Liquid purification or separation – Processes – Ion exchange or selective sorption
Reexamination Certificate
2002-04-17
2004-12-21
Hopkins, Robert A. (Department: 1724)
Liquid purification or separation
Processes
Ion exchange or selective sorption
C210S681000, C210S502100, C210S504000, C210S505000, C210S506000, C502S407000
Reexamination Certificate
active
06833075
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of solution and fluid treatment devices, primarily to aqueous solution and water treatment, devices for gases and industrial fluids and other aqueous liquids, which modify the components of the gas or aqueous liquid solution passed through them. In its more particular aspects, the invention relates to the field of such devices that reduce chemical and microbiological contaminants, including toxic metals and water treatment chemicals, bacteria and viruses and their components, contained in water or aqueous solutions.
DESCRIPTION OF RELATED ART
Purification or filtration of water or other aqueous solutions is necessary for many applications, from the provision of safe or potable drinking water to biotechnology applications including fermentation processing and separation of components from biological fluids, and to industrial processes that require waste stream treatment and recovery of process chemicals. Similarly, the removal of contaminants from fluids used in medical procedures and semiconductor fabrication processes, where ultrapurified fluids are required, and in environments where the fluids will be recirculated, such as aircraft or spacecraft, is also an important application for filtration and fluid treatment materials. In recent years, the need for water filtration and purification in the home has become more recognized, and the competing concerns of energy efficiency and residential fluid quality have lead to numerous filtration products, that purport to remove small particles, allergens, microorganisms, intentionally introduced biotoxins, pesticides, and toxic metals such as lead, mercury, and arsenic.
There are many well-known methods currently used for water purification, such as reverse osmosis, distillation, ion-exchange, chemical adsorption, coagulation, and filtering or retention. Particle filtration may be completed through the use of membranes or layers of granular materials. Other fluid purification techniques involve chemical introduction which alters the state or chemical identity of the contaminant. Examples of chemical additives include oxidizing agents, flocculating agents, and precipitation agents.
In many fluid purification applications a combination of techniques are required in order to completely purify fluids, such as water. Combinations of technologies may be implemented by combining functions in a single device or using several different devices and technologies in series where each performs a distinct function. Examples of this practice include the use of mixed ion-exchange resins that remove both negative and positively charged chemical species and oxidation/filtration methods where oxidizers are used to generate particulate matter that may be subsequently filtered.
Many of these fluid purification technologies, techniques, and practices are costly, energy inefficient and/or require significant technical know-how and sophistication to implement on both large and small scales. As a result, many advanced fluid purification technologies have had limited application in residential point of entry (POE) and point of use (POU) applications.
Unfortunately, currently available low cost, simple techniques and inexpensive devices fabricated for residential POU/POE markets do not adequately meet the contaminant removal levels required by regulatory agencies. For example, simple sink POU water purification devices containing activated carbon or portable units for campers and hikers can not remove microorganisms or chemical toxins such as heavy metals to regulatory levels.
Technologies and devices that are inexpensive for continual use on an annual basis, simple to operate, contain low concentrations of safe chemicals, and are highly efficient at removing both microbiological and chemical impurities have numerous applications if they can be developed. In particular, technologies and devices with these characteristics have application in potable water treatment, cooling water treatment, and in the fields of semiconductor fabrication and manipulation, mining, biotechnology, healthcare, and the food and beverage industries. Such technologies and devices would also be useful in the processing of fluids in many industries where fluids require recycling or reuse. Furthermore these technologies and devices would be invaluable reclamation tools for recovering chemical constituents from known environmental waste sites such as abandon mines and super-fund locations.
In the treatment of many fluids the surface properties of the filtration media are manipulated to best suit the contaminant or fluid component targeted. Surface properties of both organic and inorganic materials are a: function of the chemical composition of the material and processing methods used to manipulate the material. Surface properties can be tuned to be ion or molecule specific or generated to interact with a broad range of different chemical and biological species.
There is much prior art in the fields of isolating natural materials and synthesizing materials with useful surface properties. Surface properties can include a range of electric charge from positive through neutral to negative, with a number of different surface active chemical species. As example carbon is known to interact differently with many chemical compounds based on the carbon source and the processing methods used to “activate” the carbon. As further example, synthetic materials know as ionic exchange resins can be manufactured to contain a range of positive or negative charged surface components. The composition of the resin and the specific identity of the surface component determine the applicability of the material for different treatment processes.
Surfaces may be modified by heat treatment, chemical action, biological action, and/or a combination thereof. Examples include calcining clay materials, steam and heat activating carbon materials, and using chemical reagents to temporarily or permanently attach many different molecules to the surface. Examples of the latter include biological compounds such as proteins and peptides, pharmaceutical compounds, and molecules carrying electrical charges for the direct interaction with chemicals, cells, microorganisms or for the purpose of controlling electrical charge buildup.
Specifically, it has been recognized in the art of surface treatment that charged surfaces can control the interaction with chemical and biological contaminants. Examples include the use of positive charged surfaces to remove negatively charged fluid contaminants including toxic metals such as arsenic, anions that contribute to the total dissolved solid content of water including sulfates and chlorides, and microorganisms such as viruses, bacteria, and the components of microorganisms.
There is much existing art involving the treatment of material surfaces to modify surface function. This art includes that which has been developed in the field of paper science, fiber processing, air filtration, and surface protection. Still further the modification of medical devices with surface coatings to improve biocompatibility is an active area of research.
However there is little known art in the surface treatment of materials used for composite formation in the field of fluid purification where composites which may or may not contain binder materials are fabricated from inexpensive fluid treatment materials.
As a result there are no known commercially available or other fluid purification devices incorporating composites composed of fluid treatment media such as carbon, metal phosphates, metal oxides, reduced metals, silicates, metal sulfates, metal carbonates, silicates, metal hydroxides, or combinations thereof, in loose particulate or fiber form or with material binders, which have been modified by chemical surface treatments.
Further, there have been no known prior descriptions of processes to prepare composite fluid purification materials and devices that contain composites carrying surface treatments. Furthermore there are no known composit
Hopkins Robert A.
Kilpatrick & Stockton LLP
Richards Robert E.
Russell Dean W.
Watervisions International, Inc.
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