The Study On Residue Phosghine Degradation By UV Light In Grain Storage

In this paper, the efficacy of stored grain fumigant phosphine degraded by UV light wasconducted with the equipment pantent of CN101559322. The effect of phosphine gas sourceoperating factors, environmental conditions, initial concentration and different equipmentmode on opitical degradation was explored. Then the changes of total phosphorus content ingrain after degradation of phosphine were analysized. The results were stated as followings:At25℃,75%RH, when the initial phosphine concentration was100mL/m3, during aprocess of80-hours, the decrease of the concentrations of phosphine was less than8mL/m3and15mL/m3in the dark and natural condition respectively. In contrtast, the concentration ofphosphine was significantly decreased by254nm UV light and the half-life time was24-32hours under the experimental condition.At75%RH、254nm UV light, when the initial phosphine concentration was100mL/m3,with the temperature of20、25、30℃respectively, the decrease of the concentrations ofphosphine was81.00、86.25、90.00mL/m3. The effect of phosphine degradation was notaffected by relative humidity at the same temperature.At25℃,75%RH, when the initial phosphine concentration was100mL/m3, with thetreatment of continue irradiating (254nm UV light), phosphine concentration was declinedfrom100mL/m3to37.50mL/m3after80-hours. The concentration of phosphine irradiatedby365nm UV light was decreased from100mL/m3to14.25mL/m3at the same time. Thehalf decreasing time of100mL/m3phosphine was48-hours under the condition of continousirradiation of365nm UV light, and that was24-hours when treated with254nm light. After80-hours, the percentage of the degradation of phosphine was73.88%、77.61%、85.82%withthe power of40、80、120W of254nm UV light, respectively. The higher power of UV light,the ercentage of the degradation of phosphine was strengthened by the increase of thepower of UV light under the same wavelength.The processing of degradation to0mL/m3were200h,160h,136h with the initialconcentration of phosphine of300mL/m3,200mL/m3,100mL/m3, respectively; the initialconcentration of phosphine significantly influenced the UV light degradation efficacy, and thedegradation percentage could reach100%eventually; By UV light, the higher initialconcentration, the higher degradation percentage, but the longer of the processing time. There were some differences between the degradation effect for phosphine underdifferent modes of UV light. It is higher degradation efficiency unit of phosphine under thecontinuous work mode. And the half time was48-56hours in the way of intermittentoperation mode with254nm light. The more phosphine can be degraded per hour in continueirradiation with254nm UVC. Intermittent operation mode has great reference value inpractical application.Phosphorus content in wheat is significantly increased after degradation by UV light.Thehigher initial concentration of phosphine gas, the phosphorus content increased with theincrease of initial concentration of phosphine gas. Phosphorus content exerts no significantchange in grain after a certain period of time using the airtight storage.In conclusion, UV light has better degradation effect on the phosphine gas, using UVdegradation device to process phosphine fumigation exhaust is promising. UV degradationtechnology of phosphine fumigation exhaust can provide support for fumigation reduction,avoid the harmful effect of environment as weel as, enhance the scientific and technologicallevel of the industry, indicating prospective application in the future.