Synthesis of efficient light harvesting Cr, N Co-doped TiO2 nanoparticles for enhanced visible light photocatalytic degradation of xanthene dyes; eosin yellow and rose bengal

• Published in: Environmental science and pollution research international 2023-08, Vol.30 (40), p.92621-92635
• Main Authors: Tehreem, Rida, Awais, Muhammad, Khursheed, Sanya, Rehman, Fahad, Hussain, Dilshad, Mok, Young Sun, Siddiqui, Ghayas Uddin
• Format: Article
• Language: English
• Subjects: Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Atomic force microscopy; Catalytic activity; Chromium; Current carriers; Degradation; Dopants; Dyes; Earth and Environmental Science; Ecotoxicology; Emission analysis; Environment; Environmental Chemistry; Environmental Health; Environmental science; Field emission microscopy; Fourier transforms; High performance liquid chromatography; Infrared spectroscopy; Ionization; Kinetics; Liquid chromatography; Mass spectroscopy; Microscopy; Nanoparticles; Nitrogen; pH effects; Photocatalysis; Photodegradation; Pollutant removal; Raman spectroscopy; Recombination; Research Article; Scanning electron microscopy; Sol-gel processes; Spectrum analysis; Synergistic effect; Synthesis; Titanium dioxide; Waste Water Technology; Water Management; Water pollution; Water Pollution Control; X-ray diffraction; Xanthene; Zeta potential
• ISSN: 1614-7499; 0944-1344; 1614-7499
• DOI: 10.1007/s11356-023-28701-8

   To solve the problem of water pollution, using environment friendly and cost effective method in short time is the need of hour. In this work, chromium (Cr) and nitrogen (N) co-doped TiO 2 nanoparticles were synthesized and were used for the photocatalytic degradation of dyes under visible light. The synergistic effect of metal and non-metal co-dopants added would result in appropriate reduction of band gap {from 3.2 eV of TiO 2 to 2.67 eV}, decrease in recombination rate of charge carriers by trapping electrons and holes, and in better light harvesting capacity. Nanoparticles were synthesized by sol–gel method and characterized using ultraviolet–visible (UV–VIS) spectroscopy, fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), zeta potential, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analysis, field emission scanning electron microscopy (FE-SEM), and RAMAN spectroscopy. Eosin yellow (EY) and rose bengal (RB) were subjected to photocatalytic degradation under solar light to check the photocatalytic activity of the synthesized nanoparticles. Effects of dye concentration, the concentration of nanoparticles, time, and pH were investigated to optimize the parameters. The results obtained were remarkable for 20 ppm EY solution took 10 min using 1 gL −1 NPs at pH 3 and 10 ppm RB solution took 5 min using 0.75 gL −1 NPs at pH 5.78 (original pH) for complete degradation. Kinetics studies were also performed and both dyes followed pseudo-second-order kinetics with R 2 values 0.99312 and 0.99712 for EY and RB, respectively. The study of degraded products was conducted using high-performance liquid chromatography (HPLC) hyphenated with electron spray ionization mass spectroscopy (ESI–MS) (LC–MS) and possible degradation pathways were made for both dyes. A reusability test was also performed showing the efficiency of the particles was up to 88% after 3 cycles of use. These notable results can be attributed to the efficient removal of organic pollutants using the proposed dopants in this study.