Surface Modifications of Superparamagnetic Iron Oxide Nanoparticles with Polyvinyl Alcohol, Chitosan, and Activated Carbon or Graphite as Methylene Blue Adsorbents—Comparative Study

Abstract

Adsorption is a popular technique and has been investigated with many different materials for removing synthetic dyes from textile wastewater. This study compares the methylene blue (MB) adsorption capabilities of surface-modified superparamagnetic iron oxide nanoparticles, (SPION) using polyvinyl alcohol (PVA) and chitosan (CS), combined with two carbon materials, activated carbon (AC) and graphite (GR), respectively. After 9 days, depending on the initial MB loading concentration (0.015 mg/mL, 0.02 mg/mL, and 0.025 mg/mL), the MB adsorption capacities onto SPION/PVA/CS/AC and SPION/PVA/CS/GR were 7.6 ± 0.2–22.4 ± 0.05 and 6.9 ± 0.02–22.4 ± 0.05 mg/g, respectively. The cumulative release percentages of SPION/PVA/CS/AC and SPION/PVA/CS/GR after 30 days were 63.24 ± 8.77%–22.10 ± 2.59% and 91.29 ± 12.35%–24.42 ± 1.40%, respectively. Additionally, both SPION/PVA/CS/AC and SPION/PVA/CS/GR can both fit the Freundlich isotherm model. The adsorption and desorption kinetics can be fitted to the pseudo-second-order linear and zeroth-order models, respectively. At 0.020 mg/mL MB initial loading, out of SPION/PVA/CS/AC, SPION/PVA/CS/GR, and SPION/PVA/CS/GO, SPION/PVA/CS/AC is the most economical adsorbent. Compared to SPION/PVA/AC, SPION/PVA/CS/AC is less economical. Since CS has antimicrobial properties, antimicrobial activities should be investigated to conclude which adsorbent is more promising: SPION/PVA/AC or SPION/PVA/CS/AC.