Amine functionalized Fe(III)-doped-ZnO nanoparticles based alginate beads for the removal of Cu(II) from aqueous solution

A novel sodium Iron silicate composite with chitosan for efficient removal of Cd(II) ions from water

Cadmium ions constitute a major threat to human health and the environment owing to their toxicity, bioaccumulation, and persistence in water bodies, causing renal dysfunction, cancer, and cardiovascular diseases. Hence, this study reports the facile fabrication of a novel sodium iron oxide silicate@amorphous sodium iron silicate product (S1) and its chitosan composite (S1@chitosan) for the high-performance separation of Cd(II) ions from aquatic environments. The Brunauer-Emmett-Teller surface area, total pore volume, and mean pore diameter of S1 were 94.97 m2/g, 0.5853 cm3/g, and 25.65 nm, respectively, while those for S1@chitosan were 30.94 m2/g, 0.09518 cm3/g, and 12.31 nm, respectively. The reduction in pore diameter, pore volume, and surface area confirms the successful functionalization of S1 with chitosan, as the chitosan coating partially blocks and fills the pores, reducing the available surface area and porosity. Also, scanning electron microscope (SEM) images revealed an uneven surface morphology for S1 and a more textured and rougher surface for S1@chitosan, supporting the incorporation of chitosan. Besides, energy-dispersive X-ray spectroscopy (EDX) and CHN analyses affirmed the existence of chitosan in the composite through the detection of carbon and nitrogen elements, characteristic of chitosan. The optimum conditions for the removal of Cd(II) ions were determined to be a contact time of 70 min for S1 and 50 min for S1@chitosan, a pH of 7.50, and a temperature of 298 K. The maximum sorption capacities were 284.09 mg/g for S1 and 389.11 mg/g for S1@chitosa. The removal mechanism for S1 primarily involves ion exchange, while S1@chitosan utilizes both ion exchange and complexation through the amino and hydroxyl groups of chitosan. Regeneration using HCl confirmed the effective reusability of both adsorbents over five successive cycles. The adsorption process was found to be chemical, exothermic, and best described by the pseudo-second-order kinetic model and Langmuir isotherm.

Natural Degradation Behavior of Poly(lactic acid) Nanocomposite Films and the Adsorption Behavior of Degraded Products on Cu(II)

In this study, the degradation behavior of poly(lactic acid) nanocomposite films (PLA/Hec-g@PS) under extreme natural environments was investigated, and the degraded PLA based films were applied to adsorb Cu(II). During the early and midstages of degradation, the surface roughness and crack propagation rate of PLA/Hec-g@PS films were significantly lower than those of PLA films. This could be due to the fact that Hec-g@PS enhanced the interaction forces between C-O-C + CH3 and C═O in the PLA chains, thereby mitigating the degradation of PLA. Neural network predictions indicated that the molecular weight of PLA films decreased to 30% after 1344 days, whereas PLA/Hec-g@PS films reached the same reduction in 1451 days, extending the lifespan of PLA by 1.08 times. The environmental impact of PLA/Hec-g@PS was further assessed by their adsorption behavior toward Cu(II). It was found that PLA films adsorbed 244.51 μg/g of Cu(II), while PLA/Hec-g@PS films adsorbed 372.63 μg/g of Cu(II). The isotherm adsorption model showed that the maximum adsorption capacities (qm) of PLA and PLA/Hec-g@PS were 326.60 μg/g and 441.51 μg/g, respectively. This improvement offers PLA based films new possibilities for applications in wastewater treatment and soil remediation.