Nanostructured MnO2 catalyst in E. crassipes (water hyacinth) for indigo carmine degradation

Abstract

The use of water hyacinth’s dried matter (Eichhornia crasippes) as a support matrix for nano-MnO2 and its application for the removal of indigo carmine (IC) was studied. Different pretreatment processes were tested and results indicated that an acid-alkali pretreatment is an efficient method to binding nanoparticles (NPs) to cellulosic matrix. In adittion, the MnO2 NPs were synthesized by sonochemical reduction of MnO4- using different methods (ultrasonic horn system, ultrasonic bath and reaction with ethanol), where the influence of the precursor concentration was observed. The synthesized material was further characterized by ATR-IR, AAS, XRD, SEM, nitrogen isotherms adsorption, EDS, and pHpzc. The IC removal capacity of the nanostructured material, the chemical nature of the degradation products and the effect of various parameters (temperature, pH, initial IC concentration, among others) were explored in water samples. After this process, the material, obtained by the ultrasonic bath method, was able to remove 97.6% of IC color in five min, without losing dye degradability efficiency for several consecutive cycles. Through this approach, environmental dangerous effluents from many commercial activities such as textile industry can be efficiently removed with low cost, using synthesize process biodegradable nanocomposite materials.

Keywords

• Eichhornia crassipes
• indigo carmine
• nanostructured material
• manganese oxide