A full factorial design for the decolorization of real textile wastewater using iron-rich montmorillonite by sonocatalytic process

Abstract

In this study, the sonocatalytic process was used to remove colour from the effluent of a textile factory located in Turkey. Clay from a brick-tile factory located in the city of Eskisehir was used to enhance the effect of ultrasound (US) at 20 kHz frequency and 750 W power. The structure, morphology and composition of the clay were identified by characterization studies including FT-IR, XRD, XRF, SEM and TGA. The clay consists mainly of montmorillonite and iron-rich montmorillonite as smectite minerals, nontronite, quartz minerals, calcite and dolomite as minor clay minerals. In the scope of the study, Design of Experiment (DoE) and a Full Factorial Design (FFD) was used to determine the operating conditions that affect the color removal efficiency of textile industry wastewater. pH, clay amount, time, and H2O2 concentration were determined as critical factors using Analysis of Variance (ANOVA). It has been confirmed that when the critical factors for color removal efficiency—specifically, a pH of 2. 2 grams of clay, a duration of 120 minutes, and 35 ppm of H2O2—are kept constant, the resulting removal percentage was predicted as 94% approximately by using regression model. The optimal levels of factors have been verified by the validation experiments.