Biosorption Of Pb(II) Ions from Aqueous Solution Using Tomato (Lycopersicum) Roots; Equilibrium, Kinetic, and Thermodynamic Study

Lycopersicum root, an agricultural waste was used as a biosorbent for the removal of Pb(II) ions from aqueous solution. The biosorptive capacity was determined using Atomic Adsorption Spectrophotometry, (AAS). Optimum metal ion concentration (5.0 mg/l), contact time (30 minutes), contact temperature (15 oC) and pH (5.5), dependence was established with a biosorbent dose of 3.0 g. The experimental data were analyzed using Langmuir, Freundlich, Temkin Dubinin – Radushkevich (D – R) isotherm models. The Freundlich Isotherm best described the biosorption process (R2 = 0.9477), followed by Temkin (R2 = 0.9130), Langmuir (R2 = 0.8860) and D – R (R2 = 0.0075). The kinetics of the adsorption process was evaluated using pseudo-first-order, pseudo-second-order and intra-particle diffusion models. The pseudo-second-order best described the process with R2 = 0.9950 and the qe, cal (0.0600 mg/g) matched more closely to the qe, exp (0.0822 mg/g). The thermodynamic analysis showed that the adsorption was spontaneous, feasible and exothermic in nature. Therefore, Lycopersicum root can be used as a biosorbent for aqueous removal of Pb(II) ions.