Biomass derived Janus solar evaporator for synergic water evaporation and purification
Graphical abstract
The loofah sponge-based solar evaporator, which is cost-effective and environmentally friendly, exhibits the synergic functions of solar evaporation and heavy metal ions adsorption. The carbonized loofah acts as the light absorber and delivers excellent self-desalting performance and high evaporation rate of 1.36 kg m−2 h−1 with corresponding energy efficiency of 83.7% under 1.0 Sun, while the alkalized loofah sponge can rapidly transport water and adsorb Cr3+ ions simultaneously.
Introduction
Given the critical issue of global clean water scarcity threatening human health and survival, it is necessary to develop a technology to use readily available renewable resources, e.g. solar energy and seawater to produce clean water. Solar thermal water evaporation, as a reliable and efficient solar energy related approach, has attracted enormous attention due to its advantage of sustainability and environmentally friendliness [[1], [2], [3], [4], [5]]. The recently developed interfacial solar steam generation paves the way for using solar energy for freshwater production. Highly efficient solar steam generation relies on the design and development of high-performance solar-thermal conversion materials, which focus on the amelioration of solar absorptance, heat localization, water transportation, and quick vapor escape [[6], [7], [8], [9], [10], [11]]. Many photothermal materials have been developed to involve in solar steam generation, including plasmonic nanoparticles [[12], [13], [14], [15], [16]], carbon-based materials [[17], [18], [19], [20], [21]], polymers [[22], [23], [24], [25], [26], [27]], semiconductors [[28], [29], [30], [31], [32], [33], [34]] and so on. However, to push forward the real-world applications, preparation of photothermal materials with low cost, excellent stability, environmental friendliness and scalability is still highly demanded. The conversion of biomass waste into value-added photothermal materials offers an ideal solution.
Currently, various evaporators originated from plants and/or plant parts have been exploited for solar steam generation due to low cost, low toxicity as well as excellent physical and chemical stabilities [[35], [36], [37], [38]]. For instance, a series of wood-based solar evaporators with elaborated designs were developed for highly efficient solar desalination [[39], [40], [41], [42], [43], [44]]. Carbonized mushroom was surprisingly found to be an excellent solar steam generation device with an efficiency of 78% under 1.0 sun illumination [45]. Tan's group demonstrated a sustainable method of repurposing food waste as porous carbon-based solar evaporator for low-cost solar desalination [46]. Beyond these, many other biomass-derived solar evaporators were also prepared, such as carbonized carrot [47], used cigarette filters [48] and wasted rice straw [49]. Accordingly, the economic and environmentally friendly biochar is a prominent solar evaporator candidate for solar steam generation device. However, the water evaporation rates of the biochar-derived evaporators still need to be further enhanced to push forward the real-world application.
Fabrication of elaborately designed porous structures is of great importance to promote thermal management and water transportation during solar steam generation [[50], [51], [52]], while the cost and feasibility in large scale production is still a vital practical issue need to be addressed. Loofah is a vigorous growing, high yield and widespread reticular fibrous plant, which possesses natural porous structures with outstanding mechanical strength. In many regions, it is used as natural dishwashing and bath sponge. Recently, loofah-sponge derived carbon materials have been investigated as environmental friendliness electromagnetic wave absorbing materials and photocatalysis materials. Lightweight carbonized loofah sponge/CoFe2O4 composites exhibited a high micro-wave absorbing performance, ascribing to the dielectric lotus-root-like carbon substrate [53]. Li et al. designed SiC-coated carbonized loofah sponge materials with polymer-like thermal insulation, outstanding electromagnetic shielding properties and flexural strength. [54] In addition, Fang's group has also successfully synthesized SnS2/carbonized loofah sponge for effective photocatalytic heavy metal ions removal owing to the large specific surface of 3D hierarchical macroporous composites [55]. Therefore, carbonized loofah sponge has a potential to be chose as a continuous and porous 3D network carbon sponge, facilitating its applications for solar driven water transpiration.
Herein, we proposed a facile strategy to fabricate loofah-derived porous biochar as a solar evaporator via the carbonization process, which embraced the favorable hydrophilicity, high light absorptance in a broad spectrum, excellent scalability and low cost. As a result, the carbonized loofah together with an alkalized loofah can achieve a high evaporation rate of 1.36 kg m−2 h−1 under 1.0 sun, delivering an energy efficiency of 83.7%. Furthermore, an all loofah sponge-based evaporator composed of alkalized loofah sponge as thermal insulator and carbonized loofah sponge as light absorber was designed, which brought dual functions of solar evaporation and heavy-metal ions absorption. This endows the loofah sponge-based evaporator prodigious prospects for efficient freshwater production without further stressing the environment.
