Electrochemical synthesis of EuVO4 for the adsorption of U(VI): Performance and mechanism

The efficient removal of uranium from aqueous solution remains of great challenge in securing water environment safety. In this paper, we reported a high temperature electrochemical method for the preparation of EuVO₄ with different morphologies from rare earth oxides and vanadate, which solved the problems of rare earth and vanadium recovery. The effects of pH, ionic strength, contact time, initial concentration and reaction temperature on the adsorption of U(VI) by prepared adsorbent were studied by static batch experiments. When the concentration of U(VI) standard is 100 mg g^-1, the maximum adsorption capacity of EuVO₄ is 276.16 mg g^-1. The adsorption mechanism was elucidated with zeta potential and XPS: 1) negatively charged EuVO₄ attracted UO₂²⁺ by electrostatic attraction; 2) exposed Eu, V, and O atoms complexed with U(VI) through coordination; 3) the hybrid of Eu was complex, which accommodated different electrons to interact. In the multi-ion system with Al³⁺, Zn²⁺, Cu²⁺, Ni²⁺, Cr²⁺ and Mn²⁺, EuVO₄ also showed good selective adsorption properties for U(VI). Five adsorption and desorption cycle experiments demonstrated that EuVO₄ possessed good renewable performance.

Vanadium-based nanomaterials for cancer diagnosis and treatment

In the past few decades, various vanadium compounds have displayed potential in cancer treatment. However, fast clearness in the body and possible toxicity of vanadium compounds has hindered their further development. Vanadium-based nanomaterials not only overcome these limitations, but take advantage of the internal properties of vanadium in photics and magnetics, which enable them as a multimodal platform for cancer diagnosis and treatment. In this paper, we first introduced the basic biological and pharmacological functions of vanadium compounds in treating cancer. Then, the synthesis routes of three vanadium-based nanomaterials were discussed, including vanadium oxides, 2D vanadium sulfides, carbides and nitrides: V_mX_n (X = S, C, N) and water-insoluble vanadium salts. Finally, we highlighted the applications of these vanadium-based nanomaterials as tumor therapeutic and diagnostic agents.

Catechin tuned magnetism of Gd-doped orthovanadate through morphology as T1-T2 MRI contrast agents

Tetragonal (t)-LaVO₄ has turned out to be a potential host for luminescent materials. Synthesis of t-LaVO₄ till date has been based on chelating effect of EDTA making it not ideal for bioimaging applications. An alternative was proposed by us through the use of catechin. In recent times there is interest for new MRI contrast agents that can through appropriate doping function both as MRI contrast and optical/upconversion materials. It is generally believed that under appropriate doping, t-LaVO₄ would be a better upconversion material than monoclinic (m)-LaVO₄. Based on these postulations, this work explores the use of gadolinium doped t-LaVO₄ as an MRI contrast agent. From literature, gadolinium oxide is a good T₁ contrast agent. Through this work, using catechin as a template for the synthesis of Gd doped t-LaVO₄, we demonstrate the possible use as a T₁ contrast agent. Interestingly, as the catechin concentration changes, morphology changes from nanorods to square nanoplates and spheres. In this process, a switch from T₁ to T₂ contrast agent was also observed. Under optimal concentration of catechin, with a rod shaped Gd doped t-LaVO₄ an r₂/r₁ value of 21.30 was observed. Similarly, with a spherical shape had an r₂/r₁ value of 1.48 was observed.

Catechin assisted phase and shape selection for luminescent LaVO4 zircon

Catechin conformers enhance luminescence from rare earth orthovanadates by tuning the structures in 0, 1 and 2 dimensions with a preferred tetragonal phase.