Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-11-05
2003-04-29
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C423S600000, C524S401000, C524S436000, C524S437000, C524S441000, C524S444000
Reexamination Certificate
active
06555611
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
1. Field of the Invention
The present invention relates to an adsorbent to an aromatic hydroxy compound and a method of removing an aromatic hydroxy compound from a liquid medium containing an aromatic hydroxy compound by adsorption.
2. Prior Art of the Invention
Metal oxide particles and metal hydroxide particles such as magnesium oxide particles, aluminum hydroxide particles and hydrotalcite compound particles are nowadays used as an adsorbent to a variety of acids and alkalis. However, these metal oxide particles or metal hydroxide particles exhibit no capability of adsorption to an aromatic hydroxy compound or an amine compound, or their adsorptive capability is poor.
Of aromatic hydroxy compounds, a bisphenol compound typified by bisphenol A is not only used as a raw material for polymers such as a polycarbonate resin and an epoxy resin, but also used for a plastic polyester, an antioxidant and a vinyl chloride resin stability, and it is assumed that a worldwide output thereof exceeds approximately 1.70 million tons.
In recent years, however, it has been clearly shown that an aromatic hydroxy compound such as bisphenol A eluted from the above resins works as an endocrine disrupter to cause greatly detrimental effects on the human body and an ecosystem. Under the circumstances, investigations of rivers and underground waters have proceeded, and a government agency has reported that rivers and ground waters in many areas are contaminated with aromatic hydroxy compounds. There is another report that an aromatic hydroxy compound has been detected in tap water.
However, no report has been found at present concerning a method, an adsorbent, etc., for effectively removing the above eluted aromatic hydroxy compounds from an organic solvent.
Problems to be Solved by the Invention
It is an object of the present invention to provide an adsorbent capable of effectively removing an aromatic hydroxy compound from a water or an organic solvent containing an aromatic hydroxy compound and a use thereof.
Means to Solve the Problem
According to the present invention, there is provided adsorbents to an aromatic hydroxy compound, the adsorbent comprising composite metal oxide solid solution particles of the following formula (1) or hydrotalcite-like composite metal hydroxide particles of the following formula (2).
(Mg
y1
M
2+
y2
)
1−x
Al
x
O
1+0.5x
(1)
(Mg
y1
M
2+
y2
)
1−z
Al
z
(OH)
2+a
(A
n−
)
b
.m
H
2
O (2)
wherein M
2+
is divalent metal ion or ions of Zn
2+
and/or Ca
2+
, A
n−
is an anion having a valence of n, and y
1
, y
2
, x, z, a, b and m satisfy the following conditions.
y
1
+y
2
=1
0
<y
1
≦1
0.1
<x<
0.5
0.1
<z<
0.5
z=a+nb
a>
0.1
z
0
≦b<z
0
≦m<
2
According to the present invention, further, there is provided a method of removing an aromatic hydroxy compound in an aqueous solvent or organic solvent containing an aromatic hydroxy compound, which comprises bringing the above solvent and the adsorbent of the present invention into contact with each other to allow the adsorbent to adsorb the aromatic hydroxy compound.
The present invention will be explained in detail hereinafter.
While the mechanism of adsorption of the above adsorbent to an aromatic hydroxy compound is not clear, the present inventors' assumption is that the adsorption is ion exchanging depend on a difference between the dissociation constant of an aromatic hydroxy compound and the counterpart of the adsorbent as will be explained below.
For developing a selective adsorbent to an aromatic hydroxy compound, first, the present inventors paid attention to a height of dissociation constant (pKa) of an aromatic hydroxy compound. A typically known hydrotalcite compound of the following formula (3) generally contains, as an anion (A
n−
), a fixed amount or more of at least one anion selected from the group consisting of CO
3
2−
, SO
4
2−
, Cl
−
, NO
3
−
and CH
3
COO
−
. The typical hydrotalcite compound of the formula (3) is a considerably strong acid due to a conjugated acid based on the anion as compared with an aromatic hydroxy compound. It is therefore assumed that there is a difficulty in an aromatic hydroxy compound undergoing dissociation to ion-exchange with an anion (A
n−
) of the hydrotalcite compound (In fact, this assumption is also considered correct on the basis of Comparative Examples 1 and 2 to be described later).
