Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand.
National Doping Control Centre, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand.
Molecules. 2020 Apr 14;25(8):1798. doi: 10.3390/molecules25081798.
A simple flow system employing a reversible-flow syringe pump was employed to synthesize uniform micron-size particles of chitosan-Cu(II) (CS-Cu(II)) catalyst. A solution of chitosan and Cu(II) salt was drawn into a holding coil via a 3-way switching valve and then slowly pumped to drip into an alkaline solution to form of hydrogel droplets. The droplets were washed and dried to obtain the catalyst particles. Manual addition into the alkaline solution or employment of flow system with a vibrating rod, through which the end of the flow line is inserted, was investigated for comparison. A sampling method was selected to obtain representative samples of the population of the synthesized particles for size measurement using optical microscopy. The mean sizes of the particles were 880 ± 70 µm, 780 ± 20 µm, and 180 ± 30 µm for the manual and flow methods, without and with the vibrating rod, respectively. Performance of the flow methods, in terms of rate of droplet production and particle size distribution, are discussed. Samples of 180 µm size CS-Cu(II) particles were tested for catalytic reduction of 0.5 mM -nitrophenol to -aminophenol by 100-fold excess borohydride. The conversion was 98% after 20 min, whereas without the catalyst there was only 14% conversion.
采用一种采用可逆流动注射器泵的简单流系统被用来合成壳聚糖-Cu(II)（CS-Cu(II)）催化剂的均匀微米级颗粒。壳聚糖和 Cu(II)盐的溶液通过三通切换阀被吸入储液盘管中，然后缓慢地被泵入碱性溶液中以形成水凝胶液滴。液滴被洗涤和干燥以得到催化剂颗粒。手动添加到碱性溶液或使用带有振动棒的流系统进行了比较研究，其中流路的末端被插入到振动棒中。采用取样方法从合成的颗粒群体中获得具有代表性的样品，并用光学显微镜测量其尺寸。对于手动和流系统，没有和有振动棒的情况下，颗粒的平均尺寸分别为 880±70 µm、780±20 µm 和 180±30 µm。讨论了流系统在液滴生成速率和颗粒尺寸分布方面的性能。对 180 µm 大小的 CS-Cu(II)颗粒样品进行了测试，考察了其对 100 倍过量硼氢化钠还原 0.5 mM -硝基苯酚为 -氨基酚的催化作用。20 分钟后转化率为 98%，而没有催化剂时只有 14%的转化率。
