Synthesis and characterization of PAMAM/CNT nanocomposite as a super-capacity adsorbent for heavy metal (Ni2 +, Zn2 +, As3 +, Co2 +) removal from wastewater

Abstract

The water cleaning applications of carbon nanotubes (CNT) have generated much research interest since their initial discovery. However, in the early stages of research, the efficiency of CNTs for the removal of heavy metal ions has been severely limited because of the intense agglomeration of CNTs and their deficiency of functional groups. In this research, a new method has been discovered for the preparation of dendrimer functionalized CNTs and a PAMAM/CNT nanocomposite was prepared. FTIR, SEM, TEM, Raman spectroscopy, zeta potential measurements, and dispersion observing methods have been employed for characterizing the synthetic nanocomposite and these techniques indicated that the dendrimer functionalized CNTs have been favorably synthesized. In addition, the uniquely high adsorption capacities properties of PAMAM/CNT nanocomposite for Ni2+, Zn2+, As3+, Co2+ were examined. The effects of several parameters including initial metal ion concentration, temperature, solution pH, the nanocomposite dosage and contact time were studied. The experimental data were analyzed using equilibrium isotherm relationships (Langmuir, Temkin and Freundlich) and the uniquely high adsorption capacities and rates were studied using (pseudo-first order, intraparticle diffusion and pseudo second-order) adsorption kinetics models. The results indicated that the maximum adsorption occurred at pH=8. With increasing nanocomposite dosage and increasing contact time, there was increased adsorption capacity. Analysis of the adsorption process demonstrated that the Langmuir isotherm and pseudo-second order kinetics are the most appropriate models for heavy metal ions adsorption onto PAMAM/CNT nanocomposite.