A new process for the extraction and recovery of strontium from acidic waste streams is described. In this process, called SREX (for Strontium Extraction), strontium is extracted from acidic ( ≥ 1 M HNO3) solution using a 0.20M solution of di-t-butylcyclohexano-18-crown-6 in 1-octanol. Extracted strontium is readily stripped from the organic phase using either water or dilute (<0.05 M) HNO3. Tests of the process on a synthetic dissolved sludge waste solution show that only strontium, barium, and technetium are appreciably extracted by the crown ether. Prolonged exposure of the process solvent to nitric acid at elevated temperatures or to ≤ 50 Wh/L γ radiation from a 60Co source produces essentially no deterioration in its performance. Benchtop batch countercurrent extraction experiments show that 99.7% of the strontium initially present in a feed solution can be removed in only three extraction stages.

Srex: a newprocess for the extraction and recovery of strontium from acidic nuclear waste streams

Cumulative study on solvent extraction of elements by N,N,N′,N′-tetraoctyl-3-oxapentanediamide (TODGA) from nitric acid into n-dodecane

The synthesis of a novel nanocomposite sorbent material, copper ferrocyanide immobilized within a mesoporous ceramic matrix, and its use as a novel cesium sorbent material is reported in this paper. Complete removal of cesium was achieved in the presence of competing metal ions for solutions containing 2 ppm cesium under a variety conditions. Loading capacity of more than 1.35 mmol Cs per g of sorbent material has been achieved. The exceptionally fast binding kinetics and high loading capacity, resulting from the rigidly open pore structure and extremely high surface area of the sorbent materials, make them potentially very useful for the removal of cesium from nuclear wastes and contaminated groundwater.

Selective sorption of cesium using self-assembled monolayers on mesoporous supports.

Cesium is the major fission product of uranium, which widely exists in radioactive wastewater. Radiocesium has potential adverse effects on human health and ecological environment. Different methods such as chemical precipitation, coagulation/co-precipitation, solvent extraction, membrane process, chemical reduction, and adsorption have been used to remove radioactive cesium from aqueous solution. However, the development of innovative technologies capable of selectively removing radioactive cesium is still imperative yet challenging. This review focused on cesium removal using various separation technologies, including chemical precipitation, solvent extraction, membrane separation, and adsorption. The key restraints for cesium removal, as well as the recent progress of these methods have also been discussed. Particular attention has been paid to the adsorption methods, which has been highlighted by introducing the latest advances in inorganic adsorbents (such as metal hexacyanoferrates, clay minerals, carbon-based-adsorbents, and ammonium molybdophosphate), organic adsorbents (such as ion exchange resin, metal–organic frameworks and supramolecular/indicator grafting adsorbents), and biosorbents (such as agroforestry wastes and microbial biomass). Adsorption-based methods are high efficient in separation of cesium ions from aqueous streams, and adsorption of cesium ions has been investigated intensively and even used in practical applications, there is still considerable scope for improvement in terms of adsorption capacity and selectivity.

Removal of cesium ions from aqueous solutions using various separation technologies

Evaluation of ammonium molybdophosphate-polyacrylonitrile (AMP-PAN) as a cesium selective sorbent for the removal of 137Cs from acidic nuclear waste solutions ☆

A principal purpose of this paper is to call out what is perceived to be a timely need for increased research to develop improved and new solvent extraction technology for recovery of 137Cs and 90Sr from strong (≥ 0.5M HNO3) acid media, technology which can be quickly scaled up to routine plant-scale operation with highly radioactive waste solutions when needed. The present and forseeable future (2020) U.S. inventory of 137Cs and 90sr is listed; much of this inventory is expected to be available only in strongly acidic nuclear waste solutions. Comparison of available methods-precipitation and ion exchange as well as solvent extraction—for recovering 137 Cs and 90Sr from alkaline and acid media demonstrates, as expected, that very limited technology is available for use with strongly acidic solutions. Solvent extraction procedures which employ either macrocyclic polyethers (crown ethers) or dicarbolide. H+{[π-(3)-1, 2-B9C2H11Cl2±2Co}−, to extract 137Cs and 90Sr from ≥ 0.5M HNO3 solutions have rece...

L. A. Bray

Papers

Solvent Extraction Recovery of Byproduct 137Cs and 90Sr from HNO3 Solutions—A Technology Review and Assessment