Adsorption mechanism of polyethyleneimine modified magnetic core–shell Fe₃O₄@SiO₂ nanoparticles for anionic dye removal

Abstract

In this paper, polyethyleneimine modified magnetic core-shell Fe 3 O 4 @SiO 2 nanoparticles (Fe 3 O 4 @SiO 2 / PEI) were innovatively synthesized and investigated using various techniques such as TEM, TGA, FT-IR, XRD, VSM and XPS. The adsorption performance based on the removal of the anionic dyes Methyl orange and Congo red from aqueous solution was studied systematically. The results showed that the adsorption rate of anionic dyes MO and CR increased rapidly then decreased gradually as the pH increased, the adsorption capacity of Fe 3 O 4 @SiO 2 /PEI for MO was better than that for CR, and the maximum adsorption capacity for MO and CR was 231.0 mg g À1 at pH 4 and 134.6 mg g À1 at pH 6, respectively. The equilibrium adsorption capacities for MO and CR increased rapidly in the initial 40 min, and reached equilibrium in approximately 180 min, while the adsorption capacity for MB was relative low even negligible, demonstrating the strong adsorptive affinity of Fe 3 O 4 @SiO 2 /PEI toward anionic compounds. Both of the adsorption processes followed the pseudo-second-order kinetics model and the Freundlich isotherm model. The mechanism of adsorption was mainly related to electrostatic attraction and the number of active sites occupied by anionic dyes. This study provides valuable guidance and is an effective method for the removal of anionic dyes from aquatic environments.

Hydrothermally engineered Eriobotrya japonica leaves/MgO nanocomposites with potential applications in wastewater treatment

“…9b shows, PZC of BC@MgO NPs was 8.7. The dominance of charge positive of BC@MgO NPs at pH<PZC (adsorption of TZ was favorable) and negatively charged when pH>PZC (adsorption of TZ was unfavorable) (Huang et al, 2019).…”

Synthesis of Fe2O3@SnO2 Core‐shell Nanocomposites via Thermal Decomposition Route and their Application as an Adsorbent

“…The adsorption of CR using Fe 2 O 3 @SnO 2 core‐shell nanocomposites (FS‐1‐C) thus follows Langmuir adsorption isotherm [85,86] . In the current work, the time required for the complete adsorption of CR and adsorption capacity for the adsorbents were compared with the data reported [87–97] . (Table S10) The reported adsorbents take longer time (60–3000 min) for the adsorption of congo red and the adsorption capacity varies from 16.6 mg g −1 to 259.0 mg g −1 .…”

Two-Step Triethylamine-Based Synthesis of MgO Nanoparticles and Their Antibacterial Effect against Pathogenic Bacteria

“…The most prominent thermal transition was appreciated between 280 and 365 °C, when the mass was reduced 46%; it is in this region of temperatures where the mayor part of the organic residuals can be calcinated and the decomposition of magnesium acetate into MgO occurs—this explains the large weight decrease detected [ 49 , 57 , 58 ]. This was confirmed by the DSC trace that showed an endothermal maximum in this region.…”