Synthesis of thorium–ethanolamine nanocomposite by the co-precipitation method and its application for Cr( vi ) removal

In the present work, a thorium–ethanolamine (Th–Eth) nanocomposite was synthesized by the co-precipitation method and used to investigate the removal of Cr( vi ) from aqueous solution. The material was highly selective for Cr( vi ) removal due to its high surface area (67 m 2 g −1 ), low pore size (3.2 nm), small particle size (4.5 nm) and good ion exchange properties. The adsorption process obeyed pseudo-second-order kinetics and the adsorption data were fitted well to the Langmuir model with an R 2 value of 0.995 with a maximum adsorption capacity of 109.89 mg g −1 . The E (10.62 kJ mol −1 ) value indicated the chemical nature of the adsorption process. About 99.53% Cr( vi ) was removed under the optimum conditions of a solution pH of 5, an adsorbent dose of 1.2 g L −1 , a stirring rate of 200 rpm and an equilibrium time of 60 min with 10 mg L −1 initial Cr( vi ) concentration in batch adsorption experiments. The material showed significant removal of Cr( vi ) even in the presence of other anions like carbonate, bicarbonate, nitrate, phosphate, fluoride, chloride and sulfate. The material was desorbed with 0.5 M NaOH solution and regenerated materials still possess a high adsorption capacity up to five consecutive cycles. The current study showed that Th–Eth can be used as an effective recyclable material for Cr( vi ) removal.