Electrospun nanofiber membranes have emerged as a promising solution for heavy metal removal from industrial wastewater, particularly in electroplating effluents. These membranes, often fabricated from polymer blends such as polyacrylonitrile (PAN) and polyethyleneimine (PEI), leverage chelation mechanisms to capture metal ions effectively. The high surface area-to-volume ratio of nanofibers enhances adsorption capacity, while the tunable chemistry of the polymers allows for selective binding of target contaminants.

The electrospinning process parameters critically influence the performance of the resulting membranes. Key variables include polymer concentration, solvent selection, applied voltage, flow rate, and collector distance. For PAN/PEI blends, a polymer concentration between 8-12 wt% in dimethylformamide (DMF) typically yields uniform fibers with diameters ranging from 100-500 nm. A voltage of 15-20 kV and a flow rate of 0.5-1.0 mL/h are commonly employed to maintain stable jet formation. The inclusion of PEI introduces amine groups that serve as chelation sites for heavy metals such as lead, cadmium, and chromium. Studies have demonstrated that increasing the PEI content up to 20% enhances metal uptake but may compromise fiber mechanical stability if excessive.

Durability of the electrospun mats under operational conditions is a crucial consideration. Crosslinking treatments, such as glutaraldehyde vapor exposure, can improve the chemical resistance and mechanical strength of PAN/PEI membranes. Tensile strength measurements indicate that crosslinked mats withstand pressures up to 0.5 MPa without structural failure, making them suitable for flow-through filtration systems. Long-term exposure to acidic electroplating waste streams (pH 2-4) shows less than 10% reduction in adsorption capacity over 10 cycles, provided adequate crosslinking is applied.

Regeneration of the nanofiber membranes is achievable through backwashing with acidic solutions (e.g., 0.1 M HCl), which protonates the amine groups and releases bound metal ions. Research indicates regeneration efficiencies exceeding 90% for lead and cadmium after five cycles, though gradual fouling from organic contaminants in real waste streams may reduce this over time. The low-pressure operation (1-2 bar) required for nanofiber filtration contrasts sharply with reverse osmosis (RO) systems, which typically demand 15-20 bar. Energy consumption analyses reveal that electrospun nanofiber systems operate at 0.5-1.0 kWh/m³, compared to 3-5 kWh/m³ for RO, representing a 70-80% reduction in energy use for comparable metal removal rates.

In electroplating wastewater treatment, PAN/PEI nanofiber membranes have demonstrated removal efficiencies exceeding 95% for copper and nickel ions at concentrations of 50-100 mg/L. A comparative study with RO showed that while both technologies achieve high purity effluent, the nanofiber system required 60% less energy and incurred 40% lower capital costs due to simpler infrastructure. The membranes also exhibited superior performance for low-concentration metal streams (below 10 mg/L), where RO membranes suffer from concentration polarization effects.

The scalability of electrospun nanofiber production remains a challenge, with current roll-to-roll systems achieving widths up to 1 meter at production rates of 10-20 m²/h. Advances in multi-needle electrospinning and solvent recovery systems are addressing these limitations. Future developments may focus on integrating photocatalytic nanoparticles into the fibers to enable simultaneous degradation of organic complexes present in electroplating waste.

Environmental lifecycle assessments indicate that electrospun nanofiber membranes generate 30-50% less carbon emissions compared to RO systems when considering both manufacturing and operational phases. The absence of high-pressure pumps and membrane replacement every 2-3 years (as required in RO) contributes significantly to this advantage. However, proper disposal methods for spent nanofiber mats containing heavy metals must be implemented to prevent secondary pollution.

In summary, electrospun PAN/PEI nanofiber membranes present a technically viable and energy-efficient alternative for heavy metal removal from electroplating wastewater. Their modular design allows for integration into existing treatment trains, while their lower energy footprint aligns with sustainable water treatment objectives. Continued optimization of spinning parameters and regeneration protocols will further enhance their economic competitiveness against conventional technologies.