DEGRADATION OF ORGANIC POLLUTANTS IN FLOCCULATED LIQUID DIGESTATE USING PHOTOCATALYTIC TITANATE NANOFIBERS: MECHANISM AND RESPONSE SURFACE OPTIMIZATION

Highlights

● Titanate NFs were synthesized and photodegraded liquid digestate for the first time.

● The long titanate NFs (bandgap of 3.16 eV) have a high VFA removal rate of 72.9%.

● RSM has been used to optimize the VFA, COD, and color removal rate.

● The quadratic model and the effects of photocatalytic dosage were significant.

Abstract

Titanate nanofibers (TNFs) were synthesized using a hydrothermal method and were employed for the first time in this study to photocatalytically degrade organic pollutants found in flocculated liquid digestate of poultry litter. The photocatalytic performance of TNFs, with a bandgap of 3.16 eV, was tested based on degradation of organic pollutants and removal of color. Five combinations of pollutant concentration and pH were examined (0.2 to 1.3 g·L⁻¹ at pH 4 to 10). Central composite design (CCD) and response surface methodology (RSM) were applied in order to optimize the removal rates of volatile fatty acids (VFA) and chemical oxygen demand (COD), and the decolorization rate. There were no significant differences between the regression models generated by the CCD/RSM and the experimental data. It was found that the optimal values for pH, dosage, VFA removal rate, COD removal rate and decolorization rate were 6.752, 0.767 g·L⁻¹, 72.9%, 59.1% and 66.8%, respectively. These findings indicates that photocatalytic TNFs have potential for the posttreatment of anaerobic digestion effluent, as well as other types of wastewater.

Graphical abstract

Keywords

titanate nanofibers / photocatalysis / poultry litter liquid digestate

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Supplementary materials

The online version of this article at https://doi.org/10.15302/J-FASE-2023503 contains supplementary materials (Figs. S1–S4; Table S1)

Acknowledgements

This research was supported by the Arkansas Agriculture Experiment Station of the University of Arkansas Division of Agriculture, the Center for Agricultural and Rural Sustainability, and the Graduate Professional Student Congress Tiffany Marcantonio Research Grant.

Compliance with ethics guidelines

Yiting Xiao, Yang Tian, Yuanhang Zhan, and Jun Zhu declare that they have no conflicts of interest or financial conflicts to disclose. This article does not contain any studies with human or animal subjects performed by any of the authors.

RIGHTS & PERMISSIONS

The Author(s) 2023. Published by Higher Education Press. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0)