Citric Acid-Treated Polyethylene-Calcium Carbonate Composites with Tunable Photoluminescence, Porosity, and Adsorption Properties for Oil Contaminants Remediation

Oil contamination from petroleum hydrocarbons and other sources poses significant environmental and health risks due to its persistence and toxicity. This study developed polyethylene-calcium carbonate (PE-CC) composites with tailored structural and surface properties to enhance oil adsorption. The composites were fabricated through melt blending (PE:CC = 40:60), with the calcium carbonate (CC) filler first modified using oleic acid (OA) (0, 0.5, and 1.5 wt.%) to improve hydrophobicity and dispersion, followed by citric acid (1 M) treatment of the composites to induce porosity and optimize oil adsorption. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed successful surface modification of CC, as evidenced by reduced diffraction peak intensities and the emergence of new functional groups at 2970 cm -1 and 1395.12 cm -1 . Citric acid treatment led to partial CC dissolution, resulting in up to 8.96 % weight loss, as confirmed by XRD and energy-dispersive spectroscopy (EDS). Scanning electron microscopy (SEM) revealed increased porosity (up to 40 μm) and enhanced surface roughness, particularly in TE 3. Wettability analysis demonstrated a maximum contact angle of 160.80° following OA modification of CC, while oil adsorption tests of the PE-CC composites showed substantial improvements in oil uptake, with vegetable oil adsorption increasing from 5.21 % (NE) to 18.75 % (TE 3), and hexane and diesel reaching 18.4 % and 12.5 % respectively, in TE 3. Photoluminescence analysis revealed wavelength-dependent blue-violet emissions with broad peaks at 405 and 570 nm when excited at 255 and 405 nm, respectively, indicating potential optical applications. These findings show the potential of OA and citric acid modifications in enhancing the surface properties, photoluminescence, and adsorption efficiency of PE-CC composites, positioning them as promising candidates for oil remediation and multifunctional industrial applications.