Solar-based technologies for removing potentially toxic metals from water sources: a review

Area of Science:

• Environmental Science
• Water Treatment Technologies
• Materials Science

Background:

• Increasing technological advancements correlate with rising environmental contaminant deposition, particularly heavy metals in water sources.
• Heavy metals pose significant risks to environmental and human health, necessitating effective remediation strategies.
• Solar radiation-based technologies offer a sustainable, cost-effective, and efficient approach to mitigate heavy metal pollution in water.

Purpose of the Study:

• To comprehensively synthesize and critically review the performance, potential, and challenges of solar radiation-based technologies for heavy metal removal from water.
• To evaluate conventional solar stills (CSS), membrane-based solar stills, and solar heterogeneous photocatalysis for removing arsenic (As), chromium (Cr), mercury (Hg), and uranium (U).
• To identify areas for improvement and future research in solar-driven water remediation.

Main Methods:

• Critical review and synthesis of existing literature on solar stills and solar heterogeneous photocatalysis.
• Analysis of the efficacy and productivity of CSS and membrane-based solar stills in heavy metal removal.
• Evaluation of solar heterogeneous photocatalysis for converting toxic heavy metals into less harmful substances.

Main Results:

• Conventional solar stills and membrane-based solar stills demonstrate high efficacy (>98%) in removing heavy metals.
• Structural and functional enhancements are needed to improve the productivity of CSS and the overall usability of both still types for real-world applications.
• Solar heterogeneous photocatalysis effectively removes or converts As, Cr, Hg, and U into less toxic forms, amenable to subsequent removal.

Conclusions:

• Solar stills are highly effective for heavy metal removal but require optimization for enhanced productivity and practical implementation.
• Solar heterogeneous photocatalysis shows promise for detoxifying heavy metals, but further research on material safety, reactor scalability, and real-world application is essential.
• Solar radiation-based technologies represent a viable and sustainable pathway for addressing heavy metal contamination in water resources.