Exploring the potential of MXene-based advanced solar-absorber in improving the performance and efficiency of a solar-desalination unit for brackish water purification

Brackish water desalination using solar still (SS) is a low-cost sustainable solution to global water scarcity, but this technology suffers from low yield and efficiency. The judicious amalgamation of highly conductive materials with superior solar absorption behavior is one of the most effective approaches to overcome this limitation. In this regard, the present work synthesizes a novel multilayered 2-D MXene from 3-D MAX phase as a coating material for the solar absorber of a SS to improve its performance. Two different loadings of MXene (0.05 and 0.1 wt%) were dispersed in turpentine oil/black paint (1:4) and coated onto the solar absorber of the SS. Higher MXene loading significantly augmented the thermal conductivity and solar absorptivity of the turpentine oil/black paint solution. The 0.1 wt% MXene coated absorber provided a higher heat transfer rate from the absorber to the water, leading to a 6% increase in water temperature and a total water yield of 2.07 kg. The theoretical calculated water yield was identical to the experimental yield with a deviation of ±5%, demonstrating the accuracy of thermal modelling. The average energy efficiency of the SS with 0.1 wt% MXene in the absorber black paint coating was 36.31%. Water quality analysis has shown that the distilled water resulting from the desalination is suitable for drinking. In conclusion, MXene with its excellent thermo-physical properties and solar absorptivity will be beneficial in development of efficient solar desalination units with augmented performance for water purification.