Department of Environmental Sciences, COMSATS University Islamabad, Abbottabad Campus, Abbottabad 22060, Pakistan.
Department of Chemistry, COMSATS University Islamabad, Abbottabad Campus, Abbottabad 22060, Pakistan.
Ecotoxicol Environ Saf. 2021 Dec 15;226:112855. doi: 10.1016/j.ecoenv.2021.112855. Epub 2021 Oct 7.
The present study reports the synthesis, photocatalytic decolorization of reactive black 5 dye and phytotoxicity of graphene quantum dots (GQDs) and iron co-doped TiO photocatalysts via modified sol gel method. GQDs were synthesized by direct pyrolysis of citric acid (CA). Scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS), Raman spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), Brunauer-Emmett-Teller (BET) and photoluminescence spectroscopy (PL) were used to determine the physicochemical properties of the best performing photocatalysts. The results indicated improved physicochemical properties of GQD-0.1Fe-TiO-300 with root mean square roughness (Rz) (33.82 nm), higher surface area (170.79 m g), pore volume (0.08 cm g), and bandgap (2.94 eV). Moreover, GQD-0.1Fe co-doping of TiO greatly improved the photocatalytic decolorization efficiency for RB5 dye. The photocatalytic reaction followed the pseudo first order reaction with gradual decrease in K values for increment in RB5 concentration. The K value was obtained as 2.45 mg L min while the K value was 0.45 L mg indicating the heterogeneous reaction system followed the Langmuir-Hinshelwood isotherm and simultaneously occurring adsorption and photocatalytic processes. Photocatalytic reaction mechanism studies exhibited the holes and OH radicals as the main active species in the GQD-0.1Fe-TiO-300 responsible for the decolorization of RB5. The proposed reaction pathway showed that both Fe-TiO and GQDs play important role in generation of electrons and holes. Additionally, GQD-0.1Fe-TiO-300 were durable up to four cycles. Phytotoxicity assay displayed that treated water and best performing photocatalysts had no effect on Lycopersicon esculentum seed germination. Therefore, the proposed system can pave a viable solution for safe usage of dye loaded wastewater and effluent for irrigation after treatment.
本研究报告了通过改进的溶胶-凝胶法合成、光催化降解活性黑 5 染料以及石墨烯量子点（GQDs）和铁共掺杂 TiO 光催化剂的植物毒性。GQDs 通过柠檬酸（CA）的直接热解合成。扫描电子显微镜（SEM）和能谱（EDS）、拉曼光谱、原子力显微镜（AFM）、X 射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、漫反射光谱（DRS）、BET 比表面积和光致发光光谱（PL）用于确定性能最佳的光催化剂的物理化学性质。结果表明，GQD-0.1Fe-TiO-300 的物理化学性质得到了改善，其均方根粗糙度（Rz）（33.82nm）、比表面积（170.79m g）、孔体积（0.08cm g）和带隙（2.94eV）更高。此外，TiO 中 GQD-0.1Fe 的共掺杂极大地提高了 RB5 染料的光催化脱色效率。光催化反应遵循准一级反应，随着 RB5 浓度的增加，K 值逐渐减小。K 值为 2.45mg L min，而 K 值为 0.45L mg，表明非均相反应体系遵循 Langmuir-Hinshelwood 等温线，同时发生吸附和光催化过程。光催化反应机理研究表明，空穴和 OH 自由基是 GQD-0.1Fe-TiO-300 中负责 RB5 脱色的主要活性物质。提出的反应途径表明，Fe-TiO 和 GQDs 都在生成电子和空穴方面发挥重要作用。此外，GQD-0.1Fe-TiO-300 在经过四周期处理后仍具有耐用性。植物毒性试验表明，处理后的水和性能最佳的光催化剂对番茄种子的发芽没有影响。因此，该系统为处理后的负载染料废水和废水的安全使用以及灌溉提供了可行的解决方案。
