Study On The Application Of Bi-layerrd CuS/Bacterial Cellulose Solar Evaporator In Seawater Desalination

With the continuous advancement of industrialization and modernization,freshwater resources have been drastically reduced,and desalination is one of the most effective ways to alleviate this problem.Traditional seawater desalination methods,membrane processes and thermal processes,need to consume a lot of fossil fuels,which are likely to cause great harm to the environment.Therefore,solar-driven interface desalination has become one of the most promising ways to solve the shortage of freshwater resources.Among them,due to the excellent heat concentration ability of the bi-layered interface solar evaporator,the seawater evaporation rate and efficiency have been significantly improved,and it is currently the most effective interface evaporation structure.In this paper,using the low cost,low toxicity and high photothermal conversion ability of the semiconductor material copper sulfide(CuS)nanoparticles and the excellent water transport ability of bacterial cellulose(BC),a bi-layered solar evaporation system was constructed and its relevant performance was studied.The main work content is as follows:The CuS/BC composite gel film was prepared by in-situ synthesis as the photothermal conversion layer,and BC-wrapped polyethylene foam was used as the water transport and heat insulation layer to build a bi-layered solar evaporation system.The system can achieve a light absorption of 100%in the full spectrum range.Under one sun irradiation,the best evaporation rate can reach 1.79 kg m^-2 h^-1,and the evaporation efficiency can reach 98.5%.After evaporation test of40 cycles,the evaporation rate remained stable,showing the excellent reusability of the prepared CuS/BC composite gel film.Meanwhile,after continuous evaporation of 12 h of the bi-layered evaporator,no crystalline salt appeared on the surface,and the evaporation rate did not decrease significantly in the first 8 h.Besides,the flexibility,customization and portability of composite photothermal films also increase their practical value in portable solar-driven seawater desalination.The CuS/BC composite film was prepared by vacuum filtration as the photothermal conversion layer,and the dissolved and regenerated BC biofoam was used as the water transport and heat insulation layer to build the bi-layered BC biofoam evaporator.The evaporator can achieve a light absorption of 99.6%in the full spectrum.Under one sun irradiation,the best evaporation rate can reach 1.44 kg m^-2 h^-1,and the evaporation efficiency can reach 83.5%.After evaporation test of20 cycles and long-term irradiation of 8 hours,the evaporation rate remained stable,showing the reusability and long-term stability of the bi-layered evaporator.Meanwhile,the evaporator also showed a long-term stable self-floating ability of more than 6 weeks,and an excellent self-cleaning ability to clean 2 g of crystalline salt within 120 min.Also,the evaporator shows outstanding photocatalytic degradation performance and can exhibit the degradation efficiency of 93.4%for methylene blue solution(10 mg L^-1).The lightweight and stability of this solar evaporator also indicate its future application potential in the purification of seawater and dyeing wastewater.