Effect of pH values on recovery of nano particles (NPs) from the fine fraction of automobile shredder residue (ASR): An application of NPs for phenol removal from the water

Abstract

Nano particles (NPs) were synthesized from leachate of fine fraction (<0.25mm) of automobile shredder residue (ASR) at pH levels of 3, 5, 7, 9 and 12. The removal of phenol using NPs in water was investigated to determine whether applying NPs for phenol removal from wastewater would be feasible. The recovered NPs were analyzed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). In this research, phenol degradation was studied with hydrogen peroxide to assess the potential applicability of NPs for the treatment of wastewater. The results of the SEM and TEM analyses show that the separated NPs were <50nm in size. The FTIR spectra indicate the presence of CO and OH bonds in the NPs. The XRD results show the presence of metals oxides of Fe, Zn, and Cu, among others, on the surfaces of the NPs. The results of the XPS analyses show that various elements (e.g., C, O, Zn, and Fe) existed in the recovered NPs. The degree of phenol degradation by NPs in the presence of hydrogen peroxide was significant. Phenol degradation was found to be 100% for NPs synthesized at pH levels of 3 and 7 at a reaction time of 210min. A pseudo-first-order kinetic model showed a very good fit to the phenol degradation results. The probable mechanism for the removal of phenol by NPs was the degradation of phenol by hydroxyl radicals which were produced during the reaction between H2O2 and NPs in a liquid medium. The results of the present study indicate that NPs recovered from low-grade ASR can be applied for the removal of phenolic compounds from water.