# US 5,702,634 A · Aqueous system containing a synergistic combination including polyether polyamino methylene phosphates for controlling calcium carbonate and calcium phosphate scale > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,702,634 A - Document ID: US5702634A - Status: Granted - Kind: A - Application number: 08/540,271 - Filed: 1995-10-06 - Granted: 1997-12-30 - Earliest claimed: 1995-10-06 - Assignees: Calgon Corporation - Inventors: Jasbir S. Gill - Web page: https://patentgrep.com/patent/US5702634A ## CPC - C02F 5/12: containing nitrogen (C02F5/14 takes precedence) - C02F 5/10: using organic substances - C02F 5/14: containing phosphorus - 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) ## Abstract An aqueous system containing scale forming salts including both calcium carbonate and calcium phosphate and characterized by high pH and high calcite concentrations which further contains a synergistic effective amount of a combination comprising (A) a polyether polyamino methylene phosphonate, and (B) a terpolymer comprising the monomers of acrylic acid, sulfophenomethallyl ether and maleic acid, is disclosed. A method for inhibiting the formation, deposition and adherence of such scale forming salts in the aqueous system employing the synergistic combination is also provided. ## Claims ### Claim 1 An aqueous system containing scale forming salts and wherein the pH of said system is at least 8.5 and the calcite saturation level of said system is at least 100 times the solubility limit of calcium as calcite, which further contains a synergistic effective amount of a combination comprising: (A) a polyether polyamino methylene phosphonate of the formula: ##STR11## where n is, or on average is, from about 2 to about 12, inclusive; M is hydrogen or a cation of an alkali metal salt; and each R may be the same or different and is independently selected from hydrogen and methyl; and (B) a terpolymer comprising the monomers of acrylic acid, sulfophenomethallyl ether and maleic acid, wherein the weight average molecular weight for said terpolymer is in the range from about 4,000 to 10,000. ### Claim 2 (depends on 1) The aqueous system of claim 1 wherein for said polyether polyamino methylene phosphonate, M is hydrogen, each R is methyl, and n is from about 2 to 4. ### Claim 3 (depends on 2) The aqueous system of claim 2 wherein n is about 2.6. ### Claim 4 (depends on 3) The aqueous system of claim 3 wherein the aqueous system is a cycled up cooling tower. ### Claim 5 (depends on 1) The aqueous system of claim 1 wherein said terpolymer is about 84 weight average molecular weight percent acrylic acid, about 8 weight average molecular weight percent sulfophenomethallyl ether, and about 8 weight average molecular weight percent maleic acid. ### Claim 6 (depends on 1) The aqueous system of claim 1 wherein the weight ratio of (A):(B) ranges from about 1:2 to about 5:2. ### Claim 7 (depends on 1) The aqueous system of claim 1 wherein said (A) polyether polyamino methylene phosphonate is present in said aqueous system to establish a concentration of at least 6.0 mg/L. ### Claim 8 (depends on 1) The aqueous system of claim 1 wherein said (B) terpolymer is present in said aqueous system to establish a concentration of at least 4.0 mg/L. ### Claim 9 (depends on 8) The aqueous system of claim 8 wherein said (A) polyether polyamino methylene phosphonate is present in said aqueous system to establish a concentration of at least 25 mg/L, wherein said aqueous system is characterized by a calcite saturation level of at least 150 times the solubility limit of calcium as calcite. ### Claim 10 (depends on 1) The aqueous system of claim 1 additionally including a stabilizer for preventing decomposition of said (A) polyether polyamino methylene phosphonate. ### Claim 11 (depends on 10) The aqueous system of claim 10 wherein said stabilizer is monoethanolamine. ### Claim 12 (depends on 1) The aqueous system of claim 1 additionally including a corrosion inhibitor. ### Claim 13 (depends on 12) The aqueous system of claim 12 wherein said corrosion inhibitor is a copper corrosion inhibitor. ### Claim 14 (depends on 13) The aqueous system of claim 13 wherein said copper corrosion inhibitor is tolyltriazole. ### Claim 15 (depends on 13) The aqueous system of claim 13 additionally including a stabilizer for preventing decomposition of said (A) polyether polyamino methylene phosphonate. ### Claim 16 (depends on 15) The aqueous system of claim 15 wherein said stabilizer is monoethanolamine.