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Weak-acid cation exchange resin preparation

A weak acid cation, exchange resin technology, applied in the field of weak acid cation exchange resin preparation

Inactive Publication Date: 2003-01-08
ROHM & HAAS CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] The problem solved by the present invention is to overcome the disadvantages of existing methods for reducing the presence of contaminants in the final weak acid cation exchange resins from the manufacturing process while still relying on the conventional hydrolysis reaction of the crosslinked polycarboxylate resin precursors , to provide the required weak acid cation exchange resin

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 2

[0045] Using the hydrogen form of WAC, the resin was steamed according to the following procedure. The hydrogen form WAC was steamed downflow at 125-135° C. for 4 hours using 100-1000 g, typically 400-800 g of steam per 100 g of resin. The steamed resin was then backwashed with deionized water for approximately 2 hours until no fine particles were visible, and then a final downwash of 2 hours using 600 ml of deionized water per 100 g of resin. Example 3

Embodiment 3

[0046] Simulated by using a water-jug drinking water filter, and measuring the percent removal of THM (chloroform) per volume of water treated with a filter cartridge containing a weak acid cation resin (prepared as described in Example 1) and particles A mixed bed of activated carbon (GAC) was used to determine the THM removal efficiency of WAC resin. The usual source of GAC was always used to make up the mixed bed for evaluation. This approach directly addresses the effectiveness of kettle-type drinking water filters in their ability to remove THMs.

[0047] Experimental ("contaminated") water was prepared as follows. Into a clean, covered 20 liter plastic bucket, put 2.02g of CaCl 2 2H 2 O, 0.48g of MgSO 4 ·6H 2 O, 2.69 g of NaHCO 3and 16 liters of deionized water. A THM stock solution (approximately 1 ml of 1% chloroform in methanol) standardized to deliver approximately 250-400 ppb chloroform was then added, and the mixture was stirred for 10 minutes. Quickly tran...

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Abstract

An improved process for cleaning weak acid cation exchange resin intermediates resulting in finished weak acid resins providing enhanced performance of mixed-bed water-treatment systems is disclosed. The cleaning process involves selected steam treatment during the manufacturing process of the resins and is applicable to weak acid cation exchange resins in general that are used as components in potable water treatment systems, such as cartridge-water-pitcher systems.

Description

Background technique [0001] The present invention relates to an improved process for the preparation of weak acid cation exchange resins. In particular the invention relates to the cleaning of weak acid cation exchange resins derived from poly(acrylonitrile). [0002] Weak acid cation exchange resins are very useful in removing hardness ions (eg, calcium and magnesium) and certain metals (lead, mercury, copper, zinc) from drinking water. In this application, high ion exchange capacity and selectivity of weakly acidic cation exchange resins are desirable properties. Likewise, weak acid cation exchange resins in combination with activated carbon have found widespread use in portable water treatment applications, such as water-jug filter applications for potable water. It is desirable that the weak acid cation exchange resin should not release any extractable material from the resin into the treated water. These extractable materials are typically by-products from the ion exch...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J39/20B01J49/00C02F1/42C08J5/20
CPCC02F1/42B01J49/0078B01J39/20B01J49/60
Inventor J·C·博灵E·G·伦德奎斯特
Owner ROHM & HAAS CO
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