Thermally modified molybdenum oxide as a potential sorbent for the removal of metal cations from aqueous solutions M. G. Kapnisti 1,3 • F. G. Noli 1 • J. Arvanitidis 2 • A. G. Hatzidimitriou 1 Received: 18 February 2015 Ó Akade ´miai Kiado ´, Budapest, Hungary 2015 Abstract The effectiveness of a low cost sorbent pro- duced by thermal modification of ammonium hepta- molybdate (AHM) in adsorption of radionuclides and heavy metals was investigated. The product was charac- terized by XRD, SEM and Raman spectroscopy. Sorption experiments were performed in Pb, U, Cs, Ba and Eu so- lutions (pH 2.0–6.0). The obtained isotherms were simulated by Langmuir and Freundlich isotherms and ki- netics data were used in order to evaluate the sorption mechanism. The results showed the high and selective ef- ficiency of the AHM-derived MoO 3 especially in Pb and U removal whereas the desorption experiments revealed its environmental applicability under real conditions for the investigated metal cations. Keywords Sorption study  Molybdenum oxide  Radionuclides  Desorption tests Introduction The presence of heavy metals in the environment is of major concern because of their toxicity and threat to plant and animal life. The discharge of heavy metals into water causes serious environmental problems. Heavy metals are not biodegradable, a fact that leads to various diseases [1, 2]. Among them, lead is one of the most hazardous elements because of its particular toxicity even in low concentrations whereas the removal of the uranium and cesium from aqueous streams is of special importance because of their connection with the nuclear fuel cycle [3– 5]. On the other hand barium and europium are frequently used as natural homologues of Ra and trivalent actinides (e.g. Am, Cm) respectively [6–9]. Lead substances are widely used worldwide in various fields (e.g. pure metal, alloying element and additives in ceramics, pigments and organic substances) [3]. Lead poisoning has been a scourge to human health and in most cases the effects are permanent, irreversible and untreat- able by modern medicine [10, 11]. The Environmental Protection Agency and the World Health Organization have suggested the limits of 0.015 and 0.01 mg L -1 , re- spectively for Pb(II) ions content in safe drinking water [12]. Uranium can be found naturally at elevated levels in rock, soil, surface water and groundwater, but its presence is mainly associated with the nuclear power production, the utilization of phosphate fertilizers, copper metallurgy and military activities. Uranium has been classified in group A as a human carcinogen by the USEPA with respect to carcinogenicity and the realistic level of 30 mg L -1 was proposed as the maximum contaminant level in drinking water [13–17]. Additionally, radioactive cesium (especially 137 Cs with half life 30 years) is a hazardous material contained in low level radioactive wastes, the majority of which originates from the nuclear fuel cycle and nuclear weapons reprocessing. Due to the fact that cesium exhibits high mobility in the environment and also because of its similarity to potassium there is a strong interest in the re- mediation of the Cs-contaminated sites [18, 19]. & F. G. Noli noli@chem.auth.gr 1 Department of Chemistry, Aristotle University of Thessaloniki, P.O. Box 135, 541 24 Thessalonı ´ki, Greece 2 Physics Department, Aristotle University of Thessaloniki, 541 24 Thessalonı ´ki, Greece 3 Department of Food Technology, Technological Educational Institute of Thessaloniki, 574 00 Sindos, Greece 123 J Radioanal Nucl Chem DOI 10.1007/s10967-015-4190-6