Kinetic and equilibrium study of (poly amido amine) PAMAM dendrimers for the removal of chromium from tannery wastewater

Abstract

Abstract Water gets polluted by industrial effluents, mainly composed of heavy metals and organic materials. Water soluble heavy metals can be taken up by living organisms. Chromium mainly occurs in the form of chromate and cationic hydroxo complexes in water. Apart from conventional methods of heavy metal removal, there are some novel approaches such as using dendrimers for removal of heavy metal. Dendrimers are extremely branched nano sized polymers with a three-dimensional symmetry around a core that imparts poly functionality. PAMAM (poly amido amine) dendrimers having ethylene diamine as core and methyl acrylate as repeating unit was divergently synthesized. Characterization of PAMAM dendrimers was evaluated by UV–Vis spectroscopy, zeta sizer, scanning electron microscopy (SEM) and Fourier-transform infrared (FT-IR) spectroscopy. Zero generation dendrimers have amine terminal groups, showed intense amide group peak at 1596.76 cm−1. The λ max value was 278 nm. SEM exhibited spherical shape for full generation while needle like structure for −0.5 generation. Evaluation of chromium removal from wastewater has been done by atomic absorption spectroscopy (AAS). The data revealed that optimal removal of Cr occurs at dendrimer concentration of 5 mL, Cr concentration of 300 ppm, contact time of 2 min and pH 7. The synthesized dendrimers have effectively removed Cr from tannery wastewater.