# US 4,657,875 A · Articles of porous glass and process for preparing the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,657,875 A - Document ID: US4657875A - Status: Granted - Kind: A - Application number: 06/757,313 - Filed: 1985-07-22 - Granted: 1987-04-14 - Earliest claimed: 1984-07-31 - Assignees: Miyazaki Prefecture - Inventors: Tadao Nakashima; Masataka Shimizu; Mikio Kawano - Web page: https://patentgrep.com/patent/US4657875A ## CPC - A01K 63/042: {Introducing gases into the water, e.g. aerators, air pumps} - C02F 3/20: using diffusers - C03C 3/091: containing aluminium - C03C 11/005: {obtained by leaching after a phase separation step} - Y02W 10/10: Biological treatment of water, waste water, or sewage - A01K: ANIMAL HUSBANDRY; AVICULTURE; APICULTURE; PISCICULTURE; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) - C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS - Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT ## Abstract Porous glass product of the invention comprises about 60 to about 80% by weight of SiO.sub.2, about 7 to about 15% by weight of Al.sub.2 O.sub.3, about 6 to about 12% by weight of B.sub.2 O.sub.3, about 3 to about 7% by weight of Na.sub.2 O and about 3 to 7% by weight of CaO and having pores about 200 to about 10000 nm in size and circular in cross section. ## Claims ### Claim 1 An article of porous glass consisting essentially of about 63 to about 70% by weight of SiO.sub.2, about 10 to about 14% by weight of Al.sub.2 O.sub.3, about 8 to about 12% by weight of B.sub.2 O.sub.3, about 4 to about 6% by weight of Na.sub.2 O and about 3 to about 6% by weight of CaO. ### Claim 2 A process for preparing an article of porous glass, the process comprising the steps of heat-treating a shaped body of base glass consisting essentially of about 48 to about 52% by weight of SiO.sub.2, about 8 to about 12% by weight of Al.sub.2 O.sub.3, about 14 to about 18% by weight of B.sub.2 O.sub.3, about 5 to about 7% by weight of Na.sub.2 O and about 15 to about 18% by weight of CaO at a constant temperature of about 680.degree. to about 800.degree. C. for about 2 to about 72 hours, and dissolving out the acid-soluble component with an inorganic acid. ### Claim 3 A process for preparing an article of porous glass, the process comprising the steps of heat-treating a shaped body of base glass consisting essentially of about 48 to about 52% by weight of SiO.sub.2, about 8 to about 12% by weight of Al.sub.2 O.sub.3, about 14 to about 18% by weight of B.sub.2 O.sub.3, about 5 to about 7% by weight of Na.sub.2 O, about 7 to about 14% by weight of CaO and about 3 to about 10% by weight of MgO at a constant temperature of about 680.degree. to about 800.degree. C. for about 2 to about 72 hours, and dissolving out the acid-soluble component with an inorganic acid. ### Claim 4 (depends on 2) A process as defined in claim 2 in which the shaped product of base glass is heat-treated at about 690.degree. to about 780.degree. C. for about 2 to about 40 hours. ### Claim 5 (depends on 2) A process as defined in claim 2 in which the inorganic acid is hydrochloric acid and/or nitric acid. ### Claim 6 (depends on 2) A process as defined in claim 2 in which the inorganic acid is in the form of about 1 to about 2 N solution. ### Claim 7 (depends on 2) A process as defined in claim 2 in which the shaped body of glass heat-treated is immersed in an inorganic acid at about 50.degree. to about 100.degree. C. for about 2 to about 24 hours. ### Claim 8 (depends on 2) A process as defined in claim 2 in which prior to acid treatment, the shaped body of glass heat-treated is immersed in about 1 to about 5% solution of hydrofluoric acid at or below 20.degree. C. for about 3 to about 15 minutes. ### Claim 9 (depends on 2) A process as defined in claim 2 in which the shaped body of porous glass treated with the acid is immersed in about 0.02 to about 0.5 N aqueous solution of sodium hydroxide at or below 50.degree. C. for about 1 to about 6 hours. ### Claim 10 (depends on 3) A process as defined in claim 3 in which the shaped product of base glass is heat-treated at about 690.degree. to about 780.degree. C. for about 2 to about 40 hours. ### Claim 11 (depends on 3) A process as defined in claim 3 in which the inorganic acid is hydrochloric acid and/or nitric acid. ### Claim 12 (depends on 3) A process as defined in claim 3 in which the inorganic acid is in the form of about 1 to about 2 N solution. ### Claim 13 (depends on 3) A process as defined in claim 3 in which the shaped body of glass heat-treated is immersed in an inorganic acid at about 50.degree. to about 100.degree. C. for about 2 to about 24 hours. ### Claim 14 (depends on 3) A process as defined in claim 3 in which prior to acid treatment, the shaped body of glass heat-treated is immersed in about 1 to about 5% solution of hydrofluoric acid at or below 20.degree. C. for about 3 to about 15 minutes. ### Claim 15 (depends on 3) A process as defined in claim 3 in which the shaped body of porous glass treated with the acid is immersed in about 0.02 to about 0.5 N aqueous solution of sodium hydroxide at or below 50.degree. C. for about 1 to about 6 hours.