Department of Chemistry, Government College Women University Faisalabad, Pakistan.
Department of Chemistry, Government College Women University Faisalabad, Pakistan.
Chemosphere. 2023 Jan;312(Pt 1):137095. doi: 10.1016/j.chemosphere.2022.137095. Epub 2022 Nov 2.
In present study, we describe the biodegradation of direct blue (DB) 297 and reactive blue (RB) 221 by immobilizing horseradish peroxidase (HRP) isolated from fresh leaves of Moringa Oliefera on iron oxide nanoparticles. Iron oxide nanoparticles were synthesized by co-precipitation method and showed a maximum immobilization efficiency of 87%. The surface topography of iron oxide nanoparticles was envisaged by scanning electron microscopy (SEM), results showed that magnetic nanoparticles (MNPs) were in the form of aggregates having size of 1 μm. Furthermore, immobilization was confirmed via functional group identification performed by Fourier transformed infrared spectroscopy (FTIR). Immobilization phenomena displaced the optimum temperature from 35 °C to 50 °C moreover, pH optima were altered from 5.0 to 7.0. V and K for free and immobilized HRP, were 303 U/mg and 1.66 mM and 312 U/mg and 1.94 mM, respectively. Enzymatic thermodynamic measurements (ΔH*, ΔS*, Ea, ΔG*) were also evaluated for immobilized HRP and its free counterpart. Optimum degradation of reactive blue (RB) and direct blue (DB) 297 with free and immobilized HRP was observed at pH 5 and at temperature 40 °C respectively. The removal efficiency of DB 297 and RB 221 with free HRP was 75% and 86% while with immobilized HRP was 81% and 92% respectively. Furthermore, biodegradation of reactive blue (RB) 221 and direct blue (DB) 297 with immobilized and free biocatalyst was also investigated by Fourier transform infrared spectroscopy (FTIR) by identification of groups involved in dye degradation. FTIR results confirmed the 100% degradation of dyes. Immobilized HRP retained significant catalytic activity after five consecutive cycles of dye degradation. In conclusion, FeO nanoparticles are promising and environmentally friendly media for enzyme immobilization. Moreover, immobilized HRP showed more thermal stability, pH stability and higher dye degradation efficiency as compared to free HRP. Furthermore, the immobilized HRP, economically more convenient and easily removable from reaction media. Owing to its thermal stability, ease of separation from reaction media and reusability, the magnetically separatable immobilized HRP can be exploited successfully for treatment of dye contaminated textile effluents.
在本研究中，我们描述了通过将辣根过氧化物酶（HRP）固定在从辣木（Moringa Oliefera）新鲜叶片中分离得到的氧化铁纳米粒子上来生物降解直接蓝（DB）297 和反应蓝（RB）221。氧化铁纳米粒子通过共沉淀法合成，最大固定化效率为 87%。通过扫描电子显微镜（SEM）观察氧化铁纳米粒子的表面形貌，结果表明磁性纳米粒子（MNPs）呈 1μm 大小的团聚体形式。此外，通过傅里叶变换红外光谱（FTIR）进行的官能团鉴定证实了固定化。固定化将最佳温度从 35°C 转移到 50°C，并且 pH 最优值从 5.0 变为 7.0。游离 HRP 和固定化 HRP 的 V 和 K 值分别为 303 U/mg 和 1.66 mM 以及 312 U/mg 和 1.94 mM。还评估了固定化 HRP 及其游离对应物的酶热力学测量（ΔH*、ΔS*、Ea、ΔG*）。游离 HRP 最佳降解反应蓝（RB）和直接蓝（DB）297 的 pH 值为 5，温度为 40°C，而固定化 HRP 分别为 81%和 92%。此外，还通过傅里叶变换红外光谱（FTIR）通过鉴定参与染料降解的基团，研究了固定化和游离生物催化剂对反应蓝（RB）221 和直接蓝（DB）297 的生物降解。FTIR 结果证实了染料的 100%降解。固定化 HRP 在五次连续染料降解循环后保留了显著的催化活性。总之，FeO 纳米粒子是酶固定化的有前途和环保的介质。与游离 HRP 相比，固定化 HRP 显示出更高的热稳定性、pH 稳定性和更高的染料降解效率。此外，固定化 HRP 更经济，更容易从反应介质中去除。由于其热稳定性、易于从反应介质中分离和可重复使用性，磁性可分离的固定化 HRP 可成功用于处理染料污染的纺织废水。
