Functionalization of cellulose nanofiber mats with phthalocyanine for decoloration of reactive dye wastewater

A versatile method is reported for the preparation of cellulose nanofiber mats immobilized with cobalt tetraaminophthalocyanine (CoPc). This functionalized cellulose nanomaterial was used as an efficient catalyst for the decoloration of reactive dye wastewater. Cellulose acetate was electrospun into nanofiber mats (CA-NM), hydrolyzed with KOH, and then oxidized by NaIO₄ to generate aldehyde groups for CoPc immobilization. The functionalization processes on the nanofiber mats were monitored by attenuated total reflection Fourier transform infrared spectroscopy (ATR/FT-IR), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscope (FESEM). We found these CoPc-functionalized nanofiber mats (CoPc-NM) have high adsorption capacity for reactive dye from synthetic wastewater, which enhances the catalytic oxidation rate of reactive dye when H₂O₂ is present as oxidant. More than 90% of reactive red X-3B can be eliminated by CoPc-NM/H₂O₂ in 90 min. UV and GC-MS analyses indicate the catalytic oxidation not only breaking the azo linkages but also decomposing the aromatic parts of reactive red X-3B, and the main products are biodegradable aliphatic acids, such as fumaric acid, succinic acid, and maleic acid, etc. Repetitive measurements also show that this CoPc-NM is quite stable and remains efficient with no obvious decrease of catalytic activity.