Removal of Pb(II) using polyaniline composites and iron oxide coated natural sand and clay from aqueous solution

•Polyaniline and iron oxide coated natural soil were effective in Pb(II) removal.•The optimum conditions for Pb(II) removal were found to be pH 11.•New peaks and slight shifts in position of bands for FTIR spectra of composites were seen.•The surface morphology of composites was dependent on the type of coating.

In this research, natural sand and clay coated with polyaniline and iron oxide were used to remove Pb(II) from contaminated water. Fixed bed column and batch studies were performed to evaluate the influence of various experimental parameters such as pH, adsorbent dosage, and contact time. Based on the results, optimum conditions for Pb(II) removal were found to be pH 11, adsorbents dosage of 10 g/L, and contact time of 45 min. In addition, the morphology and chemical structure of the adsorbents were studied via scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The column tests were conducted with a flow rate of 4 mL/min with different bed depths of 10 and 25 cm. It was found that when iron oxide/clay, iron oxide/sand, polyaniline/clay and polyaniline/sand were used as adsorbent in a fixed-bed column method, the removal percentages of Pb(II) were 97.50, 99.24, 72.99, 68.80% and for the completely mixed batch reactor (CMBR) method were 99.84, 99.89, 93.91 and 90.77%, respectively. These results indicated that iron oxide coated sand and clay are an attractive source of adsorbents that can be used for removal of Pb(II) in water treatment processes.