LAUSR

Dyes and pigments utilized for colouring purposes by textile industries play a pivotal role in the accumulation of numerous toxic substances in an aquatic environment. This provokes a keen interest in the environmentalist in developing a novel sorbent material that could remove the organic pollutants from the waste effluent. In the current study, Lemna minor, a duckweed plant, acts as the low cost, eco-friendlier sorbent to remove the toxic acid blue 113 dye from the effluents. The characteristic traits of the dried biosorbent were analysed by scanning electron microscope to analyse the porous and rough exterior surface, Fourier transform infrared spectroscopy reveal the presence of specific entities such as amine, hydroxyl, carboxyl and alkyl groups and gas chromatography and mass spectroscopy for the presence of numerous polyphenolic compounds. Optimization was done by response surface methodology to study their potential in the adsorption capacity of the adsorbent. The removal efficiency of 98.5% was attained in the batch study at optimized parameters of contact time (40 min), pH (4.0), temperature (40 °C) and concentration of sorbent (1 g). The reaction mechanism was evaluated with the kinetics and isotherm studies. Kinetics study includes pseudo-first-order, pseudo-second-order, Elovich and intra-particle diffusion, and the isotherm study includes Langmuir, Freundlich, Langmuir–Freundlich and Temkin isotherm models. The system follows the pseudo-second-order kinetics model, Langmuir and Langmuir–Freundlich isotherm model with the maximum sorption capacity of 395.7 mg/g. Thermodynamic studies were evaluated to determine the spontaneous and endothermic nature of the reaction.