Removal of uranium(VI) and thorium(IV) by insolubilized humic acid originated from Azraq soil in Jordan Fawwaz I. Khalili 1 • Alia’a Khalifa 1 • Ghadeer Al-Banna 1 Received: 16 June 2016 Ó Akade ´miai Kiado ´, Budapest, Hungary 2016 Abstract Humic acid from Azraq soil in Jordan has been extracted and insolubilized as the sodium form (INaAZHA). It was characterized by Fourier transform infrared spectroscopy, elemental analysis, thermal gravi- metric analysis, X- ray diffraction, scanning electron microscopy and differential scanning calorimetry. Sorption of Th(IV) and U(VI) by INaAZHA was studied using batch and column. The kinetic studies fitted pseudo second–order kinetic model. The data were fitted to Langmuir, Fre- undlich and Dubinin–Radushkevich (D–R) sorption iso- therms. Thermodynamic functions, DG°, DH° and DS° were determined for the sorption. Desorption from column was best using 1.0 M than 0.5 and 0.1 M HNO 3 for both. Keywords Azraq humic  Insolubilized  Sorption  Kinetic  Thermodynamic  Thorium(IV)  Uranium(VI) Introduction The occurrence of uranium and thorium in soil, rocks, groundwater, is a serious problem from the environmental viewpoint. Uranium and thorium presence in the environ- ment can be hazardous to health. Cellular and animal studies have shown that uranium is a kidney toxin, neu- rotoxin, immunotoxin, mutagen, carcinogen, and teratogen [1]. Where, the main radiological hazard from uranium is alpha radiation. When it is inhaled or ingested, alpha radiation is the most damaging form of ionizing radiation [1]. The solid and liquid effluents containing Th(IV) are known to cause acute toxicological effects and harmful diseases for human such as lung, pancreatic and liver cancer through inhalation, smoking and oral intake [2]. Uranium and thorium are very essential elements in nuclear energy programs. Their separation and recovery are essential to minimize their discharge into the environment from the point of view of safety and economy [3]. In Jor- dan, there are several sites contain considerable reserves of uranium and thorium ores [4]. Enhanced levels of uranium and thorium and their daughter products might be present in ground water in areas that are rich in natural radioac- tivity. The earth’s crust in Jordan is covered by phosphate rocks that could make the water sources rich in 238 U and its daughters which may be found dissolved or suspended in the water [5]. Various techniques are employed for the removal and separation of radionuclides (uranium and thorium), such as precipitation, ion exchange, solvent extraction, and sorption [2]. Sorption is the process that involves nothing more than the preferential partitioning of substances from the gaseous or liquid phase onto the sur- face of solid substrate; the sorption phenomenon has become a useful tool for purification and separation [2]. The sorption procedures mainly involve the develop- ment of low cost adsorbents over a wider range of pH values at lower concentrations with easy manipulation and regeneration for possible reuse [6–8]. Many researchers have used various solids, which are natural, organic, and inorganic; for example, coir pith, zeolite, activated carbon, cement, alumina, silica, and natural substances like organic matter (humus) and clay minerals [4, 7–10]. Humic substances (HS) are a series of naturally occur- ring high molecular weight compounds, which are the main component of organic matter in soils and waters. The humic substances can be classified according to their & Fawwaz I. Khalili fkhalili@ju.edu.jo 1 Chemistry Department, The University of Jordan, Amman 11942, Jordan 123 J Radioanal Nucl Chem DOI 10.1007/s10967-016-5031-y