Ultrasound assisted mixed azo dye adsorption by chitosan-graphene oxide nanocomposite

•Simultaneous adsorption of acid yellow AY and acid blue AB by GO-Cs-Nc was studied.•Process was optimised for best results using RSM (CCD) and modelled with ANN.•On ultrasonication 0.5 g L−1 of GO-Cs-Nc adsorbed 99.58% AY and 99.60% AB in 6 min.•Endothermic chemisorption followed Langmuir isotherm and pseudo 2nd order kinetics.•GO-Cs-Nc highly suitable for real effluent treatment in reduced dosage and time.

Mixed azo dyes present in various effluents may often impair adsorption efficiency thereby questioning applicability of the same in a real-time scenario. In this study, simultaneous adsorption of acid yellow 36 (AY) and acid blue 74 (AB) from their aqueous solutions was carried out with graphene oxide nanoplatelets embedded in chitosan matrix (GO-Cs-Nc) with assistance of ultrasound exposure. Results obtained were subjected to analysis for process isotherms, kinetics and thermodynamics. This process was also optimized for best results using response surface methodology (RSM) and modelled with artificial neural network (ANN). The nanocomposite was characterised both before and after adsorption using FTIR, SEM, TEM and AFM. Under the experimental conditions prescribed by RSM, 0.50 g L−1 of adsorbent was responsible for 98.18% and 98.80% removal of AY and AB respectively when exposed to 6.48 min of ultrasonic irradiation. Hence, ultrasound assisted GO-Cs-Nc proved to be a cost effective and sustainable adsorbent effective in low dosage and significantly reduced time with possible application for treatment of real industrial effluents rich in mixed dyes.

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