Liquid purification or separation – Filter – Supported – shaped or superimposed formed mediums
Reexamination Certificate
1997-10-27
2002-10-22
Wong, Edna (Department: 1741)
Liquid purification or separation
Filter
Supported, shaped or superimposed formed mediums
C210S500260, C210S504000, C210S509000, C096S154000
Reexamination Certificate
active
06468428
ABSTRACT:
This i a national stage application of JP97/00623 filed Feb. 28, 1997.
TECHNICAL FIELD
The present invention relates to a glass material for carrying a photocatalyst, a filter device using the same and a light irradiating method, particularly for improving an efficiency of light irradiation to a photocatalyst and increasing a photocatalyst reaction.
BACKGROUND ART
A photocatalyst reaction is characterized in oxidization reaction using a string oxidizing force produced under light irradiation. Therefore, attempts are positively made to utilize this technique in a filter and applies the technique to water treatment and environmental purifying.
As a filter using a conventional photocatalyst, a filter with TiO
2
or another photocatalyst carried on a thermal resistant fiber or a porous substance, a filter with TiO
2
or another photocatalyst carried on a metallic mesh, or the like is used. With a light from a luminous source, photocatalyst action is attained.
As specific examples available are a filter provided with a honeycomb cell carrying a photocatalyst inside a reaction container containing a reaction solution and a reaction solvent and an optical fiber for guiding light in the cell (Document 1. Publication of the patent application laid-open No. Hei 5-154387); a filter with a translucent thin film of titanium oxide carried on a flat substrate of a glass, ceramic or another style or on glass beads or ceramic halls for removing toxic substance contained in city water or the like by irradiating a light to the thin film (Document 2. Hashimoto and Fujishima, “Water and Drain” Vol.36 No.10 (1994), p5-11); a filter with photocatalysts carrying titanium oxide powder on a honeycomb carrier positioned at both sides of a luminous source for purifying air inside an automobile or various environments (Document 3. Suzuki, “Toyotta Chuo Kenyasho R&D Review” Vol.28 No.3 (1993.9), p47-56); a filter with a TiO
2
pellet positioned inside an annular container having a luminous source in its middle for treating trichloroethylene or another volatile organic chlorine compound (Document 4. Yamazaki, “Chemistry and Industry”, Vol.47 No.2 (1994) p152-155); and the like.
However, in either of the aforementioned prior arts, a photocatalyst action is produced with a light from a luminous source slightly apart from a photocatalyst. Therefore, following common problems exist.
(1) If a filter is covered with dirt, dust, sludge or the like, light has difficulty in reaching a photocatalyst, thereby decreasing a catalyst function. For this, very strong ultraviolet rays are necessary. Especially in case of almost black sewage raw water containing a large quantity of substances, light does not reach a photocatalyst, and a photocatalyst reaction is inactivated or only slightly activated, which cot be practically used.
(2) Light strikes portions and does not strike other portions, and only the light struck portions act. To eliminate the disadvantage, a hybrid photocatalyst is prepared by mixing adsorbent and titanium oxide. The portions not struck by light are collected with the adsorbent and moved to the light-struck portions for decomposition. Such a complicated system needs to be designed.
(3) Even when light irradiates a photocatalyst from a luminous source to a photocatalyst, only a slight quantity of the irradiated light can reach the photocatalyst. Most of the light energy is wasted. Therefore, to efficiently irradiate light, the designing of a device is Important. For this, a structure provided with an annular container having inside a photocatalyst and a luminous source in its middle or another complicated structure needs to be designed.
An object of the invention is to provide a photocatalyst filter, its device and a fluid treatment method using the same which can solve the aforementioned prior-art problem and efficiently produce a photocatalyst function by a sample structure of irradiating light f m a support body carrying a photocatalyst directly to the photocatalyst.
Also, to enhance a capacity for treatment such a photocatalyst, a large quantity of light is heretofore introduced to the photocatalyst.
Specifically, the conventional application of the photocatalyst are restricted to the following.
(1) To enhance the capacity, the irradiation of a large quantity of light is devised.
(2) To enhance the capacity, a way of light irradiation is devised.
(3) To enhance the capacity, the increasing of a photocatalyst activity is devised.
(4) The low capacity restricts the application to the commercial goods developed in accordance with the capacity: for example, deodorization (treating a small quantity, with a rate-determining step in diffusion); prevention of pollution (treating a all quantity over a long time period); antibacterial treatment (treating a small quantity: sterilization is impossible) and the like.
In this manner, even when a photocatalyst action is used, the development giving weight to a light quantity restricts enhancement in capacity of a photocatalyst reaction. When there are a large quantity of objects of photolysis, they cannot be treated by the action of a photocatalyst.
The present invention has been developed in the aforementioned background, to provide a photocatalyst filter device and a filtering method which can remarkably enhance a filtering capacity.
Here, as a filter used for filtering gas, liquid or another fluid generally known is a filter having a filtering face vertical to a passage of fluid to be filtered (e.g. the patent application laid-open No. Hei 7-224632); a filter having a filtering face parallel with a passage of fluid (e.g. the patent application laid-open No. 56-129020) or the like.
In the former, to increase a filtering capacity, a filtering area orthogonal to the passage needs to be enlarged. However, if the passage is enlarged in the vicinity of the filter, it is difficult to uniformly hold the fluid pressure exerted to each portion of the filter. Therefore, the collecting density disadvantageously not uniform, and an efficient filtering cannot be attained.
For the latter, since the filtering face is parallel with the passage, it is effective in that the passage does not have to be necessarily enlarged because the latter has a larger filtering area as compared with the former. However, then the fluid to be filtered advances in a filtering portion, the fluid to be filtered is gradually discharged to the outside through the filtering face serving also as the passage. Therefore, there arises a difference in pressure among respective filter portions, which cases a deviation in collecting density. Therefore, a sufficiently efficient filtering cannot be attained.
Also, attempts are being made to apply a photocatalyst reaction to various water treatment, air treatment, and environmental purifying. However, even if the reaction is used in the aforementioned filter, it is very difficult to irradiate light all over the filter.
The invention has been developed in the aforementioned background, and its object is to provide a filter device which can obtain an efficient filtering action and can be effectively given a filter purifying function using a photocatalyst reaction.
When fluid is to be filtered by a filter, generally following three types of filters are used.
The first type is a filter using a short-fibrous fiber (hereinafter referred to as the short-fibrous filter).
The second type is a filter using a long-fibrous fiber (hereafter referred to as the long-fibrous filter). A base material of the filter is in a form of cloth woven with a long-fibrous fiber.
The third type is a filter using particulates (including a porous body), or a porous body formed by sintering the particulates. Alternatively, the filter is formed by filling a filter forming space with the particulates.
However, either of the aforementioned conventional type filters has the following problems. It is difficult to provide a sophisticated filter inexpensively.
First, in the first type of short-fibrous filter, a fiber filling density is changed mainly by adjusting filter holes (mesh). A localized di
Hachitani Yoichi
Higashida Masayuki
Maeda Nobuhiro
Nishii Yoshikazu
Ogawa Shin-ichi
Hoya Corporation
Perman & Green LLP
Wong Edna
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