Atmospheric pressure plasma-assisted epichlorohydrin-grafting onto pineapple fiber and immobilization with polyethyleneimine for p-nitrophenol removal.

The cost-effective, eco-friendly, and easily available adsorbent prepared using atmospheric pressure plasma (APP)-induced epichlorohydrin-grafting onto alkali-treated pineapple leaf fiber (APF) and immobilization with polyethyleneimine (PEI) was investigated and applied for p-nitrophenol (PNP) removal. The results from main characterization methods such as morphological observation, Fourier transform infrared analysis, and x-ray photoelectron spectroscopy revealed the surface changes and confirmed the success of the surface modifications. According to the experimental data, APP pre-treated adsorbent following by PEI immobilization (t-APF-e-PEI) exhibited fast and efficient adsorption with the adsorption capacity up to 128†mg/g, whereas the adsorption capacities for APF-e-PEI and APF were 115 and 21†mg/g, respectively, at 30†°C. The adsorption process was exothermic whereas the adsorption behavior conformed to the pseudo-first-order kinetics, intra-particle diffusion, and Langmuir isotherm models. Electrostatic ion-dipole interaction between protonated amines of PEI and negative-charged sites of PNP was proposed as the main mechanism. The prepared adsorbents exhibited good adsorption efficiency with possessing high adsorption capacity for repeated uses. The modified adsorbent provided from agricultural waste had a great potential as low cost, eco-friendly, and easily available adsorbent material to adsorb PNP from aqueous solutions.