Method for removal of guanidine compound from aqueous media
View Patent ↗Disclosed is a method for removing a neutral or an ionic guanidine compound from aqueous media optionally comprising an alkali metal halide, wherein the method is selected from the group consisting of (a) adsorption onto a carbonaceous adsorbent, (b) adsorption onto a clay adsorbent, (c) filtration through a nanofiltration membrane, and (d) removal of water and calcination.
1. A method for removing a neutral or an ionic guanidine compound from aqueous media comprising less than 4 wt. % of an alkali metal halide, wherein the method consists of filtration through a nanofiltration membrane
wherein the nanofiltration membrane has a molecular weight cut-off sufficient to retain from about 70% to about 100% of the guanidine compound.
2. The method of claim 1 , wherein the guanidine compound has the formula
wherein each of R 2 , R 3 , R 4 and R 5 is independently a primary alkyl radical and R 1 is a primary alkyl or bis(primary alkylene) radical, or at least one of the R 1 -R 2 or R 3 -R 4 combinations with the connecting nitrogen atom forms a heterocyclic radical; and the value of the parameter n is 1 or 2.
3. The method of claim 1 , wherein the guanidine compound has the formula
wherein each of R 2 , R 3 , R 4 , R 5 and R 6 is independently a primary alkyl radical and R 1 a primary alkyl or bis(primary alkylene) radical, or at least one of R 2 , R 3 , R 4 , R 5 and R 6 is hydrogen, or at least one of the R 1 -R 2 , R 3 -R 4 or R 5 -R 6 combinations with the connecting nitrogen atom forms a heterocyclic radical; the moiety X is an anion; and the value of the parameter n is 1 or 2.
4. The method of claim 1 , wherein both a neutral and an ionic guanidine compound are removed from the aqueous media.
5. The method of claim 1 , wherein the concentration of guanidine compound present initially in the aqueous media ranges from about 0.5 parts per million to about 100,000 parts per million.
6. The method of claim 1 , wherein the aqueous media is free of alkali metal halide.
7. The method of claim 1 , wherein the aqueous media comprises an alkali metal halide in an amount of between about 0.01 wt. % and about 4 wt. %.
8. The method of claim 7 , wherein the alkali metal halide is selected from the group consisting of sodium chloride and potassium chloride.
9. The method of claim 1 , wherein the concentration of guanidine compound following removal is less than 30% of the initial concentration.
10. The method of claim 1 , wherein the concentration of guanidine compound following removal is less than 15% of the initial concentration.
11. The method of claim 1 , further comprising the step of recovering the guanidine compound.
12. The method of claim 1 , wherein an additional inorganic or organic component is removed in addition to the neutral or ionic guanidine compound.
13. The method of claim 12 , wherein the additional component is sodium phenylphosphinate.
14. The method of claim 13 , wherein the additional component is chlorophthalic acid.