Effects of Protective Shell Enclosures on Uranium Adsorbing Polymers

Abstract

This study aims to evaluate the impact of shell enclosures on the uranium uptake of amidoxime-based polymeric adsorbents they contain. Researchers have observed that the tensile strength of the adsorbent's polyethylene backbone is degraded after γ-irradiation to induce grafting of the amidoxime ligand. A two-part system was developed to decouple the mechanical and chemical requirements of the adsorbent by encapsulating them in a hard, permeable shell. The water flow in six shell designs and an unenclosed adsorbent for control in a recirculating flume was analyzed via a novel method developed using the measurement of radium extracted onto MnO 2 impregnated acrylic fibers. Although the water flow was found to vary with enclosure design, orientation to the flow, and placement within the flume, little to no difference was observed in the uranium adsorption rate between all enclosures. The results of this study will be used to design a large-scale ocean deployment of a uranium harvesting system.

Results of an Ocean Trial of the Symbiotic Machine for Ocean uRanium Extraction

“…This indicates that the system movement, though it increased water flow to the adsorbent and decreased biofouling on the shells, did not increase the adsorbent uptake of uranium. These results agree with those from a prior study by Haji et al in which a temperature-controlled, recirculating flume experiment of six shell designs found no significant difference in uranium adsorbed by encased fibers, despite drastic differences in water flow rate between shell designs. The results are also in agreement with the suggestion by Ladshaw et al that for flow rates >5.52 cm/s the uptake of the adsorbent will no longer increase with increasing velocity.…”

“…A novel method using the collection and measurement of radium adsorbed onto MnO 2 impregnated acrylic fibers was used to quantify the volume of water passing through each of the different types of enclosures. The details of this method are described in Haji et al 26 In summary, the MnO 2 impregnated acrylic fibers, which adsorb radium, were placed in each of the different types of enclosures in the ocean for approximately 6.25 h. At the same time, seawater was pumped from below the ocean surface at the test site to fill a 120 L container that was then pumped at 1−2 L/min through a control cartridge containing MnO 2 impregnated acrylic fibers. After seawater exposure, the fibers were ashed at 820 °C.…”

“…Additionally, the mesh bags have more open space allowing for water flow. Results from a recirculating flume experiment with a linear velocity of 4.8 cm/ s showed that a statistically significant difference between the water flow to six shell designs and a control in a recirculating flume did not affect the uranium adsorbed, 26 suggesting the uranium uptake of the ocean prototypes will be similarly unaffected by the differences in water flow.…”

Efficient adsorption of methyl orange and methyl blue dyes by a novel triptycene-based hyper-crosslinked porous polymer

“…The adsorption capacity and removal percentage of MO and MB on TPP-PP, TPP and PP are calculated according to the following equations. [24][25][26]…”

Linear β-Cyclodextrin Polymer Functionalized Multiwalled Carbon Nanotubes as Nanoadsorbent for Highly Effective Removal of U(VI) from Aqueous Solution Based on Inner-Sphere Surface Complexation

“…The possible risk of the aquatic system being contaminated by uranium is a salient environmental concern because of its severe ramifications for human health. , Accordingly, the removal of uranium from aqueous solutions is of great importance toward environmental control and public health. An adsorption technique has been developed because of its conspicuous advantages of having lower cost, convenient operation, and extensive applicability in the disposal of various pollutants, − and it has been employed for removing uranyl ions in effluent water. − In the past decades, the rapid progress in nanotechnology provides intriguing new opportunities for developing nanomaterials. − Especially, prodigious efforts have been made to discover novel adsorption materials for the removal of uranyl ions in uranium-containing wastewater, such as carbon nanotubes (CNTs)/ multiwalled carbon nanotubes (MWCNTs), − mesoporous carbon, − metal–organic frameworks, − natural/synthetic polymers, − leather waste, tripolyphosphate LDH, titanate nanotubes, graphitic carbon nitride, biomass, and Fe 3 O 4 @PDA@TiO 2 . Among the various adsorbents, CNTs/MWCNTs have attracted considerable interest because of their good stability toward acid–base, excellent mechanical properties, large surface area, and higher thermal/radiation resistance. , However, the inherent hydrophobicity and easy aggregation of CNTs/MWCNTs in aqueous solution might impede their adsorption behaviors and decrease the removal efficiency of pollutants, consequently limiting their wide application in real work .…”