Development of energy efficient flower-shaped defective TiO₂ materials for wastewater remediation of agro-industries and oil refineries

Wastewater containing high concentrations of phenolic compounds (PhCs), produced in large quantities by the world's expanding agro-industries and oil refineries, is one of the main polluters of rivers and streams. It is economically and technically reasonable to treat such wastewater using TiO₂-based photocatalysis. But in order for photocatalysis to be used on a large scale, it must degrade PhCs efficiently while using less electrical energy (EE) and treating them at lower costs (t-cost). In this study, a modified hydrothermal method was used to produce the flower-shaped defective black TiO₂ (BTNFs) from pre-prepared black TiO₂ nanoparticles (BTNPs) as an energy saving strategy in wastewater remediation. The adsorption and photocatalytic performance, energy needs, and t-costs for both materials were examined for photodegradation of PhCs from simulated oil refinery wastewater (ORW), palm oil mill wastewater (POW), and olive oil mill wastewater (OMW). The findings revealed that BTNFs have improved properties which made them more effective in adsorption of PhCs and photocatalyzing their degradation. Combining photocatalysis and adsorption based on BTNFs led to an improved removal (49.75–98.40%) of PhCs depending on the wastewater matrix and reduced the EE consumption and t-cost by 8.96–23.86% for treating OMW, POW, and ORW.