Lead and cadmium adsorption by electrospun PVA/PAA nanofibers: Batch, spectroscopic, and modeling study. (October 2019)

• Record Type: Journal Article
• Authors: Zhang, Shujuan; Shi, Qiantao; Christodoulatos, Christos; Meng, Xiaoguang
• Is Part Of: Chemosphere. Volume 233(2019)
• Page Start: 405
• Page End: 413
• Publication Date: 2019-10
• Subjects: Electrospun PVA/PAA nanofibers -- Lead -- Cadmium -- EXAFS -- Surface complexation model; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.05.190
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Water-stable PVA/PAA nanofibers were fabricated through electrospinning and evaluated for their performance in lead (Pb(II)) and cadmium (Cd(II)) removal from water in a batch experiment. The adsorption mechanism of Pb(II) was explored using the extended X-ray absorption fine structure (EXAFS) spectroscopic analysis. The PVA/PAA nanofibers showed a pH-dependent behavior for heavy metal removal, and its adsorption capacities for Pb(II) and Cd(II) could reach as high as 159 and 102 mg/g, respectively. The calcium ion (Ca(II)) had no effect on Pb(II) removal at pH 5.0 whereas it significantly reduced Cd(II) removal at pH 7.0. The adsorption of Pb(II) and Cd(II) was spontaneous and exothermic in nature with a decrease in randomness. The saturated PVA/PAA nanofibers could be regenerated using acidic solutions for reuse. The Fourier-transform infrared (FTIR) spectroscopic analysis indicated the formation of surface complexes between adsorbed Pb(II) and Cd(II) and carboxyl groups on PVA/PAA nanofibers. Moreover, EXAFS analysis suggested that a Pb(II) cation was chelated with three carboxyl groups on the nanofibers. This molecular-level adsorption structure was successfully implemented into a surface complexation model for the prediction of the macroscopic Pb(II) and Cd(II) adsorption behaviors. The results gained from this study provided complementary information on heavy metal removal by a new generation of adsorbents and improved the fundamental understanding for the removal process. Graphical abstract: Image 1 Highlights: Electrospun PVA/PAA nanofibers were evaluated for Pb(II) and Cd(II) removal. The adsorption capacity for Pb(II) and Cd(II) was 159 and 102 mg/g, respectively. The active adsorption sites for Pb(II) on nanofibers were carboxyl groups. Each Pb(II) atom was complexed with three carboxyl groups on nanofibers. Surface complexation model successfully predicted Pb(II) and Cd(II) adsorption.