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  Combined chemical oxidation/assisted bioremediation of contaminatsUSPTO Application #: 20070225192Title: Combined chemical oxidation/assisted bioremediation of contaminats Abstract: Particles containing a metal peroxide in which the metal is chosen from the groups IIa and IIb of the periodic table and in which at least 50% by weight of the particles have a diameter higher than 20 μm. Process for the preparation of such particles comprising: (a) mixing at least one metal oxide or hydroxide, the metal being chosen from the groups IIa and IIb of the periodic table, in the form of an aqueous solution, a suspension or a solid, with an aqueous hydrogen peroxide solution, (b) allowing the metal oxide or hydroxide to react with hydrogen peroxide to form a suspension of the corresponding peroxide, (c) adding to this suspension at least one additive, and (d) drying the resulting peroxide suspension. (end of abstract)
Agent: Oblon, Spivak, Mcclelland, Maier & Neustadt, P.C. - Alexandria, VA, US Inventors: Noel Boulos, Alastair McNeillie, Jason Muessig USPTO Applicaton #: 20070225192 - Class: 510367000 (USPTO) Related Patent Categories: Cleaning Compositions For Solid Surfaces, Auxiliary Compositions Therefor, Or Processes Of Preparing The Compositions, Cleaning Compositions Or Processes Of Preparing (e.g., Sodium Bisulfate Component, Etc.), With Oxygen Or Halogen Containing Chemical Bleach Or Oxidant Component The Patent Description & Claims data below is from USPTO Patent Application 20070225192. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The invention relates in general to compositions and methods for cleaning contaminated materials such as soil and water. [0002] Additional advantages and other features of the present invention will be set forth in part in the description that follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from the practice of the present invention. The advantages of the present invention may be realized and obtained as particularly pointed out in the appended claims. As will be realized, the present invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the present invention. The description is to be regarded as illustrative in nature, and not as restrictive. SUMMARY OF THE INVENTION [0003] The invention objectives are accomplished, in general, by the combined use of metal (e.g., Fe) chelates, especially transition metal chelates, and a source of peroxide, especially Mg, Ca, and/or Zn peroxide or sodium percarbonate (PCS) or hydrogen peroxide. An underlying concept is the reaction of hydrogen peroxide which is used as such or which is generated from, e.g., PCS or CaO.sub.2, with a metal chelate. One advantage of a metal chelate is that it is kept in solution under alkaline conditions allowing the H.sub.2O.sub.2 to react with the metal generating a modified Fenton process thereby producing hydroxyl free radicals which are very strong oxidants that degrade contaminants. BACKGROUND OF THE INVENTION [0004] The strongest oxidizing agent suitable for soil and groundwater remediation is the hydroxyl free radical. The typical way to generate OH radicals is through the Fenton system using H.sub.2O.sub.2 and ferrous ions at pH 3-4. Hydroxyl free radicals can also be generated by the use of a combination of ozone and H.sub.2O.sub.2 or UV and H.sub.2O.sub.2. [0005] While these technologies are effective, they suffer from some drawbacks: [0006] Fenton technology is only suitable at a low pH, hence the need to acidify which requires the use of stainless steel piping and is expensive. [0007] Ozone/H.sub.2O.sub.2 technology requires on site generation of ozone and can be expensive. [0008] UV/H.sub.2O.sub.2 technology is not suitable for in-situ remediation. [0009] Hydrogen peroxide solutions are available in several concentrations. The typical concentration used in soil remediation is the 35% grade. This is further diluted to lower concentrations for example 5-12%, before introduction in the contaminated material to be treated. [0010] Sodium percarbonate (PCS) is a peroxyhydrate composed of sodium carbonate and H.sub.2O.sub.2. Its solubility in water is .about.12%. Upon dissolution in water, it releases its components and the resulting solution contains both soda ash and H.sub.2O.sub.2. [0011] Calcium and magnesium peroxide are solid peroxygens that are insoluble in water. When they are mixed with water, they slowly release oxygen at their natural pH (>pH 10). They are used in soil