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. 2023 Jun 25;16(13):4583.
doi: 10.3390/ma16134583.

Adsorption Behavior and Mechanism of Cesium Ions in Low-Concentration Brine Using Ammonium Molybdophosphate-Zirconium Phosphate on Polyurethane Sponge

Hao Wang  1 , Guihua Ma  1 , Ke Zhang  1 , Zhi Jia  1 , Yuzhuo Wang  1 , Li Gao  1 , Bingxin Liu  1
Affiliations

Adsorption Behavior and Mechanism of Cesium Ions in Low-Concentration Brine Using Ammonium Molybdophosphate-Zirconium Phosphate on Polyurethane Sponge

Hao Wang et al. Materials (Basel). .

Abstract

Salt lake brine originating from Qinghai, China has abundant cesium resources and huge total reserves. The inorganic ion exchangers ammonium molybdophosphate (AMP) and zirconium phosphate (ZrP) have the significant advantages of separating and extracting Cs+ as a special adsorbent. Nevertheless, their high solubility in water leads to a decrease in their ability to adsorb Cs+ in aqueous solutions, causing problems such as difficulty with using adsorbents alone and a difficult recovery. In this work, an environmentally friendly polyurethane sponge (PU sponge) with a large specific surface area is employed as an adsorbent carrier by physically impregnating dopamine-coated AMP and ZrP onto a PU sponge, respectively. The experiment found that under the same conditions, the AMP/PU sponge performs better than the ZrP/PU sponge for Cs+ adsorption. When the amount of adsorbent reaches 0.025 g, the adsorption capacity reaches saturation. The adsorption efficiency remains above 80% when the concentration of Cs+ is 5-35 mg/L. The kinetic calculations show that adsorption is spontaneous, feasible, and has a higher driving force at high temperatures. In addition, the power and mechanism of the interaction between adsorbent and adsorbent are explained using the density functional theory calculation. This efficient, stable, and selective Cs+ adsorbent provides design guidelines.

Keywords: Cs+ adsorption; ammonium molybdophosphate; polyurethane sponge; zirconium phosphate.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
SEM of PU sponge (a,b), AMP/PU sponge (c,d), and ZrP/PU sponge (e,f).
Figure 2
Figure 2
TG−DTG of AMP/PU sponge (a) and (b) ZrP/PU sponge.
Figure 3
Figure 3
FT−IR of AMP/PU (a) and (b) ZrP/PU sponges and the corresponding precursors.
Figure 4
Figure 4
Effect of dosage on adsorption capacity (a) and adsorption efficiency (b) of Cs+.
Figure 5
Figure 5
Effect of pH on adsorption capacity (a) and adsorption efficiency (b) of Cs+.
Figure 6
Figure 6
Effect of contact time on adsorption capacity (a) and adsorption efficiency (b) of Cs(I) ions.
Figure 7
Figure 7
Kinetic model fitting of adsorbent for Cs+: (a,b) quasi-first-order kinetics, (c,d) quasi-second-order kinetics, and (e,f) particle diffusion kinetics.
Figure 8
Figure 8
Effect of initial Cs+ concentration on adsorption capacity (a) and adsorption efficiency (b) of Cs+.
Figure 9
Figure 9
Isothermal adsorption model fitting of Cs+ on adsorbent: (a,b) Langmuir, (c,d) Freundlich, and (e,f) Temkin.
Figure 10
Figure 10
Effect of temperature on adsorption capacity (a) and adsorption efficiency (b) of Cs+.
Figure 11
Figure 11
Van’t Hoff plot of adsorbents regarding the adsorption of Cs+: (a) AMP/PU and (b) ZrP/PU.
Figure 12
Figure 12
DFT calculation before and after Cs+ adsorption: (a) AMP, (b) AMP after adsorbing Cs+, (c) ZrP, and (d) ZrP after adsorbing Cs+.
See this image and copyright information in PMC

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