Nitrobenzene Degradation from Aqueous Solutions Using Zero-valent Iron Nanoparticles / Polyaniline Composite

Background and Nitrobenzene (NB) as the main material of synthetic fuels, cleaners, rubber and explosives is discharged into the environment and groundwater in large-scale. This compound is considered as a persistent organic pollutant with high toxicity and stable chemical structure which can cause serious risks for human health and ecosystem even in low concentrations. Therefore, the aim of present study was to synthesize polyaniline/zero-valent iron composite nano-fiber (CNFs) and its ability in degradation of nitrobenzene from aqueous solution.
Characterization of CNFs was determined using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and vibrating sample magnetometer. The effect of operational parameters such as pH, NB concentration and nanocomposite dosage on nitrobenzene degradation were analyzed by response surface methodology. Box Behnken model was used to investigate the interaction among variables. Analysis of variance was considered as statistical method for responses analyzes.
ANOVA test showed a significant relationship between statistical model and test data. The observations also revealed that the distribution of residuals were normal and parameters i.e. pH, NB concentration, nanocamposite dosage and interaction of nano-composite and NB concentration had significant effect on removal of NB. The degradation efficiency was over 98% in optimized conditions (pH=2, NB concentration= 40 mg/l, and nanocomposite dosage= 0.88 g/l) that was achieved in 45 minutes. Limit of Detection (LOD) and Limit of Quantification (LOQ) were calculated as 1.5 and 5 mg/l, respectively.
According to the results, polyaniline nanofiber composite/zero-valent iron has a good efficiency in NB degradation. NB kinetic studies showed that the NB degradation process by nanocomposite followed the one order kinetic model. In addition, the nano-composite separation is simple due to its magnetism properties that it can improve its application.