Microcosmic Mechanism of the Particle Release under Different pH Values

摘要

With the silver sand as the study object, the microcosmic mechanism for the particle release influenced by different pH values (pH=6,7,9)is discussed through horizontal laboratory sand column experiments. The results indicate that different pH values have obvious influence effects for the particle release processes with the condition of same salt concentration. The acid atmosphere will restrain the particle release strongly and result in a phenomenon of particle re-release. But, the trend of the particle release under alkaline conditions is strengthened obviously with the great increase of release quantity and the great growth of release time.The reason for the above phenomenon can be gotten by the analysis of microcosmic mechanics, and it is the change of the zeta potential of the particles and sand grains under different pH values which results in the increase or decrease extents of the Van der Waals attraction and double electric layer repulsion changing discordantly, and it induces both the quantity and the direction of the resultant forces transforming, and the attraction and repulsion is dominant at acid and alkaline atmospheres respectively.