Stable salt-free polyaluminum chlorosulfates
View Patent ↗Highly sulfated, high basicity polyaluminum chlorosulfate compositions that can be made by mixing dry aluminum hydroxychloride with a solution of aluminum sulfate or by diluting a dry mixture of aluminum hydroxychloride and aluminum sulfate with water.
1. Polyaluminum chlorosulfate (PACS) having a basicity of 55 to 75% and formula (I):
Al(OH) x Cl (3-x-2y) (SO 4 ) y (I)
wherein 1.78<x<2.02, 0.03<y<0.45, and 1.8<x+y/2<2.1;
Al:SO 4 =2 to 34; Al:Cl=0.9 to 3.0, Al:OH=0.5 to 0.6; and
the average molecular weight of the PACS is greater than or equal to 95 and less than or equal to 111, and
wherein salts present in the PACS comprise 0-1.0% sodium chloride by weight and 0-1.0% sodium sulfate by weight.
2. The PACS of claim 1 , further comprising a sulfate content of 0.5-13% by weight in solution or 2.0-30% by weight in a dry state.
3. The PACS composition of claim 1 , wherein:
x=1.78 to 1.82; 3−x−2y=0.35 to 1.1; y=0.065 to 0.45; and x+y/2=1.83 to 2.02; or
x=1.95 to 2.02; 3−x−2y=0.6 to 1.0; y=0.03 to 0.20; and x+y/2=1.95 to 2.1.
4. A process for producing the polyaluminum chlorosulfate (PACS) of claim 1 , said process comprising:
a) providing solid aluminum hydroxychloride and aqueous aluminum sulfate;
b) mixing said aluminum hydroxychloride with said aqueous aluminum sulfate to form an aqueous milky suspension, wherein, on a dry weight basis, the ratio of said aluminum hydroxychloride to said aluminum sulfate is 0.75-20 parts aluminum hydroxychloride to 1 part aluminum sulfate; and
c) maintaining the milky suspension of step b) for a period sufficient to allow said milky suspension to form a clear to slightly turbid solution.
5. The process of claim 4 , wherein, in step b), 62-83% basic solid aluminum hydroxychloride is added to said aqueous aluminum sulfate solution to form said aqueous milky suspension.
6. The process of claim 4 , wherein said process is carried out at a temperature of 5-50 degrees centigrade.
7. The process of claim 4 , wherein said process is carried out at a temperature of 10-40 degrees centigrade.
8. The process of claim 4 , wherein said clear solution is formed in step c) by mixing said milky suspension while gradually increasing its temperature until the clear solution is obtained.
9. A process according to claim 4 , wherein said aluminum hydroxychloride has 1.5 or less moles of hydration.
10. A process according to claim 9 , wherein said aluminum hydroxychloride has 1.0 or less moles of hydration.
11. A process for producing the polyaluminum chlorosulfate (PACS) of claim 1 , said process comprising:
a) providing a dry mixture of solid aluminum sulfate and solid aluminum hydroxychloride in an amount sufficient to provide a ratio on a dry weight basis, of said aluminum hydroxychloride to said aluminum sulfate of about 0.75-20 parts aluminum hydroxychloride to 1 part aluminum sulfate;
b) dissolving said dry mixture in water to form a milky suspension; and
c) maintaining the milky suspension of step b) for a period of time sufficient to allow said suspension to form a clear to slightly turbid solution.
12. The process of claim 11 , wherein said process is carried out at a temperature of 5-50 degrees centigrade.
13. The process of claim 11 , wherein said process is carried out at a temperature of 10-40 degrees centigrade.
14. The process of claim 11 , wherein the clear solution is formed in step (c) by mixing said milky suspension while gradually increasing its temperature until the clear solution is obtained.
15. A process according to claim 11 , wherein said aluminum hydroxychloride has 1.5 or less moles of hydration.
16. The process of claim 11 , wherein said ratio of aluminum hydroxychloride to aluminum sulfate is 5-10 or 10-20 parts aluminum hydroxychloride to one part aluminum sulfate.
