Non-oxidizer particles

Abstract

Particles containing a strong oxidizer (classified as PG I according to the standard test method of the UN Manual of Tests and Criteria, 5.sup.th revised Edition, sub-section 34.4.1) and at least one other constituent, the amount and nature of the constituent(s) other than the strong oxidizer in the particles being such that the particles are classified as non-oxidizer according to the standard test method of the UN Manual of Tests and Criteria, 5.sup.th revised Edition, sub-section 34.4.1. Process for the production of these particles.

Claims

1. A process for the preparation of particles that comprise CaO.sub.2, comprising: adding hydrogen peroxide to slaked lime to form crystals of CaO.sub.2; adding at least one other constituent to the slaked lime, the other constituent selected from the group consisting of magnesite and aluminum hydroxide; and drying the CaO.sub.2 crystals; wherein the at least one other constituent is added to the slaked lime either before the hydrogen peroxide, or after addition of hydrogen peroxide but before drying the CaO.sub.2 crystals, and wherein the at least one other constituent is added in an amount effective to render the particles as non-oxidizers.

2. The process according to claim 1, wherein the at least one other constituent is aluminum hydroxide.

3. The process according to claim 1, wherein the particles are classified as non-oxidizer according to the standard test method of the UN Manual of Tests and Criteria, 5.sup.th revised Edition, sub-section 34.4.1.

4. The process according to claim 1, wherein the particles have a content of available oxygen between 6.0% and 9.0% by weight.

5. The process according to claim 2, wherein the aluminum hydroxide does not alter the crystallization behavior of the CaO.sub.2.

6. A process for the preparation of particles that comprise CaO.sub.2, comprising: adding hydrogen peroxide to slaked lime to form crystals of CaO.sub.2; adding at least one other constituent to the slaked lime, the other constituent selected from the group consisting of magnesite and aluminum hydroxide; and drying the CaO.sub.2 crystals, wherein the at least one other constituent is added to the slaked lime either before the hydrogen peroxide, or after addition of hydrogen peroxide but before drying the CaO.sub.2 crystals, and wherein the at least one other constituent is added in an amount effective to render the particles to be classified as non-oxidizer according to the standard test method of the UN Manual of Tests and Criteria, 5.sup.th revised Edition, sub-section 34.4.1, and, wherein the particles have a content of available oxygen between 6.0% and 9.0% by weight.

7. The process according to claim 6, wherein the at least one other constituent is aluminum hydroxide.

8. The process according to claim 7, wherein the aluminum hydroxide does not alter the crystallization behavior of the CaO.sub.2.

Description

(1) In a preferred embodiment, the strong oxidizer is CaO2. TG (thermogravimetric) analysis of CaO.sub.2 (namely: of the commercial grade available under the trade name IXPER 75C from Solvay Chemicals, and which contains an average of 75% by weight of CaO.sub.2) has namely shown that this product releases oxygen (which is a combustion booster) between 200 and 350 C. under normal atmospheric conditions, in an open system. The number in mentioned IXPER tradename reflects the average content of industrially produced IXPER grades, e.g. IXPER75C or IXPER30C represents IXPER grades containing 75% or 30% by mass of calcium peroxide on the average.

(2) It has now been found that this range is the ideal range in which or below which the diluent(s) (constituent(s) other than CaO.sub.2) should release water and/or a gas. More specifically, it has been found that substances which release water and/or gas at a temperature above ambient (for instance, above 50 C. or even, above 60 C.) but below 350 C. give good results.

(3) Examples of such substances are molecular sieves, preferably of the zeolite type (hydrated alumino-silicates), aluminium or magnesium hydroxide, and basic magnesium carbonate hydrates. Among zeolites, those of the type A, X, Y, L, more precisely of the type 3A, 4A, 5A, 10X and 13X or any comparable grade like mordenite can be used. Zeolites of the type 13X as an example give good results within the tested frame of the invention. Aluminium hydroxide as well as basic magnesium carbonate monohydrate are particularly efficient. Aluminium hydroxide is particularly preferred.

