Sustainable grafted chitosan-dialdehyde cellulose with high adsorption capacity of heavy metal

A novel adsorbent was prepared using a backbone comprising chemically hybridized dialdehyde cellulose (DAC) with chitosan via Schiff base reaction, followed by graft copolymerization of acrylic acid. Fourier transform infrared spectroscopy (FTIR) confirmed the hybridization while scanning electron microscopy (SEM) revealed intensive covering of chitosan onto the surface of DAC. At the same time, energy dispersive X-ray (EDX) proved the emergence of nitrogen derived from chitosan. The X-ray diffraction (XRD) indicated that the crystallinity of the backbone and graft copolymer structures was neither affected post the hybridization nor the grafting polymerization. The adsorbent showed high swelling capacity (872%) and highly efficient removal and selectivity of Ni2+ in the presence of other disturbing ions such as Pb2+ or Cu2+. The kinetic study found that the second-order kinetic model could better describe the adsorption process of (Cu2+, Ni2+) on the graft copolymer. In contrast, the first-order kinetic model prevails for the binary mixture (Pb2+, Ni2+). Moreover, the correlation coefficient values for the adsorption process of these binary elements using Langmuir and Freundlich isotherms confirmed that the developed grafted DAC/chitosan exhibits a good fit with both isotherm models, which indicates its broadened and complicated structure. Furthermore, the grafted DAC/chitosan exhibited high efficient regeneration and high adsorption capacity for Pb2+, Cu2+ and Ni2+.

Synthesis of Magnetic Chitosan Composite Beads as an Adsorbent for Removal of Organic Matter from Peat Water

Groundwater in peatlands has the potential to be utilized as a water source, but its high organic matter content presents challenges. This study aimed to improve the quality of peat water through the adsorption of organic matter using chitosan magnetic beads composite adsorbent. Magnetic chitosan beads (KMB) composite was synthesized by mixing chitosan, acetic acid, and a mixture of Fe2+/Fe3+ solution with a mole ratio of 1:2. This mixture was then dropped into a sodium hydroxide solution. In addition to KMB, magnetic composite beads containing glutaraldehyde crosslinking agent (KMBG) were also synthesized. The results of composites analysis using a Fourier transform infrared (FTIR) spectrophotometer showed typical Fe-O absorption bands at 582 cm-1 and 578 cm-1 for KMB and KMBG. The typical C=N absorption band for glutaraldehyde in KMBG appeared at 1631 cm-1. X-ray diffraction (XRD) analysis revealed the characteristic peaks of Fe3O4 for KMB and KMBG at 2θ = 30.2°, 35.5°, 43.2°, 57.0°, and 62.8° with an amorphous structure. The adsorption of organic matter was performed by varying the pH (2, 3, 4, and 5) of peat water and the mass of the adsorbent (50, 70, 100, 200, and 300 mg). The optimum adsorption occurred at pH 2 with an absorbent mass of 0.1 g KMB and 0.07 g KMBG. Applying KMB on peat water reduces turbidity, color, and absorbance at a wavelength of 254 nm (Aλ=254), which is better than using KMBG. These three parameters’ efficiency percentages were 44%, 78%, and 74% for KMB and 17%, 30%, and 59% for KMBG.