Preparation and Characterization of Triethylenetetramine Modified Electrospun Membranes (TETA - PVC) and Their Adsorption Behavior in Removing Lead(II) From Water

Abstract

Water pollution is a global environmental concern threatening the entire biosphere and posing a significant risk on aquatic environments, leading to deterioration in the quality of water, thus affecting living organisms and limiting access to clean water. The development of sustainable and affordable water purification methods is crucial, yet remains challenging due to the wide range of pollutants (organic, inorganic, and heavy metals) present in water bodies. Owing to their persistence, toxicity, and bio-accumulative nature, heavy metals gained special attention from researchers investigating efficient approaches for the sequestration of metals from water. Adsorption is one of the most favored water treatment technologies due to its low cost, simplicity in design, and high efficiency. Electrospun polymeric nanofibrous membranes are among the developed adsorbents employed for water treatment due to their high porosity, large surface area, and ease of surface modification.

In this study, functionalized nanofibrous membranes were designed and fabricated to sequester lead(II) selectively from water. PVC membranes were prepared through electrospinning technique and modified with an organic linker, triethylenetetramine (TETA) resulting in TETA-PVC membranes. The membranes were characterized and their adsorption behavior towards the removal of lead was investigated. The incorporation of TETA on the membrane’s surface significantly improved the removal efficiency of lead(II), at ambient conditions, up to 99.8% in 30 minutes. The adsorption mechanism was investigated and kinetic data showed the best fit for the pseudo-second-order. Similarly, the equilibrium data best fitted with the Langmuir adsorption isotherm model with a maximum adsorption capacity of 1250 mg/g for lead(II) ions. The membrane also showed high selectivity to lead(II) in a tertiary system containing lead(II), mercury(II), and cadmium(II). The functionalized membrane was regenerated, where desorption of lead(II) was achieved, under mildly acidic conditions. The removal efficiency of the regenerated membrane was maintained at 98% of its removal efficiency after six cycles of adsorption/ desorption. The proposed design offers a simple yet effective, sustainable, and environmentally friendly solution for water treatment.