Ag/TiO₂ Photocatalytic Degradation Of Phenol Under Pulse Laser Irradiation

With population growth and industrial development, human society needs more fresh water resources in recent years. “Quality water” shortage caused by environmental pollution has become a global issue. Therefore, to find a cost-effective, high efficient, low energy consumption water pollution control technology has become the essential of wastewater treatment.Photocatalytic water treatment technology has been considered as one of the most promising wastewater treatment technologies. However, most of the photocatalytic reaction has been using conventional light sources(such as xenon lamps, black lights and mercury lamps). These light sources have many drawbacks. First, consumption of their light energy is large. Second, these light provide unstable electricity. Third, the light beam is scattered and their life is short. Now a highly efficient and stable light source is the pulse laser. Their characteristic includes high energy and photon flux, a good direction and monochrome, so the pulse laser is considered as an ideal light source.In this experiment, using two different methods which was sol-gel and photochemical reduction to make Ag/Ti O2 was studied. Through degrading rhodamine B, the performances of the two Ag/TiO2 were compared. Using Ag/TiO2 with better performance degraded phenol under pulse laser. Single-factors including irradiation time, pH, phenol concentration, catalyst concentration, irradiation time, laser intensity during photocatalytic reaction with better Ag/TiO2 were analyzed. Finally, UA and pulse laser degrading phenol at the same conditions were analyzed. The conclusions as follows:(1) The best performance of those two methods was the photochemical reduction.(2) Results of single-factors as follows:a. Irradiation time: as time increases, the rate of phenol degradation increased. The total degradation time under pulse laser is 60 min.b. pH value: as p H decreased, the rate of phenol degradation increased. When pH = 5, the rate is the fastest.c. Phenol concentration, as phenol concentration increased, the degradation rate of phenol decreased. When phenol concentration was 50mg/L, the rate is the fastest.d. Catalyst concentration. When the catalyst concentration was 0.83 g /L, 1.76g/L and 2.50g/L, the degradation rate increased with increasing catalyst concentration. When the catalyst concentration was 2.50g/L, 3.30g/L and 5.00g/L, the degradation rate increased with decreasing catalyst concentration. When the concentration is 2.5g/L, photocatalytic activity is the beste. Laser intensity, when the laser pulse energy was 150 mJ, phenol degradation rate was the highest.(3) Comparative analysis of phenol degradation under different light source(pulse laser and UV).The results as follows:On the reaction time aspect, rate of phenol degradation under pulse laser was six times faster than UV; on the starting time of each reaction, degradation rate was 4.65% within 1min; however, the UV was only 0.83% within 1min; on degradation rate per unit of energy, pulse laser is about 39 times faster than UV.