| As the source of life,water is the basic material for human survival.According to the definition of Food Safety Law of the People’s Republic of China,water is not only an important part of food,but also a necessary raw material in the production and processing of other food.However,human society is facing a serious crisis of water resources due to the increase of population and the deterioration of environment.Seawater desalination and wastewater purification is an effective way to solve the water resources crisis.Traditional desalination and purification technologies will cause a large amount of greenhouse gas emissions and environmental degradation,which restricts its further development and application.Therefore,the development of low-energy and environmentally-friendly water treatment technology is of great significance to realize the sustainable development of society.Besides,the low-energy and environmentally-friendly water treatment technology is also important for the peaking carbon dioxide emission and carbon neutrality in China.Solar evaporation technology is a new kind of desalination and purification technology based on sustainable energy.The core of the above technology is the phoththermal material,which can convert solar energy into heat and provide the heat to evaporate water.The high energy conversion efficiency of solar evaporation technology mainly depends on the following two aspects:the first strategy is to enhance the capture capacity of sunlight;the second is to effectively reduce the energy loss caused by diffuse reflection and thermal radiation heat loss.Therefore,the development of new photothermal conversion materials and evaporation devices is an important way to enhance the solar energy capture ability and reduce the energy loss caused by diffuse reflection and thermal radiation heat loss.In this thesis,we firstly developed a method to improve the stability of black phosphorus（BP）and successfully applied BP for solar interfacial evaporation.Next,we developed a new type of carbonized biomass material based on sorghum straw and built a solar evaporator based on carbonized sorghum straw.Finally,we prepared a three-dimensional（3D）cup-shaped evaporator based on carbonized sorghum straw.The results are as follows:（1）A solar interface evaporator was developed based on BP.A simple and applicable passivation strategy was established by encapsulating BP nanosheet into zeolitic imidazole framework-8（ZIF-8）.The synthesis of BP@ZIF-8 was proved by transmission electron microscope（TEM）,Raman spectroscopy and X-ray diffraction（XRD）.The stability of BP@ZIF-8 in water and phosphate buffered saline（PBS）was investigated by the thermal camera and inductively coupled plasma-mass spectrometry（ICP-MS）.Notably,BP nanosheet endows the prepared BP@ZIF-8 with prominent photothermal conversion efficiency（30.86%）.Next,BP@ZIF-8 was coated on the polyvinylidene fluoride（PVDF）film to construct a solar interface evaporator.The evaporation rate can reach 1.8342 kg m-2h-1 under 1 Sun illumination,and the solar steam conversion efficiency was 79.84%.The reusability of the solar interface evaporator was evaluated by 5 cycles testing under 1 Sun illumination,and the evaporator showed a steady evaporation rate.Bo Hai sea water,strong acid（p H 1.0）/alkaline water（p H 14.0）and wastewater containing organic dyes were chosen as the simulative water source to further investigate the potential application of the evaporator.After purification,the concentrations of K+,Ca2+,Na+and Mg2+dropped to1/6883,1/952,1/2087 and 1/12095 comparing with the original Bo Hai sea water.The electrical resistance raised from 163.2 KΩto 2.52 MΩand the bacteria can be removed during the progress of purification.The p H values of purified water obtained from acid or alkali aqueous were all close to neutral（p H 7.0）,and the treated wastewater did not contain dye.The desalinated water prepared by soalr evaporator based on BP@ZIF-8 was applied for the producing of mung bean sprouts,and the growth situation was observed.The results show that the desalinated water has certain application potential in food production.