Photothermal Surface Heating Membrane Distillation Using 3D-Printed Ti₃C₂T_x MXene-Based Nanocomposite Spacers

Abstract

To address the growing global need for freshwater, it has become essential to use nonpotable saline water. Solar membrane distillation is a potential desalination method that does not need conventional electricity and may cut water production costs. In this study, we develop a photothermal surface heating membrane distillation using a new class of photothermal spacers constructed with Ti 3 C 2 T x MXene-based nanocomposites. In contrast to traditional membrane distillation, which utilizes energyintensive bulk feed heating, solar-powered surface heating membrane distillation removes the external thermal energy input requirements, hence reducing operating costs significantly. In particular, three-dimensional (3D)-printing technology was used to fabricate the functional spacer, which allowed the design and materials to be fine-tuned per the needs of the process. Under solar illumination, the printed spacer can exhibit a localized photothermal conversion-driven heating effect near the surface of distillation membranes, which generates vapor pressure strong enough to operate distillation across membranes. Importantly, a two-dimensional Ti 3 C 2 T x MXene with outstanding photothermal conversion efficiency and stability in hypersaline ionic solutions was incorporated into the 3D-printed spacers as the crucial nanofiller for imparting a local heating effect of feed. The fabricated nanocomposite spacers showed superior photothermal heating response under sunlight with an average permeate flux and energy conversion efficiency of 0.49 kg•m −2 •h −1 and 30.6%, respectively. An enhancement in both photothermal efficiency and permeate flux was noticed as the amount of MXene nanosheets increased in the 3D-printed spacers. This study demonstrates the feasibility of using 3D-printed photothermal spacers for high-performance and sustainable surface heating membrane distillation, providing a promising avenue for further improvement with other photothermal nanofillers or spacer modifications.

Synergistic Effect of Ti3C2Tx MXene Nanosheets and Tannic Acid–Fe3+ Network in Constructing High-Performance Hydrogel Composite Membrane for Photothermal Membrane Distillation

“…Photothermal materials, mainly including carbon-based nanomaterials (e.g., carbon nanotube), plasmonic nanoparticles (e.g., Au), semiconductors (e.g., metal oxide), and polymer materials (e.g., polydopamine), play a dominant role in the design of high-performance PMD membranes. Among them, an emerging 2D MXene family, especially transition titanium carbide (Ti 3 C 2 T x , T x = −F, −O, and −OH), has attracted great attention for solar water production with broad-band light absorption and superior light-to-heat conversion efficiency resulting from its localized surface plasmon resonance (LSPR) effect. − Besides, the intrinsic hydrophilicity of Ti 3 C 2 T x nanosheets endowed them with desired antifouling property and good compatibility with hydroxyl-abundant materials via hydrogen bonding. , However, the utilization of Ti 3 C 2 T x in the design of a PMD membrane is limited and the performance needs to be further improved. ,− Our previous work demonstrates that a hydrogel composite Janus membrane exhibits a high vapor flux and robust fouling and wetting resistance when treating saline feed contaminated by oils and surfactants. , Inspired by the excellent photothermal conversion efficiency of MXene and antiwetting/antifouling property of functional hydrogels, the innovative combination of MXene with a hydrogel might be a feasible way to construct an advanced Janus PMD membrane, which has not been investigated yet.…”

Environmentally Friendly Photothermal Membranes for Halite Recovery from Reverse Osmosis Brine via Solar-Driven Membrane Crystallization

“…Beyond the pioneering concept of photothermal MD (PhMD) for desalination operation [30,31], our recent studies demonstrated the opportunity to exploit photothermal membranes to dehydrate brine up to their supersaturation, inducing the crystallization of dissolved salts [29,32]. This operation, called photothermal MCr (PhMCr), can have a considerable impact on the practical feasibility of the revolutionary concept of seawater and brine mining [33,34].…”

Reusable Floating Spherical Hydrogel Evaporator for Solar Desalination with Salt Mitigation and Contaminant Elimination

“…The scarcity of fresh drinking water is a pervasive global problem affecting people worldwide. , Desalination is considered as an effective, sustainable approach to generate fresh water from seawater and brackish water. , Current desalination technologies are based on reverse osmosis, multistage flash distillation, and electrodialysis, which are expensive. − Solar-induced desalination treatment is a cost-effective as well as eco-friendly approach that uses an interfacial evaporation system to isolate the evaporation interface from bulk water. Heat localization is conducted at the air–water interface to avoid the conduction of heat to the entire water mass and achieve efficient evaporation. ,, The use of various photothermal materials having high light absorption and light-to-heat conversion efficiency concentrates heat on the evaporation surface, which accelerates water transport that balances the evaporation rate. − …”