Materials treatment

Details Materials treatment Materials treatment

1999-06-07

2003-06-03

Warden, Sr., Robert J. (Department: 1744)

Chemical apparatus and process disinfecting, deodorizing, preser

Physical type apparatus

Means separating or dissolving a material constituent

C422S260000, C210S511000, C210S634000, C210S648000, C210S774000, C210S806000, C159S901000, C159SDIG001, C159SDIG001, C159S020200, C202S170000, C203S043000, C203S067000, C203S094000, C203S098000, C585S864000, C568S918000

Reexamination Certificate

active

06572831

ABSTRACT:

This invention relations to materials treatment and particularly, although not exclusively, relates to a process for removing at least one material from a mass of material.
Many industries use so-called “organic solvents” (also known as “volatile solvents”) during the manufacture of their products. For example, organic solvents such as toluene, methyl iso-butyl ketone, ethyl acetate, butyl alcohol and others are extensively used in the pharmaceuticals industry as reaction media and for selective solvent extraction of a single component from a mixture of components present as a solution or suspension in an aqueous medium.
Where a solvent is present as a reaction medium, it simply provides a medium in which the reaction can take place and is not consumed in the reaction. Generally, therefore, the solvent has to be removed at the end of the reaction. Such removal may be carried out by:
(i) Filtration—the solvent forms part of the permeate solution (or mothor liquor) and the solvent-wet product is dried by heat and/or vacuum;
(ii) Evaporation—the solvent is removed from the final reaction mixture by distillation using heat and/or vacuum;
(iii) Extraction—the target component is removed from the reaction mixture by stirring with an immiscible solvent, normally water, followed by settling and subsequent physical separation of the two phases.
The aforementioned industrial processes generate large volumes of aqueous streams containing small levels of organic solvents, typically in the range of 0.05 to 2.0% v/v. These aqueous streams could be process streams comprising an aqueous phase or target compound and solvent as a contaminant. The contaminant could be detrimental to downstream process steps. Alternatively, aqueous effluent streams having had a target compound removed by solvent extraction may then be contaminated with solvent traces which have to be removed prior to discharge as effluent.
Another area where such solvents are extensively used is in the food industry. Here solvents such as hexane and dichloromethane have been used for many years in the manufacture of, for example, colouring and spice oleo-resins as flavouring substances.
It is important to reduce the solvent content from process streams and final products for economic, product efficacy, processing requirements, environmental and legislative reasons. Also in many cases the solvent contaminant is valuable and needs to be recovered for recycling.
Traditional methods for reducing concentrations of organic solvent contaminants from effluent, process streams and final products to acceptable levels involve solvent “stripping” using heat and/or vacuum. However, the use of these methods presents several commercial and technical problems. For example, they require high energy input, the cost of which will ultimately contribute to the unit cost of the final product and, especially in the case of generic pharmaceuticals manufacture, would inevitably affect competitiveness and profitability. Also, there are important environmental issues resulting from the inherent inefficiencies of this type of operation. In this regard, it is well known to those conversant in the art that the efficiency of recovery of organic solvents by conventional means, depending on volatility, can be as low as 75% with as much as 25% of the solvent present escaping to air, sea or land.
There are additional drawbacks specific to the manufacture of some pharmaceutical products where the target compound is a fragile fermentation metabolite. Many of these products are heat sensitive and often produce unwanted and even toxic degradation products. As a result, there may be a tendency to carry out the solvent stripping at a lower temperature and in a shorter time than is optimum to reduce solvent levels as required by legislation, with the danger of either product failing quality assurance tests or product leaving the factory with unacceptable levels of solvent contamination.
It is an object of the present invention to address the aforedescribed problems.
According to a first aspect of the present invention there is provided a process of removing a first material from a mass of material in which the first material is not naturally occurring, the process comprising
(a) contacting the mass of material with solvent comprising a C
1
-C
4
fluorinated hydrocarbon so as to charge the solvent with the first material; and
(b) separating charged solvent from the remainder of the mass of material.
Said first material is preferably a volatile contaminant.
Said first material may have a boiling point of greater than 25° C., suitably greater than 30° C., preferably greater than 35° C., more preferably greater than 40° C., especially greater than 50° C.
Said first material may have a boiling point of less than 300° C., suitably less than 250° C., preferably less than 200° C., more preferably less than 150° C., especially less than 100° C.
Said first material may have a melting point of greater than −200° C., suitably greater than −150° C., preferably greater than −125° C., more preferably greater than −100° C., especially greater than −80° C.
Said first material may have a melting point of less than 60° C., suitably less than 40° C., preferably less than 30° C., more preferably less than 15° C., especially less than 0° C.
Said first material is preferably a liquid at the temperature at which said material is contacted with said solvent. Said material may be contacted with said solvent at a temperature of less than 100° C., suitably less than 80° C., preferably less than 60° C., more preferably less than 40° C., especially at ambient temperature.
Said first material is preferably a solvent, more preferably an organic solvent. Suitable solvents include optionally substituted cyclic, aromatic or aliphatic hydrocarbons, alcohols, esters, ketones, ethers, nitriles and amines. Said solvent may be a halogenated, for example a chlorinated hydrocarbon such as tetrachloromethane, dichloromethane, perchloromethane or trichloromethane; an aliphatic hydrocarbon such as hexane; an ether such as diethylether or tetrahydrofuran; an ester, such as ethylacetate; an aromatic hydrocarbon such as benzene or toluene; an alcohol such as ethanol; a nitrile such as acetonitrile; a ketone such as methyl isobutylketone or di-isobutylketone.
Said first material is preferably brought into contact with other components in said mass of material in an upstream process step, for example as described in the introduction of this specification. For example, said first material may comprise a medium added to one or more other materials in order to facilitate a chemical or physical process. For example, said first material may be a reaction solvent or it may be a solvent used in the selective extraction of one material from a mass of material.
In one embodiment, the process may be used to remove a first material from a solid, for example, an inert solid matrix which may be polymeric, for example a polystyrene or polyacrylic polymer or a copolymer.
In this case, the first material may comprise relatively non-polar impurities for example, waxes, naphthalene, cyclic and linear ketones and the like.
The C
1
-C
4
fluorinated hydrocarbon may be non-chlorinated. Preferably it comprises one or more carbon, fluorine and hydrogen atoms only. Preferably, said hydrofluorocarbon is a C
1
to C
3
, more preferably, a C
1
to C
2
hydrofluorocarbon. Especially preferred is a C
2
hydrofluorocarbon.
Said hydrofluorocarbon may include up to 10, preferably up to 8, more preferably up to 6, especially up to 4, fluorine atoms. Preferably, said hydrofluorocarbon includes at least 2, more preferably at least 3, fluorine atoms.
Said hydrofluorocarbon is preferably aliphatic. It is preferably saturated.
Said hydrofluorocarbon may have a boiling point at atmospheric pressure of less than 20° C., preferably less than 10° C., more preferably less than 0° C., especially less than −10° C. The boiling point may be greater than −90° C., preferably greater than −70° C., more preferably greater

Affiliated with

Also associated with

Rating

Materials treatment does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Materials treatment, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Materials treatment will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3106792