Method of preparing a biocidal material

Details Method of preparing a biocidal material Method of preparing a biocidal material

1998-07-09

2001-08-07

Harrison, Robert H. (Department: 1619)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Biocides; animal or insect repellents or attractants

C424S405000

Reexamination Certificate

active

06270786

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to the preparation of a biocidal material. More particularly, it relates to the regeneration and reuse of immobilized biocide from an existing biocidal material.
BACKGROUND OF THE INVENTION
Microbial growth occurs in many systems in which aqueous media such as water, aqueous solutions and aqueous dispersions are employed.
For example, significant biofouling can occur in many areas of photoprocessing systems and, in particular, where low flow rate washes and water recycling is used. The problem may be overcome by adding biocides to the wash water tanks when bacterial biofilm formation becomes evident visually. However at this point the biocides may not work and even at quite high concentrations are not particularly effective because the bacteria have attached to surfaces to form colonies which have built up in layers. Hence, any biocide in solution can only reach the outer biofilm layer and not the inner layers of the biofilm which are protected. Furthermore, widespread use of such biocides is not desirable because they are relatively expensive and toxic chemicals which require specialised disposal to protect the environment.
It is known that in addition to being used up in the process of inhibiting the growth of microorganisms, biocides tend to degenerate and lose their activity through prolonged contact with the aqueous medium being treated.
EP-A-0 733 304 describes a biocidal material comprising a biocide immobilized on a support characterised in that the biocide has a log P value of at least 1.5, the support has a hydrophobic surface and the biocide is immobilized on the hydrophobic surface by hydrophobic exclusion. The support may take the form of polymer beads which may be held in a container having an inlet and an outlet so that the aqueous medium to be treated can be contacted with the beads by passing it through the container. An advantage of the material is that the biocide remains attached to the support. The material may be used to inhibit microbial growth in the wash water or other solutions used in a photoprocessor.
PROBLEM TO BE SOLVED BY THE INVENTION
After prolonged use, the biocidal material comprising immobilized biocide becomes exhausted and needs to be replaced. It would be economically and environmentally advantageous if further use could be made of the material without disposing of it and replacing it with completely new material.
It has been found unexpectedly that significant amounts of active biocide can be removed from the material by solvent extraction and the extracted biocide re-used to provide new biocidal material.
SUMMARY OF THE INVNETION
The invention provides a method of preparing a biocidal material which comprises
taking a biocidal material comprising a biocide having a log P value of at least 1.5 immobilized by hydrophobic exclusion on a support having a hydrophobic surface which has been used for inhibiting microbial growth in an aqueous medium,
extracting biocide from the biocidal material with a solvent, and
immobilising the extracted biocide by hydrophobic exclusion on a support having a hydrophobic surface.
ADVANTAGEOUS EFFECT OF THE INVENTION
A significant amount of active biocide can be recovered from used material and re-used.


REFERENCES:
patent: 5322834 (1994-06-01), Hsu
patent: 5648086 (1997-07-01), Redlich et al.
patent: 5703105 (1997-12-01), Redlich et al.
patent: 6059980 (2000-05-01), Leeming et al.
patent: 106563 (1984-04-01), None
patent: 0 733 304A (1996-09-01), None

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