Magnetically recoverable copper ferrite for catalytic ozonation of surfactant-containing simulated laundry wastewater

Abstract

Laundry detergent wastewater is a valuable renewable resource released in vast quantities that can be reused to alleviate water shortage issues. The primary contaminant found in laundry wastewater, which is the surfactant has harmful impacts on the ecosystem, resulting in the eutrophication of lakes and rivers. This study examines the effectiveness of catalytic ozonation treatment using a magnetically recoverable copper ferrite to treat surfactant-containing laundry wastewater. A magnetically recoverable copper ferrite was successfully prepared using a modified sol-gel method for the remediation of detergent wastewater. The modified sol-gel method uses a low calcination temperature (350 °C) synthesis process to prepare spinel-structured copper ferrite. The physicochemical properties of the prepared copper ferrite were evaluated using XRD, FT-IR, XPS, FESEM, BET, and VSM analyses. Various process parameters such as initial concentration, solution pH, catalyst dosage, and ozone dosage were investigated to reveal the ozone activation capability and catalytic mechanism. The surfactant degradation performance in catalytic ozonation was compared with the non-catalytic ozonation, respectively. Results indicated that the copper ferrite exhibited excellent ozone activation ability, with 98.4% of surfactant degradation at an initial concentration of 10 ppm, a reaction time of 30 min, a catalyst dosage of 0.2 g/L, an initial pH of 7 and an ozone dosage of 3.68 mg/min. The chemical oxygen demand (COD) elimination rate at this setting was 79.5% compared to 26.7% for non-catalytic ozonation. The biochemical oxygen demand (BOD) removal percentages for ozonation and catalytic ozonation were 33.3% and 93.3%, respectively. Simple economical assessment using electrical energy per order (EE/O) showed that low electrical energy was consumed by the catalytic ozonation (60.31 kWhm−3order−1) compared to the ozonation process (381.68 kWhm−3order−1). The copper ferrite can be quickly recovered from the treated water by applying an external magnet, enabling catalyst reuse and easy collection of treated water. Several limitations restrict its application, including metal leaching and catalyst agglomeration. This is the first application of copper ferrite-catalysed ozonation for the remediation of laundry effluent-containing surfactants. These findings showed a vast application potential of catalytic ozonation using copper ferrite for surfactant-containing laundry wastewater treatment.