Oil-in-water (O/W) emulsion separation has received wide attention in the field of industrial water treatment. Mixed matrix polyvinylchloride (PVC) membranes containing 0.1–1.5 wt% silicon oxide (SiO2) as an inorganic additive obtained from two different sources were fabricated via the phase inversion method. The impact of embedding SiO2 in the PVC texture was studied by making a comparison between SiO2 nanoparticles prepared from common water reeds as a bio-source (namely bio SiO2) and commercial SiO2. The fabricated membranes were characterized via Fourier-transform infrared spectroscopy, field emission scanning electron microscope, and atomic force microscopy. Also, the water contact angle and water flux were measured. The results of the water contact angle revealed that modification of the PVC membrane by 0.5 wt% bio SiO2 reduced the contact angle from 82.3° for the neat PVC membrane to 29.7° showing that high enhancement in the membrane's hydrophilicity. The effect of oil feed concentrations (100–1000 mg/L) and temperature (25, 35, and 45 °C) on the treatment efficiency and permeate flux was investigated at trans-membrane pressures (1.5, 2.5, and 3.5 bar). The results showed that the permeation flux of the modified membranes was higher than that of the neat membrane due to enhancing the membrane's properties. Finally, the membranes were evaluated in a crossflow system with simulated O/W emulsion as a feed. The bio SiO2/PVC membranes have applicable potential in the oily wastewater treatment for their low price, good antifouling performance, and high removal efficiencies of NTU (over 98.15 %), COD (up to 99.19 %) for a membrane containing 0.5 wt% bio SiO2 used for 100 mg/L O/W emulsion.