Department of Materials Science and Engineering, Taiwan Tsing Hua University, Hsinchu, Taiwan, China; Department of Systems Engineering & Engineering Management, City University of Hong Kong, Hong Kong, China.
Department of Mechanical Engineering, Hanyang University, Haengdang-dong, Seoul, South Korea.
J Environ Sci (China). 2016 Dec;50:38-48. doi: 10.1016/j.jes.2016.03.029. Epub 2016 Jun 24.
Catalytic ozonation is progressively becoming an attractive technique for quick water purification but efficient and stable catalysts remains elusive. Here we solvothermally synthesized highly-dispersed CoO nanocrystals over microscale nitrogen-doping graphene (NG) nanosheets and tested it as a synthetic catalyst in the ozonation of phenol in aqueous solutions. Transmission electron microscopy, powder X-ray diffraction, Fourier transform infrared spectra and X-ray photoelectron spectroscopy were used to determine its morphology, crystallinity, elemental composition and molecular bonds, respectively. The comparative experiments confirmed the highest catalytic activity and oxidation degree (AOSC) of CoO/NG among four nanocomposites (G, NG, CoO/G, and CoO/NG). CoO/NG also has exhibited the highest degradation rate: complete conversion of a near-saturated concentration of phenol (941.1mg/L) was achieved within 30min under ambient conditions with only a small dosage of CoO/NG (50mg/L) and ozone (4mg/L, flow rate: 0.5L/min). It also resulted in 34.6% chemical oxygen demand (COD) and 24.2% total organic carbon (TOC) reduction. In this work, graphene nanosheets not only functioned as a support for CoO nanocrystals but also functioned as a co-catalyst for the enhancement in phenol removal efficiency. The surface nitridation and CoO modification treatment further improved the removal rate of the phenol pollutants and brought in the higher oxidation degree. Our finding may open new perspectives for pursuing exceptional activity for catalytic ozonation reaction.
催化臭氧化技术逐渐成为一种快速水净化的有吸引力的技术，但高效稳定的催化剂仍然难以捉摸。在这里，我们通过溶剂热法在微尺度氮掺杂石墨烯（NG）纳米片上合成了高度分散的 CoO 纳米晶体，并将其作为合成催化剂用于水溶液中苯酚的臭氧化反应。透射电子显微镜、粉末 X 射线衍射、傅里叶变换红外光谱和 X 射线光电子能谱分别用于确定其形态、结晶度、元素组成和分子键。比较实验证实了 CoO/NG 在四种纳米复合材料（G、NG、CoO/G 和 CoO/NG）中具有最高的催化活性和氧化度（AOSC）。CoO/NG 还表现出最高的降解速率：在环境条件下，仅使用少量的 CoO/NG（50mg/L）和臭氧（4mg/L，流速：0.5L/min），即可在 30 分钟内完全转化近饱和浓度的苯酚（941.1mg/L）。它还导致化学需氧量（COD）降低 34.6%，总有机碳（TOC）降低 24.2%。在这项工作中，石墨烯纳米片不仅作为 CoO 纳米晶体的载体，而且作为增强苯酚去除效率的共催化剂。表面氮化和 CoO 改性处理进一步提高了苯酚污染物的去除率，并带来了更高的氧化度。我们的发现可能为追求催化臭氧化反应的卓越活性开辟了新的视角。
