Floating Amphiphilic Biomass-Based Material Obtained by Plasma Processing for Enhanced Wastewater Remediation

A self-floating amphiphilic biosorbent (SFAB) was prepared by dispersing the plasma-modified water hyacinth (WH) (Eichhornia crassipes) fibers on the beeswax support. The synthesis process takes advantage of the functionalising properties of plasma with polar groups (–OH, –CO, –COOH) and the binding effect of beeswax. The characteristics of the obtained biosorbent exhibited significant changes in surface chemistry and roughness confirmed by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and energy dispersive X-ray spectroscopy (EDX). The resulting functionalised material offers appropriate anchoring sites for pollutants leading to a biomaterial with hydrophilic and lipophilic properties. The removal performance of the SFAB outperforms the natural biomass fibers taking alone, with an uptake capacity of 20.83 mg/g for merbromin (MB) (50 mg/L) and 19.90 mg/g for Green Naphthol B (GNB) (50 mg/L), based on the successfully fitted general-order kinetic model. The effects of some key adsorption parameters were optimised, and the equilibrium data (298–323 K) were best fitted by the Liu isotherm reaching 47.20 and 36.40 mg/g of uptake amounts for MB and GNB, respectively at 298 K. The removal mechanism is governed by π–π interplay, hydrophobic interaction, and hydrogen bonding effects.