A novel network montmorillonite composite particle directly separated from water after adsorption pollutants

Abstract

• Polyvinylformal-Montmorillonite particle with the network structure was prepared. • Particle structure, morphology, performance and separation from water were studied. • Composite particle can directly separate montmorillonite (Mt) from water. • The adsorption performance of composite particle is better than that of Mt. • Particle adsorption mechanism for Pb(II) and methylene blue was discussed. Montmorillonite (Mt) has good adsorption for organic pollutants and heavy metal ions well, so it is essential for application in wastewater treatment. However, Mt has difficulty being separated from water, which limits its widespread application in wastewater treatment. Based on this problem, polyvinylformal-Mt (PVFM-Mt) composite particles were prepared with Mt, polyvinyl-alcohol (PVA), and formaldehyde serving as raw materials, and their structure, morphology and properties were studied. The results showed that the Mt in PVFM-Mt has a layered structure (d 001 = 1.24 nm ∼ 1.84 nm); the PVFM in PVFM-Mt exhibits a mesh-bag structure and the PVFM mesh-bag density increased with increasing formaldehyde dosage; the surface of PVFM-Mt is porous and grooved; the zeta potential of PVFM-Mt (–23.8 mV) is equivalent to that of Mt (−24.5 mV); PVFM-Mt has a swelling property in water; and the particle diameter expansion time is doubled, equivalent to Mt raw materials (2.07). In addition, PVFM-Mt is easily separated from water (ω = 1.68%∼2.20%,ω is the loss rate of particles in water) and Mt was difficult to engineer separation (ω = 57.92%∼59.60%); and the removal rates of methylene blue (MB) and Pb(II) can reach 99.60% and 99.05%, respectively, significantly better than those obtained with Mt (96.99% and 96.36%). PVFM-Mt adsorbs MB and Pb(II) mainly by the electronegativity of the Mt layer, by coordination with oxygen, aluminum hydroxyl groups or broken bonds, and by coordination with oxygen atoms of the hydroxyl and ether bonds of PVFM. The PVFM in the PVFM-Mt adsorption winding also contributes to the adsorption of MB. This work provides a theoretical and application basis for the extensive application of clay mineral materials in wastewater treatment and large-scale production.