Adsorption Isotherm and Kinetic Modeling of the Congo Red (CR) and Indigo Carmine (IC) Dyes Removal onto Novel Bentonite Hybrid Material

Abstract The present study focuses on investigating the adsorption characteristics of anionic Congo Red (CR) and Indigo Carmine (IC) dyes using hexadecyltrimethyl ammonium bromide‐modified Bentonite (HDTMA‐Bentonite) with varying loading amounts. The removal effectiveness of anionic dyes was examined as a function of the HDTMA + loaded amount, contact time, initial concentration, and adsorbent dosage. The XRD data revealed that the interlayer spacing of Bentonite increased from 1.42 to 1.98 nm. The FTIR approach was used to analyze the surface modification of hybrid Bentonite; however, the hydrophobic nature of hybrid Bentonite was confirmed by ATG measurements. A kinetic investigation of sorption was done. The results demonstrated that the pseudo‐second‐order model fitted the adsorption kinetic data better than the pseudo‐first‐order rate equation, and that the amount of HDTMA + loaded affects the adsorption capacity. According to the Weber‐Morris intra‐particle diffusion equation, the CR and IC dyes diffused faster as the amount of added cationic surfactant rose from 0 % to 100 % of the CEC value. Temkin and Langmuir equation is found to best represent the equilibrium data for two dye‐HDTMA‐B systems. Hybrid Bentonite was regenerated by NaOH, and reused without a significant decrease in its sorption efficiency, supporting the prosperity of its utilization as an effective adsorbent against toxic dyes from wastewater.