Capillary Action Promoted Enhanced Photothermal Desalination and Separation of Impurities from Water using Honeycomb Structured Porous Magnetic Nanoparticles Derived from Waste Biomass

Abstract

Utilizing the interfacial solar steam generation process occurring at the interface between liquids and air has emerged as a compelling and economically viable technique. This method shows significant potential in effectively treating water, desalinating seawater, and capturing energy, all while capitalizing on solar power. By leveraging solar energy for enhanced evaporation, this inventive method offers a powerful solution to various issues concerning water. Herein, an easy and effective methodology for interfacial photothermal-based water purification from seawater and wastewater has been reported. A simpler approach has been described for the synthesis of honeycombstructured porous magnetic nanoparticles (MNPs) from waste cotton using a flame-assisted carbonization technique for high rejection of salts and impurities to achieve usable water. In the study, MNPs were well characterized by using various microscopic and spectroscopic techniques. The photothermal desalination results with MNPs showed a high evaporation rate of ∼3.79 kg/m 2 •h from saline water, which is quite comparable to that in existing reports. The augmentation in the evaporation rate was due to the enhanced mass transfer by increasing the diffusion rate through a porous medium similar to that of transpiration and the capillary action, which helps water molecules travel upward comparatively at a faster rate. Additionally, the adhesive force is more dominant in saline water, which resulted in decreased contact angle and acceleration of the rate of evaporation. The optical tensiometer analysis confirmed that the contact angles of the MNPs with DI water and 3.5 wt % saline water were 145.31 ± 2°and 118 ± 2°, respectively. Further to support the viability of the reported procedure, a comparative inductively coupled plasma mass spectrometry analysis was performed where the photothermal desalination results showed that the rejection rates were ∼98% Na + ions, ∼95% Mg 2+ ions, ∼75.52% Ca 2+ ions, and ∼80% K + ions with MNPs and light irradiation, due to the combined effects of capillary action and the repulsive forces because of the hydrophobic nature of the MNPs.

Enhanced Total Contactless Photothermal Desalination by Translucent Thin Film Coating of Crystalline Nanocellulose

“…Evaporation efficiency for different systems and structure of materials play an important role as reported in several previous studies. − Therefore, it is important to estimate the system efficiency for better understanding. Thus, the evaporation efficiency (η) was calculated using the following equation to compare the results obtained by three different systems reported in this investigation: η = m x normalΔ H normalvap / I ; where Δ H vap was calculated by Δ H vap = C Δ T + h LV , m x is the mass change rate or evaporation rate of respective setup in kg/m 2 r·h, I is the irradiation intensity in kW/m 2 , C is the specific heat capacity of water (4.2 kJ/kg °C), Δ T is the difference in temperature at stable conditions, and h LV is the latent heat of vaporization of the water. It must be noted that the efficiency is calculated on the basis of the maximum surface temperature of the coated lid, which can have an error of precision for the interfacial surface of saline water as the resolution of the IR camera cannot quantify this smallest interfacial gap that was used in experiments.…”

Superhydrophobic Carbon Aerogel Derived from Edible-Sugar for Removal of Oils and Nitro Aromatics

“…Additionally, S-CA showed minimum surface wettability by water, showed the pseudospherical form of water droplets on its surface, and displayed a static contact angle of ∼155°as in Figure 4b. 55,56 The superhydrophobic nature of porous S-CA was proven by the formation of a silver mirror-like surface when in contact with the surface of the water. 57 Thus, S-CA resists water absorption by trapping air in its pores, as shown in Figure S3.…”