Synergistic Effect of Ti₃C₂T_x MXene Nanosheets and Tannic Acid–Fe³⁺ Network in Constructing High-Performance Hydrogel Composite Membrane for Photothermal Membrane Distillation

Abstract

Photothermal membrane distillation (PMD) has emerged as a promising and sustainable approach for seawater desalination and wastewater purification. However, the wide application of the technique is severely impeded by low freshwater production and membrane fouling/wetting issues. Herein, we developed an advanced hydrogel-engineered membrane with simultaneously enhanced photothermal conversion capacity and desired fouling and wetting resistance for PMD. By the synergies of photothermal Ti 3 C 2 T x MXene nanosheets and the tannic acid−Fe 3+ network in the hydrogel, the membrane was endowed with excellent surface self-heating ability, yielding the highest freshwater production rate (1.71 kg m −2 h −1 ) and photothermal efficiency among the fabricated hydrogel composite membranes under 1 sun irradiation. Meanwhile, the PMD membrane could robustly resist oil-induced fouling and surfactant-induced wetting, significantly extending the membrane lifespan in treating contaminated saline water. Furthermore, when desalinating real seawater, the membrane exhibited superior durability with a stable vapor flux and excellent ion rejection (e.g., 99.24% for boron) for 100 h.

Hypercrosslinked Hydrogel Composite Membranes Targeted for Removal of Volatile Organic Compounds via Selective Solution-Diffusion in Membrane Distillation

“…As shown in Figures A and S10, all membranes sustained a stable flux (20.1–21.1 kg·m –2 ·h –1 ) along with near-perfect salt rejection during 12 h operation with a saline feed containing 100 ppm phenol, demonstrating that the addition of phenol did not induce membrane wetting. Besides, the introduction of the Alg/Al hydrogel layer did not adversely affect vapor flux of membrane, consistent with the results in previous studies. ,, The PTFE and P PTFE membranes exhibited low phenol rejection rates (below 10%) at various concentrations (Figure B), which indicated that the PDA/PEI layer made little contribution to phenol interception. The Alg/Al PTFE membrane displayed a sufficient phenol rejection efficiency of 99.52% with saline feed containing 100 ppm phenol, which was attributed to the Alg/Al layer.…”