Sustainable Synthesis of Zeolitic Imidazolate Framework-8 Nanoparticles and Application in the Adsorption of the Drug Chlorhexidine

Abstract

In an attempt to synthesize nanomaterial concerning chemistry, the sustainable synthesis of Zeolitic Imidazolate Framework-8 (ZIF-8) nanoparticles by a low-cost approach through the recycling of waste mother liquors was explored and then indicated the potential to remove chlorhexidine (CHLX) from an aqueous solution. ZIF-8 was produced under solvothermal reaction at 25°C and characterized by Fourier Transform Infrared Spectroscopy, X-ray diffraction, adsorption/desorption of N<sub>2</sub>, dynamic light scattering and contact angle. The water Chemical stability test was conducted using ZIF-8 and it was immersed in pure water for 24 h at room temperature. Batch-type adsorption was used to check the potential of ZIF-8 (first and second generation) for the adsorption of the chlorhexidine with initial chlorhexidine concentration (0.05, 0.06 and 0.07 mol/L), agitation time (1, 3.5 and 6 h) and the mass of nano-adosrbent (0.04, 0.05 and 0.06 g). Process optimization was performed through a Factorial experimental design. The optimum conditions were selected for the nano-adsorbent mass of 0.04 g, agitation time of 1 h and initial chlorhexidine concentration 0.07 mmol/L. The ZIF-8 sustainable synthesis was efficient and generated a crystalline nanomaterial. The result shows that ZIF-8 is stable in water under ambient conditions. The ZIF-8 first generation and ZIF-8 second generation exhibit a high adsorption capacity (27.17 mg/g and 30.96 mg/g). It was found that, under the synthesis conditions, the recycled mother liquor user did not affect the final characteristics of this nanomaterial. The results indicated that the initial concentration of chlorhexidine and nano-adsorbent mass influenced the adsorption capacity. Experimental design provided the process optimum conditions (1 h, 0.04 g of adsorbent mass and 0.07 mmol/L).