Degradation of perchlorate in water using aqueous multivalent titanium: Effect of titanium type, ionic strength, and metal and solid catalysts

In this study, chemical degradation of perchlorate was investigated using partially oxidized titanium ions (Ti(II) and Ti(III)). Results of UV spectra showed that the patterns of absorbance at all ratios of F/Ti(0) were similar each other, except the lowest F/Ti(0) of 0.5 (25 mM F−) where mixture of Ti(II) and Ti(III) might be present, resulted in shift of the peak to wavelength of 480 nm. The rate of perchlorate degradation was fastest at lowest F/Ti(0) ratio. Among catalysts investigated, only rhenium enhanced the perchlorate degradation in the presence of Ti(II), but no effect of catalysts in Ti(III). In addition, high ionic strength did not enhance the perchlorate-Ti(III) reaction, but high acid concentration did. Addition of solid acid catalysts (SACs) to Ti(III) solution showed slower perchlorate degradation, probably due to decrease in Ti(III) concentration by adsorption onto SAC. Rate constants for perchlorate degradation in Ti(III) were twofold higher than in Ti(II) when 5 N HCl used.

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► Lower molar ratios of F/Ti(0) enhanced perchlorate degradation.
► Rhenium (Re) increased the degradation rate to a small degree.
► The solid acid catalyst decreased the reaction rate between Ti(III) and perchlorate.
► Ti(III) degraded perchlorate rapidly than did Ti(II) at 5 N HCl.
► Higher concentration of HCl increased the reaction rate.