| The increasing shortage of freshwater resources,coupled with the expanding demand for agricultural and industrial water,has led to increasingly severe issues of water supply,demand,and redistribution.Therefore,promoting sustainable development of water resources is urgent.Seawater desalination,as one of the most effective ways to obtain freshwater resources,has attracted widespread attention.Membrane distillation,as an emerging seawater desalination technology,has low requirements for equipment,requires a small space,is not limited by the use environment and cost,and can meet stricter water quality standards.In addition,the combination of photothermal technology and membrane distillation technology to realize solar-driven membrane distillation can effectively solve the problems of high energy consumption and low thermal efficiency in the traditional membrane distillation process.Therefore,solar-driven membrane distillation technology has great potential in the field of seawater desalination.In this paper,two kinds of photothermal hollow fiber membranes for solar-driven membrane distillation were designed and prepared by in-situ precipitation of copper sulfide particles and blending of carbon black masterbatch with polypropylene hollow fiber membrane as the substrate.Fiber membrane,the main research contents are as follows:（1）In situ precipitation of copper sulfide on the surface of the hollow fiber membraneA composite hollow fiber membrane（PP@Cu S）with photothermal performance was obtained by in-situ precipitation of copper sulfide particles on the surface of polypropylene hollow fiber membranes,which showed good light absorption performance（light absorption rate:～75%）and light-to-heat conversion capability.Under the irradiation of simulated sunlight(1 k W m-2),the evaporation rate is 1.21 kg m-2h-1,and the evaporation efficiency is64.6%.By changing the concentration of saline water to simulate a complex seawater environment,the results showed that even in a 21 wt%sodium chloride solution,PP@Cu S-0.15 still maintaining stable evaporation,the evaporation rate is 1.02 kg m-2h-1.Choose a 3.5 wt%sodium chloride solution for 5 cycles of evaporation testing for a total of 40hours,its average evaporation rate is maintained between 1.13-1.21 kg m-2h-1.In the outdoor evaporation test,the conductivity of the 3.5 wt%sodium chloride solution configured was 55.4ms cm-1,and the conductivity of the condensate collected after evaporation was 13.01 us cm-1.The difference in conductivity of the solution before and after evaporation was 3-4 orders of magnitude,indicating that the composite hollow fiber membrane has the ability to desalinate salt water.（2）Carbon black blended polypropylene hollow fiber membraneIn the melt-spinning process,carbon black masterbatches in different proportions were added,and hollow fiber membranes（PP@CB）with photothermal properties were prepared by blending and spinning.The light absorption rate of PP@CB-9 reaches more than 77%in the spectral range of 300 nm-2500 nm.Under the irradiation of simulated sunlight(1 k W m-2),its evaporation rate is 1.69 kg m-2h-1,and the corresponding evaporation efficiency is 89.7%.In five cycles of light evaporation experiments,its fluctuation range of the average evaporation rate is controlled between 0-0.07 kg m-2h-1,indicating that the composite hollow fiber membrane has good long-term stability.In the outdoor evaporation test,the conductivity of the3.5 wt%sodium chloride solution configured was 47.6 ms cm-1,and the conductivity of the collected condensate was 10.19 us cm-1.The difference in conductivity of the solution before and after evaporation was 3-4 orders of magnitude,indicating that the composite hollow fiber membrane has the ability to desalinate salt water... |
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