Hofmeister effect driven salt-resistant evaporator for efficient evaporation of high concentration brine, synergistic photocatalytic degradation and electric energy harvesting

Currently, the solar interface evaporation technology (SIE) has become an important way to alleviate the shortage of fresh water resources. However, the actual desalination process is complex and faces challenges such as high concentration of salts and organic pollutants. Herein, this study developed a salt deposition resistant solar evaporator (SPBP/PVA) based on the Hofmeister effect for high concentration brine evaporation. By integrating photothermal materials of polypyrrole (PPy) and photocatalyst bismuth vanadate (BiVO 4 ) into the polyurethane sponge modified with appropriate concentration of sodium alginate (1% SA), this system achieves a multifunctional coupling of efficient evaporation, photocatalytic degradation of organic pollutants, and concentration gradient power generation. This evaporator exhibits excellent salt deposition resistance and stable evaporation rate in high-concentration salt solutions (15% NaCl, 2.95 kg m −2  h −1 ). The mechanism is attributed to the enhancement of hydration due to Cl − -induced Hofmeister effect, reduction of evaporation enthalpy, and promotion of salt reflux. During actual outdoor tests in seawater, the evaporator demonstrated highly efficient evaporation performance (with an average evaporation rate of approximately 2.97 kg m −2  h −1 ). At the same time, it can photocatalytically degrade volatile organic contaminants, prevent secondary pollution of fresh water, and realize concentration gradient power generation (voltage of 107.6 mV, current of 14.0 μA) through the salt concentration gradient at the evaporation interface. The multifunctional salt-resistant deposition evaporator prepared in this study provides a new solution for balancing rapid evaporation and the challenges it brings regarding salt deposition.