Removal of phosphate with a polyacrylonitrile composite functionalized by a metal organic framework-enhanced layered double hydroxide

Water Sci Technol. 2023 Apr;87(7):1672-1685. doi: 10.2166/wst.2023.083.

Abstract

Excessive phosphorus causes eutrophication problems. The adsorptive removal of phosphate is prevalent and practical in large-scale applications, such as column adsorption. A metal organic framework (MOF)-enhanced layered double hydroxide (LDH) adsorbent material was developed and studied for batch adsorption and then combined with polyacrylonitrile (PAN) to form MOF/LDH/PAN composite beads working as a functional material for columns. Scanning electron microscopy (SEM) images showed the well-dispersed adsorbent powder in porous composite beads. The Fowler-Guggenheim isotherm model described the phosphate adsorption behavior of the MOF/LDH powder with a maximum capacity of 74.96 mg P/g. Mass transfer in the composite beads was successfully described with the Fickian diffusion model. The composite-packed fixed bed treated 37.95 BVs of the influent (55.51 mg P/L phosphate solution) and achieved an uptake of 18.92 mg P/g, with a removal efficiency of 96.42%, before the breakthrough point in the column study. The phosphate-loaded composite bed was regenerated with 0.1 M NaOH to 70% efficiency within 30 BVs. The polymer composite can be considered a practical solution for adsorption-based water treatment applications in tank and column processes where powder adsorbents cannot be applied.

MeSH terms

  • Adsorption
  • Hydroxides
  • Kinetics
  • Metal-Organic Frameworks*
  • Phosphates
  • Powders
  • Water Pollutants, Chemical* / analysis

Substances

  • Phosphates
  • Metal-Organic Frameworks
  • polyacrylonitrile
  • Powders
  • Water Pollutants, Chemical
  • hydroxide ion
  • Hydroxides