水体中常见阴、阳离子对Fe(Ⅲ)/UV催化降解罗丹明B的影响

Influence of the addition of anions and cations on photocatalytic degradation of Rhodamine B under Fe(Ⅲ)/UV

为研究溶解氧和外加阴、阳离子对Fe(Ⅲ)/UV催化降解罗丹明B的影响,在间歇式光化学反应器中进行了系列对照试验,用一级动力方程拟合得到了各种条件下罗丹明B的降解速率常数k.结果表明,溶液中氧含量增加能加速罗丹明B的Fe(Ⅲ)/UV催化降解,k提高程度与溶液pH值有关;阴离子草酸根、柠檬酸根、硝酸根能促进罗丹明B的Fe(Ⅲ)/UV催化降解,最佳草酸根和柠檬酸根用量分别为Fe(Ⅲ)物质量浓度的3和4倍,HCO3-、Cl-、腐植酸会不同程度地抑制罗丹明B的Fe(Ⅲ)/UV催化降解;阳离子钾、钠、钙、镁均可促进罗丹明B的Fe(Ⅲ)/UV催化降解,但它们对降解速率的提高程度各不相同,并与其溶液的质量浓度有关.上述结果提示Fe(Ⅲ)/UV用于处理含罗丹明B的实际废水时应注意水中其他共存离子对催化降解过程的影响.

Effects ofdissolved oxygen, anions, and cations on the degradation of rhodamine B （RB） by Fe（ Ⅲ ）/UV were investigated in the batch photoreactor. The rate constants for degradation of RB by Fe （ Ⅲ）/UV in the presence ofoxygen, anions, and cations were calculated by using the pseudo -first -order kinetic mode/. The obtained results showed that bubbling air, adddditon ofoxalate, citrate, and NO^3- could accelerate the degeradtion of RB by Fe （ Ⅲ ）/UV. The optimal dosages of oxalate and citrate were 3 and 4 times of Fe （Ⅲ ） in souhion by molar ratios HCO3^- and humic acids had the negtive effects on degradation of RB by Fe （Ⅲ ）/UV. In contrast, addition of cations, such as K^＋,Na^＋,Ca^2＋, Mg^2＋, enhanced the degration of RB under Fe（ Ⅲ ）/UV system. The extents of enhancement in removal were dependent on species of cations and their concentration in soultion. Results further indicate that when Fe（ Ⅲ ）/UV/O2 is used to treat wastewater containing RB the coexisting anions and cations should be considered to get a good decoloration efficiency.