Polypyrrole multilayer-laminated cellulose for large-scale repeatable mercury ion removal

Abstract

In this research, we report a polypyrrole (PPy) multilayer-laminated cellulose network aimed at the cost-effective removal of aqueous potentially toxic metal ions with high adsorption efficiency and good adsorbent recyclability. The preparation of conformal adsorbent coatings on a fibrous cellulose network was accomplished by performing multiple cycles of simple dip-coating of a non-toxic oxidant and vapor-phase polymerization of PPy. The resultant PPy multilayer-deposited cellulose exhibited stable adhesion between the vapor-deposited PPy and the underlying cellulose support even in a strongly acidic solution. Using this non-hazardous hybrid adsorbent, mercury ions could be efficiently adsorbed over a large pH range with a maximum specific adsorption capacity of 31.689 mg g⁻¹, either in the form of a thick suspended adsorbent for large-scale decontamination or a thin dripper-type membrane for portable water purification. Furthermore, the PPy multilayer-laminated cotton fabric enabled the large-scale repetitive removal of mercury ions (100 ppm, 1 liter) with efficiency above 91%. This study suggests that the PPy-cotton hybrid may serve as a large-scale, economical, and recyclable decontamination platform for efficient removal of highly potentially toxic metal ions (e.g., Hg(II) and Cr(VI)), which could be beneficial for water purification, particularly in resource-limited locations.