Liquid purification or separation – Filter – Material
Patent
1982-05-17
1983-11-08
Van Balen, William J.
Liquid purification or separation
Filter
Material
210638, 428141, 4283179, 428336, 428338, 521 27, 521 32, B05D 310, B05D 500
Patent
active
044141114
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a shaped composite adsorbent for removal or recovery of relatively low molecular weight substances from a large quantity of solution which contains impurities of relatively large-sized molecules such as colloids and the like, or for selective removal or recovery of specific solutes from a large quantity of low concentration solution, and also relates to a process for preparing the same. More particularly, the present invention is concerned with a shaped composite adsorbent made of a shaped porous material of a skin-core structure comprising a powdery ion-exchange type adsorbent and an ionic group-containing acrylonitrile polymer, and also concerned with a process for preparing the same.
DESCRIPTION OF THE PRIOR ARTS
To remove harmful substances or recover useful substances from a large quantity of solution, there may be employed sedimentation, floatation, filtration, coagulation, adsorption, dialyzation and other methods. Among them, adsorption is generally utilized as a method for removing or recovering relatively low molecular weight substances such as heavy metal ions, ammonia, pigments, surface active agents or the like from a low concentration solution in high yield. The adsorbents to be used for adsorption include an activated charcoal, an ion exchange resin, a zeolite, an activated alumina, a silicate and the like. Adsorptivity of each of these adsorbents is dependent heavily on the physicochemical affinity between the surface of the adsorbent and the solute, and on the effective surface area of the adsorbent. Accordingly, with a view to developing an adsorbent of improved adsorptivity, there has been made an attempt to enlarge the effective surface area of an adsorbent in addition to a physicochemical treatment of the surface of an adsorbent. To enlarge the effective surface area of an adsorbent, there is generally employed a measure of minimizing the grain size of the adsorbent or increasing the porosity thereof. An attempt for minimizing the grain size of an adsorbent is restricted, because a problem may arise in handling during the step of the adsorption operation. Moreover, a solution to be subjected to adsorption operation may contain a large quantity of colloidal substances having a property to be readily adsorbed onto the surface of the finely-granulated or microporous adsorbent. Such colloidal substances present in a solution tend to be adsorbed onto the surface of the adsorbent, thereby causing the adsorption capacity of the adsorbent to be lowered.
In order to cope with these problems, there was proposed in Japanese Patent Application Laid-Open Specification No. 50-70288 a method wherein the surface of the adsorbent in the form of granules is coated with a hydrophilic group-containing polymeric material. Further, in Japanese Patent Application Laid-Open Specification Nos. 50-80985 and 52-63189, there were proposed methods in which a solution having an organic polymer, inclusive or acrylonitrile polymer, dissolved therein and having a powdery adsorbent dispersed therein is extruded into a coagulating liquid to effect coagulation-shaping thereof. The characteristic feature common to these methods is that the surface of the adsorbent is coated with a semi-permeable coating layer of a polymeric material which is capable of passing therethrough low molecular substances. It is expected that these methods are effective for providing an adsorbent which is capable of preventing lowering of adsorption capacity caused by direct adherence of colloidal substances to the surface of the adsorbent, and are effective for simplification and expedition of the handling of the finely granulated absorbent. However, due to the presence of the semi-permeable coating layer on the surface thereof, the shaped adsorbent obtained by these methods is inevitably accompanied by lowering of the rate of adsorption which the adsorbent inherently has.
DISCLOSURE OF THE PRESENT INVENTION
With a view to giving a solution to this problem, the present inventors made intens
REFERENCES:
patent: 4265959 (1981-05-01), Sano et al.
patent: 4360434 (1982-11-01), Kawaguchi et al.
Inoue Akio
Iwaisako Toshiyuki
Asahi Kasei Kogyo Kabushiki Kaisha
Van Balen William J.
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