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
2001-02-08
2003-03-11
Sanders, Kriellion A. (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...
C524S423000, C524S435000, C524S437000, C524S850000, C523S001000
Reexamination Certificate
active
06531531
ABSTRACT:
TECHNICAL FIELD
The present invention relates to the method and composition of a hydrophilic polymer dispersion containing an inorganic flocculant to be used for the treatment of waste water. More particularly, it relates to the method and composition of a hydrophilic polymer dispersion containing an inorganic flocculant, which has the properties of declining and reducing the water content of flock as well as water content of sludge cake obtained after treating the waste water.
BACKGROUND ART
It has been recognized that the reduction of water content of sludge cake in the waste water is an important technical matter for protecting the environmental contamination. Especially, the reduction of industrial waste and waste water sludge becomes an important matter for the environment. The reduction of sludge has an advantage of the efficient development of land by minimizing the waste treatment space.
To minimize the content of water in the sludge, the method using thermal energy has been used. However, it has a lot of drawbacks to require high energy together with high operation cost. Accordingly, the use of flocculant to treat the waste water has been considered as an efficient method for treating the waste water.
The method of flocculation using a flocculant can be explained by following mechanism. Firstly, colloidal particles are enhanced to be coagulated by the addition of inorganic flocculant in the waste water; secondly, the coagulated particles become larged by the influence of flocculant; lastly, the flocculated particles are separated by the difference of sedimental velocity or floating velocity in the waste water.
In the waste water having metal hydroxide, the anionic flocculant is desirable, whereas the cationic flocculant is desirable in the waste water having sulfur compound or clay. Further, the anionic flocculant is effective for treating the water in the neutral waste water.
Recently, the technology using polymer flocculant has been developed. The polymer flocculant used for the treatment of colloidal materials in waste water is high molecular weight compound, and it neutralizes and collects the suspended particles. Further, the polymer flocculant is classified into following groups: i) anionic polymer flocculant, such as, sodium alginate, sodium polyacrylate, salt of maleic acid copolymer, partly hydrolyzed salt of polyacrylamide, ii) cationic polymer flocculent, such as, acrylate, methacrylate, hydrophilic aniline resin hydrochloride salt, polythiourea hydrochloride salt, polyethylene amino triazole, polyvinyl benzyl trimethyl ammonium fluoride, chitosan, polyethylene amine, vinylpyridine copolymer, and iii) nonionic polymer flocculent, such as, starch, hydrophilic urea resin, polyacrylamide, polyoxyethylene.
Generally, it has been reported that the polymer flocculant forms the flock induced by bridging between colloid particle and polymer flocculant according to the force between them. The commercially marketed polymer flocculant has molecular weight in the range of 10,000~10,000,000.
The commercially marketed product contains the polymer or copolymer of quaternary acrylate, dimethyl diallyl ammonium chloride, tertiary acrylate and acrylamide.
The flocculation by the polymer flocculant depends upon the degree of linear polymerization of the polymer flocculant, that is, molecular weight and ionic density. Further, the degree of polymerization is controlled by condition of polymerization, whereas the ionic density is controlled by molar ratio of cationic monomer.
Generally, the polymer flocculant having high degree of polymerization makes a large flock, and the polymer flocculant having strong ionic density raises a strength of flock. Also, there is a correlation between degree of polymerization and ionic density, so that the higher molecular weight of polymer flocculant becomes, and the lower ionic density of polymer flocculant becomes.
The flock formed by single injection of the polymer flocculant contains a large amount of water. Therefore, it requires additional steps for lowering water content of the flock. However, it has some limitation for fully drying the flock, because the flock has hygroscopic property in itself.
The water content of the flock can influence the water content of dehydrated sludge cake, which is removed and reclaimed. The smaller water content of the sludge cake induces the smaller amount of cake, which causes the efficient treatment of the sludge. Further, such smaller cake sludge saves the cost for removing and reclaiming it.
The aqueous dispersions of water-soluble nonionic and anionically charged vinyl and allyl addition polymers were disclosed in WO 97/34933. Also, they can be obtained by polymerizing in the presence of an anionically charged water-soluble polymer stabilizer in a saturated salt solution.
Further, the polymerization process of preparing a water-soluble polymer in the form of a water-continuous dispersion was described in European Pat. 0 630,909 A1. In this process, the peak in-production viscosity developed in the aqueous reaction mixture is lower than the peak in-production viscosity developed in an equivalent batch polymerization.
For forming dialkylaminoalkyl (meth)acrylamide polymer dispersions, a novel dispersant system was disclosed in U.S. Pat. No. 5,597,859. Further, European Pat. 0 839,767 A2 suggested a method for clarifying ink-laden water obtained from the recycling of paper stocks by treating said water with a conventional coagulant followed by treatment with a hydrophilic dispersion polymer. In this method, the hydrophilic dispersion flocculant is a copolymer of DMAEA·MCQ [dimethylaminoethyl (meth)acrylate methyl chloride quaternary] and (meth)acrylamide.
The improved process for the preparation of water soluble polymer dispersion was disclosed in European Pat. 0 657,478 A2.
However, none of prior references discloses the far enhanced waste water treatment activity compared to formerly developed hydrophilic polymer dispersion.
DISCLOSURE OF INVENTION
The present invention relates to a hydrophilic polymer dispersion composition containing an inorganic flocculant and a method for preparing such composition which comprises the following steps of: i) mixing acrylamide, cationic monomer, anionic monomer, polymer of cationic monomer, anionic salt and inorganic flocculant, ii) 1st-polymerizing the mixture obtained in previous step, iii) 2nd-polymerizing the 1st-polymerized mixture containing unreacted monomers completely, and iv) adding and mixing anionic salt to obtained polymers.
Further, the hydrophilic polymer dispersion containing an inorganic flocculent of the present invention is prepared by following steps of: i ) mixing 1.0~25 wt % of acrylamide, 0~2 wt % of anionic monomer selected from the group consisting of acrylic acid, methacrylic acid and itaconic acid, 1.0~30 wt % of cationic monomer mixture of compound of formula I and formula II, 0.5~5 wt % of polymer selected from the group consisting of homopolymer of compound of formula I, homopolymer of compound of formula II and copolymer of compound of formula I and formula II, 10~30 wt % of anionic salt, 1~10 wt % of inorganic flocculant, 0.01~1 wt % of nonionic surfactant, 0.05~2 wt % of dispersion stabilizer and 40~75 wt % of water;
ii) 1st-polymerizing the mixture in addition to 0.001~0.1 wt % of polymerization initiator to said mixture;
iii) 2nd-polymerizing the 1st-polymerized mixture containing unreacted monomers completely ; and
iv) adding and mixing 10~30 wt % of anionic salt to obtained polymers.
wherein
R
1
is hydrogen atom or methyl
R
2
and R
3
are each independently alkyl group having 1 to 3 carbon atoms
A
1
is oxygen atom or NH;
B
1
is alkylene group having 2 to 4 carbon atoms or hydroxypropylene; and
X
1
is anionic counter ion.
wherein
R
4
is hydrogen atom or methyl
R
5
and R
6
are each independently alkyl group having 1 to 2 carbon atoms
R
7
is hydrogen atom or alkyl group having 1 to 2 carbon atoms
A
2
is oxygen atom or NH;
B
2
is alkylene group having 2 to 4 carbon atoms or hydroxypropylene ; and
X
2
Green Technology Inc.
Sanders Kriellion A.
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