Kurita Water Industries Ltd.

Ikunori Yokoi

Takeo Fukui

Tetsuo Mizuniwa

Yoshiaki Ide

Yoichi Tanaka

Takaaki Chuuman

A purification method for an aqueous hydrogen peroxide solution, includes passing the aqueous hydrogen peroxide solution through a first H-form strong cation exchange resin column, a salt-form strong anion exchange resin columnand a second H-form strong cation exchange resin column. An H-form strong cation exchange resin having crosslinking of 6% or less, an H-form strong cation exchange resin having crosslinking of 9% or more, or an H-form strong cation exchange resin produced by steps (a) and (b) is used as an H-form strong cation exchange resin packed in the second H-form strong cation exchange resin column: (a) copolymerizing a monovinyl aromatic monomer with a crosslinkable aromatic monomer having a non-polymerizable impurity content of 3% by weight or less therein using a predetermined amount of a specified radical polymerization initiator at a predetermined polymerization temperature to obtain a crosslinked copolymer; and (b) sulfonating the crosslinked copolymer.

Aqueous hydrogen peroxide purification method and purification system

Contaminants present inside an ultrapure water production system are prevented from being fed into a feed pipe connected to a water use point and, after sterilization cleaning, the system is prevented from being contaminated by contaminants captured on a microparticle removal membrane during sterilization cleaning. Ultrapure water having high quality is thereby fed to a water use point within a short period of time. An ultrapure water production system is provided with a tank, a pump, a heat exchanger, an ultraviolet device, an ion-exchange device, a first microparticle removal membrane device, and a second microparticle removal membrane device. Parts of sterilization water and flush water are fed into the first microparticle removal membrane device and discharged from a feedwater-side potion to a concentrated-water-side portion without permeating through a microparticle removal membrane thereof, and the remaining part of the water is passed through the second microparticle removal membrane device.

Ultrapure water production system, ultrapure water production feed system, and method for cleaning thereof

In a method of cleaning and sterilizing an ultrapure water manufacturing system including an ultrapure water manufacturing apparatus, a point of use of ultrapure water, and an ultrapure water channel connecting the ultrapure water manufacturing apparatus and the point of use, a cleaning and sterilizing process including an alkali cleaning step for cleaning at least part of the inside of the system with alkaline solution and a sterilizing step for sterilizing the system with sterile water after the alkali cleaning is treated twice or more. By treating the cleaning and sterilizing process twice or more, metals, organic substances, particles, and bacteria inside the ultrapure water manufacturing system can be highly efficiently removed, and thereby ultrapure water satisfying required water quality can be produced within a short period of time after the cleaning and sterilizing.

Cleaning and sterilizing method for ultrapure water manufacturing system

A water quality evaluation method capable of evaluating quality of water to be evaluated with high precision and a substrate contacting apparatus used in the water quality evaluation method are provided. The substrate contacting apparatushas a sealing performance keeping the interior at a vacuum degree lower than or equal to &#x2212;0.094 MPa. A substrate W is accommodated in the substrate contacting apparatusand water to be evaluated is fed therein, after stopping feeding water, the interior of the substrate contacting apparatusis sealed, and the substrate contacting apparatusis sent to an analysis device with the substrate W accommodated therein.

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Tokyo, Japan

Ikunori Yokoi