17. The process of claim 11 , wherein said dry mixture provides a ratio of said aluminum hydroxychloride to said aluminum sulfate of about 5-10 parts aluminum hydroxychloride to 1 part aluminum sulfate.
18. The process of claim 11 , wherein said dry mixture provides a ratio of said aluminum hydroxychloride to said aluminum sulfate of about 10-20 parts aluminum hydroxychloride to 1 part aluminum sulfate.
19. A PACS according to claim 1 , wherein the polyaluminum chlorosulfate is dry.
20. A PACS according to claim 1 , comprising 14-38% Al 2 O 3 and a basicity of 55-70%.
21. A PACS according to claim 1 , having a basicity of 55-70% and a ratio of Al to SO 4 of 2-3.0.
22. A PACS according to claim 1 , wherein said aluminum hydroxychloride has 1.0 or less moles of hydration.
23. A premixed package of polyaluminum chlorosulfate for the treatment of wastewater, said package comprising:
a) a dry, pre-mixed amount of the PACS of claim 1 , said PACS comprising 0.75-20 parts aluminum hydroxychloride to 1 part aluminum sulfate, said aluminum hydroxychloride having 1.5 mole of hydration or less; and
b) instructions for using said dry, pre-mixed composition in the treatment of wastewater.
24. The PACS of claim 1 in solution, comprising 15-16 wt % Al 2 O 3 , 60-66% basicity; and 2-7% sulfate.
25. The PACS of claim 1 , comprising 38 wt % Al 2 O 3 , 66-70% basicity; and 6% sulfate.
26. The PACS of claim 1 , wherein said PACS composition has the following formula: Al(OH) 1.83 Cl 0.75 (SO 4 ) 0.21 or Al(OH) 2.01 Cl 0.93 (SO 4 ) 0.03 .
27. A method for treating water to remove impurities, said method comprising:
a. adding the PACS composition of claim 1 to said water to coagulate and flocculate impurities; and
b. separating the coagulated and flocculated impurities from the treated water to produce a treated water reduced in impurities.
28. The method of claim 27 , wherein said PACS composition comprises formula (I): Al(OH) x Cl (3-x-2y) (SO 4 ) y , wherein:
a) 1.78≦x≦2.02, and 0.03≦y≦0.45, and 1.8≦x+y/2≦2.1;
b) Al:SO 4 =2 to 34; Al:Cl=0.9 to 1.3; Al:OH=0.5 to 0.6;
c) % Basicity=55 to 70%; and
d) the average molecular weight of said PACS is greater than or equal to 95 and less than or equal to 111.
29. The method of claim 28 , wherein:
x=1.78 to 1.82; 3−x−2y=0.35 to 1.1; y=0.065 to 0.45; and x+y/2=1.83 to 2.02; or
x=1.95 to 2.02; 3−x−2y=0.6 to 1.0; y=0.03 to 0.20; and x+y/2=1.95 to 2.1.
30. Polyaluminum chlorosulfate (PACS), made by the process of:
a) mixing solid aluminum hydroxychloride having 1.5 or less moles of hydration with an aqueous aluminum sulfate solution to form an aqueous milky suspension, wherein, on a dry weight basis, the ratio of aluminum hydroxychloride to aluminum sulfate is 0.75-20 parts aluminum hydroxychloride to 1 part aluminum sulfate; and
b) maintaining the milky suspension of step a) for a period of time sufficient to allow said milky suspension to form a clear or slightly turbid solution;
wherein said PACS comprises a sulfate content of 0.5-13% by weight of said composition in solution, or of 2.0 to 30% by weight of said composition in a dry state, and a basicity of 55 to 75%; and
wherein salts present in the PACS comprise 0-1.0% sodium chloride by weight and 0-1.0% sodium sulfate by weight.