Chitosan-based Zeolitic Imidazolate Framework-8 for water remediation: kinetic and isotherm insights into the removal of organic and inorganic pollutants
摘要
This study explores the removal of inorganic contaminants [copper (II) and lead (II)] and organic pollutants [anthracene (ANT), phenanthrene (PHE), and methylene blue (MB) dye] from simulated solutions using the green CS/ZIF-8 sorbent. The sorbent was characterized by FTIR, BET, XRD, AFM, EDX, and SEM. Adsorption experiments were conducted under different variables such as time, pollutant concentration, temperature, and pH. The kinetic adsorption and isotherms were analyzed to evaluate CS/ZIF-8’s efficiency in water pollution treatment. The results showed that removal efficiency (%R) increased over time and with higher initial pollutant concentrations. As pollutant concentration rises, a great competition for adsorption sites on the surface occurs, which promotes greater occupancy of the adsorbent’s surface and thus higher overall efficiency (%R). Optimal %R was achieved at 25 °C and pH 6 for Cu (II), pH 8 for Pb (II), pH 11–12 for MB dye, at pH 3 and 4 for ANT and PHE, respectively achieving maximum performance at 55 °C. The pseudo-second-order kinetic model and Langmuir isotherm best describe adsorption, with maximum capacities of 599.72, 599.81, 399.81, 399.77, and 499.42 mg/g for Cu+2 (600 ppm), Pb+2 (600 ppm), ANT (400 ppm), PHE (400 ppm), and MB dye (500 ppm), respectively. The data reveals that CS/ZIF-8 exhibited exceptional adsorption capacities for organic and inorganic toxic species from simulated solutions. An experimental design was introduced for lab treatment of petroleum wastewater in a two-stage filter comprising physical clearance in the first stage and treatment with the green adsorbent in the second stage. The prepared composite’s reusability was also verified to underscore its potential in treating real petroleum wastewater.
Graphical abstract