Performance Of Carbon Modified Hollow Fiber Membrane And Its Interface Evaporation Module

With the development of society and the increase of global population,the shortage of fresh water resources has become one of the most critical problems facing human society.As a new water treatment technology,solar interface evaporation technology,which produces fresh water for the area with lack of fresh water resources and does not destroy the environment,has become the focus of researchers in recent years.Although great progress has been made in the efficiency of photothermal conversion,the large-scale application of solar interface evaporation system is still restricted by the complexity and high cost of material preparation process.Therefore,it has great potential and commercial value to develop a solar interface evaporation system with low cost,simple structure,easy processing,good optical absorption and high evaporation efficiency.The surface of PVDF was modified by physical and chemical methods.Two kinds of carbon composite hollow fiber membrane filaments,namely GR-PVDF and CNT-PVDF,were successfully prepared.Two new types of carbon composite membrane filaments were characterized and tested,including light absorption Mechanical properties,tensile stress,scanning electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy and Raman spectroscopy were analyzed.It is found that the two kinds of carbon composite film filaments greatly improve the light absorption performance of the original PVDF film filaments,and CNT-PVDF has better light absorption and larger external contact area than GR-PVDF.Therefore,in theory,CNT-PVDF has stronger heat collection efficiency and thermal conductivity than GR-PVDF.The evaporation module of hollow fiber membrane interface based on the above two carbon materials is designed independently.A solar desalination water system based on the carbon material modified hollow fiber membrane is built.The water yield of the system is analyzed.The influence of membrane material and solar irradiance on the surface temperature of membrane and working medium temperature in membrane module is studied.The results show that:The system is in the process of The average membrane flux of GR-PVDF and CNT-PVDF components increased by 33%and 46%respectively when the irradiance of 800W/m² was stable for 6 hours;The change of membrane material and irradiance on the surface temperature of membrane and working medium temperature in membrane module was basically the same,and all of them rose rapidly at a large rate,and the rising rate began to decrease after a period of time,and finally became stable,all of which were positively correlated The results showed that the temperature of GR-PVDF and CNT-PVDF was 29.0%and 45.5%higher than that of PVDF membrane wires,and the average working medium temperature of the film was23.1%and 34.9%higher than that of PVDF membrane wires.The water production performance of the system was optimized by heating the working medium at room temperature.The system worked stably for 6 hours under800W/m² irradiation,and the optimal membrane flux was 4.23 L·m^-2·h^-1（GR-PVDF）and4.67 L·m^-2·h^-1（CNT-PVDF）is 20.5%and 21.3%higher than that before optimization.According to the optimization results,a large-scale carbon composite hollow fiber membrane solar desalination water system is built.It is estimated that the system can work stably for 8 hours under 800W/m²,and the daily average water production can reach 64L and 70L in theory,which can meet the daily water demand of a three port family.The cyclic repeat experiment was carried out to evaluate the cycle performance and durability of the composite membrane module.