# Removal of Cu(II) from Aqueous Solutions Using Amine-Doped Polyacrylonitrile Fibers
## 1 Introduction  
Environmental problems affect humans, animals, and plants worldwide. In particular, rapid industrialization has increased water pollution, and thus water sanitation has become a significant global concern. Owing to the increasing environmental and economic impacts of heavy metal ions, their removal from industrial wastewater has been studied in depth [1]. Heavy metals, such as Cr, Cu, Fe, Pb, Ag, Ni, and Zn, which are highly toxic and nonbiodegradable, could cause problems for both the environment and living organisms [2]. The presence of heavy metal pollutants in water could lead to serious health problems, such as stomach aches, nausea, dehydration, dizziness, nervous system damage in young children, skin rashes, vomiting, abdominal pain, lung irritation, eye irritation, and liver damage [3]. Cu is not only an essential nutrient but also a water contaminant. Moreover, Cu has many commercial and industrial applications; it can be used to manufacture pipes, valves, and fittings, and could also be a constituent of different types of alloys and coatings. Copper(II) sulfate pentahydrate (CuSO\({}_{4}\cdot\)5H\({}_{2}\)O) is sometimes added to surface waters to control the growth of algae [4]. The typical oxidation states of Cu are +1 and +2, and the corresponding compounds are referred to as cuprous and cupric, respectively [5]. Cu compounds, whether organic complexes or organometallics, could beused to promote or catalyze numerous chemical and biological processes [6]. Copper(I) and copper(II) sulfides are important examples of copper sulfides. CuSO\({}_{4}\)5H\({}_{2}\)O is the most frequently used Cu compound in the laboratory. Highly toxic amounts of Cu are present in the industrial wastewaters of the metal cleaning and plating facilities, refineries, paper and pulp plants, fertilizer mills, and wood preservative factories [7]. Furthermore, exposure to environmental sources of Cu could cause vomiting, headaches, stomach cramps, nausea, liver and kidney damage, and even death [8]. Cu is found in drinking water at concentrations in the range of 0.005 to 30 mg/L, and it mainly originates from the corrosion of Cu plumbing [9]. The concentration of Cu in treated water often increases during distribution, particularly in systems where the pH of the water is acidic or basic, or where the water is high in carbonates [4]. According to the U.S. Environmental Protection Agency, the maximum allowable limits for Cu in drinking and industrial waters are 1.3 and 3.0 mg/L, respectively [10]. Several methods could be used to reduce the amounts of heavy metal from effluents, including chemical precipitation, electrodialysis, reverse osmosis, ion exchange, evaporation, and adsorption [8]. Of these, adsorption is an effective and economical method of wastewater treatment [2]. Many adsorbents, such as activated carbon, biosorbents, illite-smectite, natural zeolites, natural bentonite, oxide minerals, polymer materials, resins, and synthetic hydroxyapatite have been used for the removal of metal ions from wastewaters [11; 12; 13]. Recently, electrospinning has attracted significant attention in academic research circles and for industrial applications because it (1) could be used to fabricate continuous fibers with diameters as small as a few nanometers; (2) could be applied to a wide range of materials, such as synthetic and natural polymers, metals, and ceramics and composite systems; and (3) could be a low-cost and high-yield method for the preparation of nanofibers [14]. Modified electrospun nanofibers have been developed as adsorbents for metal ions from solutions because they have high porosity, high specific surface area, and controllable surface functionality [15]. In this study, polyacrylonitrile (PAN) fibers were prepared via electrospinning, and diethylenetriamine (DETA) was used to modify the PAN fibers. The purpose of the study was to fabricate surface-modified PAN fibers for the removal of heavy metals from aqueous solutions.