Highly efficient solar desalination and wastewater treatment by economical wood-based double-layer photoabsorbers

Design of rational photoabsorbers is a promising approach to produce drinking water. Herein, a highly efficient and scalable wood-based photoabsorber device composed of poplar wood as a substrate coated with FeNi with mole ratio of Fe/Ni = 85% and reduced graphene oxide (RGO) as top and bottom layers, respectively was designed for the interfacial solar desalination of seawater and heavy metal removal as a sorbent. Benefiting from high sunlight utilization and rapid water transport, high photothermal conversion fluxes of 1.50 and 4.77 kg m−2h−1 were achieved by the most efficient double-layer photoabsorber of W / F e N i 4 ∙ 5 R G O 4 ∙ 5 (wood coated with 4.5 g L−1 of FeNi as a top layer and 4.5 g L−1 of RGO as a bottom layer) under 1 and 3 sun, respectively (1 sun = 1 kW m−2). Also, a significant reduction in the salinity (four orders of magnitude), the electrical conductivity (3000 times) and the pH (1.35 times) of the seawater was achieved after 40 min solar desalination. The ratio of produced steam rate per cost was calculated as 9 cm3 h−1 $−1 which is compared with other double-layer devices reported in the literature. In addition, W / F e N i 4 ∙ 5 R G O 4 ∙ 5 acted as an excellent sorbent for Pb (II).