（2）A solar evaporator was developed based on biochar.The sorghum straw was chosenfor the further experiments,and biochar was obtained after a simple carbonization treatment.The results of X-ray photoelectron spectroscopy（XPS）,XRD and Raman spectrum showed that amorphous carbon was the main content in carbonized sorghum straw.The results of scanning electron microscope（SEM）showed that the carbonized sorghum straw consisted of dragon-like vascular bundle structure and dragon scale-like parenchyma cells.The pore size distribution of the carbonized sorghum straw was further investigated by a mercury porosimeter and the pore size distribution ranged from 3 to 130μm.The results of fourier transform infrared spectrometer（FT-IR）showed that the carbonized sorghum straw contained rich carboxyl groups.The contact angle of the carbonized sorghum straw was nearly 0°.Thermal imaging results showed that the carbonized sorghum straw had good photothermal properties.The thermal conductivity of the carbonized sorghum straw was0.0405 W m-1 K-1.The evaporation rate can reach 3.173 kg m-2 h-1 under 1 Sun illumination,and the solar steam conversion efficiency was 100%.The reusability of the evaporator was evaluated by 20 cycles testing under 1-4 Sun illumination,and the evaporator showed a steady evaporation rate.In addition,the carbonized sorghum stalk also displayed good resistance to salt crystallization,and the evaporation rate showed no obviously decrease during the whole evaporation process.Bo Hai sea water,strong acid（p H 1.0）/alkaline water（p H 14.0）and wastewater containing organic dyes were chosen as the simulative water source to further investigate the potential application of the evaporator.After purification,the concentrations of K+,Ca2+,Na+and Mg2+dropped to 1/2083,1/1066,1/3020 and 1/9755 comparing with the original Bo Hai sea water.The electrical resistance raised from 156.9 KΩto 1.4 MΩand the bacteria can be removed during the progress of purification.The p H values of purified water obtained from acid or alkali aqueous were all close to neutral（p H 7.0）,and the treated wastewater did not contain dye.The desalinated water prepared by soalr evaporator based on biochar was applied for the producing of mung bean sprouts,and the growth situation was observed.The results show that the desalinated water has certain application potential in food production.The present biochar opens a novel avenue for the prospective optimization and fabrication of high-efficiency solar steam evaporator.（3）A 3D cup-shaped solar evaporator based on carbonized sorghum straw was constructed.The characterization results showed that the heating rate did not affect the morphology,composition,hydrophilia and light absorption properties of the obtained carbonized sorghum straw.The pore size distribution range was wider than the previous part（2-150μm）.The evaporation rate can reach 3.27 kg m-2 h-1 under 1 Sun illumination,and the solar steam conversion efficiency was 131.2%.Compared with two-dimensional（2D）solar evaporator,the evaporation rate was increased by 2.15 times.The mechanism of the high energy efficiency for 3D cup-shaped solar evaporator was investigated by thermal camera.The wall of the 3D evaporator can efficiently absorb the reflected light and thermal radiation heat loss.The 3D cup-shaped evaporator also demonstrated excellent resistance salt ability,the evaporation rates in 3.5 wt%and 20.0 wt%Na Cl aqueous solution were3.19 kg m-2 h-1 and 3.16 kg m-2 h-1,respectively.The 3D cup-shaped solar evaporator showed stable evaporation performance in different concentrations of Na Cl solution.Bo Hai sea water,strong acid（p H 1.0）/alkaline water（p H 14.0）and wastewater containing organic dyes were chosen as the simulative water source to further investigate the potential application of the evaporator.After purification,the concentrations of K+,Ca2+,Na+and Mg2+dropped to 1/162333,1/805,1/2102 and 1/41709 comparing with the original Bo Hai sea water.The electrical resistance raised from 151.9 KΩto 1.78 MΩand the bacteria can be removed during the progress of purification.The p H values of purified water obtained from acid or alkali aqueous were all close to neutral（p H 7.0）,and the treated wastewater did not contain dye.The desalinated water prepared by 3D cup-shaped solar evaporator was applied for the producing of mung bean sprouts,and the growth situation was observed.The results show that the desalinated water has certain application potential in food production.The prepared 3D cup-shaped evaporator provides a novel solution to combating the scarcity of fresh water. |
