In the field of industrial oily wastewater treatment,the SFM surface-modified filter media filter is a product worth dismantling from a technical bottom-up perspective. Its core competitiveness does not lie in the structural design of the filter—that is engineering optimization—but in the surface chemical modification of the filter media itself. Today we break it down from three technical dimensions: modification principle, comparative advantage, and emulsified oil separation mechanism.

I. Modification Principle: Covalent Grafting+ Strong Hydrogen-Bonded Hydration Layer

The starting point of SFM modification technology is the silanol groups (Si–OH) on the quartz sand surface. Unmodified quartz sand has limited and randomly distributed silanol group density, which is the chemical root cause of its insufficient hydrophilicity. SINOKLE’s modification process introduces high-density hydrophilic functional groups onto the quartz sand surface through covalent bonds via chemical reaction—including hydroxyl (–OH), carboxyl (–COOH), and sulfonic acid (–SO₃H) groups. The advantage of covalent bonding lies in stability: these functional groups are not physically adsorbed on the surface but are firmly connected to the quartz sand substrate through chemical bonds and will not fall off under long-term water flow scouring.

The interaction mechanism between these functional groups and water molecules is strong hydrogen bonding. Each–OH, –COOH, –SO₃H group can serve as a hydrogen bond donor or acceptor to form a multiple hydrogen-bond network with water molecules, ultimately building a hydration layer with a thickness of no less than 8 nanometers on the filter media surface. This hydration layer changes the wettability of the filter media surface from a physical-chemical essence—the static water contact angle of quartz sand before modification is about 20°–40°, and after modification it drops sharply to below 5°, reaching the superhydrophilic range (θ<10°). This means the spreading coefficient (S = γ_SV − γ_SL − γ_LV) of water on this surface is positive, and water droplets instantly spread completely.

II. Multi-dimensional Comparison with Traditional Quartz Sand

From the perspective of engineering parameters,the gap between SFM modified filter media and traditional quartz sand is comprehensive:

① Desorption rate: SFM conventional water backwash >95%, traditional quartz sand about 60%–70%;

② Backwash cycle: SFM extended by 3–5 times;

③ Contact angle: SFM <5°, traditional quartz sand 20°–40°;

④ Filter media life: SFM designed for 5 years, traditional quartz sand 2–3 years;

⑤ Surface modification method: SFM uses covalent chemical grafting, traditional quartz sand relies on natural silanol groups. The difference in these parameters originates from the qualitative change in surface chemical properties—the former is a superhydrophilic functional interface, the latter is merely a weakly hydrophilic inert surface.

III. Emulsified Oil Demulsification-Coalescence Mechanism

Emulsified oil treatment isanother key battlefield where SFM filter media differs from traditional quartz sand. The stability of emulsified oil droplets originates from the interfacial film formed by surface-active substances adsorbed on the oil droplet surface. The high-density active groups (–OH, –COOH, –SO₃H) and micro-nano structures on the SFM filter media surface can interact with the emulsified oil droplet surface: the active groups break the original adsorption equilibrium on the oil droplet surface through hydrogen bonding or electrostatic action, reducing the mechanical strength of the interfacial film; the micro-nano structures provide a large number of high-curvature sites, promoting the preferential aggregation of oil droplets at these sites.

When the emulsion passes through the filter media layer, the destabilized oil droplets collide, coalesce, and coalesce on the filter media surface—gradually merging from small oil droplets (μm level) into large oil droplets (mm level). The large oil droplets detach from the filter media layer under buoyancy and float to the liquid surface, completing oil-water separation. Throughout the process, the superhydrophilic hydration layer on the filter media surface continuously ensures that the water phase preferentially passes through the filter media pores, while the hydrophobic oil phase is continuously intercepted outside the filter media layer—water takes the water path, oil takes the oil path, and the two phases are spatially separated. This is the working logic of SFM filter media’s integrated "physical demulsification + coalescence separation."

From a technical depth perspective,SFM modified filter media successfully transforms the design idea of interfacial chemistry into an industrially replicable filtration material, backed by the intersection of three disciplines: materials science, chemical engineering, and fluid mechanics. For technicians engaged in industrial water treatment, this is a scheme worth studying carefully.