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

点击翻译按钮获取中文摘要

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.