Adsorptive removal of Direct Red 81 dye from aqueous solution onto Argemone mexicana

A low cost adsorbent has been tested for its adsorption ability to remove a hazardous dye from textile wastewater. The present paper assesses the results pertaining to the investigation conducted on removal of a di azo sulphonated dye, Direct Red 81 by adsorption onto a natural adsorbent, Argemone mexicana. Adsorption studies were carried out in both batch and column mode to examine the influence of various parameters on the removal efficiency of the uncharted natural adsorbent. A fixed-bed column has been designed and necessary parameters have been calculated by applying mass transfer kinetic approach. The data obtained have been successfully used to equate different adsorption isotherm models. Isothermal data were found to fit well with Langmuir adsorption model. The estimated mean adsorption energy from the D–R isotherm model has been obtained as 1.34 × 104 J mol−1 further conferring to the chemical process of the adsorption. The adsorption interaction of direct dye on to A. mexicana obeyed pseudo second-order rate equation. Intraparticle diffusion studies revealed the dye adsorption interaction was complex and intraparticle diffusion was not only the rate limiting step. Column operations depicted good adsorption leading with 98% saturation of dye.