西班牙科学家赫尔瓦大学, have used 3D printing to create a spiral structure capable of removing eighteen disinfection by-products (DBPs) from drinking water.
Chronic exposure to such chemicals has been demonstrated to increase health risks, including the threat of cancer, and the team’s research project aims to make the purification process more efficient at removing them. The scientists’ novel approach could have applications at water treatment facilities, to identify and separate the most dangerous chemicals, and make water safer to drink.
Disinfection by-products in drinking water
While water disinfection is essential to public health, toxic substances can be formed as a consequence of the process. These include a particularly volatile non-regulated group of chemicals called Haloketones (HKs), Trihalomethanes (THMs) and Nitrogenous disinfection by-products (N-DBPs), which are formed after several treatment processes. Many different methods exist for removing HKs, but even though the first technique was devised in 1995, research is ongoing in order to streamline the process. Researchers from the科尔多瓦大学for instance, developed a method of removing 14 HKs from treated water in 2015, which provided lower limits of detection than previous studies.
According to the Huelva researchers, the Cordoba method presented drawbacks, such as poor reproducibility and a low capacity of the extraction due to the small absorbent area. The Huelva scientists opted to build upon an existing technique called hollow-fibre liquid phase microextraction (HF-LPME) instead.
Using 3D printing to create the assembly made it easy to operate, more robust and available at a lower cost than previous iterations, according to the researchers. In addition, the structure displayed a higher superficial area for the extraction, and the disposable nature of the fiber reduced the risk of cross-contamination or carryover effect. Additive manufacturing also enabled the scientists to overcome shortcomings identified in previous projects, such as difficulty miniaturizing the assembly and producing commercial prototypes.
The 3D printed support structure and new methodology
Designed using CAM software, the device was 3D printed using Wuppertal polypropylene hollow-fibre materials, in a Prusa i3 open source 3D printer. The final device featured an internal diameter of 600 μm, a wall thickness of 200 μm, and 0.2 μm pores. Composed of five pieces: the cap septum, septum, stopper piece, hollow fibre positioner and closure piece, the design was connected by a syringe needle leading through all the components.
Once these parts had been combined, the device’s hollow fiber positioner was then entered into the acceptor phase. This involved the application of 20 μL of octanol for 2 minutes to open its pores, in addition to making it more flexible. A mixture of sodium sulphate and pH adjusted water were then added to increase the extraction efficiency of the DBPs, before it was introduced to 20ml of sample drinking water.
目标的提取化学物质over a period of 30 minutes, with the solution being heated to a temperature of 45oC.泡腾以二氧化碳气泡的形式应用于该过程，从而导致挥发性分析物从供体相（液体）转移到受体相（气体）。这阻止了样品水被加热，有利于选择性，因为只能在低温下回收挥发性化合物。此外，液体在液体中产生的湍流是通过形成bubbles favoured natural agitation, which then minimized the extraction time.
The 3D printed device was pivotal to the process, with its simple fibre handling, reproducibility and extraction efficiency representing important improvements on other needle-based techniques. The structure also allowed for an increased fibre surface even with a low sample volume, which significantly facilitated the extraction.
测试结果显示，检测限为10至35 thms和10至16 hks不等，在80-100μg和20-70μg的范围内，由世界卫生组织（WHO）推荐用于安全饮用水。该方法的适用性在6个局部水分配系统中进行了评估。尽管储层中THM的浓度高于其源工厂处理过的水的浓度，但研究人员认为这是因为沿分配系统可能降解。
Huelva科学家认为该方法是可重现的，并能够促进现有的净化操作，为将来使用微型工具提供了进一步调查的机会。
净水中的增材制造
3D printing has been utilized in a similar way by hobbyists and business groups, with the intention of making different water supplies safer to drink.
In July 2017, a hobbyist 3D printing project from a multidisciplinary team at theUniversity of Bathcreated aplastic ‘slab.’Designed to provide clean drinking water to communities in parts of Asia, Africa, and Latin America, its maze-like design harnessed the heat and ultraviolet light from the sun, to kill harmful microbes living in contaminated liquids.
研究人员使用了3D printed advanced spacer mesh2016年11月，为了使反向渗透性更有生产力地生产安全饮用的水。该材料被发现降低了该过程的成本，时间和风险，该团队的目的是制定墨西哥太平洋海岸逆渗透膜的战略。
The firstAdditive Manufacturing Consortium(Conmad) in Latin America, was hosted in Mexico in 2018, with more than $13m invested in 3D printing projects. Mexican government agencyConacytattended the event, pledging tohelp provide clean drinking waterto communities on the Pacific Coast of Mexico.
The researchers’ findings are detailed in their paper titled “Effervescence-assisted spiral hollow-fibre liquid-phase microextraction of trihalomethanes, halonitromethanes, haloacetonitriles, and haloketones in drinking water” which was published in volume 397 of the危险材料杂志. It was co-authored by A. Dominguez-Tello, A.Dominguez-Alfaro J.L. Gómez-Ariza, A. Arias-Borrego and T. García-Barrera.
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特色图像显示了研究人员的五个部分螺旋设计与注射器针并连接其3D打印支撑设备。通过危险材料照片。
