Photocatalytic performance of biochar-modified TiO 2 (C/TiO 2 ) for ammonia–nitrogen removal

• Published in: RSC advances Vol. 13; no. 35; pp. 24237 - 24249
• Main Authors: Wang, Jiawei, Wang, Guoqiao, Yu, Tian, Ding, Nengjie, Wang, Meicheng, Chen, Yao
• Format: Journal Article
• Language: English
• Published: 11-08-2023
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/D3RA03789D

Biochar-modified TiO
2
(C/TiO
2
) was prepared by a sol–gel method in this study to improve the photocatalytic capacity for ammonia–nitrogen (NH
3
–N) removal from aqueous solutions. The results showed that biochar was successfully modified on TiO
2
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/TiO
2
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/TiO
2
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 TiO
2
. SEM-EDS and BET analyses displayed that C/TiO
2
had a larger surface area and more pores than the raw materials. XRD spectroscopy illustrated that C/TiO
2
had typical characteristic peaks of anatase-TiO
2
and presented a good photocatalytic degradation performance. It was confirmed from XPS and FT-IR analyses that –COOH groups were present in C/TiO
2
and originated from biochar modification, and these enhanced the photocatalytic performance. Through radical quenching experiments, it was found that superoxide radicals (˙O
2
−
) played a dominant role in NH
3
–N photocatalytic reactions with hydroxyl radicals (˙OH) and valence band holes (h
+
) playing a synergistic role. N
2
was the main degradation product after 6 h NH
3
–N photocatalytic degradation, which was much larger than NO
3
−
/NO
2
−
(both almost undetected) and NH
3
(
ca.
2 times lower than N
2
). The new composite C/TiO
2
has potential for ammonia–nitrogen degradation in wastewater treatment and favorable for treating sewage sludge.