Chromium removal from contaminated wastewaters using biodegradable membranes containing cellulose nanostructures

The removal of chromium from contaminated water was investigated using biodegradable membranes and functionalized cellulose nanoparticles. We used poly(butylene adipate-co-terephthalate), a flexible polymer, for membrane development via phase inversion technique. CNS, with and without phosphorylation (CNS-P), was used aiming to improve the removal of chromium from contaminated drinking water. The neat CNS showed limited efficiency on the Cr removal. On the other hand, CNS-P indicated removal of 93% and 88% of Cr(VI) and Cr(III), respectively. The Cr removal can be associated with CNS higher surface area and active sites, which allows more regions for immobilization of chromium species. Also, at lower pH the CNS-P presents a surface charge that can interact via electrostatic forces with the chromium species, which increases the removal efficiency. CNS-P also showed greater thermal stability due to phosphorylation. The addition of CNS and CNS-P improved the membranes' mechanical performance, which improves the applicability of this material, with potential application in domestic houses and water treatment stations. A small device for domestic use was tested to confirm the efficiency of the membranes, and the functionalized membranes showed 71% of chromium removal, which highlights its potential for water decontamination.