Efficient vanadium recovery from highly alkaline solution using Lanthanum doped Mg-Al LDH: A promising approach for sustainable resource extraction

•La doped Mg-Al LDH with varying Al/La molar ratio was prepared.•La doping in the LDH increased the V sorption capacity in alkaline solution.•The stability of the LDH particle increased from La doping in alkaline pH.•V was removed from the solution by anion exchange mechanism.•Adsorbed V was successfully recovered using 2 M NaNO3 – 1 M NaOH mixed solution. Metal recyclability from secondary sources is vital in the context of circular economy. Vanadium (V) is one such critical metal due to its increasing demand in various industries. Herein, a series of NO3– intercalated Lanthanum (La)-doped Mg–Al layered double hydroxides (LDHs) were synthesized to remove V oxyanions from alkaline solution. Characterization of the synthesized material suggested that incorporation of La into the LDH structure did not change the basic layered structure of LDH but mainly affected the interlayer distances. Batch adsorption experiments showed that La doping enhanced the removal of V compared to pristine Mg-Al LDH, especially in alkaline solution and the V removal capacity was dependent upon the La content in the LDH. Pseudo-second order and inter-particle diffusion model were able to explain the V removal kinetics, and the sorption equilibrium data fitted well with the Langmuir model. Spectroscopic investigation of the spent LDH demonstrated that an anion exchange mechanism was mainly responsible for the V uptake from solution. Different concentrations of NaOH and NaNO3 solution were investigated to recover the maximum amount of V adsorbed. Recyclability test showed that 2 M NaNO3 – 1 M NaOH solution was not only able to recover most of the adsorbed V but could also regenerate the LDH activity, as tested for 5 cycles. Thus, the study clearly indicates that La-doping onto the Mg–Al LDH increases the LDH alkaline stability and can be a promising material for effective separation and recovery of V from alkaline secondary sources, ensuring resource sustainability.