Photothermal Diatomite/Carbon Nanotube Combined Aerogel for High‐Efficiency Solar Steam Generation and Wastewater Purification

Abstract

Solar‐driven interface evaporation is a sustainable and green method for seawater desalination and wastewater purification which has attracted great attention due to the expectation to solve the global fresh water crisis. Currently, its commercial application is still limited by high cost, a complicated preparation process, and unsatisfying photothermal conversion efficiency, which are difficult to be achieved simultaneously. Herein, a nontoxic, high efficient, low cost, and facile strategy to fabricate a solar steam generator is demonstraterd, in which biocompatible agar powder, carbon nanotubes, and diatomite are combined to achieve an aerogel. All materials involved are commercially available. The aerogel exhibits a water evaporation rate of 1.67 kg m−2 h−1 with 91% conversion efficiency under one sun illumination, and can produce drinkable water from sea water, lake water, and even strong acid/alkaline water with nearly 100% rejection of organic dyes. Most importantly, the cost to produce such an aerogel is only 6.67 $ m−2, and is expected to produce 5–8 kg m−2 of fresh water per day under natural sunlight, which is enough for a family of three to live normally for one day. Present high‐efficient and economic water purification system provides promise for commercial application in seawater desalination and wastewater purification.

Surface Functional Modification for Boosting Power Density of Hydrovoltaic Devices

“…It could be concluded from schematics i, iv, and v that dry CNTs/CB/PVDF@CC, submerged CNTs/CB/PVDF@CC, and heated dry CNTs/CB/PVDF@CC do not generate current. This not only excludes the interference of thermoelectric effects, [ 33,34 ] but also demonstrates that the interaction of water with the carbon material and the evaporation of water from the surface of the carbon material are essential for the generation of current. On the contrary, as shown in ii, iii, and vi, as the surface temperature of the carbon materials increases, the evaporation of water from their surface accelerates, leading to higher current.…”

Cost Effective Photothermal Materials Selection for Direct Solar-Driven Evaporation

“…The original carbon cloth was initially hydrophobic, with a contact angle of approximately 137°, before the plasma treatment, which caused it to exhibit superhydrophilic behavior. 115 For improving the light absorption capacity, a natural mineral, diatomite (DE) is employed by Li and his team 116 due to its large number of micropores arranged in an orderly manner inside, lightweight, strong adsorption capacity, and stable chemical properties, and it has a wide source of raw materials and low cost, however, with exhibited excellent combination with carbon nanotube and aerogel (excellent hydrophilicity) with cost-effectiveness around 250.37 (g h −1 $ −1 ). DE has a 67% light absorption capacity, and the composite aerogel after the addition of carbon nanotubes CNT shows absorption capacity over 95%.…”

“…A bullet chart illustrating the cost-effectiveness, evaporation rate, and cost of various solar evaporators. ,,,,,,,,,,,,,,,,,,,,, …”

“… A bullet chart illustrating the cost-effectiveness, evaporation rate, and cost of various solar evaporators. 107 , 124 , 109 , 125 , 126 , 122 , 127 , 79 , 121 , 128 , 116 , 113 , 86 , 129 , 46 , 130 , 131 , 132 , 133 , 87 , 118 , 85 …”

Towards highly salt-rejecting solar interfacial evaporation: Photothermal materials selection, structural designs, and energy management

“…The preparation methods and raw materials of the foam materials are varied. Cellulose, as a widely used material, is an important raw material for the preparation of foam structure [76][77][78][79][80][81][82][83][84][85][86][87][88][89]. A bilayer hybrid biomass foam composed of bacterial nano cellulose (BNC) and rGO was prepared by the researchers, as shown in Fig.…”