Comparison of hydrochloric acid and phosphoric acid activated clays

Abstract

To determine if a calcium phosphate has been formed, x-ray diffraction traces were taken of the appropriate samples. To determine if there is calcium phosphate forming on the layers of the clay, the trace of the phosphoric acid washed clays was compared to the analogous hydrochloric acid washed clay. The infrared spectrum was also taken of all samples to aid in this determination. When Inspecting the data, there were noticeable shifts in both the x-ray diffraction traces and the infrared spectra peaks between the sample that had been washed with hydrochloric acid and titrated with calcium hydroxide and the analogous clay sample that had been washed with the phosphoric acid and titrated with calcium hydroxide. These shifts are not indicative of the formation of the hypothesized calcium phosphate but they do give information about the atomic environment on the clay. In the infrared spectra, the phosphoric acid washes had peaks for the Si-O-metal bond shifted to a higher wavenumber as well as the water peaks. This indicates that they have a higher energy in the phosphoric acid washed clays than in the hydrochloric acid washed clays. The x-ray diffraction traces had values of 2-theta shifted to a higher 2-theta indicating a more compact atomic environment. The compact environment would increase the energy of the bonds and therefore increase the peaks present on the infrared spectra of the samples.