Zeolitic imidazolate frameworks (ZIF-8 and ZIF-67) were synthesized for energy storage by utilizing cobalt (II) nitrate hexahydrate, zinc nitrate hexahydrate, and 2-methyl imidazole. The redox peaks in the CV plots showed the existence of faradaic processes. The specific capacitance of ZIF-8 and ZIF-67 reduces with an increase in scan rate. ZIF-8 and ZIF-67 have estimated specific capacitances of 625, 312, 208, 156, and 125 F/g and 932, 468, 312, 234, and 187 F/g at scan rates of 10 to 50 mV/s. ZIF-8 and ZIF-67 have electrolyte resistances of 1.25 and 1.15 Ω, respectively, with active electrode resistances of 0.03 and 0.02 Ω. Great capacitive performance was indicated by the low charge transfer resistance seen in the Nyquist plots. Both ZIF-8 and ZIF-67 have estimated specific capacitances of 276.91 F/g according to the GCD tests. ZIF-8 and ZIF-67 had an energy density of 7999.89 when the current density was 2.0 A/g. ZIF-8 and ZIF-67 nanocrystals differ in their XRD patterns, as the structure of ZIF-8 remains intact. The nanoparticles exhibit high crystallinity, as evidenced by the distinct peaks observed, particularly the sharp (001) peak at 7.4o. The high-pitched and defined peak at the 2θ position of 7.6° confirmed the crystalline nature of synthesized ZIF-67. The (011) crystal plane was identified as the source of the intense peak at 2θ position 7.6°. The bandgap value of ZIF-67 is 3.27 eV, in contrast to ZIF-8 which has a value of 3.0 eV.

This study explores the green synthesis of cobalt-based ZIF-67 using methanol, ethanol, and isopropanol as solvents. Alcoholic solvents enhance the morphology, particle size control, and stability of ZIF-67, making it suitable for moisture-sensitive applications. The synthesis was performed at room temperature via reflux, avoiding hazardous solvents. XRD, FTIR, and SEM analyses confirmed the solvent’s significant influence on particle size and uniformity. Isopropanol-synthesized ZIF-67 exhibited the highest methylene blue adsorption capacity (29.1 mg/g), followed by ethanol (22.94 mg/g) and methanol (19.37 mg/g). Adsorption studies (pH 7, 0.02 g adsorbent, 7 mg/L dye, 180 min) revealed that the process follows the Langmuir isotherm, indicating a spontaneous, endothermic, monolayer adsorption. This study highlights the critical role of solvent choice in optimizing ZIF-67 properties and suggests isopropanol as a promising solvent for enhanced adsorption applications in environmental and industrial fields.

In this research, the zeolitic imidazolate framework 67 (ZIF-67) and carboxymethyl cellulose (CMC)/ZIF-67 biocomposite (CMC/ZIF-67) were synthesized. Different analyses were used to characterize the synthesized materials. Then, carboxymethyl cellulose and CMC/ZIF-67 biocomposite were used to remove the dye (Malachite Green: MG). The results showed that the dye removal capability of biocomposite (92.35%) is higher than that of carboxymethyl cellulose polymer (9.41%). As the adsorbent dose increases, the removal percentage of MG also increases. As the adsorbent dose increases, the active sites of the adsorbent surface are more accessible, and the dye removal percentage is higher. The dye removal percentage in 1, 2, 3, and 4 mg of composite adsorbent was 25, 54, 79, and 92.35%, respectively. With the increase in dye concentration, the amount of dye removal decreased. The dye removal in 20, 30, 40, and 50 mg/L concentrations with composite was 92.35, 85, 79 and 71%, respectively. The presence of imidazole rings in the structure of ZIF-67 as a ligand can be one of the main reasons for the high adsorption capacity of the biocomposite. Due to the double bonds in the imidazole rings, Π-Π stacking interactions occur with the aromatic rings of MG. This special interaction enables the biocomposite to adsorb the high capacity of MG. The isotherm and kinetics of dye adsorption by CMC/ZIF-67 biocomposite followed the Langmuir isotherm and pseudo-second-order kinetics.  

In this study, ZIF-67 was synthesized through solvothermal method to remove Cr (VI) ions from aqueous solution. To improve the structural properties of ZIF-67 and its adsorption capacity, optimization of the synthesis conditions was carried out based on maximum Cr (VI) uptake. From experiments, the optimum condition comprised solvent: metal ion molar ratio of 4. 6: 1, ligand: metal ion molar ratio of 318: 1, and temperature of 23 ℃ . The physio-chemical properties of as-synthesized ZIF-67 were investigated by BET, XRD, FTIR, and FESEM analyses. Effects of adsorption pH, adsorbent dosage, initial concentration, and contact time on adsorption process were investigated. Based on the results, the maximum adsorption capacity of Cr (VI) was 26. 27 mg/g which was obtained at 35 ℃ , pH of 5, adsorbent dosage of 3 g/l, and initial concentration of 107. 82 mg/l. The equilibrium time for Cr (VI) adsorption varied from 180 min for low initial concentration of 9 mg/L to 240 min for a high initial concentration of 90 mg/L. For the synthesized ZIF-67, maximum uptake capacity was reported 26. 27 mg/g at the initial concentration of 107. 82 mg/l. The equilibrium data were described by Langmuir-Freundlich isotherm model better than the other models at three different temperatures. Pseudo-second-order model fitted the experimental data better than pseudo-first-order one. Adsorption thermodynamics indicated that the adsorption process was endothermic and spontaneous in nature. The regenerability of ZIF-67 was also studied in three sequential cycles, and the Cr (VI) adsorption was almost retained after two cycles.

Polymer-modified metal organic frameworks (MOFs) can enhance water purification processes by offering increased adsorption capacity, making them highly effective in separating pollutants from contaminated water. In this research, a facile and low-cost route was used to prepare Polydopamine@Zeolitic Imidazolate Framework-67 (PDA@ZIF-67). The structure, morphology, surface functional groups and particle size distribution of PDA@ZIF-67 was studied using Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Energy dispersive spectroscopy (EDS), and Brunauer-Emmet-Teller (BET) analyses. The specific surface area and pore diameter of PDA@ZIF-67 nanoparticles were found to be 203. 78 m2/g and 4. 179 nm, respectively. The PDA@ZIF-67 was used as an adsorbent for removal of methylene blue dye from aqueous solution. The results showed that the maximum adsorption capacity of PDA@ZIF-67 for removal of MB was achieved at pH 2, 65 °C, 10 mg of adsorbent, and methylene blue concentration of 7. 5 ppm. Moreover, the adsorption process isotherms, thermodynamics, and kinetics were studied to ascertain the adsorption mechanism. The methylene blue molecules located in the fine pores of the PDA@ZIF-67 adsorbent determine the adsorption rate. Moreover, it was found that the adsorption process of methylene blue at elevated temperature is a spontaneous and endothermic reaction. The adsorption capacity of PDA@ZIF-67, after six recovery cycles decreased to 62. 21%, which can be considered as an excellent advantage for this adsorbent.