Biosorption of zinc on functionally activated Lantana camara leaves: equilibrium, kinetic, and thermodynamic studies

In this study, the possibility of using Lantana camara leaves to prepare an efficient biosorbent LCLB (Lantana camara leaves’ biosorbent) has been explored which plays a very crucial role in elimination of Zn (II) ions from contaminated wastewater solution. Brunauer–Emmett–Teller (BET) surface area, Fourier-Transform Infrared (FTIR) spectroscopic analysis, and scanning electron microscope (SEM) analysis were carried out to characterize the prepared biosorbent. Energy Dispersive X-ray Spectroscopy (EDX) results illustrated the elemental composition of LCLB before and after sorption of Zn (II) ions. It was reported that increasing biosorbent dosage and contact duration improve Zn (II) ion removal while it decreases with rising initial concentration of Zn (II) ions and temperature. At pH 6, 5 g adsorbent dosage, and 45-min contact time, excellent removal capabilities (85.06%) were reported. The pseudo-second-order rate model fit the kinetics of Zn (II) adsorption well (R² > 0.998), and the predicted adsorption capacity of the model agreed well with the experimental outcomes. The Langmuir isotherm (R² > 0.996) was the best suited isotherm model for Zn (II) adsorption onto LCLB, implying monolayer adsorption with maximum adsorption capacity of 2.778 mg/gm. Thermodynamic experiments revealed that Zn (II) adsorption on the biosorbent’s surface was spontaneous and exothermic. Desorption studies implied that the biosorbent can be recycled effectively up to two cycles. The results of this study revealed that LCLB is an effective, inexpensive, and environmentally acceptable biosorbent for removal of heavy metal ions from contaminated aqueous media.