Obayomi Kehinde Shola, Lau Sie Yon, Xie Zongli, Gray Stephen R, Zhang Jianhua
Department of Chemical Engineering, Curtin University, CDT 250, Miri 98009, Sarawak, Malaysia.
Institute for Sustainable Industries and Liveable Cities, Victoria University, Werribee, VIC 3030, Australia.
Nanomaterials (Basel). 2024 Jul 22;14(14):1234. doi: 10.3390/nano14141234.
In this work, zinc oxide (ZnO)/granular activated carbon (GAC) composites at different ZnO concentrations (0.25M-ZnO@GAC, 0.5M-ZnO@GAC, and 0.75M-ZnO@GAC) were prepared by an in-situ hydrothermal method and demonstrated synergistic photocatalytic degradation and adsorption of rhodamine B (RhB). The thermal stability, morphological structure, elemental composition, crystallographic structure, and textural properties of developed catalysts were characterized by thermal gravimetric analysis (TGA/DTG), scanning electron microscopy equipped with energy dispersive-x-ray (SEM-EDS), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. The successful loading of ZnO onto GAC was confirmed by SEM-EDS and XRD analysis. The BET surface areas of GAC, 0.25M-ZnO@GAC, 0.5M-ZnO@GAC, and 0.75M-ZnO@GAC were 474 m/g, 450 m/g, 453 m/g, and 421 m/g, respectively. The decrease in GAC could be attributed to the successful loading of ZnO on the GAC surface. Notably, 0.5M-ZnO@GAC exhibited the best photocatalytic degradation efficiency of 82% and 97% under UV-A and UV-C light over 120 min, attributed to improved crystallinity and visible light absorption. The photocatalytic degradation parameters revealed that lowering the RhB concentration and raising the catalyst dosage and pH beyond the point of zero charge (PZC) would favor the RhB degradation. Photocatalytic reusability was demonstrated over five cycles. Scavenger tests revealed that the hydroxyl radicals (OH), superoxide radicals (O), and photoinduced hole (h) radicals play a major role during the RhB degradation process. Based on the TOC results, the RhB mineralization efficiency of 79.1% was achieved by 0.5M-ZnO@GAC. Additionally, GAC exhibited a strong adsorptive performance towards RhB, with adsorption capacity and the RhB removal of 487.1 mg/g and 99.5% achieved within 90 min of equilibrium time. The adsorption characteristics were best described by pseudo-second-order kinetics, suggesting chemical adsorption. This research offers a new strategy for the development of effective photocatalyst materials with potential for wider wastewater treatment applications.
在本研究中，采用原位水热法制备了不同氧化锌（ZnO）浓度（0.25M-ZnO@GAC、0.5M-ZnO@GAC和0.75M-ZnO@GAC）的氧化锌/颗粒活性炭（GAC）复合材料，并证明了其对罗丹明B（RhB）具有协同光催化降解和吸附性能。通过热重分析（TGA/DTG）、配备能量色散X射线的扫描电子显微镜（SEM-EDS）、X射线衍射（XRD）和布鲁诺尔-埃米特-泰勒（BET）分析对所制备催化剂的热稳定性、形态结构、元素组成、晶体结构和织构性质进行了表征。通过SEM-EDS和XRD分析证实了ZnO成功负载在GAC上。GAC、0.25M-ZnO@GAC、0.5M-ZnO@GAC和0.75M-ZnO@GAC的BET表面积分别为474 m²/g、450 m²/g、453 m²/g和421 m²/g。GAC表面积的减小可归因于ZnO成功负载在GAC表面。值得注意的是，0.5M-ZnO@GAC在UV-A和UV-C光照下120分钟内表现出最佳的光催化降解效率，分别为82%和97%，这归因于其结晶度的提高和可见光吸收能力。光催化降解参数表明，降低RhB浓度、提高催化剂用量以及将pH值提高到零电荷点（PZC）以上有利于RhB的降解。光催化剂的可重复使用性在五个循环中得到了验证。清除剂试验表明，羟基自由基（OH）、超氧自由基（O）和光生空穴（h）自由基在RhB降解过程中起主要作用。基于总有机碳（TOC）结果，0.5M-ZnO@GAC实现了79.1%的RhB矿化效率。此外，GAC对RhB表现出很强的吸附性能，在平衡时间90分钟内吸附容量和RhB去除率分别达到487.1 mg/g和99.5%。吸附特性用伪二级动力学描述最佳，表明为化学吸附。本研究为开发具有更广泛废水处理应用潜力的有效光催化剂材料提供了一种新策略。
