Magnetic Nanocomposites Containing Low and Medium-Molecular Weight Chitosan for Dye Adsorption: Hydrophilic Property Versus Functional Groups

Abstract

The azo dye removal from polluted water is vital from a sustainable viewpoint. In this study, we investigated the influence of chitosan molecular weight on the adsorptive removal of basic blue 41. For preparing nanocomposite containing medium-molecular weight chitosan (NC(M)), cross-linking of chitosan was done using diethylenetriaminepentaacetic acid, silica-modified magnetite nanoparticles and graphene oxide. Techniques including FT-IR, XRD, FESEM, TGA/DTG, VSM and N2 adsorption/desorption isotherm were applied for characterization of NC(M). The adsorption behavior of synthesized NC(M) was compared with as-prepared adsorbent containing low-molecular weight chitosan (NC(L)) (Asadabadi 2021). The experimental design was carried out using the Central Composite Design. The effect of initial pH, temperature and adsorbent concentration on the percentage of dye removal were examined and the optimum values of variables were determined. Despite NC(M) which had maximum 31% dye removal, NC(L) led to approximately 95% adsorptive removal at optimum conditions. An increase in the monomer number of chitosan caused to reduce hydrophilic property of NC(M), which in turn resulted in a repulsion force between adsorbent and dye. However, H-bonding, coulumbic attraction and pi-stacking interactions contributed in the adsorption mechanism of NC(L). The kinetics study showed that about 30 min necessitated reaching the equilibrium and the rate-limiting steps changed from film diffusion to intraparticle diffusion as time passed. The kinetics data were satisfactorily fitted by the modified pseudo-n-order model.The maximum adsorption capacity of NC(L) was obtained 55.87 mg•g -1 . The modified Langmuir-Freundlich isotherm was the best model to reproduce data. NC(L) was recovered seven times without dramatic changes in its adsorption efficiency.

Phosphate removal by acid-activated and chitosan-composite clayey soils

“…Chitosan, with a higher degree of deacetylation, is assumed to contain a greater proportion of active amino groups, which play a crucial role in the adsorption process. Conversely, a decrease in molecular weight indicates fewer monomeric units in a single polymer chain, leading to a reduction in the number of active adsorption sites [14]. In the current study, low-and high-molecular-weight chitosan were derived from shrimp shells, whereas medium-molecular-weight chitosan was obtained from a combination of crab and shrimp shells.…”

Design and Synthesis of Magnetic Immobilized Pineapple Cellulose/EDTA for Removal of Copper(II) and Zinc(II) by Coordination

“…Fe3O4@SiO2@NH2 (0.5700 g), modified cellulose (0.6000 g) and EDTA (0.3700) were mixed in DMF (50.0 mL) in the presence of DCC and NHS at 60.0 °C for 24 h. The reagents reacted to form amide (RCONHR') [20]. The product was rinsed by DMF and ethanol and dried at room temperature for 12 h [21].…”

Anchoring carboxylated pineapple peel cellulose and EDTA onto magnetic (3-aminopropyl)triethoxysilane to effective diminish copper(II) and zinc(II) from polluted water

“…Fe3O4@SiO2@NH2 (0.5700 g), carboxylated cellulose (0.6000 g) and EDTA (0.3700) were mixed in DMF (50.0 mL) in the presence of DCC and NHS at 60.0 °C for 24 h. The reagents reacted to form amide (RCONHR') (Asadabadi and Merati 2021). The product was rinsed by DMF and ethanol and dried at room temperature for 12 h (Mirzai and Asadabadi 2022).…”