Advances in adsorption for oily wastewater treatment: eco-friendly adsorbents and analytical insights

Oil spills are of great concern because oily wastewater disrupts the aquatic ecosystem, causes mutations in animals, contaminates surface water resources, and causes diseases such as cancer in humans. Current efforts are geared towards recovering spilled oil from aquatic environments and ensuring the effective separation of oil and water in the collected emulsion. After oil separation from the emulsion, a polishing step is required to treat the residual oil in the water before discharging the effluent into the aquatic environment. Oily wastewater treatment methods such as electrochemical treatment, membrane filtration, flocculation, membrane bioreactor, and advanced oxidation processes are intricate, costly, and achieve varying removal efficiencies. Adsorption using environmentally friendly and cost-effective adsorbents is seen as an attractive option. This paper provides an overview of oily wastewater treatment using adsorption. Recent adsorption studies have focused on optimizing parameters such as adsorbent dosage, pH, initial oil concentration (IC), and contact time (CT) to enhance treatment efficiency. Principal component analysis was conducted based on previous studies to understand the key parameters influencing adsorption and gain insights into the interactions between these operating variables. The findings indicated a strong positive correlation between the first principal component (PC1) CT and IC, with coefficients of 0.704 and 0.702, respectively. This suggests that positive values of CT and IC significantly contribute to the variance in PC1, meaning that the variation in PC1 is closely linked to the variation in CT and IC. New materials could be produced to enhance selectivity to target specific pollutants in oily wastewater.