Citric acid modified wheat bran as a potential adsorbent for removal of Cu(II) and Malachite Green from aqueous solutions

Abstract

The contamination of water bodies by heavy metal ions and synthetic dye molecules from the wastewater streams of industries is a serious environmental problem. Wheat bran is currently an undervalued agricultural by-product. Therefore, the primary aim of this study was to develop a new economic wheat bran-based adsorbent with relatively high adsorption capacity for industrial wastewater treatment. Wheat bran was thermochemically modified with citric acid to prepare a biodegradable cationic adsorbent. The potential of using the prepared adsorbent for removal of Cu(II) and Malachite Green (MG) from aqueous solutions was then investigated using batch equilibrium tests. Operational parameters, such as solution pH, adsorbent dose, initial adsorbate concentration as well as temperature, greatly influenced the adsorption efficiency of the adsorbent. The Freundlich isotherm model showed excellent fit to the equilibrium data of Cu(II) while the Langmuir isotherm described best the adsorption data of MG. The sorption processes followed the pseudo-second-order rate kinetics. Thermodynamic study showed spontaneous and exothermic nature of the sorption processes. Results suggest that the use of citric acid modified wheat bran as adsorbent is a thoughtful and economic attempt for its needy utilization for treatment of industrial effluents.

Keywords:

• Adsorption
• Citric acid-modified wheat bran
• Cu(II)
• Malachite Green
• Kinetics
• Thermodynamics