THE USE OF LOW RANK BROWN COAL AS AN ION-EXCHANGE MATERIAL .2. IONIC SELECTIVITY AND FACTORS AFFECTING UTILIZATION

Victorian brown coals from Loy Yang, Yallourn and Yallourn North Extension open cut mines were studied. When these coals are used as ion exchange materials, their ionic selectivities follow the Irving-Williams order for metals from the first transition metal series i.e. Mn < Co < Ni < Cu > Zn. The cation exchange capacity (CEC) of the coal for a particular metal in a mixture of metals is lower than in a single metal solution, presumably due to the relative increase in ionic strength in the mixed metal situation. The solid:liquid ratio has also been shown to influence CEC, with maximum CEC occurring at low solid:liquid ratios. Temperature has a marginal influence on CEC, at least over the range 25-70 °C, whereas the presence of non-aqueous solvents can have a significant influence. © 1990.