Electrothermal interfacial evaporation through carbon-nanostructured composite membranes

Area of Science:

• Materials Science
• Chemical Engineering
• Energy Science

Background:

• Membrane distillation (MD) faces challenges due to high energy requirements for feed water heating.
• Surface heating membrane distillation (SHMD) presents a viable alternative by directly heating the membrane and feed.
• SHMD utilizes solar or electrical energy, bypassing the need for external feed heating.

Purpose of the Study:

• To explore electrothermally-driven interfacial evaporation using a multi-walled carbon nanotube (MWCNT)-based composite membrane.
• To evaluate the potential of this membrane for high-efficiency SHMD applications.
• To investigate the localized surface heating performance and energy efficiency of the MWCNT composite membrane.

Main Methods:

• Fabrication of a composite membrane incorporating multi-walled carbon nanotubes (MWCNTs).
• Application of voltage across the MWCNT membrane to induce electrothermal heating.
• Measurement of evaporative water flux, energy efficiency, and localized surface heating performance.
• Assessment of membrane resistance and surface temperature stability under varying electric field directions.

Main Results:

• The MWCNT-based composite membrane achieved an evaporative water flux of up to 2.34 kg m⁻²h⁻¹.
• An energy efficiency of 61% was recorded, alongside outstanding localized surface heating.
• The membrane demonstrated stable performance, with no significant variations in resistance or temperature irrespective of electric field direction.

Conclusions:

• The developed MWCNT composite membranes show significant potential for energy-efficient and cost-effective localized heating in SHMD.
• Quantitative agreement of energy parameters with existing electrothermal MD systems validates the proposed approach.
• This technology addresses the energy demand challenge in MD, paving the way for broader adoption.