Chlorophyll catalyse the photo-transformation of carcinogenic benzo[a]pyrene in water

Abstract

Algal blooms cause great damage to water quality and aquaculture. However, this study showed that dead algal cells and chlorophyll could accelerate the photo-transformation of benzo[a]pyrene (BaP), a ubiquitous and persistent pollutant with potently mutagenic and carcinogenic toxicities, under visible light irradiation. Chlorophyll was found to be the major active substance in dead algal cells, and generated a high level of singlet oxygen to catalyse the photo-transformation of BaP. According to various BaP metabolites formed, the degradation mechanism was proposed as that chlorophyll in dead algal cells photo-oxidized BaP to quinones via photocatalytic generation of singlet oxygen. The results provided a good insight into the role of chlorophyll in the photo-transformation of organic contaminants and could be a possible remediation strategy of organic pollutants in natural environment.

Microcystis aeruginosa Synergistically Facilitate the Photocatalytic Degradation of Tetracycline Hydrochloride and Cr(VI) on PAN/TiO2/Ag Nanofiber Mats

“…Catalysts 2018, 8, 628 8 of 13 number of the functional groups to sequester additional metal ions. They are also able to significantly accelerate the photodegradation of pollutants, because algae intracellular substances (such as chlorophylls) can absorb light energy and generate reactive species (OH, 1 O2, HOO, O2 − ) [30,31]. This work demonstrates that pure M. aeruginosa can induce the simultaneous photodegradation of TC and Cr(VI) (Figure 4), which is consistent with the previous theory that algae photolysis is a possible strategy for pollutant degradation [32].…”

“…Although both slight decrements were observed in each cycle, the M. aeruginosa-PAN/TiO 2 /Ag NF sustained high activity even after three consecutive cycles and 12 h of continuous irradiation. This result is consistent with the previous results showing that the damaged algae was efficient in the photolysis of pollutants [30,32]. These results demonstrate that bionano hybrid nanofibers have relatively high photocatalytic activity and may be recovered and reused in the combined pollutant treatment.…”

“…Algae cells can improve the absorption ability of toxic pollutants due to their extracellular organic substances release and increase the number of the functional groups to sequester additional metal ions. They are also able to significantly accelerate the photodegradation of pollutants, because algae intracellular substances (such as chlorophylls) can absorb light energy and generate reactive species (OH, 1 O 2 , HOO, O 2 − ) [30,31].…”

Algae decorated TiO2/Ag hybrid nanofiber membrane with enhanced photocatalytic activity for Cr(VI) removal under visible light

“…Although slight decrements in photocatalytic activity were observed, the algae-TiO2/Ag NF still maintained a high level of activity in successive cycles. A similar phenomenon was found in photo-transformation of aniline and benzo[a]pyrene by algae cells, and the photolysis of pollutants were still efficient in the presence of dead algae cells [26,40]. This finding confirmed that algae-TiO2/Ag NF was stable and effective for the reduction of Cr(VI) and could be easily recovered based on its good settling properties.…”

Removal of pharmaceuticals and personal care products from wastewater using algae-based technologies: a review

“…The photodegradation of Norfloxacin was enhanced with algae concentration and was influenced by temperature and pH of the solution (Zhang et al 2012a). Chlorophyll from dead algal cells has been found to be able to catalyze the photodegradation of benzo[a]pyrene by acting as a photosensitizer (Luo et al 2015). Extracellular secretions from M. aeruginosa have also been found to be able to accelerate the photodegradation of triclosan (Huang et al 2016).…”