Comparison of IR spectroscopic analysis and X-ray diffraction of aluminum hydroxide gel

Data are presented which demonstrate the IR spectrophotometry is more sensitive than X-ray diffraction to structural changes occurring in aluminum hydroxide gel during aging. By examining changes in peak shape and position in the IR spectrum, evidence is seen for an increasing degree of order as the gel ages. The increased order may be responsible for the loss of acid reactivity observed during aging. IR analysis is also recommended for routine monitoring of aluminum hydroxide gels.