Precipitated silica — grade specifications
Censil Silica precipitated silica is a synthetic amorphous silica (SiO₂·nH₂O, CAS 112945-52-5) produced by controlled precipitation. The grade family below spans feed additives, food powders, oral care, agrochemical, edible oil refining and industrial fluoride removal — each differentiated by surface area, particle size and absorption to match the target application.
Typical physical properties — grade family comparison
| Property | Unit | CS-C200 Carrier | CS-F120 Flow Aid | CS-A070 Abrasive | CS-T400 Thickener | CS-WG180 WG Carrier | CS-OE550 Adsorbent | Test method |
|---|---|---|---|---|---|---|---|---|
| BET specific surface area | m²/g | 170 – 230 | 100 – 150 | 45 – 90 | 350 – 450 | 160 – 210 | 400 – 600 | ISO 9277 / DIN 66131 |
| Oil absorption (DOP) | g/100g | 240 – 290 | 180 – 230 | 90 – 140 | 260 – 310 | 200 – 250 | 180 – 260 | ISO 4652 / DIN 53617 |
| Particle size D50 | µm | 10 – 18 | 5 – 12 | 6 – 12 | 8 – 15 | 12 – 22 | 8 – 18 | ISO 13320 (laser diffraction) |
| Sieve residue (45 µm) | % | ≤ 0.10 | ≤ 0.05 | ≤ 0.05 | ≤ 0.10 | ≤ 0.15 | ≤ 1.0 | ISO 2591-1 |
| Bulk density (poured) | g/L | 90 – 140 | 110 – 170 | 180 – 260 | 70 – 110 | 100 – 160 | 350 – 500 | ISO 60 |
| Tapped density | g/L | 140 – 210 | 170 – 250 | 280 – 400 | 110 – 170 | 150 – 230 | 450 – 600 | ISO 697 |
| pH (5% aq. suspension) | — | 6.0 – 7.5 | 6.0 – 7.5 | 6.5 – 7.5 | 6.5 – 7.5 | 6.0 – 7.5 | 4.0 – 6.5 | ISO 6588 |
| Loss on drying (105 °C, 2 h) | % | 4.0 – 7.0 | 4.0 – 6.0 | 4.0 – 6.0 | 5.0 – 8.0 | 4.0 – 7.0 | ≤ 8.0 | ISO 787-2 |
| SiO₂ content (dry basis) | % | ≥ 97.0 | ≥ 98.0 | ≥ 98.0 | ≥ 97.0 | ≥ 96.0 | ≥ 98.0 | Gravimetric / XRF |
| Loss on ignition (1000 °C) | % | ≤ 6.0 | ≤ 5.0 | ≤ 5.0 | ≤ 7.0 | ≤ 7.0 | ≤ 10.0 | ISO 6798 |
CS-DA300 Fluoride Adsorbent — separate specification
CS-DA300 is a functionalised adsorbent rather than a conventional precipitated-silica grade, so its parameters are not comparable to the table above. The active aluminium species is supported on a precipitated silica framework; it is neither granular activated alumina nor food-grade white carbon black. Scope is industrial fluoride-bearing wastewater only — not drinking water, municipal supply or household treatment.
| Property | Unit | CS-DA300 |
|---|---|---|
| SiO₂ content (dry basis) | % | ≥ 70 |
| Al₂O₃ content (active component, dry basis) | % | 8 – 15 |
| Na₂O content | % | ≤ 0.5 |
| BET specific surface area | m²/g | 250 – 350 |
| Particle size (granular) | mm | 0.5–1 / 1–3 (customisable) |
| Bulk density (granular) | g/cm³ | 0.45 – 0.65 |
| Crush strength | N/particle | ≥ 25 (1–3 mm) |
| Attrition rate | % | ≤ 1.0 |
| pH (5% aq. suspension) | — | 6.0 – 8.0 |
| Loss on ignition (1000 °C) | % | ≤ 10 |
| Saturated static fluoride capacity (Langmuir Qmax) | mg F⁻/g | ≥ 20 |
| Optimal operating pH | — | 5 – 7 (usable 4 – 8.5 at ≥ 80% capacity) |
Static capacity measured at 25 ± 2 °C, 2 g/L dosage, 24 h to equilibrium, pH 6.5. Dynamic capacity runs at roughly 70–80% of the static figure — size columns on the dynamic number. Full grade data, regeneration procedure and competing-ion behaviour are on the fluoride removal solution page.
Grade application map
| Grade | Application track | Typical use | Key performance focus |
|---|---|---|---|
| CS-C200 Carrier | Feed additives · Food powders | Premix carrier, liquid-additive powdering, vitamin/trace-mineral blends | High liquid absorption, carrier capacity, dispersion uniformity |
| CS-F120 Flow Aid | Feed additives · Food powders | Anti-caking, flow aid for seasoning powders, dry blends | Free-flow improvement, shelf stability, anti-bridging |
| CS-A070 Abrasive | Oral care | Toothpaste abrasive, cleaning-type paste formulations | Controlled RDA, cleaning efficiency, paste stability |
| CS-T400 Thickener | Oral care | Toothpaste thickener, structure-building, thixotropy | Thickening, paste structure, extrusion performance |
| CS-WG180 WG Carrier | Agrochemical | WP/WG inert carrier, SC anti-caking / rheology modifier | Active loading, disintegration, suspension stability |
| CS-OE550 Adsorbent | Edible oil refining | Silica adsorbent for degumming / soap & phosphatide removal / filter aid | Phospholipid & soap adsorption, high surface area & pore volume, filtration |
| CS-DA300 Fluoride Adsorbent | Industrial fluoride removal | Deep fluoride removal and end-of-line polishing after front-end precipitation, in industrial wastewater | Fluoride capacity (≥ 20 mg F⁻/g), pH tolerance, dynamic breakthrough, regeneration life |
Regulatory & compliance
- REACH: Registered under EINECS 231-545-4 (silicic acid)
- Food additive (EU): E 551 — Reg. (EU) No 231/2012 (food-grade grades only)
- Food additive (US): 21 CFR § 172.480 (food-grade grades only)
- Feed material: Listed in EU Register of Feed Materials (silicic acid, precipitated)
- Cosmetics (EU): INCI: Hydrated Silica — Reg. (EC) No 1223/2009
- Nano status: Not a nanomaterial as defined by EU 2015/2283
- Hazard classification: Not classified as hazardous per CLP Reg. (EC) 1272/2008
- Kosher / Halal: Available upon request (food-grade grades)
Typical heavy-metal content (food / feed grade)
| Parameter | Unit | Typical max | Reference limit |
|---|---|---|---|
| Lead (Pb) | mg/kg | ≤ 5 | FCC / EU 231/2012: ≤ 5 ppm |
| Arsenic (As) | mg/kg | ≤ 3 | FCC / EU 231/2012: ≤ 3 ppm |
| Cadmium (Cd) | mg/kg | ≤ 1 | Industry standard: ≤ 1 ppm |
| Mercury (Hg) | mg/kg | ≤ 1 | FCC / EU 231/2012: ≤ 1 ppm |
| Heavy metals (as Pb, total) | mg/kg | ≤ 10 | FCC: ≤ 10 ppm |
Packaging
- 20 kg paper bag — 3-ply kraft with inner PE liner, standard export packaging
- 25 kg paper bag — 3-ply kraft with inner PE liner, palletized and stretch-wrapped
- 500 kg big bag (FIBC) — Type C or D with PE inner liner, bulk industrial shipments
- 1,000 kg big bag (FIBC) — Type C or D with PE inner liner, bulk industrial shipments
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