Adsorption of hexavalent chromium from aqueous solution by polyamidoamine dendrimer polycondensate

摘要

Cr(VI) is a toxic heavy metal ion, which can cause serious hazards to human health. The present study explored that polyamidoamine (PAMAM) dendrimer polycondensate was a potential promising adsorbent for removal of Cr(VI) from aqueous solution. The surface morphology of PAMAM dendrimer polycondensate was characterized by SEM. The adsorption capacity of Cr(VI) onto PAMAM dendrimer polycondensate was found to be dependent on Cr(VI) initial concentration, pH value of aqueous solution, adsorbent dosage, adsorption time, and adsorption temperature. In addition, the adsorption equilibrium could be described by Langmuir isotherm, Freundlich isotherm, and Temkin isotherm. The kinetic of the adsorption process is fitted with pseudo-second-order model and intraparticle diffusion model. The thermodynamic study showed that a negative value of Delta G(theta) indicated that the adsorption process was spontaneous in nature, while positive value of Delta H-theta indicate that the adsorption is endothermic and higher temperature makes the adsorption easier, and positive value of Delta S-theta reflected good affinity of Cr(VI) toward PAMAM dendrimer polycondensate.