Designing of functional zirconium silicates for vanadium ions recovery from model and real wastewaters

The efficient removal of vanadium(V) from model and real wastewaters by using adsorption is challenging due to the different oxidation states of this element. To address this problem, three adsorbents with different functionalities - ZrO2, ZrO2-SiO2, and ZrO2-SiO2-NH2 - were prepared via in situ sol-gel synthesis. To optimize the adsorption process conditions, different pH values, adsorbate concentration, adsorbent mass, temperature, and phase contact time, were evaluated, and the results of static experiments were presented. Furthermore, to describe the process in detail, commonly known kinetic, equilibrium as well intraparticle diffusion models were applied and analyzed. A kinetic study showed that V(V) removal occurred quickly and reached a level higher than 90% within 30 min when ZrO2-SiO2-NH2 was used. What is more, it was demonstrated that the ZrO2-SiO2-NH2 adsorbent exhibited the best properties and capacity in V(V) sorption, with maximum sorption (89.31 mg/g) achieved at optimum process conditions. The prepared adsorbents were thoroughly evaluated in terms of chemical composition, surface nature, morphology and structural properties. The incorporation of vanadium ions into the surface of ZrO2-SiO2-NH2 was proved and the mechanism of adsorption was proposed. The obtained results provided the high potential of the synthesized zirconium silicates in the uptake of vanadium ions from model and real wastewaters, and may open up new possibilities for the design of effective wastewater treatment methods.