Removal of Arsenic from Contaminated Water by Polypyrrole-Based Adsorbents

Worldwide, there is growing concern over the toxicity of arsenic in drinking water. The US Environmental Protection Agency and Central Pollution Control Board (India) have set a safe limit of 50 parts per billion for arsenic in drinking water. Millions of people are at immediate risk due to high concentrations of arsenic in drinking water, particularly in developing nations where arsenic poisoning symptoms have been observed. One of the essential techniques described in this article is the absorption of arsenic from contaminated water by sustainable cellulosic materials like jute and wood sawdust after suitable modification. Jute and sawdust are cheap and abundantly available in South Asia. They are functionalized with polypyrrole coating by in situ chemical polymerization of pyrrole in aqueous medium in the presence of ferric chloride. Polypyrrole-coated jute fabric (with 11.28% polypyrrole add-on) and polypyrrole-coated sawdust (with 5.28% polypyrrole add-on) are found to be excellent adsorbers of arsenic ion (As3+) from water. The effect of dosage of polypyrrole-coated adsorbents, treatment time and pyrrole concentration on the As removal efficiency have been investigated in this work. The arsenic concentration in water is determined using a microwave plasma atomic emission spectrometer with the highest level of accuracy. Maximum As removal efficiency by the polypyrrole-coated sawdust and polypyrrole-coated jute fabric is found to be 80.90% and 97.3%, respectively, from a 50 mL, 7.5 parts per million As solution with a dosage of 1 g at neutral pH. The polypyrrole-coated jute and sawdust are characterized by Fourier-transform infrared spectroscopy to understand the chemical interaction between cellulose and polypyrrole molecules. The scanning electron microscope studies reveal a uniform coating of polypyrrole around the surface of jute fibre and sawdust particles. Thermo-gravimetric analysis shows good thermal stability of jute and sawdust after polypyrrole coating.