2,2′-(butane-1,4-diylbis(oxy))dibenzaldehyde cross-linked magnetic chitosan nanoparticles as a new adsorbent for the removal of reactive red 239 from aqueous solutions

In the current work, 2,2'-(butane-1,4-diylbis(oxy))dibenzaldehyde cross-linked magnetic chitosan nanoparticles (Fe3O4@CS-BAL) were successfully synthesized as the new magnetic adsorbent through crosslinking modification of magnetic chitosan nanoparticles (Fe3O4@CS) using 2,2'-(butane-1,4-diylbis (oxy))dibenzaldehyde (BAL) as a crosslinker at room temperature. The chemical structure, surface properties and morphology of the synthesized nanoparticles were characterized by Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD) and Scanning electronic microscope (SEM), Thermogravimetric analysis (TGA) and N-2 adsorption-desorption isotherms. The 2,2'-(butane-1,4-diylbis-(oxy))dibenzaldehyde-modified magnetic chitosan nanoparticles (Fe3O4@CS-BAL) were used as an effective adsorbent for removal of an anionic reactive dye, Reactive red 239 (RR239) from aqueous solutions by batch adsorption procedure. The effects of various experimental parameters such as adsorbent dosage, pH, contact time and initial dye concentration on the RR239 adsorption onto the Fe3O4@CS-BAL were investigated and optimized. The Langmuir and Freundlich adsorption models were used to describe adsorption isotherms and constants. The equilibrium results revealed that the adsorption behavior of the RR239 dye on the Fe3O4@CS-BAL nanoparticles fitted well with the Langmuir model. On the basis of the Langmuir analysis, the maximum adsorption capacity (q(m)) of the Fe3O4@CSBAL for RR239 was found to be 200 mg/g. The experimental results showed that the Fe3O4@CS-BAL could be remove more than 99% of investigated dye within the first 2 min of contact time. Therefore, the Fe3O4@CS-BAL adsorbent can be successfully applied as an efficient and low-cost adsorbent for removal of anionic reactive dyes from aqueous solutions. (C) 2018 Elsevier B.V. All rights reserved.