Water‐Light Induced Self‐Blacking System Constituted by Quinoa Cellulose and Graphene Oxide for High Performance of Salt‐Rejecting Solar Desalination

Abstract

Recently, considerable interests have been attracted by agriculture and forestry resources for efficient solar steam generation, due to that of inexhaustible nature source with many extremely good performances, such as renewability, biodegradability, biocompatibility, and importantly inherent porous structures. [3,[12][13][14] Many nature plant based materials have been carbonized directly to achieve high efficiency solar steam generation, such as carbonized corncob, [3] carbonized mushrooms, [5] carbonized pollen power activated by CuCl 2 where a piece of basswood used as substrate, [6] carbonized willow catkins with nano tubal surface structure [15] with the evaporation rate of 4.16, 1.47, 1.87, 2.17 kg m −2 h −1 under one sun respectively. Also, cellulose [16] and softwood pulp, [17] which are extracted from plants, are employed to manufactured evaporator with the help of sun light absorber polymer (poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, PEDOT:PSS) and carbon black respectively.Many efforts have largely improved the efficiency of solar energy utilization and achieved significantly results in high speeds for evaporation water. [1,3,18] However, the promotion of these photothermal materials is restricted by high-temperature pyrolysis process or their complex polymeric methods, which would need much more extra energy, time and cost. In addition to the water evaporation rate, salt pollution is another challenge for long team, stabilization, sustainability, and low operation and maintenance costs solar steam generation technology. [19,20] Normally, after a certain period of evaporation with seawater, the surface of the evaporator would be suffered from salt scaling pollution, which will deteriorate the evaporation efficiency and system functions. In order to address the salt scaling problems, few types of technologies have been proposed, including: [20] 1) using the manual and mechanical methods to remove the surface deposited salts, [21,22] 2) unique structure that only selective water can be transported, [23,24] 3) Janus membranes which upper layer keeps the salt from reaching surface and dissolve the deposited salt back to bulk water through the underneath layer, [25][26][27] 4) hydrophobized surfaces by some polymers to prevent salt clogging, [6] 5) local crystallization by unique geometry designed, [3,28,29] 6) provides a salt return channel by unique structure designed, [30,31] and 7) auto-cleaning or selfcleaning technologies driven by chemical potential. [32] Among them, auto-cleaning strategy is an attractive technology for Salt deposits are a key challenge of solar driven desalination technology due to the fact that the evaporation rate of the system sharply deteriorates when salt accumulates. In this paper, a self-blacking aerogel (SBA) is first demonstrated with excellent deposited salt self-cleaning performance, and the self-cleaning mechanism is illustrated by the theory of chemical potential. The color of the SBA can be changed from light brown to black under the inducement of water ...

Carbon fiber coated by quinoa cellulose nanosheet with outstanding scaled salt self-cleaning performance and purification of organic and antibiotic contaminated water

“…It should be noted that evaporation rates of CFQC based evaporator are far beyond the theoretical value under the light intensity of 1000 W m −2 (1.592 kg m −2 h −1 , the detailed calculation process as shown in supplementary information), with apparent energy utilization rate over 100%, and those results seems unreasonable. But similar experimental phenomena have been observed in some previous literatures, such as polyvinyl alcohol (PVA) based evaporators 19 , 53 , 54 , self-blacking cellulose and graphene oxide composite gel 41 and hollow carbon fiber 13 have the higher evaporation rate than that of theoretical under one sun, where a water clusters based evaporation have been proposed and can be well elucidate the phenomenon of beyond the biggest value 53 – 55 .…”

“…Driving force ( ) between the evaporator and bulk salt water would prompt the salt to migrate back to bulk water with the help of the channels (gaps) between the decorated carbon fibers. According to the previous studies 41 , 62 , the marvelous salt-cleaning capability can be chalked up to adequate salt-water transmission network (gaps), which provided by 2D cellulose-based carbon decorated carbon fibers (Fig. 3 ) in Zn-CFQC, and good hydrophilicity (Fig.…”

“…Chemical composition and crystalline structure of the QBC has been investigated and analyzed by XRD and FTIR in our previous work 41 , and corresponding results as shown in Fig. S1 .…”

“…Manufacture process of nano-cellulose sheets conditions is based on previous studies 50 , 64 and our previous study 41 . The mainly steps are as following: (1) A benzene/absolute ethanol with the 2:1 volume ratio was applied to treat the quinoa bran (QB) with the assistance of Soxhlet extractor at the temperature of 90 °C for 360 min.…”

“…Additionally, some new advanced technology has been introduced in solar steam generation field to enhance the water evaporation efficiency 31 – 35 , such as atomic layer deposition (ALD) 31 technology, Janus materials fabricating technology 30 , 32 , 33 , 36 , piezoelectric and solar steam synergistic technology 35 , 37 and photovoltaic and solar steam generation synergistic technology 23 , 38 . For photo-thermal conversion materials, carbon materials have attracted largely interests in virtue of its excellent chemical stability, thermal stability, broadband absorption of solar lights, and extensive sources from nature and industrial goods 13 , 39 – 41 . Carbon fiber (CF) as commercial products with the performance of “light and strong” is widely used in advanced composites materials (aerospace, military, sports, automobile and others applications) due to its excellent properties, including low density, outstanding mechanical properties, corrosion resistance, creep resistance, chemical stability, good thermal conductivity, and peculiarly good adsorption of sunlight 42 – 45 .…”