Lawsone redox (LQ) mediator was covalently bound to granular activated carbon (GAC) by Fischer esterification. A high LQ adsorption capacity on GAC was achieved (~230 mg/g), and desorption studies showed strong chemical stability. Furthermore, kinetic experiments with solid-phase redox mediator (RM) and their controls (soluble RM, GAC and anaerobic sludge) were tested for decolorization of congo red dye at initial concentration of 175 mg/L. Benzidine, a by-product of complete congo red reduction, was also measured by HPLC analysis along the kinetic experiments. The highest percentage of decolorization after 24 h of incubation was achieved in cultures with soluble (77%) and immobilized (70%) LQ. In contrast, low decolorization efficiency was reached in anaerobic bio-reduction assays with unmodified GAC (47%) and anaerobic sludge (28%) after 24 h. Removal of congo red by adsorption onto LQ-GAC was negligible. The rate of benzidine production was slower than decolorization rate, suggesting that one azo bond of congo red is selectively broke and followed by a slower breaking of the second azo bond, consequently, appearance of benzidine in solution. These issues could be attributed to the steric rearrangement and the inhibitory effects of the produced aromatic amines in the biotransformation process.

劳森酮氧化还原（LQ）介体通过Fischer酯化共价键合到颗粒活性炭（GAC）。实现了对GAC的高LQ吸附容量（〜230 mg / g），并且解吸研究显示出强大的化学稳定性。此外，还测试了使用固相氧化还原介体（RM）及其对照（可溶性RM，GAC和厌氧污泥）的动力学实验，以初始浓度175 mg / L对刚果红染料进行脱色。沿动力学实验还通过HPLC分析测量了完全还原刚果红的副产物联苯胺。孵育24小时后，在具有可溶性（77％）和固定（70％）LQ的培养物中获得了最高的脱色率。相反，在24小时后，使用未经修饰的GAC（47％）和厌氧污泥（28％）进行厌氧生物还原测定时，脱色效率较低。通过吸附到LQ-GAC上去除刚果红的方法可以忽略不计。联苯胺的生成速率比脱色速率慢，这表明刚果红的一个偶氮键被选择性地破坏，随后第二个偶氮键的破坏被缓慢地破坏，因此，溶液中出现了联苯胺。这些问题可以归因于在生物转化过程中空间重排和所产生的芳族胺的抑制作用。