Phosphorylated polyacrylonitrile-based electrospun nanofibers for removal of heavy metal ions from aqueous solution

Fabrication and optimization of curcumin-multiwalled carbon nanotube (C-MWCNT) conjugate reinforced electrospun polyacrylonitrile membrane for water treatment applications

In the recent times, one of the most crucial tasks related to water resources is the treatment of polluted water. This study reports the development of a functionalized nanofibrous membrane with enhanced filtration performance, heavy metal removal, and photocatalytic dye degradation for the effective treatment of contaminated water. The nanofibrous mats were developed by the process of electrospinning using a polymeric solution of polyacrylonitrile (PAN) reinforced with curcumin-multiwalled carbon nanotube (C-MWCNT) conjugate. The experimental trials for membrane fabrication were adapted based on the design of experiments (DoE) approach by making use of the Box-Behnken design (BBD) for a three-variable system, a component of response surface methodology (RSM). The three variable parameters selected for optimization of the electrospinning process were the dopant concentration (in weight percentage), the flow rate (in millilitre per hour), and the spinning time (in hours), respectively, and a total of 15 fibrous membranes were fabricated. The SEM analysis of the fabricated membranes revealed alterations in the surface morphology of the fibrous mats with variations in the electrospinning parameters. The infrared spectrum of the fibrous mats, validated the incorporation C-MWCNT conjugate in PAN, thereby confirming the formation of PAN/C-MWNCNT membrane. The mean flow pore size and breaking force of the PAN/C-MWCNT membranes was also obtained using a universal testing machine (UTM) and porometer, respectively. To choose the best membrane for efficient filtration experiments, the performance of each of the prepared membranes was assessed in terms of solute rejection percentage (SR%), permeate flux (PF), and pure water flux (PWF). The statistical analysis of the assessed parameters in accordance with the membranes prepared was done using the MINITAB software, and the three-dimensional (3D) surface plots were constructed using the STATISTICA software to visualize and validate the relation between each of the electrospinning parameters and the corresponding membrane performance characteristics. Similarly, the potential of the electrospun membranes for efficient heavy metal ion removal and photocatalysis were also tested independently and the optimal electrospinning parameters were determined for the same. Based on the results, it was observed that the PAN/C-MWCNT membranes could serve as potential candidates for the treatment of polluted water.

Removal of lead from aqueous solution using electrospun nanofibers: preparation, characterization, adsorption isotherm, and kinetic study

Lead is one of the most hazardous toxic heavy metal ions in industrial wastewater. The removal of Pb(II) from aqueous environment is an extremely essential topic due to acquiring clean water resources and its significant impact on human health. Adsorption is an effective and the most widely used method for heavy metal removal from an aqueous medium. Nanofibers have potential advantages in the adsorption of heavy metal ions from wastewater. In this study, nanofibers based on polyvinyl alcohol (PVA) were fabricated for the removal of lead ions from aqueous samples. Nanofibers produced by electrospinning were characterized by scanning electron microscopy (SEM/EDX) and Fourier transform infrared (FT-IR) techniques. A batch system was used for the adsorption of Pb(II) ions onto cross-linked PVA (%10) and PVA (%10):MSs (%2) (Malva Sylestris L. seed biomaterial) nanofibers. The effectiveness of cross-linking was determined by the water absorbency test. The pH, adsorbent amount, adsorption kinetics, isotherms, and thermodynamic values were thoroughly investigated in the adsorption tests. Pb(II) adsorption on the polymer was confirmed by EDX analysis. The optimum values found were a pH of 6, an adsorbent dose of 5.0 mg, and a contact time of 120 min. Lead ion concentrations were determined by flame atomic absorption spectrometry (FAAS). The Freundlich models could explain the results from the adsorption data. Similar results were obtained from adsorption isotherm models, and the results were found to support each other. The adsorption capacity for PVA (10%) and PVA (10%):MSs (2%) nanofibers were found to be 444.2 mg g^-1 and 588.2 mg g^-1, respectively. The adsorption capacity increases with the addition of MSs (2%) biomaterial. As a result, nanofibers can be used as effective adsorbents in the removal of Pb(II) ions. The developed methods are environmentally friendly and promising for the separation of toxic Pb(II) ions from aqueous systems, which is a major problem for environmental pollution.

Review of the Recent Advances in Electrospun Nanofibers Applications in Water Purification

Recently, nanofibers have come to be considered one of the sustainable routes with enormous applicability in different fields, such as wastewater treatment. Electrospun nanofibers can be fabricated from various materials, such as synthetic and natural polymers, and contribute to the synthesis of novel nanomaterials and nanocomposites. Therefore, they have promising properties, such as an interconnected porous structure, light weight, high porosity, and large surface area, and are easily modified with other polymeric materials or nanomaterials to enhance their suitability for specific applications. As such, this review surveys recent progress made in the use of electrospun nanofibers to purify polluted water, wherein the distinctive characteristics of this type of nanofiber are essential when using them to remove organic and inorganic pollutants from wastewater, as well as for oil/water (O/W) separation.

Fabrication of PAN Electrospun Nanofibers Modified by Tannin for Effective Removal of Trace Cr(III) in Organic Complex from Wastewater

Removal of chromium ions is significant due to their toxicity and harmfulness, however it is very difficult to remove trace Cr(III) complexed with organics because of their strong stability. Herein, a novel electrospun polyacrylonitrile (PAN) nanofibers (NF) adsorbent was fabricated and modified by tannic acid (TA) by a facile blend electrospinning approach for removal of trace Cr(III) in an organic complex. Utilizing the large specific area of nanofibers in the membrane and the good affinity of tannic acid on the nanofibers for hydrolyzed collagen by hydrophobic and hydrogen bonds, the as-prepared PAN-TA NFM exhibited good adsorption toward Cr(III)-collagen complexes and effective reduction of total organic carbon in tannage wastewater. The maximal adsorption capacity of Cr(III) is 79.48 mg g-1 which was obtained at the pH of 7.0 and initial Cr(III) concentration of 50 mg g-1. Importantly, the batch adsorption could decrease the Cr(III) concentration from 10-20 mg L-1 to under 1.5 mg L-1, which showed great application potential for the disposal of trace metal ions in organic complexes from wastewater.