Waste Polyvinyl Chlorine-Based Evaporator for Solar Steam Generation

Remote islands often face chronic freshwater shortages due to the lack of natural
freshwater resources, limited infrastructure, and vulnerability to extreme weather
events. Although existing desalination technologies can effectively produce freshwater,
they typically rely on substantial energy input, complex equipment, and centralized
facilities, limiting their applicability in small and remote island settings.
In this study, discarded polyvinyl chloride (PVC) waste was transformed into a
photothermal gel evaporator through a simple solvothermal process. During the
reaction, conjugated structures and hydrophilic functional groups were
simultaneously generated, endowing the material with efficient solar-energy
harvesting and water-transport capabilities. The resulting evaporator exhibited a high
evaporation rate of 1.489 kg m-2 h-1 under one-sun irradiation, with a solar-to-vapor
efficiency of 93.6%. By adopting a three-dimensional (3D) architecture with an
enlarged evaporation area, the evaporation rate was further increased to 1.976 kg m-2
h-1
. Desalination tests using natural seawater demonstrated excellent salt rejection,
reducing the concentrations of major ions (Na+
, Mg2+, Ca2+, K+
, and Cl-
) to levels well
below international drinking-water guidelines. Outdoor experiments further confirmed
stable freshwater production under natural sunlight and concentrated solar conditions.
With optimized condictions, a 1 m2 evaporator can generate 6 L of potable freshwater
within 3 h, sufficient to meet the emergency drinking-water needs of a small family.
By integrating plastic-waste upcycling with solar desalination, this project provides
a low-cost, portable, and decentralized freshwater solution for remote islands and
emergency water-supply scenarios. Beyond addressing freshwater shortages, the
proposed approach offers a sustainable pathway for converting waste PVC into a
value-added material with practical environmental and societal benefits.