Remediation of micro- and nanoplastics by robotic technology: Performance, critical factors and marketing barriers

Microplastics (MPs) and nanoplastics (NPs) have been considered as environmental threats because of their unique physicochemical properties, resistance to degradation, chemical stability, higher toxicity, and strong affinity for coexisting contaminants. Despite of ubiquitous pollution of MPs/NPs, its cost-effective remediation remains a dispute due to their low concentration, widespread distribution, and smaller size in water bodies. Numerous conventional treatments methods, including adsorption, filtration, coagulation, bioremediation, and advanced oxidation, have shown their competence to eradicate MPs/NPs. However, certain limitations, such as lower removal performance, expensive operational and maintenance costs, and generation of secondary pollutants, are hindering their market penetration. Recently, robotic technology has been considered as a ground-breaking invention for environmental remediation due to their unique intelligence-based self-propelled programmable mobility, promising controllability, smaller size, and surface catalytic activity. It can improve remediation practicability by overcoming diffusion-limited reactions and stimulate rapid interaction with targeted MPs/NPs. Notably, MPs/NPs can be captured and degraded simultaneously via the combination of diverse mechanisms. Therefore, this critical review has been designed to discuss the synthesis modulations of robotic technology for the remediation of MPs/NPs from aquatic environments. The synthesized robots have been categorized into four major classes: iron (Fe)-based, catalytic material-based, polymer-based, and bio-based robots, and their trapping/capturing and degradation performances have been critically explored. Importantly, the sway of diverse critical factors, such as characteristics of robots, properties of plastic particles, reaction time, operating distance, solution pH, co-existing/interfering ions, and natural organic matter, on the treatment performance of robots have been critically evaluated. In addition, the prospective of robotic technology in eradicating MPs/NPs from real sewage has been revealed. Importantly, barriers in marketing of robotic technology for MPs/NPs remediation from water environments have been critically elaborated to assist experts in transferring it from laboratory to market. Finally, the existing knowledge gaps and prospects are emphasized to help scientists to improve robotic technology to combat plastic particles pollution.