Multifunctional alginate-sulfonate-silica sphere-shaped adsorbent particles for the recovery of indium(iii) from secondary resources Joris Roosen, ab Steven Mullens b and Koen Binnemans a a KU Leuven, Department of Chemistry, Celestijnenlaan 200F, P.O. Box 2404, B-3001 Heverlee, Belgium. b VITO, Sustainable Materials Management, Boeretang 200, B-2400 Mol, Belgium. SUPPORTING INFORMATION S1
Table S1: Reported wavelengths and view mode (AX/RAD) for ICP measurements Cd Zn Co Ni Fe Al In Ga Ge λ (nm) 228.80 213.86 228.62 231.60 238.20 396.15 230.61 417.21 265.12 view mode RAD RAD RAD RAD RAD RAD AX AX AX Rheological data of sodium alginate solutions with different alginate concentrations were fitted with the Ostwald de Waele (power-law) model, which is based on equation (S1): 1 µ = K γ n 1 (S1) with, µ [Pa s] is the apparent viscosity, γ [s -1 ] is the shear rate, K [Pa s n ] and n [dimensionless] are the flow consistency index and the flow behavior index, respectively. The empirical parameters derived from fitting the Ostwald de Waele model to the experimental data give information on the flow behavior and the consistency of the solution (Table S2). The sodium alginate solutions showed shear-thinning behavior: the higher the shear rate, the lower the apparent viscosity. Additionally, a higher sodium alginate concentration resulted in an upward shift of the viscosity curve, as expected. Solutions with different viscosities may be used to obtain droplets with different diameters, due to a changing surface tension. S2
Viscosity (mpa.s) 1500 1250 2.0% (wt/vol) 1.5% (wt/vol) 1.0% (wt/vol) 1000 750 500 250 0 0 200 400 600 800 1000 Shear rate (s -1 ) Figure S1: Ostwald de Waele viscosity fits at 25 C for solutions of sodium alginate (1.0% (wt/vol), 1.5% (wt/vol) and 2.0% (wt/vol)), after 24 h of settling. Table S2: Ostwald de Waele model parameters at room temperature for solutions of sodium alginate (1.0% (wt/vol), 1.5% (wt/vol) and 2.0% (wt/vol) after 24h of settling Sodium alginate concentration %(wt/vol) K n Viscosity at γ = 1000 s -1 (mpa s) 1.0 0.206 0.937 133 1.5 0.753 0.882 332 2.0 2.051 0.831 636 The Feret ratio (S2) quantifies the degree of circularity: 2 Feret ratio = d D (S2) Here, d is the minimum Feret diameter and D the maximum Feret diameter. A Feret diameter is defined as the distance between two parallel tangential lines of a spheroid. 2 A S3
Feret ratio of 1 indicates a perfectly spherical particle. A measure for the width of the particle size distribution is the d 90 /d 10 value, defined by the ratio between the 90% largest and 10% smallest spheres. The closer this ratio approaches a value of 1, the higher the monodispersity. Upon drying of the wet (gel) beads, shrinkage was observed. The shrinkage factor (S3) can be defined as: Shrinkage factor = d av,wet d av,dried d av,wet 100% (S3) Here d av,wet is the average diameter of the wet (gel) spheres and d av,dried the average diameter of the spheres that were (irreversibly) dried by supercritical CO 2. Diameters were calculated as equivalent projected circle values. The equivalent projected circle is the diameter of a circle that has the same projected area as the actual particle. 2. A Feret ratio higher than 0.90 quantitatively confirmed the high circularity of the three batches of ASS spheres. So did the d 90 /d 10 value, which was very close to 1 for each batch, meaning that the spheres were nearly monodisperse. Uniform, spherical particles have the advantage that they allow very close packing of the solid phase in a chromatography column, thus maximizing (ion) exchange with the (aqueous) mobile phase and avoiding preferential percolation pathways. Table S1: Compressive strength of alginate-silica-sulfonate (ASS) particles Maximal compressive force (N) gel spheres dried spheres ASS 2.2 mm 0.05 ( 0.01) > 100 ASS 2.8 mm 0.08 ( 0.01) > 100 ASS 3.5 mm 0.20 ( 0.02) 24 (± 4) S4
