In this study, cellulose nanocrystals (CNCs) were produced from pea peels by acid hydrolysis to be used with pectin and acrylic acid (AAc) to form Pectin-PAAc/CNC nanocomposite by γ-irradiation. The structure, morphology, and properties of the nanocomposite were investigated using Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) techniques. The nanocomposite hydrogel was used for the removal of methylene blue dye (MB) from wastewater. The results revealed that the presence of CNCs in the polymeric matrix enhances the swelling and adsorption properties of Pectin-PAAc/CNC. The optimum adsorbate concentration is 70 mg/L. The kinetic experimental data were fit by pseudo-first-order (PFO), pseudo-second-order (PSO), and Avrami (Avr) kinetic models. It was found that the kinetic models fit the adsorption of MB well where the correlation coefficients of all kinetic models are higher than 0.97. The Avr kinetic model has the lowest ∆q_e (normalized standard deviation) value, making it the most suitable one for describing the adsorption kinetics. The adsorption isotherm of MB by Pectin-PAAc follows the Brouers–Sotolongo model while that by Pectin-PAAc/CNC follows the Langmuir isotherm model. The negative values of ∆G confirmed the spontaneous nature of adsorption, and the positive value of ∆H indicated the endothermic nature of the adsorption.

Nanocomposite hydrogels were synthesized by γ-radiation-induced copolymerization and crosslinking of Chitosan biopolymer (CS), acrylic acid (AAc) and TiO₂ nanoparticles (CS-PAAc/TiO₂). The structure, morphology, and properties of the nanocomposites were investigated using Fourier-transform infrared spectroscopy, X-Ray Diffraction, Scanning electron microscopy, Transmission electron microscopy, and thermogravimetric analysis techniques. The nanocomposites hydrogel was used for the removal of methylene blue dye (MB) from wastewater. It was found that the presence of TiO₂ in the copolymeric matrix enhances the adsorption by increasing the physical interaction between the dye molecules and the adsorbent surface. The removal percentage increases with the increase in pH of the medium of all investigated samples and the maximum value is obtained at the solution pH is 10. The maximum adsorbent dosage for CS-PAAc/TiO₂ nanocomposites is 0.20 g and for CS-PAAc hydrogel is 0.15 g per liter of the adsorbate. This study revealed that the loading of TiO₂ nanoparticles into the polymeric matrix of CS-PAAc does a remarkable increase in the removal parentage of MB dye from its aqueous solution.

Bio-based hydrogels (denoted as PC-PAAc/GA) comprised of Pectin (PC) and polyacrylic acid (PAAc) reinforced with different ratios of gallic acid (GA) were prepared by gamma radiation at irradiation dose 20 kGy. The prepared hydrogels were investigated by different analytical tools. The swelling performance was studied versus time, pH of the medium and gallic acid content. The experimental data depicted that the swelling increases with pH of medium until the equilibrium of swelling after 350 min. The maximum swelling was attained at pH10 for both PC-PAAc and PC-PAA/GA1.5. Also, the data reveal that the incorporation of GA in the hydrogel matrix enhanced the swelling performance of the hydrogel up to an optimum value of GA, i.e. PC-PAA/GA1.5. Further increase in GA concentration leads to formation of a highly crosslinked structure with reduced swelling. The results demonstrated that the prepared hydrogels displayed excellent antibacterial activity against gram + ve bacteria (E.coli) and gram-ve bacteria (S.aureus). This potent antimicrobial activity is mainly originated from GA which was proved as a strong antibacterial agent. Moreover, the removal performance of the investigated hydrogels was verified towards Pb⁺²cation as one of the most poisonous heavy metals. The data revealed that the maximum removal percentage of Pb (II) was attained by PC-PAAc/GA1.5 hydrogel (90 mg g⁻¹). The correlation coefficients of the Langmuir model are too higher than that of the Freundlich model that assumed the adsorption of lead cations is mainly a chemical process.