New insights into nanocomposite adsorbents for water treatment: A case study of polystyrene-supported zirconium phosphate nanoparticles for lead removal

By encapsulating zirconium phosphate (ZrP) nanoparticles into three macroporous polystyrene resins with various surface groups, i.e., -CH2Cl, -SO3 (-), and -CH2N+(CH3)(3) three nanocomposite adsorbents (denoted as ZrP-Cl, ZrP-S, and ZrP-N) were fabricated, respectively for lead removal from water. Effect of the functional groups on nano-ZrP dispersion and effect of ZrP immobilization on the mechanical strength of the resulting nanocomposites were investigated. The presence of the charged functional groups (-SO3 (-) and -CH2N+(CH3)(3)) are more favorable than the neutral -CH2Cl group to improve nano-ZrP dispersion (i.e., to achieve smaller ZrP nanoparticles). ZrP-N and ZrP-S had higher capacity than ZrP-Cl for lead removal. As compared to ZrP-N, ZrP-S exhibits higher preference toward lead ion at high calcium levels as a result of the potential Donnan membrane effect. On the other hand, nano-ZrP immobilization would simultaneously reinforce both the compressive strength and the wear performance of the resulting nanocomposites with the ZrP loadings up to 5 wt%. The results reported herein would shed some light on the generation of environmental nanocomposites with high capacity and excellent mechanical strength.