Preparation of Poly(vinyl Alcohol)(PVA)/peat/clay Composite Beads as Adsorbents for the Removal of Pb (II) and Zn(II) Ions from Aqueous Solutions

Abstract

A new type of poly(vinyl alcohol)(PVA)/peat/clay composite bead was prepared and shown to be suitable for use as an adsorbent. The mass transport process for the adsorption of metal ions onto the composite beads in an aqueous system was investigated. In the external mass transport process, the rate of ion diffusion decreased and increased with increasing initial metal ion concentrations for Pb+2and Zn+2 ions, respectively. In the intraparticle diffusion process, the diffusion coefficient decreased with increasing initial metal ion concentrations in the range of 1×10-3 to 4×10-3 M, and the diffusion coefficient maintained an almost constant value in the range of 6×10-3 to 22×10-3 M. The rate of ion diffusion within the adsorbent for the Pb+2 ions was faster than that for the Zn+2 ions. The adsorption mechanism was controlled by the intraparticle diffusion process. The maximum amount of adsorbed metal ions at adsorption equilibrium for Pb+2 and Zn+2 ions in this study was 134.57 and 13.28 mg/g composite bead, respectively.

Thermomechanical performance and high Brunauer‐Emmett‐Teller surface area of poly(vinyl alcohol)/silica/clay and poly(vinyl alcohol)/(fumed silica)/clay nanocomposites

“…The first step was associated with the moisture loss or evaporation of trapped solvent. The second step was associated with the weight loss process corresponding to dehydration reaction on polymer chain, usually occurring from 250°C to 450°C . The third step was associated with the PVA residues degradation at about 450°C, to produce carbon and hydrocarbon .…”

“…The clay and silica were well intercalated with polymer matrix by covalent bonds, as proven by the moisture absorption test. The presence of silica nanoparticles along with clay in the polymer chain prevented complete decomposition of the PVA-si-clay nanocomposites main chain [24,34,35]. According to the TGA thermographs, the first step of degradation occurred at 858C.…”

“…Thus, PVA, silica, and clay are chosen to be used throughout this research by taking into account of the issues of biocompatibility, biodegradation, high mechanical properties and mechanical properties, and smooth surface of the nanocomposites with the reduction of the hydroxyl groups. PVA‐si‐clay and PVA‐fsi‐clay nanocomposites are expected to be used as a promising material to remove and recover heavy metal ions in water as they have large surface areas .…”