Effect of carbonization temperature on adsorption property of ZIF-8 derived nanoporous carbon for water treatment

The heat treatment effect on the adsorption capabilities of nanoporous carbon particles derived from Zeolitic Imidazolate Framework-8 (ZIF-8) was investigated at 600, 1000 and 1200°C in this study. The results showed that heat treatment at 1000°C had a significant effect on the adsorption capacity of ZIF-8 (almost 10 times) for the removal of methylene blue (MB) dye from water. Nanoporous carbons were synthesized by direct carbonization of ZIF-8. SEM and TEM images showed that the carbon resulting from ZIF-8 carbonization at various temperatures retained the original structure and morphology of ZIF-8. The carbon nanoparticles carbonized at 1000°C exhibited outstanding adsorption capacities (186.3 mg/g) compared to nanoparticles carbonized at 600°C (49.5 mg/g) and 1200°C (36.7 mg/g) as well as ZIF-8 (19.5 mg/g) due to the change in surface charge and pore size distribution. The surface functionalities of materials were also characterized by Raman Spectroscopy, N2 adsorption-desorption, FTIR and TGA. The surface charge of the carbon particles changed from positive (ZIF-8) to negative as a result of conversion to carbon confirmed by zeta potential of the samples. The ZIF-8 derived carbon nanoparticles were found to be efficient adsorbents for water treatment purposes due to the satisfactory adsorption properties such as high adsorption capacity and good wettability.