Date of Award


Document Type


Degree Name

Master of Science (MS)


Chemical Engineering


The removal of Na from subbituminous coal by ion ex change was investigated on a batch basis with H-ion donated by dilute aqueous The exchange of K, Mg, Ca, and A1 from the coal was also observed. The four parameters stud ied were initial H2SC>4 concentration, coal particle size, residence time, and liquid to solid mass ratio.

Results from this investigation indicate that at equi librium 95 % of the initial Na content of the subbituminous coal can be removed by ion exchange with dilute aqueous H2S04 . It was also determined that Na removal is directly proportional to the residence time, and inversly proportion al to particle size. The concentration of H-ion, as con trolled by the liquid to solid mass ratio, and initial H2S04 concentration have no significant effect on the rate of Na removal, provided there is sufficient H-ion present to com plete the exchange.

Experimental results indicated that particle diffusion was the rate determining step. The following Vermuelen's approximation was used to predict the kinetic response for the removal of Na by ion exchange with good results. % of initial Na removed = 1 - exp <0 r 0 *X*(100%) where D is the self-diffusion coefficient for H-Na ion exchange within the particle, mm /min; t is the time of the exchange, min; r is the radius of the exchange particle, mm; and X is the fraction of Na removal at equilibrium.

The H-ion:Na-ion self-diffus ion coefficient was found to be nearly constant over the range of H2SO4 solution con centration used, at a value of 0.0018mm^2/min (3.0 x 10^-7 cm^2/sec).