Photodegradation of methylene blue with a titanium dioxide/polyacrylamide photocatalyst under sunlight

Abstract

Hydrogels containing TiO 2 nanoparticles (NPs) have photocatalytic properties and degrade pollutants under light. In this study, a polyacrylamide (PAAm) hydrogel was synthesized with TiO 2 P25 NPs as the initiator, acrylamide as a monomer, and N,N 0 -methylene bisacrylamide as a crosslinker in aqueous media under sunlight. Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and transmission electron microscopy were applied to characterize the TiO 2 /PAAm hydrogel. The effects of different synthetic conditions, such as the initiator concentration, crosslinker, and dilution, on swelling were investigated. The maximum swelling of the TiO 2 /PAAm hydrogel was 45 g/g in the hydrogel synthesized with optimum conditions by 0.2% TiO 2 . The photocatalytic degradability of the hydrogel was investigated with methylene blue (MB) as the pollutant target. Also, the effects of the pH and MB concentration were studied. Under optimum conditions, 95.00% of the MB was degraded by the TiO 2 / PAAm photocatalyst after 5 h of irradiation under sunlight. The comparison of the results with those of the TiO 2 P25 powder showed that the TiO 2 NPs had better activity than the hydrogel, but unlike the hydrogel, the activity of these NPs decreased in each recycling time because of the aggregation of NPs. Finally, the hydrogel was recycled seven times without a considerable reduction in the degradation efficiency.

Tuning morphology and mechanical property of polyacrylamide/Laponite/titania dual nanocomposite hydrogels by titania

“…Due to low toxicity and ease of preparation [10], compositing of titania (TiO 2 ) nano-particles into hydrogels not only is expected to improve the strength of gels, but also give gels some new properties. However, most of reports only focus on reinforcement of TiO 2 in polymer matrix composites as the filler [11][12][13][14]. As a result, a problem of compatibility between TiO 2 and polymers might rise, which would weaken the strength of the resultant hydrogels.…”

Photodegradation of Methylene Blue in Fe<sub>2</sub>O<sub>3</sub>–Oxalate Suspension Under UV Light Irradiation

“…Hence the percentage degradation falls. Foad Kazemi et al found the same pattern while studying photodegradation of methylene blue with a titanium dioxide/polyacrylamide photocatalyst under sunlight [26].…”

Fotodegradação Solar De Efluente Têxtil Utilizando Tio2 Imobilizado Em Alumínio Reciclado

“…Pode-se justificar uma maior eficiência do sistema com TiO2 suportado pois, apesar de se ter uma perda na área de contato superficial do catalisador com a radiação ao realizar a imobilização, sistemas com catalisador suportado podem se tornar equivalentes aos sistemas em suspensão dependendo de sua configuração (Martins et al, 2016), o que foi o caso deste trabalho. Além disso, a quantidade de catalisador em suspensão utilizada nos experimentos pode ter causado impedimento na passagem de luz, diminuindo a superfície ativa do catalisador e, com isso, gerando menores taxas de degradação; esse efeito foi observado no trabalho de Kazemi et al (2016), que estudou a remoção do corante têxtil azul de metileno por poliacrilamida contendo nanopartículas de TiO2. O uso do catalisador imobilizado apresenta como principal vantagem a fácil reutilização deste catalisador, já que a sua recuperação em suspensão é dificultada devido ao pequeno tamanho das partículas.…”