Abstract
In order to improve the adsorption capability of solvent-impregnated resins (SIRs) for vanadium(IV) (V(IV)), the dual extractant (D2EHPA (Di-(2-ethylhexyl) phosphoric acid) and TBP (Tributyl phosphate)) impregnated resins (D-TIRs) were prepared by impregnating AmberliteTM XAD-16HP macroporous resins with the mixed extractant that is composed by different molar ratios of D2EHPA to TBP. The effects of the ratio of D2EHPA to TBP on the performance of D-TIRs were investigated. The results show that the impregnation ratio of the D-TIRs decreases gradually with the increasing proportion of TBP in the mixed extractant. The sole-TBP impregnated resins (TIRs) have no adsorption capability for V(IV), indicating that the adsorption of V(IV) is attributed to D2EHPA. The adsorption capacity of D-TIRs for V(IV) attained the maximum when the ratio of D2EHPA to TBP is 7:3 at pH 1.8, and it can be improved by increasing the extractants concentration during the impregnation process. Adsorption isotherm indicates that the addition of TBP can increase the adsorption capacity of D-TIRs for V(IV) from 24.65 to 29.75 mg/g after 16 h reaction. Adsorption kinetics verifies that the addition of TBP can largely accelerate the adsorption equilibrium of V(IV) onto the D-TIRs and V(IV). Electrospray ionization (ESI) mass spectra and Fourier transform infrared spectra (FT-IR) analysis indicates that the addition of TBP to D2EHPA can make some dimeric D2EHPA change to monomers by breaking the hydrogen bonds of D2EHPA-dimers, leading to the result that the pseudo-second order kinetic for the adsorption of V(IV) onto the D2EHPA impregnated resins (DIRs) converts to the pseudo-first order kinetic for that onto the D-TIRs. Also, D-TIRs have better separation capability of V(IV) from Fe(II) and Al(III) in the vanadium leaching solution than DIRs.
Highlights
Vanadium, which is a rare element with unique physical and chemical properties, is widely used in alloys, catalyst, vanadium redox battery, and aerospace [1,2]
It was found that the adsorption capacity of Di-(2-ethylhexyl) phosphoric acid (D2EHPA) impregnated resins (DIRs) for V(IV) is only 14.43 mg/g after 18 h reaction and that the process is time-consumed
Our study proposes a novel method to enhance the adsorption performance of solvent-impregnated resins (SIRs) for vanadium
Summary
Vanadium, which is a rare element with unique physical and chemical properties, is widely used in alloys, catalyst, vanadium redox battery, and aerospace [1,2]. Minerals 2018, 8, 206 are dissolved in the acid leaching solution together with vanadium [5], rendering the separation and recovery of vanadium from the complex leaching solution as a necessary process for the production of V2 O5 [6,7,8]. Has been widely used as an excellent extractant for the recovery of vanadium because of its low price, high extraction efficiency, and the effective separation of vanadium(IV) (V(IV)) from impurity ions [10,11], it was used by many researchers to prepare SIRs for the separation of vanadium [12,13,14]. Liang et al [12] studied the adsorption and separation of V(IV) from the vanadium leaching solution containing Fe(III) and Al(III) with D2EHPA impregnated resins (DIRs). Tang et al [14] investigated the vanadium adsorption onto DIRs
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