(4) Other examples of such substances are hydrates of salts of a metal like Na, K, Ca, Mg and Al; and bicarbonates like sodium bicarbonate.

(5) The latter has the advantage of being cheap and of releasing both water and CO2 on decomposition below 200 C. so that it is very effective in reducing the speed of decomposition of CaO2. It is also a pH buffer and it is besides environmental friendly.

(6) For the same reasons, the use of sodium bicarbonate is also advantageous for rendering ammonium persulfate non oxidizer.

(7) There are several methods for manufacturing the particles according to the invention.

(8) In a first embodiment, a commercially available grade of CaO.sub.2 or (NH.sub.4).sub.2S.sub.2O.sub.8 (or a similar strong oxidizer) is mixed with the at least one other constituent. In particular, the above mentioned commercial grade IXPER 75C can be used and for instance be mixed with at least 40% of diluent (in weight based on the total weight of the particles), preferably with at least 50% in weight of diluent, or even with up to 60% diluent, depending on its nature.

(9) In this embodiment, sodium bicarbonate is preferred. Mixed with commercial grade IXPER 75C in an amount of 50% (in weight based on the total weight of the particles), sodium bicarbonate namely allows reaching an UN 0.1 test burning time of above 180 sec. Similar results can be obtained with ammonium persulfate.

(10) Metal salt hydrates also give good results in this embodiment and more particularly, Mg sulphate heptahydrate. Like sodium bicarbonate, mixed with commercial grade IXPER 75C in an amount of 50% (in weight based on the total weight of the particles), this substance also allows reaching an UN 0.1 test burning time of above 180 sec. Another metal salt hydrate allowing to reach the same result is tri-sodium citrate pentahydrate.

(11) Since commercial CaO.sub.2 is rarely pure but instead, comprises other constituents (which may be diluents as well, or inert substances (not emitting water at least in the required temperature range) like Ca(OH).sub.2 or other inorganic calcium compounds for instance), the CaO.sub.2 concentration of the particles with these dilution ratios is generally below 60, 50, and 40% respectively. It generally is of not more than 45% in weight (based on the total weight of the particles), preferably of not more than 40% and even more preferably, of not more than 37.5% in weight. Sometimes, it may even be below 30% in weight.

(12) These concentrations correspond respectively to theoretical AvOx values for the CaO.sub.2 particles of 9.9%, 8.8%, 8.3%, and 6.6% (calculated according to the formula 0.22*concentration in w %, where 0.22 corresponds to the molecular weight of O.sub.2 (16) divided by the molecular weight of CaO.sub.2 (72)). In fact, the maximum content of available oxygen (AvOx) of the CaO.sub.2 particles to stay below the classification as 5.1 material is depending to some extent on the nature of the additive(s), as will be shown in the examples below.

(13) In a second embodiment, the strong oxidizer is CaO2 and the diluent may be introduced in the CaO.sub.2 particles during the manufacture thereof. Generally, CaO.sub.2 is manufactured by adding hydrogen peroxide (H.sub.2O.sub.2) to slaked lime (slurry of Ca(OH).sub.2 in water) to form crystals of CaO.sub.2, which are then dried and finally packaged. Hence, according to that embodiment, the diluent(s) may be introduced in the slaked lime before reaction with the H.sub.2O.sub.2; after said reaction and just before drying; or after drying prior to packaging the particles. Preferably, it is introduced after said reaction and just before drying. This embodiment allows a simple and economic manufacturing route but requires that the diluent does not release (at least all or too much of) its water or gas during said drying.

(14) In this embodiment, magnesite and aluminium hydroxide give good results and more particularly, aluminium hydroxide. It has namely been found that aluminium hydroxide does not alter the crystallisation behaviour of the CaO2, which may happen with other constituents for instance if the slurry to be dried is stored before said drying while already containing the diluent.