Section snippets
Fabrication of carbonized Loofah evaporators
Loofah purchased from local market was cut into pieces (10 × 10 cm). Then, they were soaked in ethanol and deionized water to remove soluble organic and inorganic substances. Alkalized loofah (AL) was prepared by immersing pieces of loofah in sodium hydroxide solution (10 wt%) at 80 °C for 2 h to remove lignin. Carbonized loofah (CL) sponge was obtained by calcination in N2 for 2 h at 500, 600, 700 and 800 °C, and accordingly, the obtained samples were named as CL-500, CL-600, CL-700 and
Results and discussion
The preparation procedure of carbonized loofah (CL) sponge used for solar evaporation is exhibited in Scheme 1 and Fig. S2. The original loofah (Fig. S2a) was cut into slices, compressed (Fig. S2b) and treated with NaOH to remove the lignin, resulted in AL (Fig. S2c, d, e). Then the AL was carbonized in a furnace with the protection of N2 gas. After carbonization, the color of the loofah sponge turned from canary yellow to black (Fig. S2f). The obtained CL inherited the porous structure and
Conclusion
A photothermal evaporator composed of AL and CL has been explored for low-cost, multifunctional and environmentally friendly solar steam generation. The excellent light absorption, hydrophilicity, strong and reticular fibrous structure of the CL enabled highly efficient light-to-heat conversion and solar evaporation, while the AL rendered an impressive ability in rapid heavy-metal ions absorption. Upon 1.0 sun illumination, the CL + AL evaporator exhibited a high evaporation rate of 1.36 kg m−2
Acknowledgements
This work was supported by the National Natural Science Foundation of China (21975129, 51902164), Natural Science Foundation of Jiangsu Province (BK20180777), Natural Science Foundation of Jiangsu Higher Education Institutions of China (18KJB430018), and Scientific Research Foundation for Advanced Talents (GXL2018046), Science Innovation Foundation for Young Scientists (CX2018012), Nanjing Forestry University, Australian Research Council (FT190100485). This work was also partially supported by
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References (65)
- et al.
Challenges and opportunities for solar evaporation
Joule
(2019) - et al.
A 3D photothermal structure toward improved energy efficiency in solar steam generation
Joule
(2018) - et al.
Photothermal materials: a key platform enabling highly efficient water evaporation driven by solar energy
Mater. Today Energy
(2019) - et al.
A hybrid hydrogel with protonated g-C3N4 and graphene oxide as an efficient absorber for solar steam evaporation
Sustain. Mater. Technol.
(2019) - et al.
Self-assembled spectrum selective plasmonic absorbers with tunable bandwidth for solar energy conversion
Nano Energy
(2017) - et al.
High-performance wastewater treatment based on reusable functional photo-absorbers
Chem. Eng. J.
(2017) - et al.
Pt nanoparticles decorated high-defective graphene nanospheres as highly efficient catalysts for the hydrogen evolution reaction
Carbon
(2018) - et al.
An interfacial solar heating assisted liquid sorbent atmospheric water generator
Angew. Chem. Int. Ed.
(2019) - et al.
A photothermal reservoir for highly efficient solar steam generation without bulk water
Sci. Bull.
(2019) - et al.
The dispersion of au nanorods decorated on graphene oxide nanosheets for solar steam generation
Sustain. Mater. Technol.
(2019)
Extremely high water-production created by a nanoink-stained pva evaporator with embossment structure
Nano Energy
Fabrication of bilayered attapulgite for solar steam generation with high conversion efficiency
Chem. Eng. J.
A flexible photothermal cotton-CuS nanocage-agarose aerogel towards portable solar steam generation
Nano Energy
Fabrication of doped SmBaCo2O5+δ double perovskites for enhanced solar-driven interfacial evaporation
Ceram. Int.
Co3O4 nanoforest/ni foam as the interface heating sheet for the efficient solar-driven water evaporation under one sun
Sustain. Mater. Technol.
Fabrication, characteristics and applications of carbon materials with different morphologies and porous structures produced from wood liquefaction: a review
Chem. Eng. J.
Food-derived carbonaceous materials for solar desalination and thermo-electric power generation
Nano Energy
Nanocomposites based on 3D macroporous biomass carbon with SnS2 nanosheets hierarchical structure for efficient removal of hexavalent chromium
Chem. Eng. J.
Carbonized daikon for high efficient solar steam generation
Sol. Energy Mater. Sol. Cells
A salt-rejecting floating solar still for low-cost desalination
Energy Environ. Sci.
Solar absorber material and system designs for photothermal water vaporization towards clean water and energy production
Energy Environ. Sci.
The revival of thermal utilization from the sun: interfacial solar vapor generation
Natl. Sci. Rev.
Highly efficient water harvesting with optimized solar thermal membrane distillation device
Global Chall.
Solar steam generation by heat localization
Nat. Commun.
Continuously producing watersteam and concentrated brine from seawater by hanging photothermal fabrics under sunlight
Adv. Funct. Mater.
Synergistic energy nanoconfinement and water activation in hydrogels for efficient solar water desalination
ACS Nano
3D self-assembly of aluminium nanoparticles for plasmon-enhanced solar desalination
Nat. Photonics
Self-floating monodisperse microparticles with a nano-engineered surface composition and structure for highly efficient solar-driven water evaporation
J. Mater. Chem. A
Plasmonic photothermic directed broadband sunlight harnessing for seawater catalysis and desalination
Energy Environ. Sci.
Chitosan/reduced graphene oxide-modified spacer fabric as a salt-resistant solar absorber for efficient solar steam generation
J. Mater. Chem. A
A 3D-structured sustainable solar-driven steam generator using super-black nylon flocking materials
Small
A facile and general strategy to deposit polypyrrole on various substrates for efficient solar-driven evaporation
Adv. Sustain. Syst.
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