Effective removal of indigo-dyed batik by chemical activation and thermal treatment of banana peel waste coupled with magnetic magnetite particle

Abstract

The magnetic adsorbent derived from banana peels (M-A-C-BP) with the high surface area was synthesized by thermal treatment and chemical activation. The M-A-C-BP composite contained crystalline magnetite (Fe3 O4 ) which presented superparamagnetic properties. The presence of saturation magnetization in M-A-C-BP was similar to bare Fe3 O4, indicating that Fe3 O4 nanoparticles were successfully coated on the A-C-BP surface. The morphology obtained from the field-emission scanning electron microscope image revealed that the nanosized spherical Fe3 O4 was uniformly dispersed on the A-C-BP surface, leading to a high Brunauer–Emmett–Teller specific surface area. The adsorption experiments were monitored via UV-spectrophotometric technique by varying the initial concentrations of indigo carmine (IC) from 10–100 ppm. The linear plot of the Langmuir isotherm equation indicated monolayer adsorption of M-A-C-BP toward IC molecules with the maximum monolayer capacity (Qm ) value of 8.72 mg/g. The chemisorbed IC on M-A-C-BP could be described by the pseudo-second-order kinetic model. The easy recovery of magnetic adsorbent M-A-C-BP represented its practical application in IC removal from aqueous solution by an external magnetic field, which was investigated over five consecutive adsorption cycles.