چكيده به لاتين
Water, food, and air are necessities for humans, but water is the most important. Most water pollution is caused by lagged agriculture, industrial development, and urbanization. These contaminants, known for their carcinogenicity and toxicity, contribute to severe health issues, particularly affecting the kidney, nervous, and gastrointestinal systems. Conventional methods such as chemical precipitation, membrane filtration, biological methods, electrochemical methods, and ion exchange have been widely employed for removal of contaminants. The adsorption process is the most widely used application in the sewage treatment process due to its advantageous properties, such as non-toxicity, easy design, ability to recover the adsorbent, and availability of a wide range of adsorbents. For this purpose, the pollutants removal from aqueous solution by modified clinoptilolite zeolite, lentil-like mordenite and chitosan-allophane nanocomposite were used as adsorbent which were characterized by utilizing X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Scanning electron microscope (SEM) images, Energy Dispersive X-ray analysis (EDXA), and the Brunauer-Emmet-Teller (BET) method. The prepared adsorbents were employed in both continuous and batch adsorption processes. Operational parameters such as flow rate, initial concentration, and bed height were varied to understand breakthrough time, mass transfer zone, adsorption capacity, and exhaustion time during continuous adsorption. Additionally, the study explored the influence of solid/liquid ratio, pH, assay time, and initial concentration on batch adsorption. The maximum adsorption capacities of the lentil-like mordenite zeolite in fixed-bed breakthrough experiments were determined to be 78.22 mg/g for Cd (II) ions and 80.82 mg/g for Pb (II) ions. In batch experiments, the maximum capacities of the lentil-like mordenite, synthetic nanocomposite, synthetic mordenite and modified clinoptilolite were 133.64 for Cd (II) ions, 239.57 for Pb (II), 112.17 for Cr (VI), for phosphate ions 23.06 and 17.9 mg/g, respectively. The kinetics study shows that the pseudo-second-order kinetic equation better describes the adsorbentsʹ adsorption behavior. The isotherms study suggests that the adsorption process of synthetic mordenite and modified clinoptilolite follow the Langmuir and Freundlich models, respectively. Freundlich isotherm shows a better fit to the adsorption of Cr (VI) ions. Dynamic continuous adsorption isotherms exhibited an excellent fit with the Thomas and Yoon – Nelson models for Cd (II) ions and Pb (II) ions, while batch adsorption isotherms conformed well to the Langmuir models.
