Removal of tartrazine by activated carbon biosorbents of Lantana camara: Kinetics, equilibrium modeling and spectroscopic analysis

• A novel biosorbent has been developed from an exotic invasive weed Lantana camara.
• Removal of an acidic azo dye tartrazine has been carried out.
• Spectroscopic characterizations confirmed the adsorption of tartrazine dye.
• Tartrazine-biosorbent system is spontaneous, endothermic and favorable in nature.
• 0.1 mol L−1 NaOH solution was suitable for regenerating the adsorbent.

Preparation of the activated carbon biosorbents from Lantana camara weed by sulphuric acid activation was carried out. Laboratory prepared activated carbon was used as adsorbents for the removal of an acidic dye tartrazine from aqueous solutions. Liquid-phase adsorption experiments were conducted and the maximum adsorption capacity of activated carbon was determined. The effects of various process parameters, i.e., temperature, pH, initial tartrazine concentration, contact time on the adsorption capacity of activated carbon were investigated. The kinetic models for tartrazine adsorption onto activated carbon were studied. Freundlich isotherm (KF, 98.401 L g−1) showed better fit than Langmuir isotherm (Q0, 90.900 mg g−1) for the activated carbon. The rates of adsorption were found to confirm the pseudo-second-order kinetics with good correlation. The separation factor (RL) revealed the favorable nature of the isotherm of the tartrazine-activated carbon system. The values of activation parameters such as free energy (ΔG°, −10.346 to −10.983 kJ mol−1), enthalpy (ΔH°, 22.976 kJ mol−1) and entropy (ΔS°, 154. 555 J mol−1 k−1) were determined, respectively, indicating that the adsorption was spontaneous, endothermic and favorable process in nature.

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