Nanomagnetic adsorbent composite derived from activated carbon modified with iron oxide for Cu2+ and Pb2+ removal.

The use of abundance agriculture waste such as sugarcane bagasse (SCB), corn stalk(CS), durian husk (DH) and mangosteen shell (MS) as the sorbent material in the form of activated carbon in the synthesis of nanomagnetic adsorbent is a new approach and not common. This study was undertaken to explore the possibility of using SCB, CS, DH and MS-Nm adsorbent composite to remove Cu2+ and Pb2+ from aqueous solution. The synthesis of SCB, CS, DH and MS-Nm adsorbent composite was successfully done by modifying the activated carbon derived from SCB, CS, DH and MS with iron oxide nanoparticle. Characterization study by SEM, EDX, FTIR, and XRD confirmed the presence of iron oxide nanoparticle in the form of maghemite (γ- Fe2O3) in SCB, CS, DH and MS-Nm adsorbent composite. Study of parameters such as pH (pH 3 to 9), temperature (30 to 50 oC), contact time (20 to 80 min) and adsorbent dose (0.05 to 0.5 g) were performed to determine the optimal condition of adsorption process for Cu2+ and Pb2+ removal. Residual concentrations of heavy metals (Cu2+ and Pb2+) in the solution were analyzed using Atomic Absorption Spectrometer. From the experiment, it can be concluded that all adsorbent composites able to remove Cu2+ and Pb2+. The removals were mostly above 90% at optimum conditions. The optimum condition for the adsorption of Cu2+ and Pb2+ onto SCB, CS, DH and MS-Nm adsorbent composites were at pH 4, temperature of 50 oC, contact time 80 min and adsorbent dose 0.5 g. Significant predictive model was obtained based on the response
surface method (RSM), input variables and empirical relationship between the response and studied parameter. Isotherm and kinetic studies showed various mechanism of adsorption, as determined by Langmuir, Freundlich and Temkin models for isotherms and pseudo first order, pseudo second order and intraparticle diffusion models for kinetics. Study of desorption-readsorption established that adsorbent efficiency maintained above 80% during three adsorption - desorption cycles. The results indicated that SCB, CS, DH and MS-Nm adsorbent composite as a novel and effective adsorbent to remove Cu2+ and Pb2+ from aqueous solution with high stability and good reusability.