Microalgal synthesis of metal nanoparticles - towards a circular economy

重金属，如镉，各种染料或其他工业过程的基本成分，被世界卫生组织列为十大公众关注的化学品之一，因为它们可能致癌并造成急性器官损伤。藻类生物修复系统（藻类修复）是非常有吸引力的，因为它们是自养的-依赖于阳光和二氧化碳作为输入。该项目旨在通过创建可扩展的废水处理方法，利用微藻提取重金属并将其升级为有价值的金属纳米颗粒，从而实现可持续发展目标。该项目利用一个模型系统，试图了解如何开发适合于原位补救的光生物反应器技术。在重金属暴露下，植物和藻类产生植物螯合素（PC）-谷胱甘肽衍生物。这些肽与金属形成稳定的复合物，保护细胞。选择硅藻三角褐指藻作为本项目的模式生物，因为已知其可生物积累镉（Cd），并可耐受各种盐度。该项目的目的是研究上游培养参数与镉纳米颗粒形成之间的相互作用，以及这些参数与工艺放大之间的关系。通过设计新的实验系统来研究重金属吸收和微环境的工程表征，该项目将寻求了解如何操纵金属纳米颗粒的形式。确定的目标：附件1：通过生长实验、细胞活力测试和分析，量化培养条件对细胞生长和镉吸收的影响。所形成的纳米颗粒将经历尺寸、形状和分布的形态学表征。氧气：研究反应器设计和操作对保留时间的影响，通过了解几何形状和流体流动条件来确定最大化通量的策略，以改善传质特性。O3：研究生物反应器可能运行的主要模式，以及这如何通过表征两种机制的优点/缺点来影响镉的后续处理：用于回收结合到细胞表面的金属的结合和重结晶相对于回收细胞和从生物质中分离镉。将评价绿色化学技术用于纳米颗粒回收。影响：我们的目标是开发一个藻类修复系统在现场应用。在SfAM支持的知识交流研讨会之后，我们建议与非政府组织合作伙伴合作，在印度确定案例研究地点，以便将以用户为中心的设计方法应用于未来的水处理工艺，并评估技术经济可行性。该项目的调查结果将为今后的设计工作提供信息，并将为试点补救系统提供证据基础。

Heavy metals, such as cadmium, essential components of various dyes or other industrial processes, are listed among the ten chemicals of major public concern by the WHO for their potential to be carcinogenic and inflict acute organ damage. Algal systems for bioremediation (phycoremediation) are highly attractive as they are autotrophic - relying on sunlight and carbon dioxide as inputs. This project aims to address sustainable development goals by creating scalable methodologies for wastewater treatment using microalgae to extract and upgrade heavy metals into valuable metal nanoparticles. Using a model system, this project seeks to understand how photobioreactor technologies suitable for in-situ remediation might be developed. Under heavy metal exposure, plants and algae produce phytochelatins (PC) - glutathione-derived compounds. These peptides form stable complexes with metal, protecting the cells. The diatom alga Phaeodactylum tricornutum has been selected as a model organism for this project as it is known to bioaccumulate cadmium (Cd) and can tolerate a wide range of salinities. The aim of this project is to characterise the interactions between upstream cultivation parameters and cadmium nanoparticle formation and how these might relate to process scale up. Through the design of novel experimental systems for studying heavy metal uptake and engineering characterisation of the microenvironment, this project will seek to understand how the form of metal nanoparticles can be manipulated. The objectives identified: OBJECTIVESO1: To quantify the impact of cultivation conditions on cell growth and Cd uptake through growth experiments, cell viability testing and analysis. The nanoparticles formed will undergo morphological characterisation of size, shape and distribution. O2: To examine the impact of reactor design and operation on retention times, to identify strategies for maximising throughput by understanding geometries and fluid flow conditions for improved mass transfer characteristics.O3: To investigate the primary mode in which the bioreactor may operate, and how this may influence subsequent processing of cadmium by characterising the benefits/drawbacks of two mechanisms: bind and elute for recovery of metal bound to the cell surface vs recovery of cells and separation of cadmium from biomass. Green chemistry techniques will be evaluated for nanoparticle recovery. IMPACT: Our goal is to develop a phycoremediation system for application in the field. Following on from a Knowledge Exchange workshop supported by SfAM we propose to work with NGO partners to identify case study sites in India in order to apply a user-centered design approach to a future water treatment process and evaluate technoeconomic feasibility. Findings from this project will inform future design efforts and will provide an evidence base for a pilot remediation system.