Exploring the use of continuously synthesised layered double hydroxides for the sorption of pharmaceuticals from wastewater

新兴污染物（Emerging Pollutants，ECs）是一类人为污染物，近年来在环境沃茨中被检测到，随着分析技术检测水平的提高，这些污染物变得更加突出。EC在水道中的存在是抗菌素耐药性（AMR）的已知驱动因素。世界卫生组织已宣布AMR是对公共卫生的主要全球威胁，如果不采取任何措施减缓AMR的传播，到2050年将有多达1000万人面临生命危险。抗生素（EC的一个亚类）进入环境的一种途径是通过释放废弃的生产废水，导致水中抗生素的浓度达到mg/L，因此找到解决这种污染的解决方案是遏制AMR传播的关键。在水行业内部，也存在着一种压力，要求补救过程变得更加循环，将污染物视为一种资源，而不是昂贵的废物。因此，在设计修复技术时，任何解决方案都需要与更可持续的循环经济模式相兼容，而不是广泛存在的线性“取-废-废”模式。吸附过程是一种补救技术，如果设计正确，可以与循环经济兼容。虽然文献中报道了一系列吸附剂材料，但目前工业上可获得的许多吸附剂材料是昂贵的并且可能是不可持续的。此外，许多关于吸附剂材料使用的研究缺乏关键考虑因素，以帮助理解吸附过程和材料是否具有工业相关性，包括：现实的废水/环境条件;污染物的代表性浓度;吸附剂材料的回收/再生循环的详细研究。建议的解决方案和方法本项目将考虑使用层状双氢氧化物，LDHs，作为吸附剂材料，用于去除生产废水中的EC。LDHs是阴离子粘土状材料，具有许多特性，这些特性使其本身成为吸附剂材料。此外，LDH可以使用诺丁汉大学开发的新型连续流动水热合成技术制备，该技术也已被证明可扩展用于未来的商业用途。在文献中可获得LDH用作从水性环境中去除EC的吸附剂材料的有限报告。然而，文献研究表明，导致对水中有机污染物的最高吸附能力的LDHs的性质是复杂的。该项目的最初目标之一是了解LDHs的哪些性质影响其吸附能力，并增加对EC吸附的结构-性质-活性关系的理解。特别是吸附性能的LDHs抗生素将进行调查，包括在环境相关的条件下的性能的考虑，与使用真实的废水样品的可能性。这项工作将考虑从LDH中回收污染物，以及LDH的再生，以确保多个吸附和解吸循环的性能，以确保该过程与循环经济兼容。该项目还考虑了循环经济的第二种方式，通过使用废物资源作为LDH合成的前体。废物资源作为LDH合成的前体的用途已在文献中得到证实，然而，将连续流合成和废物衍生的前体一起使用还有待报道。该项目还将研究这种合成路线是否可行，以及这些材料是否可以用作成功的吸附剂材料。

Emerging contaminants (ECs) are a class of anthropogenic pollutants, and these have recently been detected in environmental waters, and these have become more prominent in recent years through improvements in the detection levels of analytical techniques. The presence of ECs in waterways is a known driver for antimicrobial resistance (AMR). AMR has been declared by the World Health Organisation a major global threat to public health, with up to 10 million lives at risk by 2050 if nothing is done to slow the spread of AMR. One route by which antibiotics, a subclass of ECs, are entering the environment is through release of waste manufacturing effluents, resulting in mg/L concentrations of antibiotics in the water, hence finding a solution to remediate this pollution is key in curbing the spread of AMR. Within the water industry there is also a pressure for remediation processes to become more circular, with pollutants being viewed as a resource rather than a costly waste. Hence, when designing remediation techniques any solutions need to be compatible with the more sustainable circular economy model than widely found linear 'take-make-waste' models. Sorption processes are a remediation technique which if designed correctly can be compatible with the circular economy. Whilst there are a range of sorbent materials reported in the literature, many sorbent materials currently available to industry are costly and potentially unsustainable. Further to this, a lot of research published on the use of sorbent materials lack key considerations to aid in understanding whether a sorption process and material can be industrially relevant, including: realistic wastewater/environmental conditions; representative concentrations of pollutants; detailed study of the recovery/regeneration cycles of sorbent materials. Proposed solution and methodologyThis project will consider the use of layered double hydroxides, LDHs, as sorbent materials for the removal of ECs from manufacturing wastewater. LDHs are anionic clay-like materials with numerous properties which lend themselves to being a sorbent material. Further to this, LDHs can be made using a novel continuous-flow hydrothermal synthesis technology developed at the University of Nottingham, which has also been shown to be scalable for future commercial use. Limited reports of LDHs being used as sorbent materials for the removal of ECs from aqueous environments are available in the literature. However, literature studies have shown that the properties of LDHs which lead to top sorption capacities for organic pollutants from water are complex. One of the initial aims of this project is to understand which properties of LDHs impact their sorption capacity and increase understanding of the structure-property-activity relationship for EC sorption. Particularly sorption performance of LDHs for antibiotics will be investigated, including a consideration of performance at environmentally relevant conditions, with the possibility of using real wastewater samples. The work will consider the recovery of pollutant from the LDH, and regeneration of the LDH for performance over multiple adsorption and desorption cycles to ensure the process is compatible with the circular economy. The project also considers the circular economy in a second way, through using waste resources as the precursors in the LDH synthesis. The use of waste resources as precursors for LDH synthesis has been demonstrated in the literature, however the use of continuous flow synthesis and waste derived precursors together is yet to be reported. This project will also aim to investigate if such as synthesis route is possible and if these materials can be used as successful sorbent materials.