| 摘要 |
One difficulty which has been encountered due to high levels of electrolyte in hypochlorite solutions is the crystallisation of the electrolyte as a solid salt around the caps of containers. More seriously, hypochlorite is both unstable on storage and corrosive to metals, hence hypochlorite shelf life is limited due to the progressive decomposition of the hypochlorite ion. Much more seriously, when acids are added to hypochlorites in amounts such that the pH falls below 4, chlorine gas is evolved into the environment. It is very well known that even low concentrations of elemental chlorine gas can present an acute and potentially lethal hazard to health and a longer term environmental hazard. Surprisingly we have determined that, in the absence of or at reduced levels of chloride ions there is a very significant enhancement of the stability of aqueous hypochlorite ions under acid conditions. Moreover, we have determined that reduced levels of chloride ions improve the stability of hypochlorite bleaches under neutral or alkaline conditions. Accordingly, the present invention provides an aqueous hypochlorite solution comprising at least 0.01 %wt surfactant, wherein the ratio of available chlorine to chloride (as alkali metal salt) is greater than 1.5:1. |
