Technical FAQ

Every parameter on the Vistasilica grade table carries its test method. BET surface area follows ISO 9277 / DIN 66131; DOP oil absorption follows ISO 4652 / DIN 53617; particle size D50 follows ISO 13320 by laser diffraction; sieve residue follows ISO 2591-1; poured and tapped density follow ISO 60 and ISO 697; pH follows ISO 6588; loss on drying follows ISO 787-2; loss on ignition follows ISO 6798.

Oil absorption measures how much liquid a carrier holds before the powder stops flowing, which is the property that decides whether a liquid additive can be converted into a free-flowing powder. Surface area describes the pore structure available for that uptake but does not translate directly into carrying capacity. VS-C200 is specified at DOP 240–290 g/100 g (ISO 4652) for this reason.

SiO₂ content on a dry basis is ≥ 97.0% for VS-C200, ≥ 98.0% for VS-F120, ≥ 96.0% for VS-WG180 and ≥ 98.0% for VS-OE550, determined gravimetrically or by XRF. Loss on ignition at 1000 °C (ISO 6798) is ≤ 6.0%, ≤ 5.0%, ≤ 7.0% and ≤ 10.0% respectively.

Dosage is set by trial rather than by a single published figure, because the working load depends on the liquid or active being carried, the mixer and the target storage condition. Vistasilica supplies a main sample together with a comparison sample around the metrics you name, so a trial can bracket the range. The dimension to measure differs by track: absorption capacity for carriers, bridging and storage set for anti-caking, disintegration time for WG.

Published industry literature reports typical loading ranges rather than a single figure, and these are starting points for a trial — not Vistasilica specifications. For anti-caking and flow in feed premixes and dry blends, hydrophilic precipitated silica is commonly reported at 0.5–2%, and EU rules cap silica at 2% of total feed. Used as a liquid carrier, the finished absorbate is commonly 30–50% silica. In agrochemical solid formulations, active loading on a porous carrier is commonly reported at 30–60% by weight. In edible-oil refining, published work reports silica adsorbent dosages from about 0.1% w/w for soap removal up to about 1.5% w/w for degumming. Confirm any of these against your own system before scaling.

The published static capacity for VS-DA300 was measured at 2 g/L, 25 ± 2 °C, 24 h contact and pH 6.5 — a laboratory test condition, not an operating recommendation. Peer-reviewed studies of alumina-based fluoride adsorbents report working doses of roughly 6–16 g/L, varying with pH, initial fluoride concentration and competing ions. The operating dose for a specific water should come from a jar test followed by a dynamic column trial.

VS-DA300 has a saturated static capacity of ≥ 20 mg F⁻/g by the Langmuir monolayer model, with R² ≥ 0.95. Measured at 25 ± 2 °C, 2 g/L dosage, 24 h contact and pH 6.5, equilibrium capacity is 2.6 mg/g at 5 mg/L initial fluoride (95% removal), 9.4 mg/g at 20 mg/L (84%) and 22.0 mg/g at 100 mg/L (55%).

VS-DA300 performs best between pH 5 and 7, which matches typical polishing-stage conditions. The usable range is pH 4–8.5, where at least 80% of capacity is retained. Above pH 9 capacity drops markedly, so front-end pH adjustment is recommended.

Sulphate, chloride and nitrate have only a minor effect on VS-DA300. Bicarbonate and carbonate compete for the same sites, so high-alkalinity water needs pH pre-adjustment or a higher dosage. Phosphate competes strongly and should be assessed before the bed is sized.

VS-DA300 is regenerated by soaking in 4% NaOH for 2–4 hours, rinsing to neutral, activating in 5% HCl for 1–2 hours and rinsing to neutral again. Capacity retention is ≥ 85% after 20 regeneration cycles and ≥ 75% after 50 cycles. Typical replacement interval is 1–2 years, depending on water chemistry and throughput.

Fluoride adsorption is a polishing step, not a primary removal stage. VS-DA300 is applied after front-end precipitation has taken out the bulk of the fluoride load, to bring the residual below the discharge limit. Asking an adsorbent to carry the full load shortens bed life and raises cost per cubic metre treated.

Samples are dispatched within 1–3 working days by air after a sample request. Vistasilica provides a main sample together with a comparison sample around the metrics you name, with a COA included.

Minimum order quantity varies by track. Formulation plants and blenders typically start at 200 kg–1 tonne with several grades in parallel; fluoride-removal trials can start at 25 kg for jar tests and comparison samples; industrial refineries and formulators usually run 1–5 tonne trial orders. Consolidation across grades is supported.

Packaging is 20 kg and 25 kg 3-ply kraft paper bags with an inner PE liner for standard export, palletised and stretch-wrapped. Bulk industrial shipments use 500 kg or 1,000 kg FIBC big bags, Type C or D, with a PE inner liner.

Vistasilica is a silica solutions brand under Vista, operated by Longyan Vista Chemical Co., Ltd. The model integrates supply with application support across the tracks — grade selection by scenario, fast sampling and repeat-order conversion — rather than quotation alone.

Vistasilica does not replicate brand premiums. Entry is through niche applications, second-source and backup supply, several grades in parallel and localised application review, which lowers trial cost for small and mid-sized plants. Brand names referenced remain the property of their respective owners.

No. The agrochemical track serves locally licensed formulators only, supplying inert carrier and rheology or anti-caking function. Active ingredients, efficacy and registration responsibility remain with the formulator.