Green and Environmentally Friendly NiO/TiO2@Chitosan Nanocomposites for the Photocatalytic Degradation of Anionic and Cationic Dyes Under Visible-Light Irradiation
摘要
The continuous discharge of organic dyes into water bodies has adverse effects on the environment and human health. The primary objective of this research was to prepare a novel biocatalyst by modifying green synthesized NiO/TiO2 nanocomposites (NCs) with chitosan (Cts) biopolymer. NiO/TiO2 NCs were successfully fabricated via green route utilizing an extract of Hyssopus officinalis plant. X-ray diffraction (XRD) analysis confirmed the crystalline structure of the synthesized materials. The successful deposition of HO-NiO/TiO2 on the surface of Cts was observed by field emission scanning electron microscopy (FESEM) analysis. Energy dispersive X-ray (EDX) and elemental mapping (MAP) analyses demonstrated the presence of Ni, Ti, O, C, and N elements in the HO-NiO/TiO2@Cts NCs. The functional groups of NCs were characterized by Fourier transform infrared (FTIR) analysis. The specific surface area and band gap value of the HO-NiO/TiO2@Cts NCs were determined by Brunauer-Emmett-Teller (BET) and diffuse reflectance spectroscopy (DRS) analyses, respectively. Compared to HO-NiO/TiO2, the HO-NiO/TiO2@Cts NCs demonstrated better visible light photocatalytic activity for bromocresol green (BCG) and safranin O (SO) degradation, which could be attributed to the potential effect of Cts polymer. Addition of Cts improved the photocatalytic performance of HO-NiO/TiO2, because it increased its surface area, enhancing the light-harvesting ability, and boosting the adsorption capacity. Under optimum reaction conditions, the photocatalytic efficiency of BCG by HO-NiO/TiO2 and HO-NiO/TiO2@Cts NCs, after 50 min of light, were 73% and 99%, respectively, while that of SO, after 120 min of light, were 61% and 87%. The rate constant values of HO-NiO/TiO2 and HO-NiO/TiO2@Cts NCs for BCG were calculated to be 0.0207 min−1 and 0.0806 min−1, respectively, and for SO 0.0068 min−1 and 0.0151 min−1, respectively. Reusability and regeneration studies showed the effectiveness of HO-NiO/TiO2@Cts in degrading BCG and SO across multiple test cycles. The photocatalytic degradation mechanism was elucidated based on the scavenger experimental result. Overall, the sustainable and eco-friendly fabrication process of HO-NiO/TiO2@Cts NCs, coupled with its outstanding capability to degrade cationic and anionic dyes, offers remarkable potential in wastewater treatment systems.