Efficient adsorption of uranium from aqueous solutions by microalgae based aerogel

In this work, microalgae based aerogel (Chlorella pyrenoidosa/Chitosan, CP/CTS) was prepared and utilized to remove uranium from an aqueous solution. Effects of pH, anions, contact time, uranium concentration, coexisting metal ions, and regeneration tests were systematically investigated. Results showed that U(VI) adsorption by CP/CTS was strongly influenced by hydrogen ions. CP/CTS showed prominent adsorption capability toward U(VI) in NO3-, Cl-, and SO4- solution media with the adsorption characteristics of pseudo-second-order model and Langmuir isotherm. The maximum experimental U(VI) adsorption capacity was 571 mg/g in 7 h at 313 K, and the distribution coefficient (K-d) of CP/CTS reached 3.2 x 10(5) at C-0(U) = 10 ppm. It was observed that K+, Ca2+, Na+, Mg2+, and NH(4)(- )have no or slight effects on U(VI) adsorption by CP/CTS. After adsorption, CP/CTS could be regenerated with 0.5 M EDTA-2Na and reused efficiently. Besides, CP/CTS performed well for U(VI) adsorption in the practical leaching solution. The removal mechanisms were ascribed to ion exchange with carboxylic or hydroxyl groups and surface complexation with amino groups. These results demonstrated that CP/CTS have the potential for application in U(VI)-containing wastewater treatment.