Photocatalytic treatment of real liquid effluent from hydrothermal carbonization of agricultural waste using metal doped TiO₂/UV system

Abstract

This study investigated treatment of real liquid effluent generated from hydrothermal carbonization (HTC) of macadamia nut shell by employing transition metals Cu, Ni, and Fe doped titanium dioxide (TiO₂) photocatalysts. The anatase TiO₂ based photocatalysts were prepared via sol-gel method, and calcined at 400 °C. The modification with metal dopants was performed via ultrasonic assisted incipient wetness impregnation method. The prepared photocatalysts were characterized using XRD, UV-Vis DRS, SEM-EDX, and N₂ physisorption. The influence of metal dopants, types of TiO₂ support, and initial pH of the wastewater on the photocatalytic degradation performance of total organic carbon (TOC) and chemical oxygen demand (COD) in the wastewater were investigated. The results revealed that Fe doped TiO₂ exhibited the highest photocatalytic activity followed by Cu and Ni, respectively. Among all, Fe doped anatase TiO₂ were the most promising catalyst as it performed the highest removal of 75.1% for TOC and 94.1% for COD after 1 h irradiation at pH 4, achieving the lowest TOC and COD concentration of 405.62 mg/L and 91.26 mg/L, respectively. The findings suggested that photocatalytic degradation of HTC liquid effluent could be a potential treatment before releasing the wastewater to the environment.

Keywords:

• Advanced oxidation process
• hydrothermal carbonization
• treatment
• photocatalysis
• transition metal
• wastewater

Disclosure statement

The authors declare that there is not conflict of interest. There are neither competing financial interests nor personal relationships that could have appeared to influence the work reported in this paper.

Data availability statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Additional information

Funding

This work was supported by the Post-Doctoral Training Program of Khon Kaen University, Thailand (Grant Number PD2563-02-20). This work was also partially supported by the Faculty of Engineering Research Fund, Thammasat University.