Removal of Th 4+ ions from aqueous solutions by graphene oxide Ning Pan • Debin Guan • Ting He • Ruibing Wang • Ian Wyman • Yongdong Jin • Chuanqin Xia Received: 4 June 2013 Ó Akade ´miai Kiado ´, Budapest, Hungary 2013 Abstract The removal of Th 4? ions from aqueous solu- tions was investigated using single-layer graphene oxide (GO) as a sorbent which was prepared by the modified Hummers’ method through batch adsorption experiments at room temperature. Structural characterizations of the sor- bent were also investigated. The influences of the pH value of solution, contact time, sorbent dose, ionic strength, the initial metal ion concentration and temperature on the adsorption of Th 4? were also investigated. These results indicated that the adsorption of Th 4? was dependent on the pH and independent on the ionic strength. The sorbent provided significant Th 4? removal ( [ 98.7 %) at pH 3.0 and the adsorption equilibrium was achieved after only 10 min. The Langmuir adsorption isotherm fit the absorp- tion profile very closely, and indicated that a maximum adsorption capacity of 1.77 mmol g -1 of GO (411 mg g -1 ) after 2 h. The thermodynamic parameters showed that this adsorption process was endothermic and spontaneous. Moreover, the desorption level of Th 4? from GO, by using 0.1 mol L -1 H 2 SO 4 as a stripping agent, was 84.2 ± 1.2 %, and that of 0.5 mol L -1 HNO 3 as a strip- ping agent, was 79.8 ± 3.0 %. Keywords Graphene oxide  Th 4?  Adsorption  Isotherm  Desorption Introduction Thorium, which mainly originates from mining operations, metallurgy, the nuclear industry and laboratory investiga- tions, is regarded as an analogue for other ?4 valence actinide ions because it has stable tetravalent states in nature [1, 2]. With the development of nuclear energy, thorium as a potential nuclear fuel has attracted tremendous attention, and thus its removal and recovery is of utmost importance, because this ion is dangerous for the envi- ronment and people’s health by its high toxicity or radio- activity even at very low concentrations [1–3]. For this reason, it is desirable to develop methods for the separation and enrichment of these ions from radioactive wastewaters. The methods used for the separation and enrichment of Th 4? from the radioactive wastewaters include: liquid– liquid extraction, biosorption and solid-phase extraction [1, 3, 4]. Among all of these methods, solid-phase extraction has been considered as an effective method for removing Th 4? from the aqueous solutions due to its low-cost, high adsorption capacity and ease of operation [1]. Currently, N. Pan  Y. Jin (&)  C. Xia (&) College of Chemistry, Sichuan University, Chengdu 610064, People’s Republic of China e-mail: jinyongdong@scu.edu.cn C. Xia e-mail: xiachqin@163.com N. Pan  D. Guan  T. He New Materials R&D Center, Institute of Chemical Materials, Chinese Academy of Engineering Physics, Mianyang 621900, People’s Republic of China R. Wang (&) Nordion Inc., 447 March Road, Ottawa, ON K2K 1X8, Canada e-mail: ruibing.wang@nordion.com I. Wyman Department of Chemistry, Queen’s University, Kingston, ON K7L 3N6, Canada C. Xia Key Laboratory of Radiation Physics and Technology, Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, People’s Republic of China 123 J Radioanal Nucl Chem DOI 10.1007/s10967-013-2660-2