Effect of support properties on preparation process and adsorption performances of solvent impregnated resins

Surface Modification of Biomass with Di-(2-Ethylhexyl)phosphoric Acid and Its Use for Vanadium Adsorption

The method of carbonizing biomass using di-(2-Ethylhexyl) phosphoric acid and tributyl phosphate impregnation (SICB) was studied in this research. SICB combines the benefits of an extractant and an ion exchange resin. The adsorption and desorption properties of vanadium were investigated, and the adsorption mechanism was analyzed. The results showed that the carrier was first prepared at a temperature of 1073.15 K using sawdust as a biomass substitute and then cooled to room temperature. The best adsorption performance was obtained by impregnating the carriers with di-(2-Ethylhexyl) phosphoric acid and tributyl phosphate for 60 min. The vanadium adsorption rate of 98.12% was achieved using the biomass at an initial V(IV) solution concentration of 1.1 g/L, a pH value of 1.6, and a solid-to-liquid ratio of 1:20 g·mL for 24 h. Using 25 wt.% sulfuric acid solution as desorbent, the desorption rate of vanadium was as high as 98.36%. The analysis showed that the adsorption of vanadium by SICB was chemisorption, and the adsorption process was more consistent with the proposed second-order kinetic equation. Therefore, SICB has high selectivity and high saturation capacity because of the mesopores and micropores produced by carbonization.

Solvent impregnated resins for the treatment of aqueous solutions containing different compounds: a review

In this review paper, a complete study and analysis of the research articles dealing with the removal of various organic and inorganic pollutants using solvent impregnated resins (SIR) is carried out. The method of impregnation, characterizations of prepared resin, and regeneration techniques of different SIRs for batch and continuous fixed bed columns are presented. The effects of different operating parameters (e.g., loading of solvent on the resin, dosage of adsorbent, initial solute concentration, pH, temperature, time, ionic strength) on the separation efficiency of SIR in the batch mode are discussed. Thermodynamic parameters (change in Gibbs free energy, enthalpy, and entropy) are tabulated from the data available in the literature, and if not given, then their values are calculated and presented. The influence of parameters (flow rate, bed height, pH, concentration of the solution, etc.) on the fixed bed column performance is analyzed. Design aspects of the column are also discussed, and the dimensions of fixed bed columns for industrial applications are proposed.

Recovery of V(V) from complex vanadium solution using capacitive deionization (CDI) with resin/carbon composite electrode

The resin-activated carbon composite (RAC) electrodes were fabricated and applied in capacitive deionization for recovery of V(V) from complex vanadium solution. The adsorption capacity of the RAC electrode for V(V) is extremely low and the reduction of V(V) is significant in low pH solution, but the adsorbed V(V) on the electrode increases obviously and the reduction of V(V) gradually diminishes with the rise of pH. However, as the pH is increased to 10, the adsorbed V(V) on the RAC electrode declines. The higher applied potential is beneficial to the adsorption of V(V) and 1.0 V is appropriate for the adsorption. The impurities ions (Al, P and Si) are mainly adsorbed in the electric double layers on the RAC electrode and V(V) is dominantly adsorbed by the resins in the electrode. The adsorbed impurity ions can be easily removed by diluted H₂SO₄ and V(V) can be effectively eluted by 10% NaOH solution. The vanadium-bearing eluent can be recycled to recover and enrich vanadium from the complex solution. The performance of the RAC electrode keeps stable during the cyclic operation. This study may provide a promising and novel method for the recovery and separation of metals from aqueous solution.

A High-Efficiency Approach for the Synthesis of N235-Impregnated Resins and the Application in Enhanced Adsorption and Separation of Vanadium(V)

Trialkylamine (N235)-tributyl phosphate (TBP) impregnated resins (N-TIRs) were prepared, so as to evaluate the effects of the addition of TBP on the preparation and adsorption performance of N235-impregnated resins (NIRs). The results show that TBP can obviously increase the impregnation ratio and shorten the impregnation equilibrium time of the N-TIRs when compared to that of the NIRs (57.73% versus 36.95% and 5 min versus 240 min). It is confirmed that TBP can interact with N235 during the impregnation process, which shorten the adsorption equilibrium time and increases the adsorption capacity of the N-TIRs for V(V) when compared to that of the NIRs (6 h versus 10 h and 50.95 mg·g−1 versus 46.73 mg·g−1). The kinetics fitting results demonstrate that the adsorption of V(V) onto N-TIRs and NIRs all conform to pseudo-second order kinetic model and chemical reaction is the rate-limiting step of the whole adsorption process. In the meanwhile, the reaction constant (Ks) implies that the chemical reaction rate of V(V) with the impregnated extractants in N-TIRs is faster than that in NIRs. The N-TIRs present higher stability and selectivity than NIRs. This study manifests that the addition of a secondary reagent may be a potential and novel technique on the preparation of SIRs and the enhancement of adsorption and separation for ions.

Ultrasound-assisted synthesis of N235-impregnated resins for vanadium (V) adsorption

N235-impregnated resins were prepared using XAD-16HP macroporous adsorption resins as support with and without ultrasonic irradiation to evaluate the effects of ultrasound impregnation (UI) on the preparation and adsorption characteristics of the resins. The results show that the impregnation ratio of the solvent-impregnated resins (SIRs) prepared by ultrasound impregnation method (SIRs-UI) increases obviously but their adsorption capacity for V(V) just slightly increases and the utilization rate of the extractant decreases with the augmentation of ultrasound power. This may be caused by the fact that more extractant can enter into the deeper pores of the resins under high ultrasound intensity, but these extractants cannot effectively react with V(V). The impregnation equilibrium time of SIRs-UI can be obviously shortened in comparison to that of the SIRs prepared by conventional impregnation method (SIRs-CI) (3 min versus 240 min) due to the cavitation effect evoked by ultrasound. Ultrasonic irradiation may cause more N235 desorbed from the pores of the resin at low N235 content, resulting in lower adsorption capacity for V(V) than that of SIRs-CI, but the adsorption capacity is inverse at higher N235 content. N235 may be distributed more homogeneously in the pores of XAD-16HP with ultrasonic irradiation, thus, SIRs-UI presents higher adsorption capacity and stronger stability than SIRs-CI. This study manifests that ultrasound-assistant impregnation method may be a potential and promising technique for the preparation of SIRs.