Optimizing coagulation of Navy Blue RX dye and comparative study of performance of polyaluminium chloride and ferric chloride

Coagulation is a well-established approach in textile wastewater treatment because of its capacity to destabilise colloidal particles, facilitate their settling, and promote efficient colour removal. Nevertheless, process optimisation is necessary to strike a balance between achieving optimal treatment efficiency and minimizing the environmental impact of excessive chemical addition. Present study aims to optimises the colour removal using response surface methodology and compare the performance of polyaluminum chloride (PAC) and ferric chloride. Additionally, the paper discusses the impact of the interaction effects of independent variables as well as the chemistry underlying the interactions. Synthetic wastewater containing Navy Blue RX dye was used in this study. Initial dye concentration, initial pH and coagulant dose were used as independent variables while decolourization/colour removal was selected as response variable for optimisation. The optimisation results showed 63.56% colour removal at 100 mg/L initial dye concentration, 9 pH, and 2.23 mM FeCl₃ dosage while 91.9% colour removal was accomplished using 340 mg/L PAC dosage with initial dye concentration of 100 mg/L and pH 7. The PAC demonstrated a greater degree of decolourization than FeCl₃. This strategy ensures that the process is optimized for optimum efficiency while also saving time and resources. Response surface methodology proved to be a potent instrument in optimizing the coagulation process to remove dye from wastewater.