ABSTRACT
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.
Subject(s)
Uranium , Water Pollutants, Chemical , Adsorption , Hydrogen-Ion Concentration , Kinetics , Oxides , Uranium/analysis , Water Pollutants, Chemical/analysisABSTRACT
This study presents an approach for developing inactivating materials to achieve an initial rapid and a long-term equilibrium P immobilization to control eutrophication based on drinking water treatment residue (DWTR), which is a byproduct of potable water production. By taking advantage of the long-term equilibrium P adsorption by DWTR, the La chemical properties, and the previous success of using La-modified bentonite clay (Phoslock®), we used DWTR as a La carrier with different ratios to develop the specific materials. The La loading mechanisms, the potentially toxic effect of La-modified DWTR on snail Bellamya aeruginosa (within 120â¯d), and the short- and long-term (within 80â¯d) P immobilization characteristics of the modified DWTR were investigated to understand the performance of the developed materials. The results showed that La loading into DWTR was based on ligand exchanges and the formation of new particles; DWTR loaded with <5% La had no toxicity against the snail. Most importantly, the loading of 5% La to DWTR substantially enhanced the rapid immobilization capacity of DWTR, achieving an initial rapid and a long-term equilibrium P adsorption in aqueous solutions. This study promotes the beneficial recycling of DWTR and results in a win-win situation for lake restoration.
Subject(s)
Bentonite/chemistry , Eutrophication , Lanthanum/chemistry , Phosphorus/chemistry , Water Pollutants, Chemical/chemistry , Water Purification , Adsorption , Animals , Bentonite/toxicity , Drinking Water , Female , Lakes/chemistry , Lanthanum/toxicity , Male , Recycling , Snails/drug effectsABSTRACT
In our searching for novel tyrosinase inhibitors from natural sources, (S)-N-trans-feruloyloctopamine isolated from garlic skin was found to be a potential mushroom tyrosinase inhibitor. Here, we examined the effects of the potential tyrosinase inhibitor in B16F10 cells on intracellular melanin contents, cytotoxicity, and the signaling mechanism involved in the expression of tyrosinase. The results showed the inhibitor displayed little or no cytotoxicity at all concentrations examined and decreased the relative melanin contents in a dose-dependent manner in the α-MSH-stimulated B16F10 cells. Real-time PCR and Western blot analysis showed that it inhibits melanogenesis signaling by down-regulates mRNA and protein expression levels of tyrosinase, which leads to a lower melanin contents. These results suggested that (S)-N-trans-feruloyloctopamine was an ideal tyrosinase inhibitor, and could be used in food and medical industry.