Adsorption and desorption characteristics of clay minerals on NH4+ in the leaching agent of weathered crust elution-deposited rare earth ore
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Abstract
In order to eliminate the environmental pollution caused by the residual leaching agent in the weathered crust elution-deposited rare earth ore, the adsorption and desorption characteristics of montmorillonite, kaolinite and illite on NH4+ in the leaching agent of weathered crust elution-deposited rare earth ore are investigated, and concentration of ammonium ion is determined by Nessler colorimetric-spectrophotometry in this paper.The results show that adsorption isotherms of ammonium on the three clay minerals are a mono-layer sorption and fitted well to Langmuir model.Maximum adsorption capacity of montmorillonite, kaolinite and illite on NH4+ is 5.99 mg/g, 0.12 mg/g and 1.10 mg/g, and release source of NH4+ is mainly from montmorillonite and illite.Desorption results show that efficiency of the eluate followed the order, Fe3+≈Al3+ ≥ Mg2+>Ca2+>K+>Na+>H2O.Experimental results show that the NH4+ desorption by magnesium salt is the fast process with high efficiency.Under the same conditions, the elution rate of residual NH4+ in weathering crust eluvial rare earth ore is more than 95%.
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