不同分子量腐殖酸的氯化反应

Chlorination of humic acid with different molecular weights

以天然水体底泥提取的腐殖酸(HA)为研究对象,进行超滤膜分级,对不同分子量区间的HA进行氯化,考察其三卤甲烷生成能力(THMsFP)以及氯化过程中UV_(254)、A_(265)/A_(465)、A_(465)/A_(665)和红外谱图的变化情况。结果表明:不同分子量级别的HA样品具有相似的结构,但其含氧官能团数量随分子量降低呈现增加趋势。氯化反应破坏了多重聚合苯环结构,生成了饱和脂肪烃类结构、烯烃类不饱和C=C结构、C=O、C-O官能团和C-Cl、C-Br结构。由于不同分子量范围HA的C=C不饱和结构和C-O官能团数量不同,导致各个分子量HA的THMsFP产率和其溴代贡献因子不同。其中10~30 kDa的HA具有最大的THMsFP产率和最小的溴代贡献因子。

The humic acid(HA)extracted from the sediment was separated by ultrafiltration,and chlorinated subsequently.The trihalomethanes formation potential(THMsFP)UV-Vis and infrared spectrum of HA fractions with different molecule weight(MW)were analyzed.The results showed that the HA samples with different MW levels had similar structures,while the number of oxygen-containing functional groups increases while decreasing the MW.The aromatic structures were destroyed and the aliphatic hydrocarbon structures,olefin unsaturated structures,C=O,C-O and C-Cl,C-Br structures were formed during chlorination.The amount of THMsFP yields and bromine incorporation in THMs,n(Br)THMs,were affected by unsaturated structures and C-O functional groups in HA fractions with different MW.The HA with MW between 10~30 kDa had the highest THMsFP yields and lowest n(Br)THMs.