Development and characterization of magnetic polyethyleneimine-bamboo nanocellulose adsorbents for enhanced performance of dye pollutant removal

Abstract

The adsorption of reactive black 5 (RB5) onto bamboo nanocellulose modified with polyethyleneimine (PEI) and magnetic nanoparticles (MNPs), referred to as MNCPEI (Fe₃O₄, ~ 10–20 nm), were incorporated via direct dispersion during the synthesis process without surface pre-functionalization was systematically examined in aqueous solution. The efficiency of dye removal increased proportionally with the amount of MNCPEI in the modified adsorbents. Characterization studies revealed that the MNCPEI modification significantly enhanced the surface chemistry of the adsorbents while providing slight improvements in their textural properties. High removal efficiencies for the anionic dyes were consistently achieved, demonstrating the superior performance of the MNCPEI adsorbents. Optimal adsorption conditions were observed at a nanocellulose-to-PEI ratio of 1:2 and an MNP dosage of 0.3 g. The findings indicated that the adsorption of RB5 was governed by monolayer adsorption, with chemical adsorption identified as the rate-limiting step. The adsorbent exhibited a high maximum adsorption capacity (99%) for RB5, attributed to the increased availability of functional groups facilitating interaction with the dye molecules. Key parameters affecting the adsorption process, including contact time (0–180 min), adsorbent dosage (0.05–2.0 g), initial dye concentration (0.025–0.3 g/L), pH (2–9), and temperature (25–70 °C), were investigated. This study underscores the potential of bamboo-derived MNCPEI adsorbents for effective textile wastewater treatment.

Graphic Abstract:

Supplementary Information: The online version contains supplementary material available at 10.1186/s40643-025-00928-y.

Fig. 1

Schematic illustration of adsorption and separation of RB5 from synthetic dye

Fig. 2

FTIR spectra of PEI-nanocellulose and MNCPEI adsorbents

Fig. 3

Magnetization of MNCPEI

Fig. 4

The effect of MNP dosage on the aggregation of adsorbent

Fig. 5

Point of zero fee for MNCPEI adsorbent

Fig. 6

Linear plots showing the (a) pseudo-first-order, (b) pseudo-second-order, and (c) intraparticle diffusion models for RB5 adsorption

Fig. 7

Thermodynamic plot for RB5 adsorption onto MNCPEI

Fig. 8

Adsorption efficiencies of the RB5 by acid and base at (0.1,1,5.0 M) (Conditions: initial dye concentration, 0.1 g/L; adsorbent dosage, 0.1 g; sample volume, 50 ml; solution pH, 7; contact time, 120 min; temperature, 27 ℃)