Recovery of phosphate from wastewater represents a sustainable alternative to phosphate rock, a limited resource. Magnesium aluminum layered double hydroxides (MgAl-LDH), are promising sorbents due to their high phosphate removal capacity by ion-exchange (26-124 mgP/g). Furthermore, an increased sorption capacity has been reported by the addition of zirconium (Zr(IV)) into the LDH lattice. However, ambiguity exists especially in relation to the incorporation of Zr and the stability of the MgAl-LDH. To understand how Zr(IV)-addition affects the phosphate sorption properties (both capacity and mechanism) on the atomic level, solid state multi-nuclear NMR spectroscopy was combined with complimentary characterization techniques to study a series of MgAl-LDH with Zr to Al ratios of 1:9 and 1:1, which had the Mg to (Al+Zr) ratio fixed at 2:1. The LDH were synthesized by coprecipitation and subsequently aged or hydrothermally treated to improve the crystallinity (particle size). No evidence of Zr(IV) incorporation in the LDH was observed, instead Zr was present as Zr(IV)-hydroxide (X-ray amorphous) and crystalline Zr(IV) oxide after aging and hydrothermal treatment, respectively. The segregation of Zr(IV)and resulting lower Al content in the MgAl-LDH decreased the phosphate sorption capacity from 45-54 to 16-20 mgP/g. Zr (hydr)oxide impurities contributed with less than 5 mgP/g. Moreover, 31 P MAS NMR spectroscopy quantified showed that the MgAl-LDH contribute to less than 60% of the total P removal capacity.
Authors
Kamilla Thingholm Bünning, Tae-Hyun Kim, Vanessa Prevot, Claude Forano, Ulla Gro Nielsen
- Bibliographic Reference
- Kamilla Thingholm Bünning, Tae-Hyun Kim, Vanessa Prevot, Claude Forano, Ulla Gro Nielsen. The effect of Zr(IV) addition on the phosphate removal properties of MgAl-LDH. Applied Clay Science, 2023, 245, pp.107125. ⟨10.1016/j.clay.2023.107125⟩. ⟨hal-04298962⟩
- DOI
- https://doi.org/10.1016/j.clay.2023.107125
- HAL Collection
- ['Université de Clermont', 'CNRS - Centre national de la recherche scientifique', 'Institut de Chimie de Clermont-Ferrand', 'ACL en Sciences fondamentales', 'Institut de Chimie du CNRS', 'Clermont Auvergne INP']
- HAL Identifier
- 4298962
- Institution
- ['Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark', 'Accelerator and Radioisotope Research Section, Korea Atomic Energy Research Institute', 'Institut de Chimie - CNRS Chimie', 'Institut national polytechnique Clermont Auvergne']
- Laboratory
- Institut de Chimie de Clermont-Ferrand
- Published in
- France
Table of Contents
- The effect of ZrIV addition on the phosphate removal properties of MgAl-LDH 2
- Kamilla Thingholm Bünning Tae-Hyun Kim Vanessa Prevot Claude Forano Ulla Gro Nielsen 2
- Abstract 3
- Keywords 3
- 1. Introduction 3
- 2. Experimental section 10
- 2.1. Materials 10
- 2.2. Methods 10
- 2.2.1. Sample preparation 10
- Table 2. 11
- 2.2.2. Phosphate isotherm batch experiments 13
- Eq. 2 13
- Eq. 3 13
- Eq. 3 14
- C V m 14
- Q K 14
- 2.2.3. Powder X-ray diffraction 14
- B2θ Kλ cos θ Eq. 4 15
- B2θ K 15
- 2.2.4. Solid State H Al and P MAS NMR spectroscopy 15
- 2.2.5. Zeta potential - and hydrodynamic size measurements 16
- 2.2.6. Transmissions electron microscopy 16
- 2.2.7. Elemental analysis 16
- 3. Results and discussion 17
- 3.1. The effect of the Zr content on the phosphate removal capacity of MgAl-LDH 17
- Figure 1. 18
- Figure 2. 20
- 3.2.Characterization of the synthesized LDH with and without Zr doping 20
- Table 3 21
- Figure 3. 23
- Figure 4. 24
- Figure 5 26
- 3.3.Characterization of the LDH after phosphate sorption 27
- 3.4. Quantification of the different phosphate removal pathways by P MAS NMR spectroscopy 29
- Figure 6. 29
- 4 site 5 30
- Figure 7. 31
- 4. Conclusions 32
- Declaration of Competing Interest 33
- Acknowledgments 33
- Appendix A. Supplementary data 33
- Data availability 33
- References 33
