Polyethyleneimine-Modified Biosorbent Based on Banana Pseudostem Biomass for Environmental Remediation and Food Analysis

Abstract

In this study, biosorbents are prepared from banana pseudostem (BPC), either raw or pre-oxidized, and subsequently functionalized with polyethyleneimine (PEI) in the presence or absence of glutaraldehyde (GLU) as a crosslinking agent. The materials are evaluated for i) the removal of the synthetic dye Direct Blue 86 (DB86) from aqueous solutions and ii) their potential use as solid-phase extraction (SPE) sorbents for nitrite determination in cured meat samples. Characterization results revealed that GLU favored PEI incorporation, whereas pre-oxidation limited PEI binding. All biosorbents achieved removal efficiencies above 89.9% across a wide pH range (2-11) with a dose of 1.0 g L- 1 and an initial DB86 concentration of 50.0 mg L-1. Adsorption kinetics are best described by the pseudo-second-order model, while equilibrium data are best fitted by the Sips isotherm. The highest DB86 adsorption capacity (225.9 mg g- 1) is achieved with oxidized BPC functionalized with PEI, due to its higher zeta potential and lower surface density of macromolecules, which facilitate improved dye diffusion. Density Functional Theory calculations revealed that primary and secondary amines constitute the main interaction sites for DB86. For the SPE application, the presence of GLU enhanced nitrite retention and elution efficiency, highlighting the potential of these biosorbents for food analysis.