Peanut shell-derived photothermal absorber for solar desalination

The development of efficient photothermal materials for solar steam generation (SSG) is important achieving high evaporation rates and efficiencies. Among various materials, biomass-derived photothermal absorbers (PTAs) can convert solar light into heat for solar desalination. This study pioneers the utilization of peanut shell as a renewable resource in solar desalination. Peanut shells, an agricultural waste with meso- and micropores, were utilized as an evaporator for interfacial solar steam generation (ISSG). Although peanut shells are an excellent source of protein, fat, and fiber, they are usually discarded after consumption. In this work, waste peanut shells were carbonized at 600 °C and 1000 °C to prepare carbonized peanut shell powder (CPS). Furthermore, the prepared CPS was coated onto polyvinyl alcohol (PVA) sponges for solar evaporation. The CPS-derived PTAs were hydrophilized with sodium alginate (SA) and cross-linked by using CaCl2 to obtain PVA@SA–CPS evaporators for solar desalination. In the seawater desalination experiment, PVA@SA–CPS–1000 exhibited a stable evaporation rate that lasted for up to 14 cycles. It presented an evaporation rate of 2.16 kg m−2 h−1 with an efficiency of 90.4 % under 1 sun illumination. Sustainability, cost-effectiveness, low greenhouse emissions, and easy adoptability are the other features of CPS utilized for desalination and water treatment.