Removal of hexavalent chromium from potable drinking using a polyaniline-coated bacterial cellulose mat

Polyaniline-based composites serve as adsorbent materials for the removal of hazardous heavy metal impurities such as Cr(vi) from wastewater. However, previous reports on polyaniline (PANi)-based adsorbents mainly focus on Cr(vi) removal from acidic aqueous solutions (pH 1-5). Nonetheless, in the case of potable water, Cr(vi) removal has to be performed at neutral pH. In this study, we demonstrate the removal of Cr(vi) from drinking water at neutral pH using a PANi/bacterial cellulose (BC) mat. The rate-limiting step observed at neutral pH is the desorption of reduced Cr(iii) from the PANi/BC adsorbent. This is contrary to that observed in acidic solution, where the adsorption of Cr(vi) is reported to be the slowest step. The aforementioned claim is confirmed by applying the Langmuir-Hinshelwood kinetic model to the adsorption-reduction-desorption processes.