Visible-light photocatalytic activity of chitosan/polyaniline/CdS nanocomposite: Kinetic studies and artificial neural network modeling

• Removal of an organic matter on CS/PAni/CdS nanocomposite was modeled.
• New kinetic model was established based on adsorption and surface photocatalytic degradation.
• A 3-layer network with optimized 5:10:1 topology could provide adequate predictive performance.

Chitosan/polyaniline (CS/PAni), chitosan/CdS (CS/CdS) and chitosan/polyaniline/CdS nanocomposite were synthesized and characterized using X-ray diffraction pattern analysis, FT-IR spectroscopy and scanning electronic microscopy. The adsorption performance and photocatalytic activity of CS/PAni/CdS was compared with CS/PAni and CS/CdS in the removal of Reactive Blue 19 (RB19) dye. After five cycles of experiments under visible light irradiation, CS/PAni/CdS retained high photocatalytic activity which confirmed good stability of nanocomposite. Moreover, the kinetics of decolorization was investigated and novel equation rate for dye removal was established by considering two parallel mechanisms including adsorption and surface photocatalytic degradation of dye by CS/PAni/CdS. Artificial neural network was employed to develop a model for predicting the decolorization efficiency and determining the relative importance of operational parameters. A 3-layer perceptron network with optimized 5:10:1 topology could provide adequate predictive performance (R2 = 0.983). Moreover, the photocatalytic degradation of RB19 was monitored by measuring the total organic carbon (TOC) and GC–MS analysis, enabling the evaluating the mineralization and identifying the intermediates. During 120 min of experiment, more than 80% of TOC was removed.

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