Activation of inert polyethylene/polypropylene nonwoven fiber (NWF) by plasma-initiated grafting and amine functionalization of the grafts for Cu(II), Co(II), Cr(III), Cd(II) and Pb(II) removal

In this study, the emulsion graft polymerization of glycidyl methacrylate (GMA) by environmentally friendly plasma-induced technique onto nonwoven polyethylene-coated polypropylene (NWF) fiber and its functionalization with 4-aminobenzoic acid (PABA) were carried out as a novel adsorbent. The influence of plasma source, irradiation time and reaction parameters were studied by a systematic approach. For the grafting of GMA, the optimal plasma treatment conditions using Ar-plasma were found to be 0.2 mbar plasma pressure, 70-watt plasma power, and 120s plasma exposure time. Grafting reaction conditions onto plasma-treated NWF was 4% GMA concentration, 40 °C graft polymerization temperature, and 4 h grafting time. The PABA modification parameters of GMA-grafted NWF fiber have also been optimized for the first time by several solvents and kinetic studies. Epoxy ring in GMA-g-NWF structures (118 ±12% grafting degree) was opened and its modification with PABA was achieved and 81 ± 3% (2.15 mmol PABA/g polymer) conversion was obtained. The samples were characterized by FTIR, XPS, EDX, SEM, contact angle, and TGA techniques. The Cu(II), Co(II), Cr(III), Cd(II) and Pb(II) removal experiments were carried out by ICP-MS in batch mode as a function of pH, contact time, initial concentration and regeneration. Between pH 2–8 range, NWF fabric adsorbent is effective at pH 5 for heavy metal removal. The maximum adsorption capacities (qmax) were determined from Langmuir isotherm as 35.08 mg Cu(II)/ g adsorbent, 31.15 mg Co(II)/g adsorbent, 34.24 mg Cr(III)/g adsorbent, 51.81 mg Cd(II)/g adsorbent and 63.36 mg Pb(II)/g adsorbent, respectively at an initial feed concentration of 100 ppm, demonstrating the promising potential of the NWF fiber-based adsorbent to steadily and efficiently adsorb these toxic metal ions. The experimental data of heavy metals followed pseudo-second-order kinetic and the Langmuir adsorption models. The adsorbent material could be easily regenerated at least five cycles with a 3% HNO3 solution.