Younis Somaya R A, Abdelmotallieb Mohammed, Ahmed Abdelaal S A
Chemistry Department, Faculty of Science, Al-Azhar University Assiut 71524 Egypt
RSC Adv. 2025 Mar 20;15(11):8594-8608. doi: 10.1039/d4ra08890e. eCollection 2025 Mar 17.
In this study, zeolitic imidazolate frameworks (ZIFs) and ZIF-8-graphene oxide (ZIF-8@GO) composites were prepared at room temperature to be used as adsorbents for cationic (methylene blue (MB)) and anionic dyes (methyl orange (MO)) from their aqueous solutions. The structural characteristics confirmed the successful preparation of amorphous ZIF-8 and its ZIF-8@GO composites at room temperature. The BET surface area of the ZIF-8@0.5GO composite was estimated to be 286.22 m g, with a mean pore diameter of 3.34 nm. The adsorption study confirmed that dye removal efficiency of ZIF-8 was significantly enhanced when blended with GO. The maximum removal efficiency of the ZIF-8@0.5GO composite was achieved within 60 min, and the removal percentages of MB and MO dyes were 95.2% and 94.6%, respectively. These values were close to those achieved by GO at 60 min (96.2% for MB and 96.3% for MO). The kinetic study confirmed that the adsorption data of MB onto GO, ZIF-8, and the ZIF-8@GO composites fitted the non-linear pseudo-first-order kinetic model, while the adsorption of MO dye obeyed the non-linear pseudo-second-order kinetic model. Moreover, the adsorption isotherm study confirmed that the adsorption of both MB and MO dyes onto the ZIF-8 and its ZIF-8@GO composites were fitted to the Langmuir model, which indicates a chemical adsorption process. The estimated maximum adsorption capacity of the ZIF-8@0.5GO composite towards MB and MO were 87.39 and 82.78 mg g, which are much higher than that achieved by pure ZIF-8 and very close to that obtained by pure GO. This indicates that our prepared ZIF-8@GO composites are comparable to pure GO. The thermodynamic study confirmed that adsorption of both the dyes onto the prepared materials is endothermic, spontaneous, and thermodynamically favorable.
在本研究中，在室温下制备了沸石咪唑酯骨架（ZIFs）和ZIF-8-氧化石墨烯（ZIF-8@GO）复合材料，用作从水溶液中吸附阳离子（亚甲基蓝（MB））和阴离子染料（甲基橙（MO））的吸附剂。结构特征证实了在室温下成功制备了无定形ZIF-8及其ZIF-8@GO复合材料。ZIF-8@0.5GO复合材料的BET表面积估计为286.22 m²/g，平均孔径为3.34 nm。吸附研究证实，ZIF-8与GO混合时，染料去除效率显著提高。ZIF-8@0.5GO复合材料在60分钟内达到最大去除效率，MB和MO染料的去除率分别为95.2%和94.6%。这些值与GO在60分钟时达到的值相近（MB为96.2%，MO为96.3%）。动力学研究证实，MB在GO、ZIF-8和ZIF-8@GO复合材料上的吸附数据符合非线性伪一级动力学模型，而MO染料的吸附服从非线性伪二级动力学模型。此外，吸附等温线研究证实，MB和MO染料在ZIF-8及其ZIF-8@GO复合材料上的吸附均符合Langmuir模型，这表明是一个化学吸附过程；ZIF-8@0.5GO复合材料对MB和MO的估计最大吸附容量分别为87.39和82.78 mg/g，远高于纯ZIF-8的吸附容量，且与纯GO获得的吸附容量非常接近。这表明我们制备的ZIF-8@GO复合材料与纯GO相当。热力学研究证实，两种染料在制备材料上的吸附都是吸热的、自发的，并且在热力学上是有利的。
