Photocatalytic performance of biochar-modified TiO2 (C/TiO2) for ammonia–nitrogen removal

• Published in: RSC advances Vol. 13; no. 35; pp. 24237 - 24249
• Main Authors: Wang, Jiawei, Wang, Guoqiao, Tian, Yu, Ding, Nengjie, Wang, Meicheng, Chen, Yao
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 14-08-2023; The Royal Society of Chemistry
• Subjects: Ammonia; Anatase; Aqueous solutions; Chemistry; Fourier transforms; Hydroxyl radicals; Infrared analysis; Infrared spectroscopy; Nitrogen; Nitrogen dioxide; Nitrogen removal; Performance degradation; Photocatalysis; Photodegradation; Photoelectrons; Raw materials; Scanning electron microscopy; Sewage sludge; Sol-gel processes; Titanium dioxide; Valence band; Wastewater treatment; X ray photoelectron spectroscopy; X-ray diffraction; Xenon lamps
• ISSN: 2046-2069
• DOI: 10.1039/d3ra03789d

Biochar-modified TiO2 (C/TiO2) was prepared by a sol–gel method in this study to improve the photocatalytic capacity for ammonia–nitrogen (NH3–N) removal from aqueous solutions. The results showed that biochar was successfully modified on TiO2 and helped improve its photocatalytic performance for pollutant degradation. The removal capacity of ammonia–nitrogen on the synthesized photocatalyst performed well at pH 10 with 1 g L−1 C/TiO2 under both 60 (12.25 mg g−1) and 120 min (16.31 mg g−1) irradiation (xenon lamp, AM1.5, 25 A). Characterization of C/TiO2 through scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectrometry (FT-IR) analyses showed the successful introduction of biochar on TiO2. SEM-EDS and BET analyses displayed that C/TiO2 had a larger surface area and more pores than the raw materials. XRD spectroscopy illustrated that C/TiO2 had typical characteristic peaks of anatase-TiO2 and presented a good photocatalytic degradation performance. It was confirmed from XPS and FT-IR analyses that –COOH groups were present in C/TiO2 and originated from biochar modification, and these enhanced the photocatalytic performance. Through radical quenching experiments, it was found that superoxide radicals (·O2−) played a dominant role in NH3–N photocatalytic reactions with hydroxyl radicals (·OH) and valence band holes (h+) playing a synergistic role. N2 was the main degradation product after 6 h NH3–N photocatalytic degradation, which was much larger than NO3−/NO2− (both almost undetected) and NH3 (ca. 2 times lower than N2). The new composite C/TiO2 has potential for ammonia–nitrogen degradation in wastewater treatment and favorable for treating sewage sludge.