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The work relates to assessing the ability of the microwave for dehydration of large amount of waste hydrous ferrous sulfate generated from the titanium pigment process industry. The popular process optimization tool of response surface methodology with central composite design was adopted to estimate the effect of dehydration. The process variables were chosen to be power input, duration of heating and the bed thickness, while the response variable being the weight loss. An increase in all the three process variables were found to significantly increase the weight loss, while the effect of interaction among the parameters were found to be insignificant. The optimized process conditions that contribute to the maximum weight loss were identified to be a power input of 960 W, duration of heating of 14 min and bed thickness of 5 cm, resulting in a weight loss of 31.44%. The validity of the optimization process was tested with the repeat runs at optimized conditions.

The oxidation yield of ferrous ion in a Fricke solution was measured in the soft X-ray region from 1.8 to 10 keV. The standard Fricke solution was irradiated with monochromatic X-rays from synchrotron radiation. The yield decreased with decreasing X-ray energy, as several theoretical calculations have predicted. No significant changes were observed in the K-shell photo-absorption of the iron and sulphur contained in the standard Fricke solution. The high-LET nature of soft X-rays is discussed.