Synthesis of Kaolin Filter Cake-Fe3O4 Composite for Reactive Black 5 Dye Removal from Textile Wastewater: Optimization with Box-Behnken Design

Pollution from industrial wastewater containing dyes poses a significant health concern in many countries, necessitating advanced remediation techniques. This study explores using a magnetized Kaolin filter cake (KFC)-Fe3O4 composite, synthesized through a co-precipitation method, as an adsorbent for removing Reactive Black 5 (RB5) from aqueous solutions. This method enables quick and easy separation of the adsorbent, resulting in no secondary pollution. The synthesized adsorbent was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) techniques to analyze its crystalline nature, microstructures, functional group, and surface area respectively. The efficiency of the adsorbent for dye removal in a batch system was examined by studying various parameters, including pH, contact time, adsorbent dosage, and initial dye concentration. To optimize the RB5 removal procedure, a Box-Behnken design (BBD) was employed under response surface methodology (RSM). The pseudo-second-order model best described the adsorption kinetics, while the Langmuir equation accurately described the isotherm. The maximum adsorption capacity was determined to be 92.84 mg/g. Thermodynamic studies revealed that the adsorption of RB5 onto the Kaolin filter cake-Fe3O4 composite is spontaneous and endothermic. Notably, the adsorption activity of RB5 by KFC-Fe3O4 composite remained effective even after five successive cycles. Overall, the Kaolin filter cake-Fe3O4 composite is a highly efficient adsorbent for treating aqueous solutions containing dyes, with easy separation from the solution using a magnet after the reaction.