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环境化学  2015 

合成腐殖酸氧化还原能力与光学性质探究

Keywords: 合成腐殖酸,氧化还原能力,光学性质,三维荧光

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Abstract:

本文以合成商业腐殖酸Aldrichhumicacids(AHA)与国药化学试剂腐殖酸(TJHA)为研究对象,与铁氰化钾反应测定不同浓度AHA与TJHA还原前后氧化还原能力.研究发现,原态和还原态的HA均能向铁氰化钾传递电子,还原后两种HA的氧化还原能力均大于其原态的氧化还原能力.原态和还原态TJHA的单位碳电子转移数(原态1.49meq·gC-1;还原态20.95meq·gC-1)均大于AHA(原态0.52meq·gC-1;还原态1.75meq·gC-1).同时随着HA浓度的增加,两种HA的原态与还原态单位碳电子转移数均逐渐降低(AHA0.91—0.52meq·gC-1;TJHA13.57—1.49meq·gC-1),而AHA单位体积电子转移数目逐渐增大(0.002—0.072meq·L-1),TJHA单位体积电子转移能力无明显变化.这是由于在HA与铁氰化钾电子转移体系中,氧化还原能力的高低与腐殖酸中氧化还原官能团数量和分布有关,与HA粒径大小,分子质量也有关系.进一步通过E465,E4/E6值表明两种HAE465值与浓度呈明显正线性关系,E4/E6值与浓度呈对数增加趋势.三维荧光分析发现,HA还原后,激发/发射(Ex/Em)峰出现蓝移,相对荧光强度降低,说明HA还原的过程中有π—π*的断裂.进一步对HA荧光测定发现TJHA中具有更多数量的氧化还原官能团而AHA中氧化还原官能团种类相对丰富.

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