmer  100  includes a propulsion module  136  that is capable of moving and rotating the skimmer  100  in response to autonomous or remote control. The propulsion module  136  permits the skimmer  100  to operate as a mobile, self-propelled, and self-balancing sorbent-based oil skimmer  100  that utilizes directionally controlled propulsion to navigate through the aquatic environment and soak up and extract oil slicks and oil sheens ( FIG. 11B ). 
     In some embodiments, the skimmer  100  incorporates a collection chamber  138  to hold larger amounts of separated oil ( FIG. 11C ). The skimmer  100  can also be constructed such that a boat  206  pulls or pushes the skimmer  100  through oil slicks and oil sheens so that the sorbent-based oil skimmer  100  may absorb and extract spilled oil from the surface oil layer  200  onto the boat  206  to hold a large amount of extracted oil and navigate through the environment ( FIG. 11D ). 
     Turning to  FIGS. 12A-D , shown therein are applications in which the sorbent-based oil skimmer  100  is deployed in array and boom configurations. The sorbent-based oil skimmer  100  may be attached to an existing oil boom  208  or placed in the corralled oil to efficiently extract the corralled oil from water ( FIG. 12A ). In other situations, it may be desirable to deploy multiple sorbent-based oil skimmers  100  in an interconnected array  140  that can be connected to one or more common peristaltic pumps  202  for efficient large-scale oil extraction from water. The array  140  of skimmers  100  could be used in conjunction with the oil boom  208  to help corral and contain the oil ( FIG. 12B ). 
     In larger applications, the sorbent-based oil skimmer  100  may be scaled-up to sizes as wide as the boat  206  in the shape of the oil boom  208  to simultaneously corral, absorb, and extract the thin oil layer  200  ( FIG. 12C ). Similarly, the array  140  of skimmers  100  could be used to function similarly to the oil boom  208  and dragged by the boat  206  ( FIG. 12D ). 
     Thus, in some embodiments, the sorbent-based oil skimmer  100  is configured to collect oil from an oil layer with a sponge and then passively deposit the oil in an encasing, where the oil can be continuously or periodically removed by pumping or other means. The sponge has a top sheet in contact with the oil layer and a shell connected to the top sheet, where the shell extends into the encasing. Oil collected by the top sheet is conveyed through the shell, where it is deposited into the encasing under the force of gravity. In some applications, the sponge is manufactured from a silicone-based polymer that has been impregnated with carbonaceous material. The skimmer may optionally include counterweights, ballast tanks, buoyancy adjustment systems and propulsion modules. The embodiments of the present disclosure are well adapted to carry out the objects and attain the ends and advantages mentioned above, as well as those inherent therein. While the skimmer  100  has been described and illustrated herein by reference to particular non-limiting embodiments in relation to the drawings attached thereto, various changes and further modifications, apart from those shown or suggested herein, may be made therein by those of ordinary skill in the art, without departing from the spirit of the inventive concepts.