Magnetic porous NiLa-Layered double oxides (LDOs) with improved phosphate adsorption and antibacterial activity for treatment of secondary effluent

Abstract

The removal of phosphate (nutrient) and E. coli (pathogen) from secondary effluent is of great importance to control the water quality of the receiving water bodies. In this study, magnetic porous NiLa-layered double oxides (NiLa-LDOs/Fe3O4) were synthesized using a simple co-precipitation method. NiLa-LDOs/Fe3O4 exhibited a high phosphate adsorption capacity of 203.10 mg g−1 in batch adsorption experiments, which can mostly be maintained within the pH range (5.5–8.5) and ionic strength range (5–20 mM) of secondary effluent, and in the presence of commonly co-existing species (anions and organics). NiLa-LDOs/Fe3O4 were further evaluated in real secondary effluent and the homogenous surface diffusion model (HSDM) was used to predict the performance in field applications. Under typical conditions, NiLa-LDOs/Fe3O4 can last for ∼1845–2448 bed volumes (BVs) before the phosphate concentration in the effluent exceeds the monthly average limit of 1 mg L−1 P. Good regeneration capacities were also demonstrated in cyclic adsorption-desorption runs in both synthetic solution and secondary effluent. In addition, the presence of Ni and La species greatly enhanced the antibacterial performance of the NiLa-LDOs/Fe3O4 toward E. coli. Results obtained from this study indicate porous NiLa-LDOs/Fe3O4 can be a promising multifunctional material for the treatment of secondary effluent.