Removal of the hazardous dyes through adsorption over nanozeolite-X: Simultaneous model, design and analysis of experiments

Dyes are known as important contaminants which can be dangerous to humans, animals, and other living organisms. Therefore, it requires considerable attention to remove them from industrial wastewater before being discharged to the environment. In this study, we synthesized nanozeolite-X (NX) via the hydrothermal crystallization method and utilized it as an adsorbent to remove Methyl Orange (MO), Reactive Blue 15 (RB-15), and Reactive Red 239 (RR-239) dyes simultaneously by an ultrasound-assisted method. The morphology and structure of NX were investigated through scanning electron microscopy (SEM), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) techniques. The effects of independent variables on the adsorption efficiency of dyes mixture were examined with the help of the response surface method (RSM). The second-order quadratic model was used to predict the response of each dye. The importance of various independent variables and their interactions were checked through analysis of variance (R-2 greater than 0.95 and P less than 0.05). The optimization of process variables for maximum absorption by NX was carried out using a quadratic model. According to the optimal conditions from RSM, the best function of the method in 0.4 g NX, pH 6, 5 mg L2(-1), obtained from a mixture of three dyes, and when they were exposed to ultrasound for 1200 s. NX could simultaneously remove more than 93% of the dye mixture in a short time under favorable conditions. Eventually, the local textile factory with the recovery of more than 82% was used to determine MO, RB-15, and RR-239 in water samples, successfully. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

In this study, nanozeolite-X (NX) was synthesized and utilized as an adsorbent to successfully remove Methyl Orange, Reactive Blue 15, and Reactive Red 239 dyes simultaneously by an ultrasound-assisted method. The response surface method was used to examine the effects of independent variables on the adsorption efficiency of the dye mixture, showing that NX could remove more than 93% of the dye mixture under optimal conditions.