Engineered amino-functionalized N-doped hollow porous carbon spheres in polyethersulfone membranes for ultra-efficient nanofiltration of beverage wastewater

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Abstract
A novel high-flux polyethersulfone (PES)-based nanofiltration (NF) membrane was developed by embedding amino-functionalized N-doped hollow porous carbon spheres (N-HPCS/NH₂) for efficient treatment of beverage-industrial wastewater. The N-HPCS/NH₂ nanofiller was synthesized via a hard-templating method and surface-functionalized using 3-aminopropyltriethoxysilane (APTES). The modified nanofiller exhibited a porous hollow structure with a high specific surface area (630.24 m2/g) and abundant amino groups, contributing to improved hydrophilicity and pollutant adsorption. The incorporation of low concentrations (0.1 wt%) of N-HPCS/NH₂ into the PES matrix resulted in membranes (M1) with superior structural, mechanical, and surface charge characteristics. Compared to the bare membrane, M1 exhibited a ~ 4.5-fold increase in pure water flux (230 L/m2·h), enhanced anti-fouling properties (FRR > 90%), and significantly higher removal efficiencies for salts (up to 84.6% for Na₂SO₄), dyes (> 99% for RR195, MB, RhB), and heavy metals (up to 99.81% for Pb2⁺). The efficiency of the M1 membrane was also studied in a salt-dye binary filtration system containing Na₂SO₄ at different concentrations (100–5000 ppm) and 200 ppm RR195. It was observed that increasing Na₂SO₄ concentration reduced RR195 removal slightly from 99.82% to 98.8%, suggesting minor interference due to ionic shielding. The membrane performance remained stable under continuous operation for 72 h and showed negligible decline in real beverage-industry wastewater treatment. The synergistic effects of enhanced hydrophilicity, surface charge, and active adsorption sites enabled the M1 membrane to achieve both high permeability and selectivity. These results demonstrate the potential of PES/N-HPCS/NH₂ membranes as robust candidates for sustainable industrial wastewater treatment. Graphical abstract The alternative text for this image may have been generated using AI.
Funding Information
  • Iran National Science Foundation (4012440)

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