Home – Home – Jornals – Chemistry for Sustainable Development 2026 number 5

The sorption of polyniobates from alkaline solutions by the anion-exchange sorbent AV-17 in the OH^- form and activated carbon ABG was studied. Deep extraction of niobium from solutions is achieved from alkaline solutions with a concentration of less than 0.5 mol/L for the sorbent AV-17-8 and less than 2 mol/L for activated carbon. The capacity of the sorbents under these conditions is 95 and 45 g/kg, respectively. The dependences of the extraction depth on potassium hydroxide concentration are exponential, and at KOH content above 5 mol/L, niobium sorption is not observed. Niobium is irreversibly extracted from diluted alkaline solutions by both types of sorbents. It is assumed that the irreversibility of sorption is associated with the accumulation of anionic niobium complexes in the sorbent structure and their subsequent polymerisation in the form of linear long-chain metaniobates. It has been established that even prolonged contact (up to 24 h) of niobium-saturated sorbents with potassium hydroxide solutions (10 mol/L) does not result in noticeable niobium desorption. Heating a niobium-saturated carbon sorbent at 100 °C also does not yield positive results. Niobium desorption is achieved by treating the sorbent with alkaline solutions containing hydrogen peroxide, and is caused by the destruction of polymer molecules and the formation of desorbed niobium peroxide complexes. These systems rapidly reach equilibrium. The developed process can be used to recycle the decomposition products of niobium concentrates during their sintering with alkaline reagents. At present, mixtures of hydrofluoric and sulphuric acids are used to decompose niobium minerals.