| abstract |
A one step process providing timed exposure to a substantially constant concentration of hypochlorite disinfectant is described, said process being completed when the hypochlorite is destroyed in an autocatalytic reaction with thiosulfate. The hypochlorite lifetime is precisely controlled by adjusting the initial pH of an alkaline disinfection solution of thiosulfate and hypochlorite, said solution containing a molar ratio of between 0.25 and 0.75 moles of thiosulfate to 1.00 mole of hypochlorite. Subsequently, with gradual evolution of acid and decreasing pH, the acid-dependent autocatalytic oxidation of thiosulfate is accelerated. This consumes the hypochlorite in a brief time interval, terminating the disinfection process. Also included in said alkaline disinfection solution is an appropriate concentration of Na2HPO4 or other chemical which is unreactive with hypochlorite and allows said initially alkaline pH to substantially decrease, but which later becomes a functioning pH buffer, controlling the final pH of the hypochlorite-free, disinfected solution. Completion of the disinfection process which is accompanied by a substantial pH decrease can be visualized by including one or more pH-color indicators in the disinfecting solution. |