Adsorption of light green anionic dye using cationic surfactant-modified peanut husk in batch mode

Abstract

Peanut husk was modified using a cationic surfactant hexadecylpyridinium bromide (CPB) and used as an adsorbent (MPH) to remove light green dye (LG, anionic dye) from aqueous solution in batch mode. Analysis of FTIR and XRF showed that CPB was adsorbed onto the surface of peanut husk. LG was analyzed using a UV spectrophotometer at the wavelength of maximum absorbance (660 nm). The results showed that it was in favor of adsorption at pH 2–4 while the presence of NaCl and CaCl2 in solution was not beneficial to LG dye adsorption. Pseudo-first-order kinetic equation and Elovich equation can describe the adsorption kinetics. The equilibrium data were better described by Langmuir isotherm and adsorption capacity of qm from Langmuir model was 146.2 ± 2.4 mg/g at 303 K. Thermodynamic calculations showed that the adsorption was spontaneous and an exothermic process. Exhausted MPH was regenerated by 0.01 mol/L NaOH solution and MPH can be reused. The results implied that MPH can be used as an effective adsorbent material to remove LG from aqueous solution.

Keywords

• Adsorption
• Modified peanut husk
• Light green dye