Efficient Removal of Pharmaceutical Contaminants from Aqueous Solution Using Plant-Derived Biosurfactant-Assisted Dissolved Air Flotation Process

Abstract

This study investigates the removal of ibuprofen and diclofenac from aqueous media via a fully pressurized dissolved air flotation system, enhanced by fenugreek-derived saponin, a plant-based biosurfactant. The use of fenugreek saponin in flotation processes distinguishes this work from previous studies as it offers an ecofriendly and efficient alternative to chemical surfactants. The biosurfactant’s surface-active properties were confirmed through FT-IR, UV–vis spectroscopy identified key functional groups and structural characteristics of the saponin, NMR provided molecular insights into its bioactive components, and surface tension analyses demonstrated its ability to reduce interfacial tension, indicating effective surfactant behavior. To optimize the saponin extraction, the ultrasound-assisted extraction (UAE) method was employed using a 70% ethanolic solution for 50 min, significantly improving the flotation efficiency. Experimental conditions were carefully optimized to maximize the removal efficiency of both contaminants. For ibuprofen, the optimal pH was 5 with a retention time of 10 min, while for diclofenac, the optimal pH was 4 with a contact time of 15 min. A saponin dosage of 0.4 wt % was used in both cases, with the flotation process operating under a pressure of 15 psig and a flow rate of 0.5 L/min. Under these conditions, the process attained a maximum removal efficiency of 98.59% for ibuprofen and 95.32% for diclofenac. GC-MS results further validated the presence of bioactive components in fenugreek saponin that are responsible for its high contaminant removal capacity. Despite the challenge of scum removal during the flotation process, this study demonstrates the high efficiency of this process in treating low-concentration pollutants. The process is not only rapid but also allows for selective pollutant removal while minimizing the use of harmful chemicals, offering a more sustainable and ecofriendly solution for wastewater treatment.