Oil spills significantly contribute to water pollution, posing severe environmental and health hazards. This study investigates the potential of functionalized composites in treating oily wastewater, utilizing natural fibers as substrates. Specifically, raw cotton was combined with activated carbon and carbon nanotubes to create three types of composites A, B, and C made up of charcoal, activated carbon, and carbon nanotubes generated from walnut shells. These composites were fabricated using ultrasonic treatment, autoclaving, and drying processes, and subsequently evaluated for their oil adsorption capacities and recovery efficiencies. Fourier Transform Infrared Spectroscopy analysis revealed the presence of functional groups such as carboxylic acids, aldehydes, alkenes, esters, and carbonyls, indicating significant chemical interactions between carbon nanotubes and oil. Scanning Electron Microscopy images showed cylindrical and twisted structures of the carbon nanotubes composites, with minor cracks becoming visible at higher magnifications. The initial weights of the charcoal, activated carbon, and carbon nanotubes composites were 1.25 g, 1.25 g, and 1.00 g, respectively, which increased to 6.74 g, 6.98 g, and 6.53 g after treatment. Activated carbon and carbon nanotubes composites demonstrated superior oil removal efficiencies, achieving recovery rates of 97.31% and 99.88%, respectively, and maintaining 100% efficiency over five cycles. In continuous flow systems, the efficiencies of activated carbon and carbon nanotubes were found to be 70% and 74%, respectively. This research underscores the high potential of carbon nanotubes-based composites for water treatment, demonstrating excellent oil recovery and adsorption capabilities.
