Patent Information Search
 
Water Purifier Patent

Macroporous manganese dioxide water purifier

Water purifier abstract

A water purifier consisting essentially of manganese dioxide particles having a 20 to 48 mesh size and macroscopic pores which are so large in size as to permit passage of water therethrough. The particles may have active sites of needle-like or columnar crystals of manganese dioxide on the surfaces thereof. A method for making such water purifier is also described.

Water purifier claims



What is claimed is:

1. A water purifier for use in the purification of water comprising means for passing water through a column which consists essentially of discrete particles of manganese dioxide, having macroscopic pores through which water is able to pass, wherein said manganese dioxide is (a) of beta form; (b) gamma and beta-mixed form and wherein said particles have needle-like or columnar crystals on the surfaces.

2. The water purifier according to claim 1 wherein said manganese dioxide is of the beta form and exhibits a sharp x-ray diffraction pattern at 2.theta.=36.degree. using iron bulbs.

3. The water purifier according to claim 1 wherein said manganese dioxide is of the beta and gamma mixed form and exhibits a x-ray diffraction pattern at 2.theta.=28.degree. or 36.degree. using iron bulbs.

4. The water purifier according to claim 1 wherein said discrete particles of manganese dioxide is of size between 20 and 48 mesh.

5. The method of purifying raw water from impurities of manganese, iron and coloring matters which consists of passing the raw water through a water purifier which consists essentially of discrete particles of manganese dioxide having macroscopic pores through which water is able to pass, wherein said manganese dioxide is (a) of beta form; (b) gamma and beta-mixed form and wherein said particles have needle-like or columnar crystals on the surfaces.

Water purifier description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to water treatments and more particularly to water purifiers which are useful in purifying raw water from lakes or rivers in order to remove manganese and iron components and colored matters therefrom. It also relates to a method for making such water purifiers.

2. Description of the Prior Art

Recent trends toward pollution of lakes and rivers are beyond the bounds of imagination, leading to an increase in amount of raw water which is rather unsuitable for use as city water. This in turn requires complicated treating apparatus with an attendant rise of treatment cost.

Several methods of removing manganese and iron components and coloring matters such as humus from raw water are known including an oxidation method using ozone or oxidizing agents, an adsorption method using active carbon, a contact filtration method using manganese-deposited zeolites, a coagulating sedimentation method using coagulants, and combinations of these methods.

The oxidation method using ozone or an oxidizing agent such as potassium permanganate is disadvantageous because of the high treating cost. Especially, use of ozone requires an additional equipment for preventing air pollution. The adsorption method using active carbon is not effective because active carbon has little adsorptivity of manganese and iron components and is low in removability of coloring matters.

The contact filtration method makes use of manganese zeolite which has manganese dioxide deposited on the surface. This type of zeolite is prepared by immersing zeolite in a solution containing divalent manganese ions and adding an oxidizing agent such as, for example, potassium permanganate to have manganese dioxide deposited on the surface of zeolite. In this method, however, a large amount of an expensive chemical such as potassium permanganate is used, leading to a high treatment cost. If raw water being treated has a high content of manganese, it cannot be removed efficiently. Because manganese dioxide is deposited on the surface of zeolite, the dioxide may readily fall off and be lost with the deposited zeolite deteriorating in quality.

It is generally accepted that manganese dioxide itself has the effect of removing manganese, iron and coloring matters from water. For use as a water purifier, manganese dioxide has to be reduced into pieces having a suitable range of size. For instance, chips of electrolytic manganese dioxide removed from the electrode or natural manganese dioxide may be crushed to have a desired particle size. Alternately, manganese dioxide powder may be bonded with use of an inorganic binder such as alumina cement and shaped to have a suitable particle size. However, the former manganese dioxide particles are disadvantageous in that a reactive area is relatively small. On the other hand, the particles obtained by using inorganic binder have the drawback that active surfaces of the manganese dioxide are covered with the inorganic binder added and the purification effect is lower than the one achieved by the starting manganese dioxide material itself.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to provide water purifiers useful for purifying water which overcome the drawbacks of the prior art.

It is another object of the invention to provide water purifiers which are useful in efficiently, economically removing manganese and iron components and coloring matters from raw water such as from lakes, rivers and the like.

