Application of sodium titanate nanofibers as constructed wetland fillers for efficient removal of heavy metal ions from wastewater

Abstract

Constructed wetlands are an environmentally friendly and economically efficient sewage treatment technology, with filler 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 NH 4 HCO 3 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 are 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.

Adsorption of Cu(II), Ni(II) and Zn(II) ions by nano kaolinite: Thermodynamics and kinetics studies

“…A comparison with other adsorbents indicated a high metal ion adsorption capacity of nano kaolinite extracted and prepared from deposits of Sweileh sand, west Amman, Jordan. Findings revealed that nano kaolinite offered promising adsorption efficiency versus various other adsorbents reported for metal ions adsorption and nano kaolinite could possibly be used for the adsorption of heavy metal ions from industrial effluents (Bulgariu et al, 2019;Chen et al, 2019;Gaikwad et al, 2010;Godiya et al, 2019a;Godiya et al, 2019b;Ibrahim and Fakhre, 2019;Jiang et al, 2019;Kausar et al, 2018a;Kausar et al, 2018b;Khera et al, 2019;Liang et al, 2013;Mousavi et al, 2019;Nadeem et al, 2016;Sandoval et al, 2019;Zafar et al, 2018;Zhao et al, 2019).…”

Wetlands for environmental protection

“…The enhancement of atrazine degradation was achieved in CW by implementation of bioaugmentation (increasing functional atrazine‐degrading bacteria) and was reported that 5 mg/L of atrazine was reduced below the threshold value within 43 days of treatment time. They also reported that among the atrazine‐degrading bacteria Pseudomonas and Arthrobacter were increased rapidly in number (Zhao, Wang, et al, 2019).…”

“…A study considering a demonstrative case of CW bioaugmented (biological wastewater treatment, BWWTs) by dosing different microbial inocula was proposed for a decision-support system (DSS) by linking Life cycle assessment (LCA) with Water Quality Model and Conjoint Analysis. The DSS provides decision makers and stakeholders a tool to analyze the sustainability of BWWTs in terms of multiple perspectives rather than just pollutant removal criteria (Zhao, Wang, et al, 2019).…”

“…Sodium titanate nanofibers have been introduced to wetlands to enhance the removal of heavy metal ions. This technology demonstrated metal adsorption capabilities 4–5 times higher than zeolite (Zhao, Wang, et al, 2019). On the other hand, Li, Li, Li and Wu 2020 discovered that pre‐aeration of the rhizosphere could potentially enhance phytoremediation.…”

Artificial wetlands and floating islands: Use of macrophytes

“…Emerging pollutants are compounds of different origin and chemical nature, whose presence in the environment and the possible damage they could cause, have largely gone unnoticed (ZHAO et al, 2019;RAI, 2019). It's possible polluting effects have been recently studied, approximately ten years ago when various drugs and other substances were found in the rivers of Germany that were not considered pollutants.…”