Toxic effects and mechanisms of cationic blue SD-GSL on Chlorella vulgaris before and after the biological decolorization process

Jie Liang; Chong-Miao Zhang; Cong-Cong Zhu

doi:10.1016/j.chemosphere.2023.140947

Toxic effects and mechanisms of cationic blue SD-GSL on Chlorella vulgaris before and after the biological decolorization process

Chemosphere. 2024 Feb:349:140947. doi: 10.1016/j.chemosphere.2023.140947. Epub 2023 Dec 15.

Authors

Jie Liang¹, Chong-Miao Zhang², Cong-Cong Zhu¹

Affiliations

¹ School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Key Lab of Northwest Water Resource, Environment and Ecology, Ministry of Education, Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
² School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; Key Lab of Northwest Water Resource, Environment and Ecology, Ministry of Education, Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, China; International Science and Technology Cooperation Center for Urban Alternative Water Resources Development, Xi'an University of Architecture and Technology, Xi'an, 710055, China. Electronic address: cmzhang@xauat.edu.cn.

PMID: 38104738
DOI: 10.1016/j.chemosphere.2023.140947

Abstract

Biodegradation is regarded as an efficient way to decolorize azo dyes. However, the changes in the algal toxicity of azo dyes during biodecolorization are still unclear. In this study, the physiological responses of Chlorella vulgaris to the hydrophobic and hydrophilic components of cationic blue SD-GSL (a typical monoazo dye) and its biodecolorization products were investigated. The toxicity of each component to Chlorella vulgaris and the sources of the toxicity were analyzed. The cationic blue SD-GSL components inhibited the algal cell division and superoxide dismutase (SOD) activity at all concentrations, and inhibited the synthesis of chlorophyll-a (Chl-a) at concentrations >100 mg/L, whereas increased the malondialdehyde (MDA) content. The hydrophobic and hydrophilic components of its biodecolorization products had enhanced inhibition rates on cell density (10.7% and 15.6%, respectively), Chl-a content (31.2% and 8.4%, respectively), and SOD activity (13.5% and 1.9%, respectively) of Chlorella vulgaris, and further stimulated an increase in MDA content (4.4% and 7.0%, respectively), indicating that the biodecolorization products were more toxic than the pristine dye. Moreover, the toxic effect of hydrophobic components on Chlorella vulgaris was stronger than that of hydrophilic components. The sensitivity sequence of Chlorella vulgaris to the toxicity of cationic blue SD-GSL and its biodecolorization product components was: Chl-a synthesis > SOD activity > cell division. SUVA analysis and 3D-EEM analysis revealed that the enhanced algal toxicity of the biodecolorization products of cationic blue SD-GSL was attributed to the aromatic compounds, which were mainly concentrated in the hydrophobic components. UPLC-Q-TOF-MS was used to verify dye biodecolorization byproducts. The information obtained from this study helps to understand the decolorization products toxicities of the biologically treated azo dyes, thereby providing new insights into the environmental safety of textile wastewater after traditional biological treatment.

Keywords: Biodecolorization products; Cationic blue SD-GSL; Chlorella vulgaris; Resin separation; Toxicity assessment.

MeSH terms

Azo Compounds / chemistry
Biodegradation, Environmental
Chlorella vulgaris* / metabolism
Coloring Agents / chemistry
Superoxide Dismutase / metabolism

Substances

Coloring Agents
Superoxide Dismutase
Azo Compounds