It is a further object of the invention to provide a method for making the water purifiers of the above-mentioned type.

The above objects can be achieved, according to the invention, by a water purifier for use in the purification of water which consists essentially of discrete particles of manganese dioxide having a 20 to 48 mesh size, the particles having macroscopic pores through which water is able to pass. Preferably, the particles should have active sites on the surfaces in the form of needle-like or columnar crystals.

The particles of manganese dioxide having such large-size pores are obtained by a method which comprises immersing starting manganese dioxide powder in an acidic solution comprising from 5 to 80 g/liter of divalent manganese ions and from 5 to 100 g/l of an acid for a term of from 2 to 7 days at a temperature of from 80.degree. to 100.degree. C., reducing the resulting manganese dioxide mass into pieces, classifying the pieces to have a size of from 20 to 48 mesh, and neutralizing the pieces with an alkali whereby manganese dioxide particles having macroscopic pores through which water is able to pass are obtained. Preferably, magnesium ions may be further added to the acidic solution. By the immersion in the acidic solution containing manganese and/or magnesium ions, the starting manganese dioxide powder which may be microscopically porous is bonded without any binder and converted into a macroscopically porous mass. In a preferred embodiment of the invention, manganese dioxide of the gamma type is used and immersed in such acidic solution as defined above under such conditions that part or all of the manganese dioxide is converted into beta-type manganese dioxide while forming a macroscopically porous mass with surface activity. The present invention also provides a method for making a water purifier of the type described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a) and 1(b) are, respectively, microphotographs by electron microscope showing the surface state of a manganese dioxide water purifier according to the invention;

FIG. 2 is a graph showing the relation between chromaticity of water treated in Example 2 and Comparative Examples 1 through 3 and time after the treatment;

FIG. 3 is a graph showing the relation between chromaticity of water treated in Examples 2 and 3 using one type of manganese dioxide water purifier according to the invention and time by days after the treatment;

FIG. 4 is a graph showing the relation between chromaticity of water treated in Examples 6 and 7 using another type of manganese dioxide water purifier according to the invention and time by days after the treatment; and

FIGS. 5(a) through 5(f) are, respectively, X-ray diffraction patterns of ordinary gamma-manganese dioxide, beta-manganese dioxide obtained in Examples 1 4 6 and 8 and a mixture of beta- and gamma-manganese dioxide substances obtained in Examples 5 and 7.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION

As described before, the manganese dioxide particles of the present invention should be macroscopically porous and have a mesh size of 20 to 48. The term `macroscopically porous particles` used herein is intended to mean particles having pores which permit free passage of water through the pores. Ordinary particles of manganese dioxide are microscopically very porous but have not such macroscopic pores.

Macroscopically porous particles of manganese dioxide according to the invention are readily obtained by immersing manganese dioxide powder in an acidic solution containing divalent manganese ions preferably along with magnesium ions for a time sufficient to convert the powder into a macroscopically porous mass of the dioxide. The acidic solution is prepared to have a concentration of an acid of from 5 to 100 g per liter of the solution. A typical example of the acid is sulfuric acid though other mineral acids such as (nitric acid, hydrochloric acid, phosphoric acid and the like) may be used. In the acidic solution, it is essential that divalent manganese ions be present in an amount of from 5 to 80 g per liter of the solution. Preferably, divalent magnesium ions should be further added in an amount up to 50 g per liter of the solution. If magnesium ions are used singly instead of the divalent manganese ions, the conversion velocity unfavorably becomes very low. The reason why magnesium ions are used is that the apparent specific gravity of the resulting particles becomes smaller than in the case where magnesium ions are used singly upon comparing at the same level of particle size, thus leading to an increase of porosity. The divalent manganese and magnesium ions may be derived from various sources. Such sources include inorganic salts such as (nitrates, sulfates, phosphates and the like of these metals).

In order to ensure high mechanical strength of the macroscopically porous mass, the temperature of the acidic solution should preferably be as high as possible but below a boiling point of the solution. Moreover, the immersion time is preferred to be as long as possible.

The macroscopically porous mass is subsequently reduced into pieces having a 20 to 48 mesh size (U.S. mesh) for use as a water purifier. The reduction into pieces may be carried out by any known means and the pieces may be classified to have a defined range of size as usual.