(15) The present invention also concerns the use of the above described calcium peroxide or ammonium persulfate (or similar strong oxidizer) particles: in environmental applications, namely to accelerate the natural attenuation of contaminated soils; for the treatment of grease traps namely to help reduce sulfide-based odors; for oxygenating the lower parts of artificial or natural lakes as well as wastewater and effluent; in oil field applications, namely as polymer breaker; for soil amendment in agricultural, horticultural, and forestry applications; in the baking industry, namely as component of dough conditioners; in personal and oral care applications; in hair care applications, namely as ingredient of bleaching compositions; as curing agent in some sealant compositions, namely one-part polysulfide-based anhydrous sealants; in metallurgy, namely as a source of oxygen in aluminothermic processes.

(16) In particular for environmental applications, the present invention relates to methods for treating or cleaning a contaminated material such as soil and/or water comprising utilizing the above described calcium peroxide particles. The contaminated material to be treated or cleaned may be subterranean or on the surface. The above described calcium peroxide particles are generally used to accelerate the natural attenuation of the contaminated material.

(17) The material is generally contaminated with organic contaminants, such as hydrocarbons and/or halogenated compounds, in particular halogenated hydrocarbons. For example, soil contaminants that can be effectively treated by such method include petrochemicals, chlorinated organics, pesticides, energetics, perchlorates, etc.

(18) The method for cleaning or treating a contaminated material may include chemical oxidation or assisted bioremediation or both of at least one contaminant in the contaminated material in the presence of above described calcium peroxide particles to remove at least a portion of such contaminant from the material.

(19) 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 contaminant(s).

(20) The method for chemical oxidation and/or assisted bioremediation of the contaminated material generally comprises contacting the contaminated material with at least the above described calcium peroxide particles.

(21) Contacting can be accomplished in any manner, for example by introducing the solid particles or slurry (particles suspended in a liquid) in or onto the contaminated material to be treated in any manner known in the art.

(22) The CaO.sub.2 peroxide compound is preferably added as a slurry. Preferred concentrations for CaO.sub.2 peroxide particles are for instance between about 20% by weight and about 35% by weight. The slurry could be more dilute (less than 20% by weight of particles) if the solid contaminated material being treated is very porous.

(23) Alternatively, the peroxide compound can be added as solid particles. They could be used in a soil remediation application as a solid mixed with the soil.

(24) The chemical oxidation reaction would proceed as a result of the slow release of H.sub.2O.sub.2 from the above described calcium peroxide particles. The calcium peroxide also may generate oxygen for long-term assisted bioremediation.

(25) With regard to treatment, the amount of the peroxide compound applied to the contaminated material being treated is not limited, and can range for example from a ratio of from 0.0001 to 10,000 (of the above described calcium peroxide particles in pounds (lbs)/cubic feet of material being treated). A generally useful range for such ratio is from 0.01 to 1.5, for example from 0.2 to 1. A preferred range of dosing is up to 2,000 mg/L.

(26) In embodiments according to the invention, the method of use further includes the use of at least one metal chelate, especially transition metal chelate, such as a Fe chelate, either as such, or in the form of the metal salt (e.g., ferrous or ferric salt) and a separate ligand (all of which are hereinafter referred to as metal chelate). The metal chelate can either be added together with CaO.sub.2 peroxide particles or slurry, or separate injections or additions to the material being treated may be made whereby the particles or slurry of CaO.sub.2 peroxide or slurry are or is added before, during, or after the metal chelate.

(27) Alternatively, the chelating agent may be added to the material being treated (e.g., soil) in order to chelate with metals such as Fe in the ground. A buffer can be also added either in the peroxide particles or slurry, or with the metal chelate to adjust the pH, preferably to 7-9. Preferred transition metals other than Fe include Mn and Cu, and are in particular those capable of generating OH radicals from H.sub.2O.sub.2.

(28) The relative amount of the above described calcium peroxide particles and metal chelate are not limited. The molar ratio of metal chelate to CaO.sub.2 peroxide is generally from 0.01 to 10 of metal chelate/peroxide. Such ratio is preferably less than 1 and/or more than 0.05, or even more than 0.1, or even more than 0.2, or even more than 0.3, etc.

