Multivariate Optimization of Removal of Pb(II) Ions from Aqueous Solution by a New Metal–Organic Framework

Heavy metals, as an important groups of pollutants of water resources, can cause serious ailments such as nausea, skin rashes, dehydration, stomach ache, vomiting, eye irritation, lung irritation, and liver damage. Lead(II), as a heavy metal, exists in many wastewaters and real samples. Metal-organic frameworks (MOFs) are a new class of nanoporous materials and consist of two main components, bridging organic ligands and metal ions or clusters of metal ions. In among methods of the synthesis of MOFs, sonochemical method is an effective and fast approach for the synthesis of smaller size MOFs. In this study, a new Ni-based metal-organic framework including bipyridine ligands, vanadate and fluoride inorganic units, was prepared using sonochemically to obtain a new highly efficient adsorbent for removal of lead ions from aqueous solution. The elemental analysis (C, H, and N), FT-IR spectroscopy, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX), and thermogravimetric analysis (TGA) were explored to identify of adsorbent structure. The Face centered composite design (FCCD) was employed to obtain the simultaneous optimal conditions of adsorption capacity (q) and removal percent (R%) of Pb(II) (adsorbent dosage = 0.0012 g, Pb(II) concentration = 390 mg/L, and pH = 5). The isotherm and kinetics studies of the adsorption process showed that Langmuir isotherm, with qmax= 2400.712 mg/g, and pseudo-second-order model describe the experimental data well. Furthermore, the adsorption process of lead is independent of temperature changes.