Adsorptive removal of aromatic amines from contaminated water using Cu۲+-impregnated zeolite ۴A

Industrial wastewaters from pharmaceuticals, pesticides, dyes, and plastics production often contain aromatic amines. Exposure to these compounds can cause serious health problems۱-۲. Therefore, efficient removal of aromatic amines from natural water is crucial. In this study, zeolite ۴A was modified by ion exchange with Cu۲+ cations with the aim of preparing an effective and selective adsorbent for aromatic amines under neutral pH conditions, simulating the acidity of natural waters. X-ray diffraction (XRD) patterns revealed a highly crystalline structure for zeolite ۴A, while the modified zeolite exhibited an entirely amorphous structure. The morphology of the modified zeolite and the pristine zeolite was investigated using scanning electron microscopy (SEM). The pristine zeolite ۴A exhibited cubic particles with smooth surfaces, while the Cu۲+-impregnated zeolite ۴A displayed nearly spherical particles with porous surfaces. Comparison of Fourier transform infrared (FTIR) spectra for the pristine and modified zeolite revealed no significant changes, indicating that the chemical structure of the zeolite remained largely unaltered upon modification with Cu۲+ cations. Adsorption studies were conducted for the removal of aniline as a model compound for aromatic amines. The adsorption quilibrium data for aniline uptake by the modified zeolite were evluated by both Langmuir and Freundlich isotherm models. It was revealed that the modification of zeolite ۴A significantly enhanced its capacity for aniline adsorption. The adsorption of aniline on the modified adsorbent exhibited relatively fast kinetics. The kinetic data for the adsorption of aniline on the modified adsorbent were well-fitted by the pseudo-second-order kinetic model, indicating that the adsorption process was rate-controlled by chemical interactions between aniline and the adsorbent surface. The modified adsorbent exhibited high selectivity for aniline in competition with common cations and anions present in natural waters.

کلیدواژه ها:

Adsorption ، Zeolite ۴A ، Water ، Pollution ، Aromatic amines