Adsorption Kinetics of Tartrazine Dye on Activated Carbon Derived from Guava (Psidium guajava) Seeds

Abstract

Azo dyes are widely used in various industries. However, many of these dyes are carcinogenic and reduce light penetration into aqueous systems, posing a threat to human health and hampering photosynthesis in aquatic environments. In this study, guava seeds were used to produce activated carbon by chemical activation with ZnCl2. The carbon was characterized and used as an adsorbent to remove tartrazine dye in aqueous medium. X-ray diffraction showed the formation of a material with disordered graphitic planes, typical of activated carbons. The equilibrium time for the dyeactivated carbon system was found to be 80 min by the Southwell plot method. The adsorbent removed 97.6% of the dye, representing an adsorbed concentration of 1.62 mg g−1 for an adsorbent dosage of 12 g L−1. The pseudo-second-order and Elovich kinetic models provided the best fit to experimental data, suggesting that chemisorption is the predominant mechanism, combined with the effect of surface heterogeneity. From an environmental point of view, the results suggest that the activated carbon produced is an efficient material for the treatment of industrial wastewater containing azo dyes.