Magnetic pectin nanocomposite for efficient adsorption of heavy metals from aqueous solution

In this study, pectin/γ-Fe2O3/gl nanocomposite was synthesized using a single-step chemical precipitation method and used as an eco-friendly adsorbent to remove Cd^2+ and Pb^2+ from aqueous solution. The nanocomposite was characterized by FE-SEM, EDX, FTIR, XRD, VSM, and TEM analyses. The effect of various parameters such as solution pH (2 to 5), contact time (0 to 60 min), initial ion concentration (10 to 200 mg. L^-1), and adsorbent dosage (0.1 to 0.4 g.L^-1) on the removal efficiency was investigated. The maximum adsorption capacity of Cd (II) in the conditions (pH: 5, dose of adsorbent: 0.2 g.L^-1, and contact time:40 min, initial concentration: 50 mg.L^-1 ) and Pb (II) in the conditions (pH: 4.5, dose of adsorbent: 0.1g.L^-1, and contact time:30min, initial concentration: 50 mg.L^-1 ) was 470 and 325 mg. g^-1, respectively. The adsorption kinetics was studied using several kinetic models including Langmuir isotherm, Freundlich isotherm, Sips isotherm, and Temkin isotherm. Results indicated that the adsorption mechanism could be well represented by the pseudo-second-order model. The equilibrium data of Cd (II) and Pb (II) adsorption were reasonably described by the Sips and Langmuir isothermal models. The positive value of delta H and negative values of delta G exhibit the endothermic and spontaneous nature of the adsorption process.