Figure 4
Panel (a) shows the measured radiolytic hydrogen yields plotted against the difference between energy absorption coefficients of the particulate phase and the aqueous phase. The highest photon energy results on this plot are measurements of radiolytic hydrogen yields from Co-60 irradiation of both magnesium hydroxide sludge and alumina sludge. The alumina measurement is taken from the literature18. The cross marks in the plot show the alumina sludge results and the magnesium hydroxide sludge results are plotted as solid circles. The horizontal axis is plotted on a logarithmic scale. The dashed line indicates the radiolytic yield for water alone. The vertical dotted line indicates the value at which inelastic scattering (Compton scattering) and direct ionization (photoelectric effect) cross-sections are equal in alumina; to the left of this line most ionization events are from inelastic scattering of the most loosely bound electrons; to the right of this line most ionization events are from direct photon absorption, which eject the most tightly bound electrons. The black curves indicate the trend in the data, which is an arbitrary step function for alumina and a linear fit for magnesium hydroxide. Panel (b) shows a plot of the measured radiolytic hydrogen consumption against the same variable but does not include the results from Co-60 irradiations. The radiolytic consumption shows no detectable trend. The dashed line plots the trend of radiolytic consumption for alumina and the solid line for trend of radiolytic consumption for magnesium hydroxide. Figure made with plots plotted with matplotlib55.
