Phosphate removal performances of layered double hydroxides (LDH) embedded polyvinyl alcohol / lanthanum alginate hydrogels

By Feng Lihua, Qian Zhang, F. Ji, Lei Jiang, Caocong Liu, Qiushi Shen, Qian Liu. Chemical Engineering Journal, 2022

196 citations recorded by the source corpus.

Abstract Lanthanum modified compounds and Layered double hydroxides (LDH) are promising adsorbents for phosphate. However, the nano-scale LDH is challenging to separate, and conventional immobilization methods weaken the adsorption performance. With the affinity between metal ions and phosphate, polyvinyl alcohol/metal ions sodium alginate (PS-M−LDH) hydrogel beads for the improvement of phosphate removal were prepared by in-situ crosslinking with different metal ion (M) solutions. Through screening, the PS-M−LDH crosslinked by La (PS-La-LDH) has the preferable phosphate adsorption performance. The phosphate adsorption behavior of PS-La-LDH hydrogel was further investigated. Results showed that the adsorption process of phosphate by PS-La-LDH hydrogel was in accordance with the pseudo-second-order kinetic model and Freundlich model. The maximum experimental adsorption capacity of PS-La-LDH was 34.2 mg P/g, converting to an equivalent LDH of 91.2 mg P/g LDH, which was 1.6 times of pristine LDH powder (58.0 mg P/g LDH). The removal of phosphate by PS-La-LDH performed well at a wide range of pH 3 ∼ 8. PS-La-LDH showed selective adsorption to phosphate with the existence of competing anions (Cl-, NO3–, and SO42–). The phosphate adsorption by PS-La-LDH hydrogel only reduced 16.57 % when the concentration of SO42– was increased to 2882 mg/L. SEM, XRD, FTIR, and XPS results showed that the electrostatic interaction, ligand exchange, and ion exchange jointly facilitated the adsorption of phosphate.

Subfields: Industrial and Manufacturing Engineering, Materials Chemistry, Surgery

View Paper: https://www.semanticscholar.org/paper/dc481de49c46f87ad25ed7064ba7fd39708460de