EFFECT OF FULVIC ACID WITH DIFFERENT MOLECULAR WEIGHT ON UV DEGRADATION OF MICROCYSTINS
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摘要: 蓝藻在生长繁殖过程中会向水体中释放具有生物毒性的微囊藻毒素(MC-LR),对人体健康存在潜在威胁。富里酸(FA)是水体中广泛存在的水环境介质,其不同分子量组分对MC-LR光降解的影响机理尚未明确。通过紫外光照实验,探究不同分子量FA及相关条件因素对紫外光降解MC-LR效果的影响。结果表明:MC-LR的降解率随着pH值的增大呈先降低再上升趋势;在纯水中紫外光降解120 min后,MC-LR降解率为60.10%;加入FA后,MC-LR降解率随着其浓度的增加而提高,在10 mgC/L时有62.18%的MC-LR降解;在不同分子量FA条件下,MC-LR降解率为54.52%~65.61%,且降解过程符合一级反应动力学方程,表观速率常数在分子量3~5 kDa,浓度10 mgC/L时最高,为0.03303 min-1。研究可为优化FA与MC-LR之间的条件配比,促进MC-LR的降解提供参考。Abstract: Cyanobacteria releases biotoxic microcystin(MC-LR) into the water column during its growth and reproduction, which is a potential threat to human health. Fulvic acid(FA) is a widely present aqueous environmental medium in water bodies, and the mechanism of its different molecular weight components on the photodegradation of MC-LR is unknown. In this study, we investigated the effects of molecular weight of FA and related condition factors on UV degradation of MC-LR through UV illumination experiments. The results showed that the degradation rate of MC-LR decreased and then increased with the increase of pH value; the degradation rate of MC-LR was 60.10% after 120 min of UV degradation in pure water; after FA was added, the degradation rate of MC-LR increased with the increase of its concentration, and 62.18% of MC-LR was degraded at 10 mgC/L. Under different molecular weight FA, the degradation rate range of MC-LR was 54.52%~65.61%, and the degradation process was in good accordance with the first-order reaction kinetic equation.The apparent rate constant was the highest when the molecular weight was 3~5 kDa and the concentration was 10 mgC/L, which was 0.03303 min-1. This study provided a reference for optimizing the conditional ratio between FA and MC-LR and promoting the degradation of MC-LR.
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Key words:
- fulvic acid /
- algal toxin /
- photocatalysis /
- influencing factors /
- degradation kinetics
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