Biomass‐derived photothermal sweet lime peel biochar absorber for efficient interfacial solar water evaporation

Abstract Recently, there has been much interest in photothermal material‐based interfacial Solar water evaporation (ISWE). This paper draws inspiration from the natural transpiration capillary process, utilizing cotton thread wicks on an expanded polystyrene (EPS) and carbon foam‐coated carbonized sweet lime peel layer. An eco‐friendly and cost‐effective photothermal material is obtained from sweet lime peel. The sweet lime peel was left to dry under the open sky for a month and then placed in a heat treatment furnace at 437°C and 354°C for 30 min to produce biochar. Sweet lime peel biochar (SLPB) was manually ground to make excellent particles. SLPB surface area, porous morphology for the capillary route, solar broadband wavelength absorbance capacity, biochar functional groups and the impact of pyrolysis temperature on biochar evaluation crystallography were characterized using a scanning electron microscope (SEM), UVVIS spectrophotometers, FTIR and XRD, respectively. The biochar coat is obtained by mixing SLPB powder with water and acrylic pouring medium. A coating layer of SLPB is applied to the EPS foam. Cotton thread wicks were made through the cylindrical EPS foam to raise water through capillaries. The water evaporation rate is measured under one sun solar simulator, with an evaporation rate of 3.42 kg/m 2 h and a solar thermal evaporation efficiency of 81% and validation of results is carried out. ISWE demonstrated incredibly favorable outcomes by using SLPB as compared with other biochar‐based ISWE. This incorporates the UN's SDG6, which focuses on clean water and sanitation, and develops appropriate water supply and waste disposal systems.