Biopolymers-based nanocomposites: Membranes from propionated lignin and cellulose for water purification

Nanocomposite membranes for water treatment were prepared by vapor-induced phase separation method from propionated lignin and cellulose triacetate (CTA). Three kinds of lignin were used: Kraft, Organosolv and Hydrolytic, which were propionated for improving their compatibility with CTA. Such chemical lignin modification was analyzed by FTIR, UV spectrophotometry and GPC. Morphology (through FE-SEM and AFM), mechanical properties (DMA), and surface potential (SPKM) were investigated for all membranes obtained. For determining membrane performance, groundwater from Chihuahua (Mexico) containing high concentrations of fluoride, arsenic, calcium, sodium and magnesium, was filtrated. Membrane rejection was 15–35% for anions present, and 12–42% and 27–54% for monovalent and divalent cations, respectively. Arsenic and fluoride removal by membranes was found to be affected by ionic and organic matter present in groundwater.