Biosorption of antimony using tea leaves and tea fibers (Camellia sinensis) as adsorbents: thermodynamics, isotherm, and kinetics

Abstract

Rapid industrial development causes environmental contamination of land, water, and air with heavy metals which pose a significant threat to human survival. This study aims to remove antimony from wastewater using tea leaves and tea fiber (Camellia sinensis) as an adsorbent to curb the environmental decay posed by industrialization. The FTIR study presents significant vibration frequencies that correspond to –OH, C-H, and C=O in both the leaves and fibers which impact the adsorption. The adsorption study was performed by the batch adsorption method, varying different parameters including pH, adsorbent dosage, temperature, initial concentration, and contact time to find best-suited conditions for the removal of antimony from aqueous media. The results show an equilibrium condition at pH 5 and 30 minutes for both tea leaves and fibers whereas for tea leaves the equilibrium concentration was obtained at a dosage of 2g, and 3g for the fiber. From the adsorption model, the sorption of antimony by tea leaves follows the Langmuir model (R2 = 0.783), whereas that of tea fiber follows Freundlich (R2 = 0.827). From Kinetic studies, the sorption of antimony by both plant parts follows second-order kinetics with approximate R2 values of 1. From the adsorption capacity, it is no exaggeration to consider tea leaves and fibers as an excellent biosorbent for the sorption of antimony.