Novel Thin-film, Chitosan-polyaniline Nanofiltration Membrane Effectively Removes Toxic Heavy Metals From Wastewaters

Membrane technology for water purification has gained much attention in many industries and for healthier human life. Also, improving the elimination of toxic heavy metals is a much needed strategy for the filtration of public water supplies. This study investigated the removal of toxic heavy metals from wastewater, using a novel thin-film membrane.

We investigated the structural, physico-chemical, and antifouling properties of the membrane, and its ability to remove toxic elements from water. Seven parameters were examined: Contact angle, water ionic contents, Fourier’s transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), 3D-surface imaging, water flux, and antifouling effects.

The results indicated that a thin-film layer formed on the membrane. The 3D-images demonstrated that the surface roughness decreased when the polyaniline ratio to nanoparticles increased. The surface hydrophilicity increased by incorporating polyaniline into the surface. The water flux increased from 8.04 (L/m2.h) to 14.74 (L/m2.h) in the virgin membrane. The sodium sulfate rejection was 61% for the virgin membrane whereas it was >67% in the thin-film coated membrane. The data demonstrated excellent anti-fouling properties for the novel membrane, with a flux recovery ratio of >94.65% while it was about 79% for the virgin one. The rejection rates of chromium and copper ions for the novel membrane were >86% and >84%, respectively. These values were significantly higher than those of the virgin membrane (>53% and >51%). 

The thin-film composite membrane significantly improved the removal rate of toxic heavy metals from the wastewater samples compared to the virgin membrane.