Optimization of biosorption of industrial dyes into Luffa cylindrica functionalized with quaternary ammonium salts

Abstract

This study presents an innovative eco-friendly approach to enhance the dye removal efficiency of Luffa cylindrica (LC) for industrial wastewater treatment. LC was modified with hexadecyltrimethylammonium bromide (CTAB), a cationic surfactant, to improve its performance in removing negatively charged dyes such as Methyl Orange (MO) and Indigo Carmine (IC). Various concentrations of CTAB (0.1 g, 0.5 g, 1 g, and 1.5 g) were used to modify LC, resulting in enhanced electrostatic interactions with the dyes. Characterization through Boehm titration, determination of the point of zero charge (pHpzc), infrared spectroscopy (IR), scanning electron microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDX) confirmed the successful modification of the material. Biosorption experiments showed that with 0.5 g of CTAB and a dye concentration of 150 mg/L, the biosorption capacity increased significantly: IC from 11.394 mg/g to 21.155 mg/g and MO from 7.41 mg/g to 17.651 mg/g. The optimal pH for biosorption was found to be 2. CTAB-modified LC with 1.5 g demonstrated high retention rates, achieving 99.98% for MO and 98.33% for IC when tested individually. Under competitive dye conditions, the retention rates were 97.00% for MO and 99.97% for IC. Kinetic modeling revealed that the Brouers-Sotolongo (BS) model best described the biosorption process. This research provides a promising method for enhancing dye removal in mixed effluents, offering a viable solution for the textile industry’s wastewater treatment challenges.