Adsorption of Ecotoxicological Congo Red Dye onto Kaolin Clay

This study was conducted to evaluate the adsorption ability of kaolin clay mineral to remove Congo red (CR), an anionic dye with ecotoxicological effects, from aqueous solution. In order to optimize the variables in the adsorption system, pH, adsorbent amount, contact time, and initial CR concentration factors were investigated. Adsorption kinetics and equilibrium isotherm of kaolin clay were investigated using Pseudo first order, Pseudo second order and Intra-Particle Diffusion kinetic equations and Freundlich, Langmuir and Temkin isotherm models. The obtained results were tested with 5 different error functions. Accordingly, it was determined that the adsorption of CR dye onto kaolin clay fit the Freundlich model with an R2 value of 0.999 and the Pseudo second order model with an R2 value of 0.999. In addition, the qmax value was calculated as 7.984 mg/g kaolin. For morphological examination, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy(SEM) images of raw and CR-loaded kaolin were examined. As a result, it was revealed that kaolin clay can be used as a low-cost alternative for the removal of resistant dyes from wastewater.