Removal of cationic dye from aqueous solution using Moroccan pozzolana as adsorbent: Isotherms, kinetic studies, and application on real textile wastewater treatment

Abstract

Beside others, textile industries are the major sources of discharging huge amount of highly colored wastewater. The objective of this work was to study the adsorption of methylene blue (MB), from its aqueous solution on Moroccan pozzolana. Adsorption kinetics and isotherms of MB have been experimentally studied. The support (adsorbent) was characterized by, FTIR, SEM, X-ray energy dispersive spectroscopy (EDS), X-Ray fluorescence, and its Point of Zero Charge (pHPZC) was determined. The adsorption data of MB on pozzolana was analyzed using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. Based on the data fitting and comparison of the correlation coefficient (R2), it is inferred that Langmuir isotherm is most closely followed with a maximum adsorption capacity of 43.86 mg g−1. The kinetic data are well described by the pseudo-second order kinetic model with a R2 value of about 0.9997. Finally, the process is used to treat the textile wastewater that mainly contains methylene blue. The Pozzolana has shown good efficiency in the treatment of real textile wastewater.