Preparation and Properties of Poly (vinyl alcohol)/Hydroxyapatite Nanocomposite Cryogel for Cadmium Sorption

Xiao Wang
School of Advanced Materials and System Engineering, Kumoh National Institute of Technology, Korea

Byung Gil Min
School of Advanced Materials and System Engineering, Kumoh National Institute of Technology,Korea

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     Last modified: April 12, 2006

Abstract
PVA/HAp nanocompostie cryogel has been prepared as a new adsorbent to remove heavy metals. The PVA/HAp nanocompostie cryogel was made by freeze-thawing process. The PVA/HAp nanocompostie cryogel is characteristic of interconnected porous structure and well dispersed and immobilized HAp in cryogel. The pore size varies from 100nm to several um. Batch experiments of cadmium sorption were performed to test the sorption ability of PVA/HAp nanocompostie cryogel. The sorption behavior was studied by fitting the experimental results to isotherm and kinetics models. The Langmiur isotherm is suitable for this system. The maximum sorption capacities from experiment and calculation both show good sorption ability of PVA/HAp nanocomposite cryogel on cadmium. The double-exponential model presents best fit compared with pseudo-first-order and pseudo-second-order models. The double-exponential model indicates a diffusion-controlled and a two-step mechanism. Moreover, the effects of temperature, pH and shaking rate were investigated. The sorption capacity increases with temperature. There is little pH dependence of cadmium removal.