Hetero-Disubstituted Sugarcane Bagasse as an Efficient Bioadsorbent for Cationic Dyes

Area of Science:

• Environmental Chemistry
• Materials Science
• Adsorption Science

Background:

• Industrial wastewater often contains toxic cationic dyes, necessitating efficient removal methods.
• Sugarcane bagasse is an abundant lignocellulosic biomass with potential for functionalization.
• Chemical modification can enhance the adsorption properties of biomass-derived materials.

Purpose of the Study:

• To prepare and characterize hetero-disubstituted sugarcane bagasse (HDSB) for dye removal.
• To investigate the adsorption performance of HDSB for cationic dyes auramine-O (AO) and safranin-T (ST).
• To elucidate the adsorption mechanism and reusability of HDSB.

Main Methods:

• Simultaneous one-pot chemical modification of sugarcane bagasse with succinic and phthalic anhydrides to produce HDSB.
• Batch adsorption experiments to study the effects of HDSB dosage, pH, contact time, and initial dye concentration.
• Isothermal titration calorimetry (ITC) and molecular dynamics (MD) simulations to understand adsorption thermodynamics and interactions.

Main Results:

• HDSB exhibited high adsorption capacities for AO (1.37 mmol g⁻¹) and ST (0.93 mmol g⁻¹) at pH 7.0.
• In binary systems, ST adsorption showed an antagonistic effect on AO adsorption, indicating preferential binding.
• Adsorption was spontaneous, exergonic, and enthalpically driven (ΔadsH° ≈ -22 to -23 kJ mol⁻¹), confirmed by ITC.
• HDSB demonstrated good reusability over multiple adsorption-desorption cycles.

Conclusions:

• HDSB is a highly effective and reusable adsorbent for removing cationic dyes from aqueous solutions.
• The adsorption process is thermodynamically favorable and driven by enthalpy.
• MD simulations provided insights into the molecular interactions between dyes and the HDSB surface.