Next, the pieces are washed with water until the washing has a hydrogen ion concentration within the regulated standard for city water, followed by neutralizing with an alkaline substance such as caustic soda. The manganese dioxide particles obtained by the above sequence of treatment steps have the high ability of removing manganese and iron components from water and also coloring matters therefrom. By the neutralization, the pH of water purified by passage through the water purifier of the invention is in the range of about 5.8 to 8.6 at the initial stage of the water passage, which is within the standard for city water.

In the above embodiment, starting manganese dioxide powder may have any crystal forms such as alpha, beta, gamma and delta forms.

In accordance with another embodiment of the invention, the macroscopically porous manganese dioxide particles are of the beta form or the beta and gamma-mixed form in crystal structure. In order to obtain these types of manganese dioxide, the starting manganese dioxide powder should be of the gamma form and is subjected to the same procedure as described with regard to the first embodiment. As a result, macroscopically porous manganese dioxide particles of the beta form or the beta and gamma-mixed form are obtained.

In general, manganese dioxide of the beta form may be prepared by several methods including, for example, heating of gamma-manganese dioxide at about 400.degree. C., treatment of gamma-manganese dioxide in an autoclave containing an aqueous solution of an oxidative salt, and electrolysis of manganese dioxide under elevated current density conditions. However, water purifiers of beta-manganese dioxide obtained by these methods are much poorer in water purification performance and bleaching ability than the manganese dioxide of the beta form or the beta and gamma-mixed form of the invention. From this, it will be appreciated that manganese dioxide useful as a water purifier should have not only the beta form or beta and gamma-mixed form in crystal structure, but also possess macroscopic pores through which water is able to pass freely and the form of needle-like or columnar crystals on the surfaces thereof.

As described before, gamma-manganese dioxide powder is converted into the macroscopically porous manganese dioxide mass of the beta or beta and gamma-mixed form under conditions defined with reference to the first embodiment. Higher concentrations of manganese and magnesium ions and an acid result in a higher velocity of conversion of from the gamma form to the beta form. It is favorable that the conversion velocity is relatively low from the standpoint of mechanical strength of the mass.

A mixing ratio of the beta to gamma form may be arbitrarily varied by changing the immersion conditions.

In order to ensure good water purification performance, the mixing ratio should preferably be in the range of ##EQU1##

The starting gamma-manganese dioxide is not necessarily pure gamma-manganese dioxide but may contain, aside from gamma-manganese dioxide, several to some dozen percent of manganese dioxide of other crystal forms. Electrolytic manganese dioxide is made of the gamma form alone or the gamma form with several percent of beta form. Thus, this dioxide is suitable as a starting material of this embodiment.

Although electrolytic manganese dioxide of the gamma form is very microscopically porous, manganese dioxide particles of the invention having macroscopic pores through which water is able to pass are very advantageous for use as a water purifier.

When the water purifiers of the invention are practically applied, it is convenient to add, to raw water being treated, oxidizing agents such as sodium hypochlorite in order to further improve the removability of coloring matters, whereby the service life of the water purifiers would be prolonged several years.

Portable ultraviolet water purifier
Diverter and water purifier having same
Remote control valve for reverse osmosis water purifier

PAT. NO. Title
5660802 Water purifier
5653868 Diverter and water purifier having same
5628900 Water purifier having a magnetic field generation device
5614068 Water purifier
5601710 Filtering apparatus of water purifier
5575908 Sewer system water purifier
5567311 Water purifier with electrical components isolated from leaked water
5562824 Gravity water purifier
5503739 Heat dissipating device for water purifier's thermoelement
5478458 Water purifier
5466366 Water temperature and conductivity detector for reverse-osmosis water purifier systems
5401395 Valve arrangement for a pressurized water purifier
5399263 Water purifier
5397468 Water purifier cartridge coupling
5250177 Water purifier with an ozone generating device
5218995 Three-way valve assembly with water quantity recording meter for a storage tank of the reverse osmosis water purifier
5194156 Water purifier faucet fitting
5192436 Tap water purifier to be directly coupled to faucet pip
5085753 Water purifier
5082557 Control head for water purifier
5071551 Water purifier
5059296 Portable self-contained solar powered water purifier
4277332 Water purifier
4253307 Solar power generator and water purifier
Copyright © 2006 - 2012 Patent Information Search