A sustainable carbon–silica based adsorption membrane system derived from asphaltene oil-contaminated sand and acrylic fiber waste for water purification

Asphaltene-contaminated sand poses a significant environmental threat and presents substantial challenges as a waste product. The immediate and serious risks it poses to ecosystems and human health demand urgent action. This study presents an innovative carbon-based SiO 2 composite that is synthesized from crude oil-contaminated sand using a carefully controlled thermal treatment process at 600 °C and 1200 °C, with the temperature difference influencing the material’s properties. The synthesized C@SiO 2 was characterized and evaluated for its ability to effectively remove copper ions (Cu²) from water. We thoroughly examined crucial factors that impact the affinity and efficiency of Cu²⁺ sorption, such as contact time, adsorbent dosage, initial concentration, and competitive adsorption behaviors. It is clearly shown that the maximum adsorption achieved 95.06% after 120 min in the presence of a 2 g/L adsorbent for C@SiO 2 -600, while C@SiO 2 -1200 exhibited a lower initial efficiency of 33.02%, reflecting the temperature effect. The Langmuir isotherm best fits the data, indicating monolayer adsorption with a maximum capacity of ~ 30.67 mg/g using sample prepared at 600 °C, which decreases with sample prepared at 1200 °C due to potential thermal degradation. Kinetic studies favor the pseudo-second-order model (R² = 0.9996) for C@SiO 2 -600, suggesting chemisorption, with a reduced fit with C@SiO 2 -1200 . The C@SiO 2 -600 adsorbent demonstrates excellent reusability, maintaining 90% efficiency over four cycles, whereas C@SiO 2 -1200 loses effectiveness by the third cycle, highlighting the temperature difference’s impact on stability. This study demonstrates an innovative and eco-friendly approach to convert asphaltene-contaminated sand into a valuable resource for water treatment, enhancing waste valorization and improving heavy metal remediation, with C@SiO 2 -600 proving more advantageous than C@SiO 2 -1200. To further enhance water purification efficiency, the synthesized C@SiO 2 was incorporated into an acrylic fiber waste matrix to fabricate ultrafiltration (UF) membranes. The resulting composite membranes exhibited improved hydrophilicity, mechanical strength, and antifouling behavior compared to pristine acrylic membranes. The modified membranes (NCM1 &NCM2), containing C@SiO 2 prepared at 600 & 1200 °C, respectively, achieved a pure water flux of approximately 60 LMH and demonstrated excellent removal performance, rejecting up to 98% of humic acid. These results confirm that the integration of upcycled C@SiO 2 into acrylic fiber-based membranes not only enhances pollutant removal efficiency but also contributes to sustainable waste valorization and advanced water treatment solutions.