Abstract
In recent times, biopolymer-metal oxide nanocomposites have gained prominent importance in the attenuation of environmental toxicants from aqueous phase. But lanthanide oxide-based biopolymer nanocomposites have scantly been evaluated for their adsorption potential. A novel guar gum-polyacrylamide/erbium oxide nanocomposite (GG-PAAm/Er
2
O
3
NC) adsorbent was synthesized by copolymerization of guar gum (GG) and acrylamide (AAm) utilizing
N
-
N
′-methylenebisacrylamide as a crosslinker and Er
2
O
3
as a reinforcing agent. The adsorptive efficacy of GG-PAAm/Er
2
O
3
nanocomposite was evaluated using nile blue (NB) as a model pollutant dye from aquatic system. The prepared adsorbent was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, Brunauer–Emmett–Teller (BET) analysis, thermogravimetric analysis, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM–EDX), and high-resolution transmission electron microscopy (HRTEM). The optimal process parameters, which include dosage (0.8 g/L), agitation time (40 min), initial solution pH (6), and initial NB concentration (80 mg/L) were determined by batch methodology. The equilibrium data for NB confiscation was better expressed by Langmuir isotherm model, with maximal adsorption effectiveness (
Q
m
) of 225.88 mg NB/g demonstrating the actively monolayer adsorption onto homogeneous surface of GG-PAAm/Er
2
O
3
NC. The kinetics of NB sorption process onto GG-PAAm/Er
2
O
3
NC was reliable with pseudo-second order model. Thermodynamic parameters such as Δ
H
°
(15–17 kJ/mol) and Δ
S
°
(0.079–0.087 kJ/mol/K), and − Δ
G
°
(8.81–10.55 kJ/mol) for NB validated the endothermic, an increased randomness at the GG-PAAm/Er
2
O
3
–NB interface, and spontaneity and feasibility of the process, respectively. The spent nanocomposite was effectively regenerated with NaOH, and could be reused proficiently for five runs demonstrating the high reusability potential of the nanocomposite. The commendable removal efficiency and high reusability of GG-PAAm/Er
2
O
3
NC recommended it to be a highly competent adsorbent for cationic dyes particularly NB diminution from aqueous waste.