Water has been acknowledged as one of the key issues of humanity in modern society and worldwide economic advancements, especially with the continuing reductions in fresh-water supply. Solar energy, which is abundant as well as widely available in various fields, has the potential to solve the global challenges of long-term freshwater and energy reduction. Researchers are attempting to address the problem in a variety of methods. Due to the fact that solar energy is the foundation for freshwater, several researches have applied it for improving the effectiveness of solar desalination, evaporation, and wastewater treatment. One of the novel methods used for achieving this is known as “hydrogel,” which comes in a variety of forms. As a unique light-absorbing material, hydro-gel can improve photo-thermal solar efficiency conversions through reducing heat loss in the process of heat transfer caused by heat localization at air–water interface. Hydrogel has a large number of pores structures allow for efficient water transportation from bottom to water–air interface. In addition, hydro-gels are durable, floatable, recycling and anti-fouling materials that are energy efficient for steam generation harvesting and amplification. The aim of the current review paper was to review relevant published studies in order to investigate the current knowledge and background information regarding thermal desalination in general and solar distillation in particular.
