Liquid purification or separation – Processes – Ion exchange or selective sorption
Reexamination Certificate
2001-08-03
2004-07-13
Barry, Chester T. (Department: 1724)
Liquid purification or separation
Processes
Ion exchange or selective sorption
C210S758000, C210S760000, C210S753000, C210S754000, C210S916000, C215S352000, C215S261000
Reexamination Certificate
active
06761825
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for treating water in situ. The invention specifically relates to a process for treating water in situ to both sterilize and remove odor and taste-producing substances in the water.
2. Description of Related Art
From a general point of view, it is known to remove undesired odors or tastes by means of adsorbing substances, e.g., activated carbon, silica gel, activated aluminum oxide, diatomaceous earth and zeolites. Zeolites are known to be useful for eliminating unwanted odors and/or tastes in plastics. For example, U.S. Pat. No. 5,436,282 discloses a process for eliminating in plastic materials (such as plastic pipes, plastic film and sheeting, plastic containers and plastic interior fittings) low contents of odor/taste-producing substance which have been formed by physical and/or chemical action in the polymerization process of the subsequent compounding/processing. During processing in the molten state, less than 0.5 wt % of a substantially hydrophobic aluminum silicate molecular sieve having a pore diameter of at least 5.5 angstroms, a Si/Al molar ratio in the crystal lattice of at least 35 is added to the plastic material.
Compounds normally associated with causing bad odor or bad taste problems are oxidized hydrocarbons. These can include aldehydes, ketones and acids. While the use of zeolites are known to help reduce such unwanted odors or tastes, typically attributed to the presence of degradation products formed during the thermoprocessing of polymers, some environments pose a more difficult problem.
Ozonation, used to sterilize water for drinking, poses a difficult odor and taste problem. Ozone is a particularly strong reactant. As well, it provides its own oxygen atom for degradation reactions. In other sterilizing methods, e.g., UV, heat gamma ray, etc., the energy is available to fuel degradation reactions but the oxygen must be supplied by the local environment. Thus, these sterilizing methods would not be expected to cause as much oxidation as quickly as that caused by ozonation. Hence, ozonation of water poses an especially difficult odor and taste problem.
BRIEF SUMMARY OF THE INVENTION
The invention provides a method of treating water in situ to both sterilize the water and remove unwanted odors or tastes produced during sterilization, comprising the steps of:
(a) filling a plastic container with water;
(b) sterilizing the water by employing a sterilizing treatment or by adding a sterilizing agent to the plastic container;
(c) sealing the plastic container with a cap having an interior surface, wherein the cap comprises an odor-scalping material;
such that any unwanted odors or tastes produced by the sterilization treatment or by the addition of the sterilizing agent are absorbed by the odor-scalping material.
The odor-scalping material is preferably a zeolite and the sterilizing treatment is preferably ozonation. The cap preferably comprises a cap liner affixed to the interior surface. The zeolite may be present in the cap liner alone at a level of about 0.05% to about 10% by weight of the capliner.
The invention also provides a container for packaging a sterilized water product for human consumption comprising:
(a) plastic container free of odor-scalping material; and
(b) a resealable cap for sealing the plastic container comprising an odor-scalping material.
The odor-scalping material is preferably zeolite and the container preferably contains sterilized water.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
“Zeolite” herein refers to molecular sieves, including alumino phosphates and alumino silicates with a framework structure enclosing cavities occupied by large ions and/or water molecules, both of which have considerable freedom of movement permitting ion exchange and reversible dehydration. The framework may also contain other cations such as Mn, Ti, Co and Fe. An example of such materials are the titanosilicate and titanoaluminosilicate molecular sieves. Unlike amorphous materials, these crystalline structures contain voids of discrete size. A typical naturally occurring zeolite is the mineral faujasite having the following formula:
Na
13
Ca
11
Mg
9
K
2
Al
55
Si
137
O
384
.235H
2
O
Ammonium and alkylammonium cations may be incorporated in synthetic zeolites, e.g. NH
4
, CH
3
NH
3
, (CH
3
)
2
NH
2
, (CH
3
)
3
NH, and (CH
3
)
4
N. Some zeolites have frameworks of linked truncated octahedral (Beta-cages) characteristic of the structure of sodalite. Numerous synthetic zeolites are available.
“Copolymer” means a polymer polymerized from two or more monomers, and includes terpolymers.
“Ethylene alpha-olefin copolymers” means such heterogeneous materials as linear low density polyethylene (LLDPE), linear medium density polyethylene (LMDPE), and very low and ultra low density polyethylene (VLDPE and ULDPE); and homogeneous polymers such as metallocene catalyzed polymers (mPE) such as Exact® supplied by Exxon and Tafmer® polymers supplied by Mitsui Petrochemical Corporation. These materials generally include copolymers of ethylene with one or more comonomers selected from C
4
to C
10
alpha-olefins such as butene-1 (i.e., 1-butene) hexene-1, octene-1, etc. in which the molecules of the copolymers comprise long chains with relatively few side chain branches or crosslinked structures. This molecular structure is to be contrasted with conventional low or medium density polyethylenes, which are more highly branched than their respective counterparts. Other ethylene/alpha-olefin copolymers, such as the long chain branched homogenous ethylene/alpha-olefin copolymers available from the Dow Chemical Company, known as Affinity® resins, are also included as another type of ethylene alpha-olefin copolymer useful in the invention herein.
“Ethylene acid copolymers” means copolymers of ethylene with an olefinically unsaturated organic mono- or di-acid such as acrylic or methacrylic acid, or maleic acid or fumaric acid or their anhydrides, the acid (or anhydride) comprising about 0.5 to 50 mole percent of the total polymeric material. The ethylene/acid copolymers and their methods of preparation are well known in the art and are disclosed in, for example, U.S. Pat. Nos. 3,264,272; 3,404,134; 3,355,319 and 4,321,337. The copolymers are termed “ionomers” when the acid is neutralized in whole or in part to produce a salt. The cations for said salts are usually an alkali metal such as sodium, potassium, zinc or the like. Ethylene/acid/acrylate terpolymer and corresponding ionomers are well known in the art to be copolymers of ethylene, an olefinically unsaturated organic acid such as acrylic or methacrylic acid and an alkyl acrylate or methacrylate termonomer (e.g. n-butyl acrylate or methacrylate or isobutylacrylate). Suitable acid copolymer and ionomers are available from the DuPont Company, Wilmington, Del., under the trade names Nucrel® and Surlyn®, respectively.
“EVA” means ethylene vinyl acetate copolymer.
“HDPE” refers to high density polyethylene.
“LDPE” refers to low density polyethylene.
“Polyester” herein refers to poly(ethylene terephthalate) (“PET”), PET modified by incorporating diacids other than terephthalic acid (such as isophthalic acid) or glycols other than ethylene glycol (such as cyclohexane dimethanol (“CHDM”)), as well as copolymers containing terephthalic acid, CHDM and other dibasic acids such as isophthalic acid. The polyesters are generally obtained by known polymerization techniques from aromatic dicarboxylic acids, preferably the lower alkyl esters thereof such as the dimethyl ester of terephthalic acid. The aromatic dicarboxylic acid or its ester or anhydride is esterified or transesterified and polycondensed with a saturated diol such as ethylene glycol. Typical saturated diols include saturated aliphatic, cyclo-aliphatic, or aromatic diols, preferably the lower alkane-diols such as ethylene glycol. Mixtures of aliphatic carboxylic acid and saturated diols may also be used, but the above-described physical properties (i.e. melting point and glass
Barry Chester T.
I. du Pont de Nemours and Company
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