(29) Optionally, in some embodiments according to the invention, the method of use further includes adding products that are considered nutrients to microbes either separately or in combination with other products to the peroxide particles or slurry. As appropriate, some of these optional products may be injected or mixed in their dry form. Metal chelates described in U.S. Pat. No. 5,741,427 and U.S. Pat. No. 6,319,328 can be used herein. A preferred metal is Fe. Preferred chelating agents (ligands) include EDTA, citric acid, nitrilotriacetic acid, EDTA acid types, diethylenetriaminepentaacetic acid, hydroxyethylenediaminetriacetic acid, methylglycinediacetic acid, phosphonates, and the TRILON chelating agents of BASF, all of which being incorporated herein by reference.

(30) The invention will now be illustrated by the Examples and Counter-examples below, the aim of which is merely to detail some specific aspects of the invention and not to limit its scope thereto.

(31) Tables 1 to 4 below show the results of the above mentioned burning test UN O.1 applied to some commercial grades of IXPER peroxides, eventually diluted with another component (if and as indicated) in a ratio 4:1 of solid to cellulose to demonstrate its natural oxidizing power.

(32) With the exception of sample IXPER 70CG (with the G for granules), all diluents were reduced to fine powders of less than 500 m before performing the test. IXPER 70CG shows no fines/particle sizes below 500 m and was tested as delivered.

(33) In case of blending procedures of solid oxidizers with mentioned additives, latter were mechanically milled to a similar range of spectrum of particle sizes of solid oxidizer to minimize risk of segregation during handling, storage or transport. All ingredients were then thoroughly mixed within a RHNRAD mixer.

(34) TABLE-US-00001 TABLE 1 t.sub.O.1 Raw IXPER material [s]: Class. IXPER75C (03.06.10) w(CaO2) = 75.9% 10 5.1, I IXPER60C (03.07.08) w(CaO2) = 61.4%. 48 5.1, II IXPER70CG (16.07.2010) w(CaO.sub.2) = 72.0% 20 5.1, II IXPER35M (16.07.2010) w(MgO.sub.2) = 38.7% 178 not 5.1
Time References (KBrO.sub.3)

(35) TABLE-US-00002 t.sub.O.1 [s]: Result 120 5.1, PGIII 50 5.1, PGII 10 5.1, PGI

(36) TABLE-US-00003 TABLE 2 t.sub.O.1 IXPER 60C + calcium carbonate [s]: Class. IXPER60C + CaCO.sub.3 w(CaO.sub.2) = 20.2% 13.07.2010 81 5.1, III IXPER60C + CaCO.sub.3 w(CaO.sub.2) = 30.1, % 13.07.2010 46 5.1, II IXPER60C + CaCO.sub.3 w(CaO.sub.2) = 40.5, % 13.07.2010 16 5.1, II

(37) TABLE-US-00004 TABLE 3 t.sub.O.1 IXPER75C + calcium hydroxide [s]: Class. 75C with Ca(OH).sub.2 (08.06.2010) w(CaO.sub.2) = 20.1% 96 5.1, III 75C with Ca(OH).sub.2 (08.06.2010) w(CaO.sub.2) = 30.4% 57 5.1, III 75C with Ca(OH).sub.2 (08.06.2010) w(CaO.sub.2) = 40.4% 22 5.1, II 75C with Ca(OH).sub.2 (08.06.2010) w(CaO.sub.2) = 50.0% 14 5.1, II

