Photothermal membrane distillation

In response to the ever-growing global water crisis, the use of innovative and sustainable solutions based on membrane technology particularly membrane distillation (MD) is essential. MD process uses a hydrophobic membrane to separate impurities from feed water by utilizing a temperature difference to create water vapor, leaving contaminants behind. It has become more favorable compared to pressure-driven processes as it operates at low temperatures and pressures. However, MD needs external energy for heating which can be expensive and consumes a lot of energy. Photothermal membrane distillation (PMD) is an advancement of MD where it uses renewable energy, which is solar energy, to increase the temperature at the membrane’s interface, eliminating the need for external power. This makes PMD more energy-efficient and eco-friendly compared to the MD. In this chapter, the fundamental of MD was first introduced, followed by a discussion on how MD employs hydrophobic membranes to create a temperature gradient, enabling selective separation. Then, the focus of this chapter shifts to PMD, an innovative approach that harnesses the power of renewable energy sources to heat the feed water. The principles behind photothermal energy conversion and its integration with MD technology were first reviewed. Then, numerous advantages offered by PMD over conventional MD, making it an attractive solution for addressing the pressing global challenges of water scarcity and wastewater treatment were highlighted. Lastly, the fabrication of membranes for PMD particularly in terms of incorporation of photothermal material into membrane matrix as well as surface modification was reviewed. Overall, this chapter aims to shed light on this cutting-edge technology's potential to revolutionize water treatment, offering sustainable, cost-effective, and environmentally friendly solutions in the face of growing water scarcity and environmental concerns.