(M
2+
)
1−x
Al
x
(OH)
2
(A
n−
)
x
.m
H
2
O (3)
wherein M
2+
is divalent metal ion or ions of Mg
2+
and/or Zn
2+
, An
−
is an anion having a valence of n and at least one member selected from the group consisting of CO
3
2−
, SO
4
2−
, Cl
−
, NO
3
−
and CH
3
COO
−
, x satisfies 0.1<x<0.5, and m is a positive number.
Further, it is also presumably because carbon dioxide gas is adsorbed on the crystal surface of each particle of the hydrotalcite compound of the above formula (3) that the typical hydrotalcite compound particles cannot adsorb an aromatic hydroxy compound.
For removing the anion as many as possible that inhibits the adsorption to an aromatic hydroxy compound, therefore, the present inventors have paid attention to composite metal oxide solid solution particles of the following formula (1), which are obtained by calcining the hydrotalcite compound particles of the formula (3).
(Mg
y1
M
2+
y2
)
1−x
Al
x
O
1−0.5x
(1)
wherein M
2+
is divalent metal ion or ions of Zn
2+
and/or Ca
2+
, and y
1
, y
2
and x satisfy the following conditions.
y
1
+y
2
=1
0
<y
1
≦1 (preferably 0.5
<y
1
≦1)
0.1
<x<
0.5 (preferably 0.2
≦x≦
0.4)
When the composite metal oxide solid solution particles of the above formula (1) were brought into contact with an aqueous or organic solvent containing an aromatic hydroxy compound, it was found that the aromatic hydroxy compound is efficiently adsorbed to the above solid solution particles.
The present inventors have also found that particles of a hydrotalcite-like composite metal hydroxide of the following formula (2), obtained by hydrating the composite metal oxide solid solution particles of the above formula (1), have excellent capability of adsorption to an aromatic hydroxy compound as well.
(Mg
y1
M
2+
y2
)
1−z
Al
z
(OH)
2+a
(A
n−
)
b
.m
H
2
O (2)
wherein M
2+
, y
1
and y
2
are as defined in the above formula (1), A
n−
is an anion having a valence of n, preferably at least one anion selected from the group consisting of CO
3
2−
, SO
4
2−
, Cl
−, NO
3
−
and CH
3
COO
−
, and z, a, b and m satisfy the following conditions.
0.1
<z<
0.5 (preferably 0.2
≦z≦
0.4)
z=a+nb
a>
0.1
z
(preferably
a>
0.5
z
)
0
≦b≦z
(preferably 0
≦b<
0.5
z
)
0
≦m<
2 (preferably 0
≦m≦
1)
The hydrotalcite-like composite metal hydroxide particles of the above formula (2) are a compound of which the anion (A
n−
) content is decreased to a considerable extent in view of its chemical formula as compared with the hydrotalcite compound of the above formula (3).
Advantageously, the adsorbent comprising particles of the compound of the above formula (1) or (2), provided by the present invention, has a BET specific surface area in the range of from 10 to 250 m
2
/g, preferably from 20 to 220 m
2
/g. When the specific surface area is large, the filtering rate of the adsorbent after adsorption tends to decrease. However, a decrease in the filtering rate can be overcome when the adsorbent is formed by granulation of a powder.
The composite metal oxide solid solution particles of the formula (1) in the present invention can be produced, for example, by calcining the hydrotalcite compound of the above formula (3), particularly, a hydrotalcite compound whose a
Okada Akira
Tachifuji Tomoko
Kyowa Chemical Industry Co Ltd.
Niland Patrick D.
Sherman & Shalloway
LandOfFree
Adsorbent for aromatic hydroxy compound and utilization thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Adsorbent for aromatic hydroxy compound and utilization thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adsorbent for aromatic hydroxy compound and utilization thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3003571