Anchoring chitosan/phytic acid complexes on polypyrrole nanotubes as capacitive deionization electrodes for uranium capture from wastewater.

Capacitive deionization (CDI) technology holds great potential for rapid and efficient uranyl ion removal from wastewater. However, the related electrode materials still have much room for research. Herein, chitosan/phytic acid complexes were anchored on polypyrrole nanotubes (CS/PA-PPy) to fabricate the electrode for the electrosorption of uranyl ions (UO22+). In this system, polypyrrole nanotubes provided specific channels for ion and electron diffusion, and chitosan/phytic acid complexes offered selective sites for UO22+ binding. The results demonstrated that CS/PA-PPy via electrosorption showed faster kinetics and higher uranium uptake than those via physicochemical adsorption. The maximum adsorption capacity toward UO22+ via electrosorption (1.2 V) could reach 799.3 mg g-1, which was higher than most of the reported CDI electrodes. Electrochemical measurements and experimental characterizations showed that the electrosorption of UO22+ by CS/PA-PPy was a synergistic effect of capacitive process and physicochemical adsorption, in which the capacitive mechanism involved the formation of an electric double layer from hollow polypyrrole nanotubes, whereas the coordination of phosphate, amino and hydroxyl groups with UO22+ was attributed to physicochemical adsorption. With the rational design of material, along with its excellent uranium removal performance, this work exhibited a novel and potential composite electrode for uranium capture via CDI from wastewater.

Theory-Driven Tailoring of the Microenvironment of Quaternary Ammonium Binding Sites on Electrospun Nanofibers for Efficient Bilirubin Removal in Hemoperfusion.

Efficient adsorbents for excess bilirubin removal are extremely important for the treatment of hyperbilirubinemia. However, traditional adsorbents, such as activated carbons and ion-exchange resins, still suffer from dissatisfactory adsorption performance and poor blood compatibility. Herein, we adopted a rational design strategy guided by density functional theory (DFT) calculations to prepare blood-compatible quaternary ammonium group grafted electrospun polyacrylonitrile nanofiber adsorbents. The calculation analysis and adsorption experiments were used to investigate the structure-function relationship between group types and bilirubin adsorption, both indicating that quaternary ammonium groups with suitable configurations played a crucial role in bilirubin binding. The obtained nanofiber adsorbents showed the bilirubin removal efficiency above 90% even at a coexisting BSA concentration of 50 g L-1. The maximum adsorption capacities were 818.9 mg g-1 in free bilirubin solution and 163.7 mg g-1 in albumin bound bilirubin solution. The nanofiber adsorbents also showed considerable bilirubin removal in dynamic adsorption to reduce the bilirubin concentration to a normal level, which was better than commercial activated carbons. Our study demonstrates the high feasibility of a theory-driven design method for the development of grafted electrospun nanofibers, which have good potential as bilirubin adsorbents in hemoperfusion applications.

Biodegradable chitosan­zirconium composite adsorptive membranes for potential arsenic (III/V) capture electrodialysis.

Combining adsorption with other technologies holds great potential in fast and deep arsenic ion removal. Herein, chitosan­zirconium composite adsorptive membranes (CS-Zr CM) were successfully prepared using simple casting and sodium hydroxide coagulation strategies, which was demonstrated the use in arsenic ion-capture electrodialysis based on their good adsorption performance. In the batch adsorption tests, the maximum adsorption capacities of CS-Zr CM for As(III) and As(V) were 134.2 mg/g and 119.5 mg/g, respectively. CS-Zr CM also exhibited satisfying adsorption selectivity and good reusability toward As(III) and As(V). However, the adsorption kinetics showed that they needed 48 h to reach the adsorption equilibrium and the adsorption ability toward trace arsenic ion was ineffective. Furthermore, CS-Zr CM was applied as the adsorptive membrane in the electrodialysis process. Under the influence of electric field, the As(III) and As(V) removal equilibrium time was shortened to 12 h and the concentrations of As(III) and As(V) ions could be efficiently reduced to below the WHO limit in drinking water (10 µg/L), which far surpassed the physicochemical adsorption method. Such good arsenic ion removal ability of CS-Zr CM together with the ease scalable fabrication, low cost, and biodegradable properties shows its huge prospects in arsenic-containing wastewater treatment.

High-efficiency and economical uranium extraction from seawater with easily prepared supramolecular complexes.

Developing effective adsorbents for uranium extraction from natural seawater is strategically significant for the sustainable fuel supply of nuclear energy. Herein, stable and low-cost supramolecular complexes (PA-bPEI complexes) were facilely constructed through the assembly of phytic acid and hyperbranched polyethyleneimine based on the multiple modes of electrostatic interaction and hydrogen bonding. The PA-bPEI complexes exhibited not only high uptake (841.7 mg g-1) and selectivity (uranium/vanadium selectivity = 84.1) toward uranium but also good antibacterial ability against biofouling. Mechanism analysis revealed that phosphate chelating groups and amine assistant groups coordinated the uranyl ions together with a high affinity. To be more suitable for practical applications, powdery PA-bPEI complexes were compounded with sodium alginate to fabricate various macroscopic adsorbents with engineered forms, which achieved an extraction capacity of 9.0 mg g-1 in natural seawater after 50 days of testing. Impressively, the estimated economic cost of the macroscopic adsorbent for uranium extraction from seawater ($96.5 âˆ¼ 138.1 kg-1 uranium) was lower than that of all currently available uranium adsorbents. Due to their good uranium extraction performance and low economic cost, supramolecular complex-based adsorbents show great potential for industrial uranium extraction from seawater.

Self-Standing Porous Aromatic Framework Electrodes for Efficient Electrochemical Uranium Extraction.

Electrochemical uranium extraction from seawater provides a new opportunity for a sustainable supply of nuclear fuel. However, there is still room for studying flexible electrode materials in this field. Herein, we construct amidoxime group modified porous aromatic frameworks (PAF-144-AO) on flexible carbon cloths in situ using an easy to scale-up electropolymerization method followed by postdecoration to fabricate the self-standing, binder-free, metal-free electrodes (PAF-E). Based on the architectural design, adsorption sites (amidoxime groups) and catalytic sites (carbazole groups) are integrated into PAF-144-AO. Under the action of an alternating electric field, uranyl ions are selectively captured by PAN-E and subsequently transformed into Na2O(UO3·H2O)x precipitates in the presence of Na+ via reversible electron transfer, with an extraction capacity of 12.6 mg g-1 over 24 days from natural seawater. This adsorption-electrocatalysis mechanism is also demonstrated at the molecular level by ex situ spectroscopy. Our work offers an effective approach to designing flexible porous organic polymer electrodes, which hold great potential in the field of electrochemical uranium extraction from seawater.