Static and dynamic adsorption of copper ions on chitosan/polyvinyl alcohol thin adsorptive membranes: Combined effect of polyethylene glycol and aminated multi-walled carbon nanotubes

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 215-216; no. 15; pp. 791 - 801
• Main Authors: Salehi, E., Madaeni, S.S., Rajabi, L., Derakhshan, A.A., Daraei, S., Vatanpour, V.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.01.2013
• Subjects: additive effect; adsorption; Aminated MWCNTs; carbon nanotubes; chemical engineering; Chitosan; copper; filtration; Kinetic; Membrane adsorption; polyethylene glycol; polyvinyl alcohol; Porogen; temperature; Porogen; Aminated MWCNTs; Chitosan; Kinetic; Membrane adsorption
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2012.11.071

► Introducing MWCNT-NH2 and PEG enhance sorption capacity of CS/PVA membranes. ► MWCNTs improve reusability, adsorption rate and stability of the membranes. ► PEG increases pore capacity compared to MWCNT. ► Adsorption of copper on CS/PVA membranes was endothermic and spontaneous. ► CPMP membrane offers superior adsorption–filtration performance. Polyethylene glycol (PEG) and amino-modified multi-walled carbon nanotubes (MWCNT-NH2) were utilized to modify chitosan/polyvinyl alcohol (CS/PVA) thin adsorptive membranes for copper ion adsorption. SEM, AFM, water affinity and mechanical analysis were performed for membrane characterization. Batch adsorption experiments were conducted to determine the effects of additive, pH, metal concentration and temperature on adsorption. Macroporous membranes were prepared by introducing PEG into the casting dopes; however, the upper limit for PEG loading was 5wt%. Adsorption capacity of CS/PVA membrane was increased from 11 to 30mg/g by addition of 5wt% PEG to the blend. Addition of MWCNT-NH2, especially at optimal concentration of 1wt%, improved membranes adsorption/transport behavior by creation of nanochannels and supplementary interstices in the compact CS/PVA matrix. Copper ion adsorption on CS/PVA membrane was elevated from 11 to 19mg/g by introducing 1wt% MWCNT-NH2. Thermodynamic parameters (ΔH°, ΔS° and ΔG°) revealed endothermic nature, favorability and spontaneity of the adsorption. Moreover, kinetic studies showed that MWCNT-NH2 plays primary role in adsorption rate enhancement. Adsorptive membranes containing combined MWCNT-NH2 and PEG (called ‘CPMP’), demonstrated superior sorption capacity (∼35mg/g) and reusability among tested membranes. Finally, thin adsorptive membranes were tested in dynamic mode using a dead-end filtration setup. CPMP showed superior performance as expected. Based on the results, introducing combined MWCNT-NH2–NH2 and PEG can greatly elevate CS/PVA membranes capability for adsorptive removal of copper ions from water.