# US 12,005,399 B2 · Desalination performance restoration agent for cellulose acetate membrane and desalination performance restoration method for cellulose acetate membrane > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,005,399 B2 - Document ID: US12005399B2 - Status: Granted - Kind: B2 - Application number: 17/633,758 - Filed: 2020-10-20 - Published: 2022-11-10 - Granted: 2024-06-11 - Earliest claimed: 2019-10-24 - Assignees: Mitsubishi Heavy Industries, Ltd.; Kyoeisha Chemical Co., Ltd. - Applicants: Mitsubishi Heavy Industries, Ltd.; Kyoeisha Chemical Co., Ltd. - Inventors: Takayoshi Hori; Katsunori Matsui; Sho Yokogawa; Yoshiaki Ito; Ryo Kamito; Yoshihisa Katsunishi; Atsuyoshi Ueda; Takahiro Masui - Web page: https://patentgrep.com/patent/US12005399B2 ## CPC - B01D 65/06: with special washing compositions - B01D 67/00: Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus - B01D 69/12: Composite membranes; Ultra-thin membranes - B01D 71/16: Cellulose acetate - B01D 2321/162: Use of acids - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) ## Abstract A desalination performance restoration agent for a cellulose acetate membrane contains: a solvent; and a modified polyvinyl alcohol mixed in the solvent. The modified polyvinyl alcohol has an acetyl group structure in at least part of polyvinyl alcohol. ## Claims ### Claim 1 An agent comprising: a solvent, a modified polyvinyl alcohol mixed in the solvent, an organic acid, and a salt of the organic acid, wherein the modified polyvinyl alcohol has an acetyl group structure in at least part of polyvinyl alcohol, and wherein the organic acid is selected from the group consisting of glycolic acid, diglycolic acid, oxydisuccinic acid, carboxymethyloxysuccinic acid, citric acid, lactic acid, tartaric acid, oxalic acid, malic acid, gluconic acid, adipic acid, sveric acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraminehexacetic acid, and mixtures thereof. ### Claim 2 (depends on 1) The agent according to claim 1, wherein degree of acetylation of the modified polyvinyl alcohol is 1% or more. ### Claim 3 (depends on 2) The agent according to claim 2, wherein degree of acetylation of the modified polyvinyl alcohol is 15% or more. ### Claim 4 (depends on 2) The agent according to claim 2, wherein degree of acetylation of the modified polyvinyl alcohol is 30% or less. ### Claim 5 (depends on 1) The agent according to claim 1, wherein pH of the agent is in a range of 3 to 8. ### Claim 6 (depends on 1) The agent according to claim 1, further comprising an inorganic salt. ### Claim 7 (depends on 1) A desalination performance restoration method for a cellulose acetate membrane, comprising a step of bringing the agent according to claim 1 into contact with a cellulose acetate membrane, wherein the agent is a desalination performance restoration agent. ### Claim 8 (depends on 7) The desalination performance restoration method for a cellulose acetate membrane according to claim 7, wherein the agent has a degree of acetylation of 1% or more. ### Claim 9 (depends on 8) The desalination performance restoration method for a cellulose acetate membrane according to claim 8, wherein the agent has a degree of acetylation of 15% or more. ### Claim 10 (depends on 8) The desalination performance restoration method for a cellulose acetate membrane according to claim 8, wherein, in the step, the modified polyvinyl alcohol has a degree of acetylation such that a clouding up point, which is a temperature at which the modified polyvinyl alcohol begins to coarsen in the solvent of the desalination performance restoration agent, is higher than a temperature of the agent. ### Claim 11 (depends on 8) The desalination performance restoration method for a cellulose acetate membrane according to claim 8, wherein, in the step, the modified polyvinyl alcohol has a degree of acetylation such that a clouding up point, which is a temperature at which the modified polyvinyl alcohol begins to coarsen in the solvent of the desalination performance restoration agent, is in a range from a lower limit to an upper limit based on a degree of acetylation where the clouding up point is equal to a temperature T of the agent, and wherein the upper limit is a degree of acetylation where the clouding up point is (T−40)° C., and the lower limit is a degree of acetylation where the clouding up point is (T+50)° C. ### Claim 12 (depends on 8) The desalination performance restoration method for a cellulose acetate membrane according to claim 8, wherein agent has a degree of acetylation of 30% or less. ### Claim 13 (depends on 7) The desalination performance restoration method for a cellulose acetate membrane according to claim 7, wherein the agent has a pH of 3 to 8. ### Claim 14 (depends on 7) The desalination performance restoration method for a cellulose acetate membrane according to claim 7, wherein the agent further contains an organic acid and a salt of the organic acid. ### Claim 15 (depends on 7) The desalination performance restoration method for a cellulose acetate membrane according to claim 7, wherein the agent further contains an inorganic salt. ### Claim 16 (depends on 1) A desalination performance improvement method for a cellulose acetate membrane, comprising a step of bringing the agent according to claim 1 into contact with an unused cellulose acetate membrane. ### Claim 17 (depends on 1) The agent according to claim 1, further comprising an inorganic salt, wherein the inorganic salt is selected from the group consisting of salt of hydrochloric acid, salt of sulfuric acid, salt of nitric acid, sodium chloride, and mixtures thereof.