Novel chitosan/poly(vinyl) alcohol thin adsorptive membranes modified with amino functionalized multi-walled carbon nanotubes for Cu(II) removal from water: Preparation, characterization, adsorption kinetics and thermodynamics

• Published in: Separation and purification technology Vol. 89; pp. 309 - 319
• Main Authors: Salehi, E., Madaeni, S.S., Rajabi, L., Vatanpour, V., Derakhshan, A.A., Zinadini, S., Ghorabi, Sh, Ahmadi Monfared, H.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 22.03.2012; Elsevier
• Subjects: Adsorption; Adsorptive membrane; alcohols; Applied sciences; aqueous solutions; carbon nanotubes; Chemical engineering; Chitosan; copper; entropy; Exact sciences and technology; Functionalized MWCNTs; Polyvinyl alcohol; sorption isotherms; Thermodynamic; Adsorptive membrane; Polyvinyl alcohol; Chitosan; Functionalized MWCNTs; Thermodynamic; Polymeric membrane; Liquid solid interface; Adsorption isotherm; Adsorption capacity; Entropy; Composite material; Adsorption; Loading; Morphology; Preparation; Kinetics; Aqueous solution; Thermodynamic properties
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2012.02.002

[Display omitted] ► MWCNT-NH2 could effectively enhance adsorption capacity of CS/PVA membrane. ► Copper ion adsorption on CS/PVA membrane is endothermic and spontaneous. ► Kinetic of the adsorption is improved by addition of MWCNT. ► MWCNTs could enhance the reusability of the CS/PVA adsorptive membranes. ► Adsorption is more favorable at higher CNT contents and elevated temperatures. In the current study, amino functionalized multi-walled carbon nanotubes (MWCNT-NH2) were synthesized from raw MWCNTs and utilized to prepare novel chitosan/PVA thin adsorptive membranes for copper ion removal from water. Various weights of the CNTs were embedded in the membranes to obtain the optimum MWCNTs content. Finger-like nanochannels appeared in the compact structure of the CS/PVA membrane by addition of 0.5 wt.% of the MWCNTs; however, fibril-shape and dense structures were generated at higher percent weights i.e. 1 and 2 wt.%, respectively. Adsorption capacity of the membrane containing 2 wt.% MWCNTs (20.1mg/g at 40°C) was almost twice as large as that of the plain membrane (11.1mg/g); however, capacity enlargement was not significant (<3mg/g), when MWCNTs content raised from 1 to 2 wt.%. This indicates that the optimum CNT loading is 1 wt.%. Freundlich isotherm could, thus, superiorly describe the adsorption equilibria. Thermodynamic studies revealed spontaneous (ΔG°<0) and endothermic (ΔH°>0) adsorption together with entropy generation (ΔS°>0) at the solid/liquid interface. Additionally, kinetic studies showed that membranes with higher MWCNTs content could support faster adsorption rate. No significant adsorption capacity loss (∼3%) was observed for the membrane containing MWCNT-NH2 in comparison to the capacity loss of the plain membrane (∼10%) after four successive adsorption/regeneration cycles. The results suggested that the novel CS/PVA/MWCNT-NH2 composite membranes can be effectively applied for the adsorptive removal of copper ions from aqueous solutions.