Filter, metal ion removing method, and metal ion removing apparatus

1. A method for removing metal ions in a solution to be treated containing a compound having an acidic group, the method comprising:

an addition step of adding a strong base to the solution to be treated; and

a passage step of allowing the solution to be treated with the added strong base to pass through a filter comprising a porous molding, the porous molding being a sintered product of mixed powder containing dry gel powder including an ion exchange resin and thermoplastic resin powder, or a swelled body of the sintered product, and when water having an electric resistivity value of 18 MΩ·cm or more is allowed to pass through the filter at a space velocity of 1200 hr−1, the electric resistivity value of water after passage is 15 MΩ·cm or more.

2. The removing method according to claim 1 , wherein the compound having the acidic group includes at least one type selected from a group consisting of a phenol resin, an acrylic resin, an epoxy resin, a silicone resin, and monomers that are raw materials for these resins.

3. The removing method according to claim 1 , wherein an equivalent ratio of the strong base to the acidic group in the solution to be treated is 1.0×10−9 or more and 1.0×10−4 or less.

4. The removing method according to claim 1 , wherein

the passage step includes:

a first passage step of allowing the solution to be treated to pass through a first filter; and

a second passage step of allowing the solution to be treated subjected to the first passage step to pass through a second filter, and the second filter comprises a porous molding, the porous molding being a sintered product of mixed powder containing dry gel powder including an ion exchange resin and thermoplastic resin powder, or a swelled body of the sintered product, and when water having an electric resistivity value of 18 MΩ·cm or more is allowed to pass through the second filter at a space velocity of 1200 hr−1, the electric resistivity value of water after passage is 15 MΩ·cm or more.

5. The removing method according to claim 4 , wherein the first filter includes a porous molding, the porous molding being a sintered product of mixed powder containing dry gel powder including an ion exchange resin and thermoplastic resin powder, or a swelled body of the sintered product.

6. The removing method according to claim 5 , wherein

the ion exchange resin in the second filter includes a sulfonic group, and

the ion exchange resin in the first filter includes at least one type of group selected from a group consisting of an aminophosphate group, an iminodiacetic acid group, and a tertiary amino group.

7. A metal ion removing apparatus comprising:

a first filter comprising a porous molding, the porous molding being a sintered product of mixed powder containing dry gel powder including an ion exchange resin including at least one type of group selected from a group consisting of an aminophosphate group, an iminodiacetic acid group, and a tertiary amino group and thermoplastic resin powder, or a swelled body of the sintered product; and

a second filter for removing metal ions from solution to be treated that has passed through the first filter,

the second filter comprising a porous molding, the porous molding being a sintered product of mixed powder containing dry gel powder including an ion exchange resin including a sulfonic group and thermoplastic resin powder, or a swelled body of the sintered product, and when water having an electric resistivity value of 18 MΩ·cm or more is allowed to pass through the filter at a space velocity of 1200 hr−1, the electric resistivity value of water after passage is 15 MΩ·cm or more.