Use of Waste Plastic Char as Adsorbent for Removal of Arsenic and COD from Aqueous Solution

Abstract In present study, the solid char derived from the pyrolysis of waste high-density polyethylene (HDPE) and polypropylene (PP) was tested for removal (adsorption) of inorganic arsenic (As5+) and organic matters (COD) from water and wastewater, respectively. It was observed that the solid char could remove 60% of arsenic (+5) at a dose of 4 gm/L for a contact time of 30 min and the COD removal was 50% at a dose of 4 gm/L with a contact time of 25 min. In both cases the adsorption data was found to fit better with Langmuir model. The adsorption capacity of mixed plastic char for As5+ was observed to be in the range of 1.45 – 1.75 mg/gm and in the range of 60.625-67.9 mg/gm for COD. Proximate and ultimate analysis indicated that the pyrolytic char had a large quantity of volatile matter (46.50-48.0%), carbon (41.3–84.7%), and a small amount of moisture (1.2-2.5%). The calorific value and density of plastic char were found to be in the range of 13.50-17.50 MJ/kg and 1.55 - 1.60 gm/m3. FTIR spectra of mixed HDPE and PP waste pyrolytic oil showed the presence of mostly alkanes and alkenes. It was found that with the increase of pyrolysis temperature, the pore size of solid char increased. The XRD pattern of the plastic chars obtained in this study showed sharp diffraction crystalline peaks. The plastic char can be used for further research for removal of other contaminants from aqueous solution.