Preconcentration and Separation of Rubidium from Salt Lake Brine by Ammonium Phosphomolybdate - Polyacrylonitrile (AMP-PAN) Composite Adsorbent

Abstract

In this study, a novel composite adsorbent of ammonium phosphomolybdate – polyacrylonitrile (AMP–PAN) was prepared for sensitive and selective preconcentration and separation of rubidium (Rb(I)) ion from salt lake brine. Several experimental parameters, such as pH value, shaking time, concentration, interference ions, regeneration, stability and reusability were systematically investigated. The experimental results clarified that the Rb(I) ion was adsorbed by the adsorbent of AMP‐PAN at pH 7. Under optimum condition, the maximum sorption capacity for Rb(I) ion by the adsorbent was 500 mg g−1 based on the Langmuir adsorption isotherm study. The adsorption equilibrium was achieved within 2 h. The presence of co‐existing ions did not interfere with Rb(I) adsorption, indicating the high selectivity toward Rb(I) ion. The desorption results demonstrated that Rb(I) ion adsorbed the composite adsorbent of AMP‐PAN could be effectively desorbed by 0.5 mol L−1 NH4Cl and regenerated into the initial form without significant deterioration in its original functionality at the same time, which exhibited good stability of the adsorbent. Therefore, the proposed adsorbent of AMP‐PAN allowed the sensitive, selective, easy to use, cost‐effective, high efficiency, fast kinetics, stable and reusability preconcentation and separation of Rb(I) ion even in the presence of competing ions. As a consequence, the AMP‐PAN adsorbent can be used potentially to preconcentration and separation of Rb(I) ion from water samples in a wide range of practical applications for extracting Rb(I) ion in environmental aqueous resources.

Efficient lead sorption by ammonium phosphomolybdate: experimental and density functional theory (DFT) studies

“…The four characteristic vibrational peaks located at 1060.67, 956.54, 860.11 and 750.19 cm À1 were assigned to the stretching vibrations of the n as (P-O), n as (MoQO), n as (Mo-O c -Mo) and n as (Mo-O b -Mo) modes for the polyhedral Keggin anion, respectively. 52 The N-H stretching and vibrations for the NH 4 + cation of APM are observed at 3182.02 and 1407.80 cm À1 .…”

Fabrication and performance of the ammonium molybdophosphate/polysulfone mixed matrix membranes for rubidium adsorption in aqueous solution

“…The Rb + adsorption capacities of the AMP/PSf mixed matrix membranes gradually decrease from 17.53 to 16.92 mg g À1 with the temperature increasing from 15 to 55 C, which means that the increasing the temperature is not conducive to Rb + adsorption, inferring that the adsorption process is an exothermic reaction, which is consistent with previous reports. 46 Thus, the experimental temperature condition is determined at 25 C based on the consideration of practical operation convenience.…”

Adsorption Behaviors of Rubidium and Cesium Ions from Aqueous Solution onto Sodium Tetraphenylborate ‐ Polyacrylonitrile (TPB‐PAN)

“…Mostly rubidium, cesium and their common salts exist in natural minerals and dissolve in aqueous solution such as geothermal water, underground water, thermal water, oil and gas field water, oceans and salt lake brine . Although rubidium, cesium and their compounds are more abundant in the worldwide salt lakes, however, there are few reports on the extraction of rubidium and cesium elements from the natural resources such as salt lake brine, mainly due to their low concentrations(about 0 −100 mg L −1 ), the complexity of numerous foreign ion species with much higher concentration in the matrix,, which increase the difficulty of extraction and separation trace elements . There are many studies on the extraction of higher concentration of essential elements including lithium, potassium, magnesium and boron, usually along with rubidium and cesium ions in salt lake brine.…”