Adsorption and desorption performances of ammonium on the weathered crust elution-deposited rare earth ore

Release of the remaining ammonium salts from the weathered crust elution-deposited rare earth ore (WCE-DREO) would pose a serious threat to the environment. Thus, in this study, the adsorption and desorption performances of the WCE-DREO and four minerals that composed it were investigated to select an efficient eluent for the remained ammonium removal. Results showed that the ammonium ion adsorbed on the WCE-DREO and the clay minerals as a monolayer, and the calculated adsorption capacities were as follows: montmorillonite > WCE-DREO > halloysite > illite > kaolinite due to their different structure. pH experiment showed that it had great effects on ammonium adsorption on both the WCE-DREO and the investigated clays. Kinetic experiments showed that ammonium sorption and desorption process were both a fast process. Co-ions experiments showed that Mg 2+ showed the highest inhibition effect on the ammonium adsorption on the WCE-DREO due to its ionic character. Based on this data, magnesium salt was chosen as the eluent, and results showed that more than 93 % of the remaining ammonium ion could be removed from the WCE-DREO in the batch and column experiments.