Application of sodium titanate nanofibers as constructed wetland fillers for efficient removal of heavy metal ions from wastewater. (May 2019)

• Record Type: Journal Article
• Authors: Zhao, Min; Wang, Sen; Wang, Hongsheng; Qin, Peirui; Yang, Dongjiang; Sun, Yuanyuan; Kong, Fanlong
• Is Part Of: Environmental pollution. Volume 248(2019)
• Page Start: 938
• Page End: 946
• Publication Date: 2019-05
• Subjects: Constructed wetland -- Titanate nanofillers -- Adsorption -- Heavy metal removal; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2019.02.040
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: Constructed wetlands are an environmentally friendly and economically efficient sewage treatment technology, with fillers playing an important role in treatment processes. However, traditional wetland fillers (e.g. zeolite) are known to be imperfect because of their low adsorption capacity. In this paper, the adsorbent sodium titanate nano fillers (T3-F) was synthesized as an alternative to traditional filler with sodium titanate nanofibers (T3) as the raw material, epoxy adhesive as the adhesive agent and NH4 HCO3 as the pore-making agent. The properties of T3-F were characterized by powder X-ray diffraction (XRD), scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), porosity. The effect of different parameters such as pH, co-existing ions, contact time, initial metal ion concentrations and temperature was investigated for heavy metal adsorption. The results showed that the adsorption of heavy metal by T3-F followed the pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacities for Cu 2+, Pb 2+, Zn 2+, Cd 2+ were about 1.5–1.98 mmol/g, which were 4–5 times that of zeolite, the traditional commonly used filler. Moreover, T3-F could entrap toxic ions irreversibly and maintain structural stability in the adsorption process, which solved the issue of secondary pollution. In the presence of competing ions, the adsorption efficiency for Pb 2+ was not reduced significantly. Adsorption was strongest at high pH. From the results and characterization, an adsorption mechanism was suggested. This study lays a foundation for the practical application of T3-F as a constructed wetland filler in the future. Graphical abstract: Image 1 Highlights: A new constructed wetland fillers was prepared by sodium titanate nanofibers. Fillers show excellent adsorption ability towards Cu 2+, Pb 2+, Zn 2+, Cd 2+ ions. Adsorption occurs through ion exchange mechanism. Fillers could entrap toxic ions irreversibly. Abstract : The filler can effectively adsorb heavy metal ions and permanently trap toxic cations in the fiber.