Solar technology commonly used for water evaporation in seawater desalination and wastewater treatment processes has been extended to soil remediation. The technique developed by University of South Australia researchers uses an efficient solar evaporation surface to draw water from soil through a sponge-like filter that traps contaminants, mimicking the process of transpiration that occurs in natural plants, but at a greatly accelerated rate.

The interfacial solar evaporation technology functions as a biomimetic plant, replicating the botanical ability to capture and transport soil water. The evaporator was assembled with both selective heavy metal adsorption and photothermal properties, harnessing the power of selective binding agents to sequester heavy metals for removal. A reduced graphene oxide was incorporated as the light absorbing material.

The low-cost system was demonstrated to reduce concentrations of arsenic, cadmium, chromium, lead and zinc in soil pore water during indoor solar evaporation tests. Plants cultured in the treated soil showed marked reductions in heavy metal accumulation relative to plants grown in untreated soils.

The research published in Chemical Engineering Journal provides a new direction in solar evaporator design for enhancing water evaporation and the efficiency of soil remediation.