Ammonium hydroxide pre-treatment as an aid to increasing extraction efficiencies of toxic metals from spent oxide waste

An ammonium hydroxide pre-treatment procedure was investigated as an approach to increasing the extraction efficiency and reproducibility of results for chromium, copper, lead, nickel and zinc compounds within spent oxide waste. A series of pre-treatments were examined in order to optimise the conditions that afforded the greatest recovery of metals from the sample. The pre-treatment method was compared specifically to a standard ISO extraction procedure recommended for contaminated soils, in order to evaluate any statistical improvement in efficiency. Under pre-treatment conditions, mean increases in recovery of 203% for copper and 307% for nickel were recorded when compared with the non pre-treatment methods. A marginal increase in recovery of 14.3% was observed for chromium, while lead and zinc demonstrated no significant change in mean recovery. Improvements in percentage standard deviation were noted when the pre-treatment was used. There were no statistically significant differences observed when the pre-treatment procedure was applied to a non-spent oxide waste sample.