Synthesis Of Copolymer Poly(N-Isopropylacrylamide-Co-Acrylic Acid) Hydrogels As Adsorbent For Copper (Ii) Ions Removal In Polymer-Enhanced Ultrafiltration (Peuf)
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Date
2013-12
Authors
Chen, Jian Jie
Journal Title
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Publisher
Universiti Sains Malaysia
Abstract
In this study, monopolymeric poly(N-isopropylacrylamide) (PNIPAM) and co-polymeric Poly(N-isopropylacrylamide-co-acrylic acid) (PNIPAM-co-AA) cross-linked hydrogels with different acrylic acid (AA) content (10, 30 and 50 mol %) were successfully prepared via free radical polymerization method. The physical properties of hydrogels including their thermo-responsiveness properties before and after Cu2+ adsorption were characterized by fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS) and transmission electron microscopy (TEM). The increasing AA content caused the increase in particle size as shown by DLS results and AFM images. More pronounced hysteresis effect was also observed on the graphs of hydrodynamic diameter (Dh) change with increasing AA content. Hydrogels with 30 mol % AA (P-30) was found to have the optimum adsorption capacity (qe) at pH 5 without precipitation of Cu(OH)2. Adsorption data of P-30 hydrogels were best fitted with Langmuir isotherm model corresponding to monolayer adsorption. The E magnitudes calculated from Dubinini-Radushkevich (D-R) isotherm model indicated the transition of adsorption mechanism from physisorption for PNIPAM to the mixed chemisorption and ion exchange with the increase in AA content. The maximum adsorption capacity (qm) of P-30 calculated from Langmuir model is 68.8705 mg g-1 at 323 K. Temperature had negligible effect on the desorption of Cu2+ from hydrogels due to the strong chemisorptions force.
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Keywords
Synthesis , Copolymer Poly(N-Isopropylacrylamide-Co-Acrylic Acid)