(38) TABLE-US-00005 TABLE 4 w(75C) w(CaO.sub.2) t.sub.0.1 Class w(75C) w(CaO.sub.2) t.sub.0.1 Class w(75C) w(CaO.sub.2) t.sub.0.1 Class dilution substance [%] [%] [s] TDG [%] [%] [s] TDG [%] [%] [s] TDG substance: calcium 24 18 129 NOT 5.1 confirmation of findings as reported in 100923.JCS.0 hydroxide sample: technical pure supplier: unkown substance: zeolite 13X 40 30 >180 NOT 5.1 50 37.5 144 NOT 5.1 55 41.3 86 5.1, PG III powder sample: 11-00071 supplier: Sud-Chemie substance: magnesium 40 29.6 139 NOT 5.1 50 37.5 139 NOT 5.1 60 45 69 5.1, PGIII hydroxide sample: Lot.: STBB4230 supplier: SIGMA- ALDRICH substance: basic magnesium 50 37.5 >180 NOT 5.1 60 45 120 NOT 5.1 due to borderline situation, carbonate mono no further tests hydrate sample: Lot.: 87197MJ supplier: ALDRICH substance: aluminium 50 37.5 >180 NOT 5.1 60 45 163 NOT 5.1 70 52.5 64 5.1, PGIII hydroxide sample: K40978091 020 supplier: MERCK

(39) As can be seen from these tables: IXPER35M is not classified as hazardous (Class 5Oxidizing Substances/Division 5.1), while grades IXPER 60C, 75C, and 75CG are (see Table 1); CaCO.sub.3 and Ca(OH).sub.2 even used in rather big amounts (actually, the first example of Table 2 corresponds to approximately 65% in weight of CaCO.sub.3 and the first example of Table 3 corresponds to approximately 75% in weight of Ca(OH).sub.2 are not efficient as diluents s according to the invention, while Mg(OH).sub.2 seems to be efficient at an amount of 74% (see Tables 2, 3, and 4); basic magnesium carbonate mono hydrate (magnesite) and aluminium hydroxide are already effective diluents at 40% in weight (for 60% in weight of IXPER 75C, which corresponds to 45% in weight of CaO.sub.2), while zeolite 13X powder and magnesium hydroxide need to be present in an amount of at least 50% in weight (see Table 4).

(40) For all the diluents tested in Table 4, a TG analysis was performed between ambient temperature and 900 C. as a maximum in order to detect the temperatures at which they release gases (mainly steam or carbon dioxide due to thermal decomposition). The results are shown in Table 5 below.

(41) The conditions of this TG test were the following: 70 l Alumina crucible with lid; 30 mg sample; dry air; air flow through oven: 20 ml/min; heat rate: 3 to 5 K/min; temp range: 25 C. to max 900 C.

(42) TABLE-US-00006 TABLE 5 Temp Range of Water/Gas Diluent Decomposition Formula Release [ C.] Zeolite 13X powder Na.sub.2O Al.sub.2O.sub.3 2.5 SiO.sub.2 n H.sub.2O 20-400 Ca(OH).sub.2 Ca(OH).sub.2 .fwdarw. CaO + H.sub.2O 350-500 Al(OH).sub.3 2Al(OH).sub.3 .fwdarw. Al.sub.2O.sub.3 + 3H.sub.2O 200-650 Mg(OH).sub.2 Mg(OH).sub.2 .fwdarw. MgO + H.sub.2O 200-650 Magnesite Mg(OH).sub.2 Mg(CO.sub.3) 2H.sub.2O .fwdarw. 150-600 (alkaline MgCO3) 2MgO + 3H.sub.2O + CO.sub.2 IXPER75C CaO.sub.2 .fwdarw. CaO + O.sub.2 250-350 Ca(OH)2 .fwdarw. CaO + H2O 350-450 CaCO3 .fwdarw. CaO + CO2 550-750

(43) This table 5 shows that Ca(OH).sub.2, which is a poor diluent, has a decomposition onset above 350 C. (while CaO.sub.2 releases oxygen roughly between 250 and 350 C.), while the other diluents of Table 4, which are good diluents, have an overlap between their decomposition temperature range and the one of CaO.sub.2.

(44) Additional trials were realized both by blending (I) and introducing during its manufacture and prior to its drying (II), sodium bicarbonate, magnesite, aluminium hydroxide and epsomite (hydrous magnesium sulfate mineral with formula MgSO4.7H2O) in CaO2.

