Patent ID: 7090820

Claim:
A method of preparing a stable, non-hygroscopic potassium monopersulfate composition, the method comprising: adding an H 2 O 2 solution containing at least 70 wt. % H 2 O 2 to a H 2 SO 4 solution containing at least 90 wt. % H 2 SO 4 at a substoichiometric ratio of H 2 SO 4 :H 2 O 2 to generate a first Caro's acid solution, wherein the first Caro's acid solution contains H 2 SO 5 , and H 2 O; combining the first Caro's acid solution and oleum that contains H 2 SO 4 and SO 3 , wherein the oleum reacts with the H 2 O in the first Caro's acid solution to produce a second Caro's acid solution; adding an alkali potassium compound to the second Caro's acid solution to achieve a partially neutralized solution containing a potassium monopersulfate composition of the formula (KHSO 5 )x.(KHSO 4 )y.(K 2 SO 4 )z, where x+y+z=1 and x=0.46–0.64, y=0.15–0.37, and z=0.15–0.37, said potassium monopersulfate composition having an active oxygen content greater than or equal to 4.9 wt. % and K 2 S 2 O 8 at a concentration of <0.5 wt. % of the potassium monopersulfate composition.