Simultaneous Visual Detection and Removal of Cu²⁺ with Electrospun Self-Supporting Flexible Amidated Polyacrylonitrile/Branched Polyethyleneimine Nanofiber Membranes

Abstract

Sensitive detection and effective removal of copper ions (Cu 2+ ) from water are still arduous tasks required to protect public health and environmental safety because of the serious impacts of Cu 2+ on humans and other organisms. Herein, we report the design and fabrication of self-supporting flexible amidated polyacrylonitrile/branched polyethyleneimine nanofiber membranes (abbreviated as aPAN/BPEI NMs) via facile electrospinning and a subsequent hydrothermal method, which are used not only as strips for the visual detection of Cu 2+ but also as effective adsorbents for the removal of Cu 2+ from water. Because aPAN/BPEI NMs are self-supporting, they can be easily removed from the solution to reduce secondary pollution to the environment. Based on the high Cu 2+ binding capacity of BPEI, Cu 2+ ions are adsorbed on the aPAN/BPEI NMs, which leads to the appearance of new absorbance bands at 280 and 636 nm and a color change from yellow to blue. aPAN/BPEI NMs are utilized for the visual detection of Cu 2+ with a linear range of 50−700 μM and limits of detection of 11.5 and 4.8 μM (absorption peaks at 280 and 636 nm). More importantly, aPAN/BPEI NMs exhibit excellent selectivity and certain recovery with a simple treatment. Furthermore, by utilizing the adsorption characteristics of Cu 2+ in aqueous media, it can be effectively removed by aPAN/ BPEI NMs with a remarkable adsorption capacity of 209.53 mg•g −1 . Additionally, the removal of Cu 2+ by aPAN/BPEI NMs does not exhibit interference by other foreign ions. The adsorption process conforms well to the pseudo-second order (PSO) kinetic model and Jovanovich model, proving that adsorption occurs via chemical and monolayer adsorption mechanisms. Accordingly, this work will provide theoretical and technical support for the design and fabrication of novel heavy metal ion detection-removal integrated materials exhibiting high sensitivity and strong adsorption.

Amine-Functionalized Membrane Adsorbers to Purify Copper from Acidic Solutions

“…Zhang et al performed Cu adsorption experiments in “unadjusted” solutions (i.e., pH was not controlled or measured) and calculated a Q max of 50.8 mg Cu (g membrane) −1 and K L of 0.001 L mg –1 . Shao et al report a Q max of 250 mg Cu (g membrane) −1 and K L of 0.0059 L mg –1 for the polyethyleneimine-functionalized nanofibers. The analysis was performed by fitting the Langmuir isotherm to pH 6 equilibrium adsorption data.…”

“…Chemisorbed (i.e., covalently bound) polymers can be “grafted from” the membrane via surface-initiated polymerizations like activator generated by electron transfer atom-transfer radical polymerization (AGET ATRP) , or plasma polymerization. , A second approach is to “graft to” the membrane by covalently attaching a polymer to the membrane surface via covalent coupling reactions. The latter approach was used to prepare Cu membrane adsorbers with applications in water treatment. − Zhang et al, synthesized self-assembled membranes from polystyrene- block -poly­(acrylic acid). Then, polyethylenimine was coupled to the membrane by activating the carboxylic acid moieties with a carbamide thereby facilitating a nucleophilic attack by the amine end groups.…”

“…Then, polyethylenimine was coupled to the membrane by activating the carboxylic acid moieties with a carbamide thereby facilitating a nucleophilic attack by the amine end groups. Recently, Shao et al coupled branched polyethylenimine to electrospun poly­(acrylonitrile) fibers to adsorb and detect Cu 2+ in near-neutral pH drinking water samples. In this work, AGET ATRPan oxygen tolerant type of ATRPis used to introduce poly­(glycidyl methacrylate) to the membrane surface.…”

Design Considerations for Next‐Generation Polymer Sorbents: From Polymer Chemistry to Device Configurations

“…In contrast, manipulating chemistry on the micrometer through millimeter length scales to pattern sorbents with varied ligands provides opportunities to simultaneously treat and identify multi-analyte feed streams. By selecting chromophores that change upon binding with analytes (e.g., through fluorescence, [75,92,130,131] UV-Vis absorption, [127,132,133] and potentiometric [134] sensing), information (e.g., the identity and concentration of analytes) is reflected in the formation of the ligand-solute complex. For instance, polymer membrane sorbents that complex copper ions turn blue.…”

Up-/Downconversion Fluorescence Dual-Channel Probe Based on NaYF4: Yb/Er/Eu Nanoparticles for the Determination of Cu(II)

“…A variety of methods are applied to detect Cu­(II), for instance, inductively coupled plasma mass spectrometry, atomic absorption/emission spectrometry, , electrochemical analysis, , colorimetry, and so forth. Fluorescence has attracted much attention and has become a powerful optical method for detecting analytes because of its high sensitivity and selectivity.…”