Utilizing Composites of Environmental Noxious Waste Materials for Decontamination of Heavy Metal Ions in Solution

Abstract

Heavy metals, sawdust and waste plastic bottles are pollutants which are threats to the environment and by extension to humans, animals and plants. Composites of waste plastic bottles and sawdust in different ratios (3:1, 6:1 and 12:1) were used to adsorb iron (III) and lead (II) from aqueous solution. Batch adsorption was used to determine the kinetics and equilibrium of the adsorption. Atomic absorption spectrometry (AAS) was used to determine the concentrations of the metals in pre and post adsorption. FTIR was used to characterize the composite adsorbents; the results showed peaks for OH (3291.2, 3336.0, 3406.8 and 3652.8cm -1 ) and CO (1714.6cm -1 ) which influence adsorption. Pseudo second order (PSO) and Weber-Morris intraparticle diffusion models were studied and experimental data largely favoured pseudo second order kinetic model; while intraparticle diffusion was dominant for the 12:1 ratio for Pb as shown by the higher R 2 value (0.921).For equilibrium studies, experimental data fitted Langmuir more than the Freundlich. Percentage adsorption of more than 90% was achieved for both metals at initial concentrations as high as 50ppm for iron and 100ppm for lead. It was also observed that the percentage adsorption of lead was more than that of iron. The results of the equilibrium and kinetic studies showed that the different ratios of waste PET plastic bottles to sawdust are potential adsorbents for iron and lead from aqueous phase.