and groundwater remediation to provide oxygen to aerobic bacteria thereby enhancing their capability of degrading various contaminants. [0012] As the pH is lowered, CaO.sub.2 and MgO.sub.2 generate increasingly larger quantities of H.sub.2O.sub.2. For example, at a pH 8, approximately 60% of the active content of CaO.sub.2 can be generated in the form of H.sub.2O.sub.2. [0013] Whereas OH radicals can be generated at any pH due to H.sub.2O.sub.2 decomposition, the optimal use of this process for chemical oxidation occurs at a pH of 3-4 whereby the Fe ions remain soluble, and cycle between a ferrous and a ferric state. [0014] U.S. Pat. No. 6,268,205 discusses the use of inorganic peroxides in conjunction with buffers and catalyst such as ferrous or ferric sulfate. The pH of such system is adjusted to 7-9. Under these conditions, the metal peroxides will release their activity partially as H.sub.2O.sub.2 and partially as oxygen. This allows for the initial chemical oxidation to take place starting the break up of the contaminants. The oxygen is then released more slowly, which will assist bioremediation over a period of several months. Although OH radicals can be generated from H.sub.2O.sub.2 at this pH, Fe will precipitate as ferric hydroxide. The net result is a reduced generation of OH radicals and clogging of the medium with the precipitated ferric hydroxide. [0015] U.S. Pat. Nos. 5,741,427 and 6,319,328 are related to the use of Fe salts or chelates that are dissolved in water, the solution is maintained at pH 5-8, and then injected to a soil that has already been injected with an oxidizing agent. This pH is lower than the pH claimed in the above patent and would lead to a very fast release of H.sub.2O.sub.2 from the solid peroxides. The order of addition claimed results in a reduced activation of H.sub.2O.sub.2 as the peroxide would be partially decomposed prior to the injection of the metal chelate. [0016] U.S. Pat. No. 6,843,618 is related to a method of decontaminating soil and ground water containing organic contaminants and divalent metal compounds. It comprises the steps of first treating such soils and ground water with an effective amount of an aqueous solution containing a peroxide and a water soluble chelating agent for a time sufficient to have the water soluble chelating agent chelate at least one of the divalent metals of the divalent metal compounds present in the soil and ground water. Next, the chelated metals are brought into contact with the peroxide to catalytically convert the peroxide to an oxidizing agent. Finally, the last step is contacting the organic contaminants in the soil and ground water with the oxidizing agent to oxidize the organic contaminants to environmentally safe, non-toxic compounds. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION [0017] The invention is related to a kit for the combined chemical oxidation/assisted bioremediation of contaminated materials, comprising: i. at least one metal chelate, and ii. at least one peroxide compound. [0018] The term "assisted bioremediation" is intended to denote enhancing the growth of aerobic microorganisms by supplying them with oxygen, thereby allowing them to multiply faster leading to an increased rate of degradation of the contaminants. [0019] The "at least one metal chelate" comprises preferably a transition metal chelate such as Fe chelate. [0020] The "at least one peroxide compound" comprises is most cases an inorganic peroxide. It comprises preferably at least one of Ca, Mg and Zn peroxide or sodium percarbonate or hydrogen peroxide. In some cases it is recommended that the kit comprises at least two different peroxide compounds. One of the two peroxides is most often chosen from sodium percarbonate and hydrogen peroxide. The other peroxide is in many cases chosen from Ca, Mg and Zn peroxides. Preferred combinations of two different inorganic peroxides include one of H.sub.2O.sub.2 and sodium percarbonate, and one of Ca, Mg and Zn peroxides (especially CaO.sub.2.), most preferably sodium percarbonate and one of Ca, Mg and Zn peroxides (especially CaO.sub.2). The combination of one of H.sub.2O.sub.2 and sodium percarbonate and CaO.sub.2 gives good results. [0021] The invention is also related to a method for the combined chemical oxidation/assisted bioremediation of contaminated materials, comprising contacting a contaminated material with at least one metal chelate and at least one peroxide compound. 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