Oxone™ PS - 16 is a registered trademark for Potassium Monopersulfate (KMPS) of LANXESS AG. Oxone™ monopersulfate compound is a white, granular, free-flowing peroxygen that provides powerful non-chlorine oxidation for a wide variety of industrial and consumer uses. The active ingredient of Oxone™ is potassium peroxymonosulfate, KHSO5 (CAS 10058-23-8), commonly known as potassium monopersulfate, which is present as a component of a triple salt with the formula 2KHSO5•KHSO4•K2SO4 (pentapotassium bis(peroxymonosulphate) bis(sulphate), [CAS 70693-62-8]). The oxidizing power of Oxone™ is derived from its peracid chemistry; it is the first neutralization salt of peroxymonosulfuric acid H2SO5 (also known as Caro’s acid).
The standard electrode potential (E°) of KHSO5 is given by the following half-cell reaction: HSO5 + 2H++ 2e- HSO4 + H2O E0 = 1.85V
The thermodynamic potential is high enough for many room temperature oxidations, including:
Figure 1: Effect of Storage Temperature on Long-Term Stability of Acidic Oxone™ Solutions (120 g/L, pH 1.6)
Figure 2: Effect of pH on Oxone™ Solution Stability
(3 wt% Solution at 32°C [90°F])
Oxone™ is a very stable peroxygen in the solid state and loses less than 0.5% (relative) of its activity per month when stored under recommended conditions. However, like all other peroxygens, Oxone™ undergoes very slow disproportionation with the liberation of heat and oxygen gas.
If a decomposition is associated with high temperature, decomposition of the constituent salts of Oxone™ may generate sulfuric acid, sulfur dioxide, or sulfur trioxide.
The stability is reduced by the presence of small amounts of moisture, alkaline chemicals, chemicals that contain water of hydration, transition metals in any form, and/or any material with which Oxone™ can react. Because the decomposition of Oxone™ is exothermic, the decomposition can self-accelerate if storage conditions allow the product temperature to rise (see Product Safety and Handling bulletin).
Aqueous solutions of Oxone™ are relatively stable when made up at the unmodified pH of the product (Figure 1). The stability is adversely affected by higher pH, especially above pH 7. A point of minimum stability exists at about pH 9, at which the concentration of the mono-anion HSO5 - is equal to that of the di-anion SO5 2- (Figure 2). Cobalt, nickel, iron and manganese are particularly strong catalysts for the decomposition of Oxone™ in solution; the degree to which catalysis occurs is dependent on the concentrations of Oxone™ and the metal ion.
Oxone™ is available in both granular and liquid* forms. By screening, grinding, or compaction/granulation processing, several granular grades (MPS CMP, PS - 16, and CG) are produced that differ in particle size distribution (Table 3). Liquid products are specially formulated to optimize active oxygen stability. Please contact LANXESS Sales and Support or an Oxone™ technical representative for more information and guidance about which grade of product is best suited for your specific application. *Liquid availability is region-dependent.
Oxone™ is highly and readily soluble in water as shown in Table 2. At 20°C (68°F), the solubility of Oxone™ in water is >250 g/L. At concentrations above saturation, potassium sulfate will precipitate, but additional active component, potassium peroxymonosulfate, will remain in solution.
Table 1*: Oxone™ Physical Properties and Typical Analysis
| Molecular Weight (Triple Salt) | 614.7 |
| Active Oxygen | |
| Min. % | 4.5 |
| Typical Analysis % | 4.7 |
| Theoretical % (Triple Salt) | 5.2 |
| Active Component KHSO5 | |
| Min. % | 42.8 |
| Typical % | 44.7 |
| pH, 25°C (77°F) | |
| 1% solution | 2.3 |
| 3% solution | 2.0 |
| Solubility, g/100 cc H2O, 20°C (68°F) | 29.8 |
| Loss on Drying at 60°C (140°F), Max. % | 0.1 |
| Stability | |
| % active oxygen loss/month | <0.5 |
| Standard Electrode Potential (E°), V | +1.85 |
| Heat of Decomposition | |
| kJ/kg | 251 |
| Btu/lb | 108 |
| Thermal Conductivity | |
| W/m•K | 0.161 |
| Btu•ft/h•ft2•F | 0.093 |
| Purity, % | 90.3 |
Table 2*: Aqueous Solubility of Oxone™ Monopersulfate Compound
| ° C | ° F | g/100cc H2O | wt% | g/L |
|---|---|---|---|---|
| 0 | 32 | 11.0 | 9.9 | 106 |
| 5 | 41 | 15.1 | 13.1 | 144 |
| 10 | 50 | 20.8 | 17.2 | 197 |
| 20 | 68 | 29.8 | 23.0 | 277 |
| 30 | 86 | 34.0 | 25.4 | 307 |
| 40 | 104 | 42.0 | 29.6 | 357 |
| 50 | 122 | 43.6 | 30.4 | 375 |
| 60 | 140 | 46.0 | 31.5 | 387 |
Table 3: Typical Bulk Density* and Particle Size Specification of Oxone™ Product Grades
| MPS CMP | PS - 16 | CG | |
| Bulk Density | |||
| lb/ft3 | 72 - 79 | 75 - 87 | 56 - 75 |
| g/cm3 | 1.15 - 1.27 | 1.20 - 1.40 | 0.90 - 1.20 |
| Particle size, % Pass Thru (or % Retained, where specified) | |||
| # 14 (1410 µm) | - | - | 0 - 4 (% Retained) |
| # 16 (1180 µm) | - | 99 - 100 | - |
| # 20 (850 µm) | 100 | 80 - 100 | - |
| # 30 (600 µm) | 95 - 100 | 63 - 100 | - |
| # < 70 (210 µm) | - | - | 0 - 4 |
| # 100 (150 µm) | 5 - 35 | 5 - 33 | |
| # 200 (75 µm) | 0 - 10 | 0 - 10 | - |
| # 325 (45 µm) | 0 - 5 | 0 - 3 | - |
Active Oxygen/Active Component
% active component (KHSO5) = % active oxygen/0.1053
Low concentrations of Oxone™ (approx. 0–20 ppm), which are commonly used in swimming pool treatments, can be measured in the presence of active chlorine by special test kits offered by Taylor (Model K-1518, Model K-1520) and Lamotte (Model 3330-01). Taylor (Model K-1518) is a titrimetric test kit, whereas Taylor (Model K-1520) and Lamotte (Model 3330-01) are colorimetric.
In the absence of active chlorine, low concentrations of Oxone™ can be measured with a standard DPD-4 test kit; the result must be multiplied by 5.0 to obtain the correct Oxone™ concentration in ppm.
In higher concentrations, Oxone™ can be measured by addition of a known quantity of ferrous ammonium sulfate (in excess), followed by back-titration with standardized potassium permanganate or ceric sulfate solution.