Environmental impacts of nanofluids: A review

Area of Science:

• Materials Science
• Environmental Science
• Thermodynamics

Background:

• Nanofluids (NFs) are engineered fluids with enhanced thermophysical properties due to nanoparticle (NP) addition.
• NFs are utilized as high-performance heat transfer fluids (HTFs) for heating and cooling, improving energy efficiency.
• Environmental impacts (EIs) of base fluids (BFs) and NPs are critical considerations for NF applications.

Purpose of the Study:

• To discuss the environmental impacts (EIs) of nanofluids (NFs), considering both base fluids (BFs) and nanoparticles (NPs).
• To identify key factors influencing the EIs of NFs, focusing on nanoparticle characteristics and production methods.

Main Methods:

• Literature review and analysis of existing data on the environmental impacts of base fluids and nanoparticles.
• Discussion on the combined environmental footprint of nanofluids, considering nanoparticle type, base fluid, and NP loading.
• Evaluation of the influence of nanoparticle synthesis routes and nanofluid production methods (one-step vs. two-step) on EIs.

Main Results:

• The environmental impacts of NFs are primarily determined by the type of nanoparticles used, followed by the base fluid and nanoparticle loading.
• Utilizing non-toxic, naturally occurring nanoparticles at low concentrations in water-based NFs significantly reduces EIs.
• Simpler synthesis and production methods for both nanoparticles and nanofluids lead to lower chemical and energy requirements, thus reducing EIs.

Conclusions:

• Nanofluid environmental impact assessment must consider the synergistic effects of base fluids and nanoparticles.
• Selection of appropriate, eco-friendly nanoparticles and optimized production processes are crucial for sustainable nanofluid applications.
• Water-based nanofluids with non-toxic nanoparticles offer a promising route to achieve high thermal performance with minimal environmental burden.