Innovative oil removal system from water using magnetic nanocluster functionalized sawdust

This study presents the development of an innovative magnetic separation system for oil removal from wastewater based on a novel hydrophobic magnetic composite. The material is derived from recycled wood sawdust, functionalized with magnetic clusters coated with a silicon dioxide (SiO₂) layer for enhanced mechanical and chemical stability and further functionalized with a thin 4–7 nm layer of 3-Trimethoxysilylpropyl methacrylate (TPM), ensuring a high surface density of hydrophobic/oleophilic groups while preserving the magnetic responsiveness of the hybrid composite. The composite exhibited a saturation magnetization of 28.5 emu/g after full surface functionalization, but the structured nature of the magnetic clusters allowed for the preservation of a strong magnetic moment, ensuring efficient separation even after immobilization onto the sawdust support. Contact angle measurements confirmed the progressive increase in hydrophobicity, reaching 150.1° after TPM functionalization, indicative of the material’s superhydrophobic and oleophilic character essential for oil–water separation. The magnetic sawdust composite demonstrated high oil recovery efficiencies (93–97 %) across four oil types, with adsorption capacities ranging from 1.93 to 2.32 g/g, depending on oil viscosity and density (highest for cooking oil, lowest for vacuum pump oil). These values are comparable or superior to those of previously reported magnetic sorbents (typically 80–90 %), confirming the material’s excellent separation performance and its potential for low-cost, sustainable water remediation applications. • Innovative composite based on magnetic clusters functionalized with a TPM hydrophobic layer. • Structured magnetic clusters supported on recycled sawdust enhance response under low fields. • TPM coating gives hydrophobicity and high oil uptake. • Structured clusters retain strong magnetic moment after full functionalization. • Oil-saturated sawdust may be valorized as biofuel pellets due to increased calorific value.