The Study Of Desorption Characteristics On Packed Moving-Bed

As a new chemical separation technology, ion exchange technology is widely uesd in modern water treatment, separation and extraction of elements.However, existing ion exchange equipments and operating modes exit many disadvantages such as material waste,low efficiency, energy consumption and so on.Because of remedyding these defects,continuous moving-bed is liked by the majority of the favor. With 001×7 strong acid cationic resin with the adsorption of K+ as solid medium, NaCl solution as desorbent, this paper study on the operating characteristics of desorption process in continuous moving-bed through orthogonal test and single factor test contrast with fixed bed experiments,based on the early adsorption operation in continuous packed moving-bed.The moving-bed test results show that the cumulative desorption rate of per L resin increased gradually from top to bottom along the axial direction, which, especially,increased more rapidly in the lower 1/5 part of the ion-exchange column, the full column resin cumulative desorption rate could reach over 90% under some conditions; the cumulative desorption rate of per L resin in each axial region increased when the initial concentration of the desorbent increased in a certain range, but when the initial concentration of the desorbent increased to a certain value, a phenomenon appeared in different axial regions of the ion exchange column that desorption and antiadsorption alternated dominantion; with the increase of the apparent velocity of the eluate in the ion exchange column and the decrease of resin moving speed and the original adsorption capacity, the cumulative desorption rate of per L resin in each axial region increased.The fixed bed test results show that different regional resin reach desorption equilibrium from the bottom to the top.Other conditions must,desorption equilibrium time would be shortened with the desorption agent increasing, too large and too small desorption agent may cause the column cumulative desorption rate to decrease. The column desorption equilibrium time and desorption rate may increase with increasing of deabsorbing superficial velocity.The lager the original resin adsorption column, the longer the column desorption equilibrium time, the desorption rate is on the contrary.The comparison between results on fixed bed and continuous packed moving bedshow that the full column resin cumulative desorption rate and desorption amount of K+were higher in a continuous moving bed than in a fixed bed during the time of the eluate flowing through the ion exchange column in one-way.The desorption process of two kinds of operating modes meet Pseudo-second-order.