Table S4: Pseudo-second-order kinetic model parameters for ASS spheres with different particle sizes Particle diameter k (mm) q e (mmol g -1 ) 2.2 9.79 0.58 0.98 2.8 4.00 0.59 0.98 3.5 2.69 0.59 0.96 R² Table S5: Comparison of different adsorbent materials regarding adsorption amount from dilute metal solutions of In(III) as the element studied here and Nd(III) as a representative element for the REEs Sorbent material Metal Concentration Alginate-sulfonate-silica (ASS) spheres (mmol L -1 ) ph q e (mmol g -1 ) Reference In(III) 2.5 3.1 0.56 present work Alginate-TMOS spheres In(III) 2.5 3.1 0.15 present work Alginate-TMOS spheres Nd(III) 2.0 3.1 0.37 [3] DTPA-functionalized chitosan-silica Nd(III) 2.5 3.0 0.27 [4] Lewatit TP207 resin In(III) 0.9 3.4 0.48 [5] DETA-functionalized chitosan nanoparticles Nd(III) 2.1 5.0 0.38 [6] P-functionalized silica Nd(III) 2.3 3.0 0.51 [7] S5
Figure S2: Raman spectrum of alginate spheres (in isopropanol) after functionalization with (3- mercaptopropyl) trimethoxysilane. Figure S3: Raman spectrum of alginate-sulfonate-silica spheres (dry) after oxidation with H 2 O 2. S6
(a) (b) (c) (d) (e) (f) Figure S4: Element mappings on cross-sectional images of ASS spheres with a diameter of 2.8 mm, (a) = C, (b) = Ca, (c) = Si, (d) = S, (e) = O, (f) = CBS reference. S7
Figure S5: N 2 adsorption-desorption isotherms at 77K of ASS spheres with a diameter of 2.2 mm. Figure S6: TGA traces of ASS spheres of 2.2 mm (green), 2.8 mm (red) and 3.5 mm (blue). S8
In(III) adsorption amount (mmol g -1 ) 0.6 0.5 0.4 0.3 0.2 0.1 0.0 20 40 60 80 Temperature ( C) Figure S7: In(III) adsorption amount on ASS spheres with a diameter of 2.8 mm as a function of the reaction temperature. (1) Chhabra, R. P.; Richardson, J. F., Non-Newtonian Flow and Applied Rheology: Engineering Applications. 2 ed.; Elsevier: Oxford, UK, 2008; p 536. (2) Yu, W.; Hancock, B. C., Evaluation of dynamic image analysis for characterizing pharmaceutical excipient particles. Int. J. Pharm. 2008, 361, 150-7. (3) Roosen, J.; Pype, J.; Binnemans, K.; Mullens, S., Shaping of Alginate Silica Hybrid Materials into Microspheres through Vibrating-Nozzle Technology and Their Use for the Recovery of Neodymium from Aqueous Solutions. Ind. Eng. Chem. Res. 2015, 54, 12836-12846. (4) Roosen, J.; Spooren, J.; Binnemans, K., Adsorption performance of functionalized chitosansilica hybrid materials toward rare earths. J. Mater. Chem. A 2014, 2, 19415-19426. (5) Lee, S.-K.; Lee, U. H., Adsorption and desorption property of iminodiacetate resin (Lewatit TP207) for indium recovery. J. Ind. Eng. Chem. 2016, 40, 23-25. (6) Galhoum, A. A.; Mahfouz, M. G.; Abdel-Rehem, S. T.; Gomaa, N. A.; Atia, A. A.; Vincent, T.; Guibal, E., Diethylenetriamine-functionalized chitosan magnetic nano-based particles for the sorption of rare earth metal ions [Nd(III), Dy(III) and Yb(III)]. Cellulose 2015, 22, 2589-2605. (7) Park, H.-J.; Tavlarides, L. L., Adsorption of Neodymium(III) from Aqueous Solutions Using a Phosphorus Functionalized Adsorbent. Ind. Eng. Chem. Res. 2010, 49, 12567 12575. S9