NO3-对二级出水DOM与Cu^2+络合作用的光谱特性影响

Effect of NO3-on spectral characteristic of the complexation of DOM and Cu2+from secondary effluent.

利用三维荧光光谱法和紫外分光光度法,研究NO3-对二级出水DOM与Cu^2+络合作用的光谱特性和络合能力的影响.随投加NO3-浓度增加,二级出水DOM与Cu^2+络合作用后代表类蛋白质(类色氨酸)物质荧光峰消失,紫外吸收峰右侧红移.投加NO3-浓度与二级出水DOM和Cu^2+络合作用后的HIX、α300、α250/α365、E3/E4和UV253/UV203值呈显著正相关,与BIX显著负相关(r为-0.958^-0.719),与S240-400和S275-295值分别呈指数增加和指数减少关系(R 2分别为0.9678~0.9952和0.9965~0.9978),对FI、α350、α355和S350-400值影响较小.二级出水DOM中的紫外光类腐殖质、可见光类腐殖质和高激发波长类色氨酸物质与Cu^2+作用后的条件稳定常数lgK分别为2.08~2.46,1.84~2.51,2.27~2.57L/mmol,配位荧光官能团比例分别为19.5%~36.5%、22.5%~33.3%和24.4%~29.2%.二级出水DOM中类腐殖质和类蛋白质与Cu^2+的络合反应强度相差不大,且样品中NO3-浓度不同时,用部分荧光参数(HIX)和紫外参数(α300、α250/α365、E3/E4、S240-400和S275-295)表示DOM的含量、分子性质存在一定的不确定性.

The effects of nitrate on the spectral characteristics and complexation ability of DOM with Cu^2+in the secondary effluent of municipal wastewater were investigated by using three-dimensional fluorescence and UV spectrophotometry.The fluorescence peak representing the protein-like(tryptophan-like)produced by complexation of DOM and Cu^2+disappeared with the increase of NO3-concentration,and the right side of the UV absorption peak occurred red-shift.The concentration of NO3-was significantly positively correlated with the values of HIX,α300,α250/α365,E3/E4 and UV253/UV203 after complexation of DOM with Cu^2+,while negatively correlated with BIX(r with-0.958^-0.719).It had an exponential increase with S240-400(R2 with 0.9678~0.9952)and an exponential decrease with S275-295(R2 with 0.9965~0.9978),but had little effect on the values of FI,α350,α355 and S350-400.The conditional stability constant lgK of ultraviolet humus-like,visible humus-like and high excitation wavelength tryptophan-like in the secondary effluent of DOM with Cu^2+were 2.08~2.46L/mmol,1.84~2.51L/mmol and 2.27~2.57L/mmol,respectively;and the proportion of coordination fluorescent functional groups were 19.5%~36.5%,22.5%~33.3%and 24.4%~29.2%,respectively.In summary,there was not significant difference in the intensity of the complexation reaction between Cu^2+and humus-like or protein-like from DOM of the secondary effluent.When the NO3-concentration in the samples was different,there were some uncertainties in expressing the content of DOM and molecular properties with partial fluorescence(HIX)and ultraviolet parameters(α300,α250/α365,E3/E4,S240-400 and S275-295).