Assembly, characterization, and adsorptive-removal efficiency of Cu-doped-ZIF-8 adsorbents

In the current work, new nanocomposite adsorbers of Cu-doped zeolitic imidazole framework (Cu-doped-ZIF-8) were constructed via in-suit assembled in the presence of both Zn and Cu ions, and analyzed using different techniques. The adsorptive efficiency of Cu-doped-ZIF-8 adsorber has been assessed toward Malachite Green (MG) dye removal. Compared with undoped-ZIF-8, adsorption uptake of Cu-doped ZIF-8 was enhanced 1.8 times, reaching 219 mg/g under constant conditions (solution pH = 6.8, initial MG concentration 30 mg/L, adsorber dose 0.5 g/L, and adsorption time 90 min). The boosted adsorption efficiency was owing to the effective π-complications originated between Cu nods and the MG dye molecules. According to the kinetic and adsorption-isotherm analyses, the Pseudo-first-order and Langmuir equations were matched well with the experimental adsorption process, suggesting that the chemisorption was controlled, and the Cu-doped-ZIF-8 sample displayed a uniform surface towards MG dye adsorption process. Furthermore, the stability of Cu-doped-ZIF-8 was tested, in which the MG adsorption capacity decreased only to 213 mg/g for after five adsorption cycles.