Adsorption performance of tartrazine dye from wastewater by raw and modified biomaterial: Equilibrium, isotherms, kinetics and regeneration studies

The massive generation of dye waste leads to environmental, social and ecological problems. The use of biomass-derived activated carbon as an adsorbent is a versatile approach that has attracted more attention due to the production of value-added products with lower environmental risk. Application of raw sawdust (SD) and activated sawdust (ASD) for the removal of tartrazine has been investigated. The physicochemical characterization of ASD showed a high surface area, a heterogenous surface with a clear porous structure, and enough functional groups. The effects of various parameters on the removal of the dye were studied. The highest removal percentages were found to be 47.88% for SD and 99.52% for ASD at optimized conditions of pH of 2, temperature of 25 degrees C, contact time of 60 min, SD mass of 1 g, ASD mass of 0.05 g and 20 mg/L of tartrazine. Langmuir saturation adsorption capacities were equal to 0.8 mg/g for SD and 127 mg/g for ASD at 25 degrees C. Regeneration of both adsorbents using NaCl showed a decrease in the tartrazine removal from 47.88% to 34.12% for SD and from 99.52% to 70.40% for ASD in five recycle runs. Even if SD shows a more limited efficiency in tartrazine removal, it can be used as it is, without any activation step, therefore it can be a convenient alternative to the activated material. In conclusion, SD and ASD are promising, biodegradable, eco-friendly, cost-effective and efficient adsorbents for the removal of tartrazine from wastewater effluents.