Optimization of process parameters for the decolorization of Reactive Blue 235 dye by barium alginate immobilized iron nanoparticles synthesized from aluminum industry waste

- Iron oxide nanoparticles synthesized from red mud (RMINP) are embedded in barium alginate beads.
- Immobilized RMINP are used to treat Reactive Blue 235 (RB235) dye solution.
- Process parameters for RB235 dye decolorization using immobilized RMINP are optimized by Box-Behnken Design based Response surface methodology.

In the present study, we report a comparative study of Reactive Blue 235 (RB235) dye removal using red mud derived biologically synthesized iron nanoparticles (bRMINP) and chemically synthesized iron nanoparticles (cRMINP), both immobilized in barium alginate beads. The parameters like initial RB235 dye concentration, immobilized RMINP concentration, hydrogen peroxide (H2O2) concentration and the contact time for RB235 dye removal were optimized based on Box-Behnken design (BBD) by Response Surface Modeling (RSM) at a constant pH and temperature. Under the optimized conditions (concentration of immobilized RMINP = 1500 mg L−1, contact time = 240 min, and initial concentration of RB235 = 10 mg L−1), the RB235 dye removal by the immobilized bRMINP and cRMINP barium alginate beads was 98.75% and 88.88%, respectively. Results show that the removal of RB235 dye increases as increasing the immobilized RMINP concentration and contact time and decreases with increase in the initial concentration of RB235 dye. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FT-IR) spectroscopy were used to confirm the adsorption of RB235 onto the surface of barium alginate beads.