| 摘要: | 近年來光觸媒降解環境污染物已有相當多的研究成果，本研究使用二氧化鈦(Degussa, P25)光觸媒進行光催化還原含六價鉻水溶液，以較能探討多種電洞捕捉劑對於UV光催化二氧化鈦後，還原六價鉻之影響。本研究為找出最佳反應條件，分別測試不同光強度、光觸媒濃度、電洞捕捉劑濃度、pH、六價鉻濃度等因素。本研究結果顯示當水中六價鉻溶液為0.04mmol時，最佳光催化反應條件為：30mmol二氧化鈦、0.1mmol檸檬酸為電洞捕捉劑劑量、pH3、檸檬酸與二氧化鈦比例為1：300，光強度為0.34mW/cm2時對六價鉻有最佳還原效果，且於40分鐘內可以完全還六價鉻。其他重要實驗結論，諸如：提高光強度時，還原六價鉻效果也越好；含鈉鹽的電洞捕捉劑比沒含鈉鹽的電洞捕捉劑的效果差；羧基數越高的電洞捕捉劑還原六價鉻效果也越好；二氧化鈦濃度在30mmol時還原六價鉻效果最佳；二氧化鈦添加濃度高於或低於30mmol時，還原效果會逐漸下降。
In recent years, many researcheshave confirmed the positiveresultson photo-catalytic degradation of environmental pollutants.In this study,titania (Degussa, P25) has been applied tophoto-catalytic reduction of hexavalent chromium in aqueous solution, which could discuss the effect of UV photo-catalytic under titanium dioxide by different hole scavengers, and the impact of hexavalent chromiumreduction.This study has controlledvarious conditions in order to reach the optimal results of chromium reduction,including different intensities of UV light, different pH values and differentconcentrations of photo-catalyst, various hole scavengers, and hexavalent chromium.The results indicated that the best effect on the hexavalent chromium reductionwas at photo-catalytic reaction conditions under 30mmolof titanium dioxide, 0.1mmol citric acid as hole scavenger, pH = 3, 1: 300 as the ratio of citric and a titanium dioxide,and 0.34mW/cm2 as the light intensity, whilethe hexavalent chromium was 0.04mmol in water,where the hexavalent chromium was complete reduced in 40 minutes. Moreover,the other important experimental results have confirmed some reactive conditions as below: The better effect of the hexavalent chromium reduction was accomplished whilethe increase of the light intensity.The worse result under sodiumsalt type hole scavenger as trapping agent was observed.The higher numbers of carboxyl functional group as hole scavenger illustrated better hexavalent chromium reduction.The best effect of the hexavalent chromium reduction was reached at the concentration of the titanium dioxidewas30mmol, where the reduction effect gradually decreased while the concentration of titanium dioxide higher or less than30mmol. |
