The Chemically Modified Leaves of <i>Pteris vittata</i> as Efficient Adsorbent for Zinc (II) Removal from Aqueous Solution

Abstract

High concentrations of zinc along with other metals are released by steel mills, and this has a number of negative effects on organism health; most notably, neurological symptoms have been recorded with a high risk of brain atrophy. In the current study, Zn (II) was eliminated from steel mill effluent, utilizing chemically processed Pteris vittata plant leaves as a biosorbent. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and energy dispersive X-ray spectroscopy (EDX) were applied to characterize the chemically modified Pteris vittata leaves, from now onward abbreviated as CMPVL. In order to identify the ideal parameter, batch studies were conducted varying a single parameter affecting the biosorption process at a time, including variations in temperature (293-323 K), initial metal concentration (20-300 mg/L), and adsorbent doses (0.01-0.12 g), pH (2-8), as well as contact time (10-140 min). To describe the isothermal experimental results, a number of models were used including Freundlich, Langmuir, Temkin, Jovanovich, and Harkins-Jura. Among these models, the Langmuir model provided a significant fit to the isotherm data with an R-2 of 0.9738. The kinetics data were fitted to the pseudo first order, pseudo second order, power function, Natarajan-Khalaf, and intraparticle diffusion models. The highest R-2 (0.9976) value was recorded for the pseudo second order model. Using the Langmuir isotherm, the highest uptake ability (84.74 mg/g) of Zn was recorded. The thermodynamic investigation, carried out at various temperatures, led to the conclusion that the biosorption process was exothermic and spontaneous in nature. The CMPVL, thus, has the potential to function well as an alternative to existing carbon-based adsorbents in the effective elimination of zinc from aquatic environments.