(45) The blending (I) was performed as described above. As to the introduction during CaO2 manufacture, it was in fact simulated as follows:

(46) Normally, as described above, CaO.sub.2 is manufactured by adding hydrogen peroxide (H.sub.2O.sub.2) to slaked lime (slurry of Ca(OH).sub.2 in water) to form crystals of CaO.sub.2 in suspension in water, which are then dried. Here, a suspension of IXPER 75C in water was used, to which the above mentioned diluents were added and finally, the mixtures were dried it in a spray drier at an average temperature of 110 C.

(47) The results are shown in Tables 6 below, from which it appears that magnesite and aluminium hydroxide lead to products with a comparable behaviour when added during the manufacture of CaO2 as when blended therewith and are therefore suitable for introduction after reaction and before drying, while sodium bicarbonate and epsomite are not.

(48) TABLE-US-00007 TABLE 6 Ratio 75C:Diluent 40:60 50:50 60:40 70:30 BLEND 30C 38C 45C 53C BICAR NOT 5.1 NOT 5.1 5.1 III n.d. Magnesite NOT 5.1 NOT 5.1 5.1 III n.d. AL(OH).sub.3 NOT 5.1 NOT 5.1 NOT 5.1 5.1, III Epsomite NOT 5.1 NOT 5.1 5.1, III n.d. Ratio 75C:Diluent 40:60 50:50 60:40 SPRAY-DRYER (FEX) 30C 37C 45C BICAR Decomposition (instantaneous gas evolution in suspension) Magnesite NOT 5.1 NOT 5.1 5.1 III AL(OH).sub.3 NOT 5.1 NOT 5.1 5.1 III Epsomite 5.1, III n.d. n.d.

(49) Finally, to check the stability of the suspension of CaO2 with the diluent, additional trials were performed using pure IXPER and IXPER:additive blends with a ratio of 1:1 as follows: a) IXPER reference: IXPER75C at 75% CaO.sub.2 by mass b) Magnesite with IXPER mash: w(CaO.sub.2)40% CaO.sub.2 by mass c) Al(OH).sub.3 with IXPER mash: w(CaO.sub.2)39% CaO.sub.2 by mass. The results in Table 7 show that Al(OH).sub.3 seems to lead to a more stable dispersion than magnesite.

(50) TABLE-US-00008 TABLE 7 Remaining CaO.sub.2 [%] IXPER CaO.sub.2 [%] IXPER CaO.sub.2 [%] IXPER time [h] Ref. Slurry Magnesite Slurry Al(OH).sub.3 Slurry 0 75 40 39 4 75 21 38 6 73 20 37

(51) Blends were also made in the same conditions as explained above, but using APS (ammonium persulfate) instead of CaO2. The results obtained are shown in Table 8 below.

(52) TABLE-US-00009 TABLE 8 Sample/Blend ratio mix t.sub.O.1 [s] Result APS pur 100:0 11 5.1, I APS pur + Al(OH).sub.3 60:40 18 5.1, II APS pur + Al(OH).sub.3 50:50 40 5.1, II APS pur + Al(OH).sub.3 40:60 81 5.1, III APS pur + Al(OH).sub.3 30:70 >180 NOT 5.1 APS pur + basic magnesium 60:40 73 5.1, III carbonate mono hydrate APS pur + basic magnesium 50:50 >180 NOT 5.1 carbonate mono hydrate APS pur + magnesium hydroxide 70:30 41 5.1, II APS pur + magnesium hydroxide 50:50 100 5.1, III APS pur + magnesium hydroxide 40:60 >180 NOT 5.1 APS pur + magnesium hydroxide 30:70 >180 NOT 5.1 APS pur + sodium bicarbonate 40:60 >180 NOT 5.1 APS pur + sodium bicarbonate 50:50 >180 NOT 5.1 APS pur + sodium bicarbonate 60:40 160 NOT 5.1

(53) As can be seen from Table 8, sodium bicarbonate is especially efficient in making APS non oxidizer.

(54) Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.