Copper catechol-driven Fenton reactions and their potential role in wood degradation
Copper catechol-driven Fenton reactions and their potential role in wood degradation
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DOI：
10.1016/j.ibiod.2007.10.006
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发表时间：
2008-06
影响因子：
4.8
通讯作者：
R. Valenzuela;D. Contreras;C. Oviedo;J. Freer;Jaime Rodriguez
中科院分区：
文献类型：
--
作者：
R. Valenzuela;D. Contreras;C. Oviedo;J. Freer;Jaime Rodriguez
金属可能在木材生物降解的非酶过程中发挥作用。二羟基苯还原Cu(II) -Cu (I)，然后与h2o2反应，驱动芬顿反应。本文研究了以邻苯二酚（catechol， CAT）为媒介，通过铜Fenton反应降解最简单的非酚木质素模型化合物戊曲醇（VA）。采用析因实验设计来评估几个实验变量，包括pH、CAT、cuc2和h2o2浓度对VA降解的影响。采用响应面建模方法（RSM）确定了优化条件。在CAT:CuCl2: h2o2比为0.287:0.313:4.062、pH为3.6时，VA降解量最大。在此实验条件下对VA降解进行了时间过程测量，反应8h后，VA的降解率为31%。在相同的实验条件下，铁cat驱动Fenton反应对VA的降解效果优于铜cat驱动Fenton反应。在类似的实验中，也测定了羧甲基纤维素（CMC）的解聚。发现只有铁cat驱动的Fenton反应能解聚CMC。我们认为，与Cu(II)CAT配合物相比，Fe(III)CAT配合物具有更大的氧化还原电位，这决定了在大多数环境条件下，VA的降解只会由铁配合物进行。该研究对木材褐腐真菌降解的机制具有重要意义，因为它消除了先前提出的解释细胞壁中纤维素氧化解聚产生自由基的机制。
Metals can potentially play a role in the non-enzymatic processes involved in wood biodegradation. Dihydroxybenzenes reduce Cu(II)–Cu(I), which then react with H2O2driving a Fenton reaction. In this work the degradation of veratryl alcohol (VA), the simplest non-phenolic lignin model compound, via a cuprous Fenton reaction mediated by 1,2-dihydroxybenzene (catechol, CAT) was studied. A factorial experimental design was performed to assess the impact of several experimental variables including, pH, and CAT, CuCl2and H2O2concentrations on VA degradation. Optimized conditions were determined using a response surface modeling methodology (RSM). The greatest amount of VA degradation occurred at a CAT:CuCl2:H2O2ratio of 0.287:0.313:4.062, a pH of 3.6. A time-course measurement for VA degradation was performed under these experimental conditions and after an 8h reaction period, 31% of the VA was degraded. Under the same experimental conditions, VA degradation by an iron CAT-driven Fenton reaction was more effective than the copper CAT-driven Fenton reaction. In a similar experiment, carboxymethyl cellulose (CMC) depolymerization was also determined. Only the iron CAT-driven Fenton reaction was found to depolymerize CMC. We suggest that the greater redox potential of the Fe(III)CAT complex compared to the Cu(II)CAT complex would dictate that under most environmental conditions, degradation of VA would occur by the iron complex only. This research has important implications for the mechanisms of brown rot fungal degradation in wood because it eliminates a pathway that had previously been proposed as a mechanism explaining free radical generation in the oxidative depolymerization of cellulose in the cell wall.