Fabrication, Characterization and Adsorption Investigation of Nano Zinc Oxide–Sodium Alginate Beads for Effective Removal of Chromium (VI) from Aqueous Solution

Abstract

Alginate–zinc oxide (Alg–ZnO) biocomposite was synthesized and tested as a chromium ions Cr(VI) adsorbent for environmental applications. Alg–ZnO biocomposite was prepared by the interaction between sodium alginate biopolymer and zinc oxide nanoparticles (ZnO–NPs), prepared by modified wet chemical method. The solid adsorption characteristics of the synthesized Alg–ZnO biocomposite were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV–Vis spectroscopy. Adsorption isotherms of chromium ions on the prepared Alg–ZnO biocomposite were investigated with varying the initial concentration of Cr(VI) under different application conditions such as pH, contact time, adsorbent dosage, and temperature. Adsorption of Cr(VI) was investigated by different isotherm models such as Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models. Maximum adsorption capacities (31.09 and 34.63 mg/g) were achieved by ZnO–NPs and Alg–ZnO, respectively at 25 °C. The results of isotherm models indicate the perfect applicability of Langmuir and Dubinin–Radushkevich models, revealing the dominance of monolayer and the physisorption of chromium ions onto the studied adsorbents.

The Antibacterial Activities and Characterizations of Biosynthesized Zinc Oxide Nanoparticles, and Their Coated with Alginate Derived from Fucus vesiculosus

“…The broad and sharp peaks denote Fu/ZnO/Alg-NCMs bio-synthesized via F. vesiculosus are semi-crystalline. The X-ray diffraction (XRD) results indicate that sodium alginate-ZnO nano-composites display a semi-crystalline nature [ 59 ]. The crystal size of Fu/ZnO-Alg-NCMs has been intended from XRD analysis by the Debye–Scherrer equation, which in this work was equal to 21.7 nm with 100% intensity.…”

“…No peak at 20-30 2θ could indicate the ZnO-NPs are pure [46]. The XRD of Arthrospira platensis-ZnO-NPs exhibited seven recognized peaks at 2 theta degree 31.7 nano-composites display a semi-crystalline nature [59]. The crystal size of Fu/ZnO-Alg-NCMs has been intended from XRD analysis by the Debye-Scherrer equation, which in this work was equal to 21.7 nm with 100% intensity.…”