A Turkish water filter manufacturer ordered 56 tons of coconut shell activated carbon powder for their CTO (Carbon Block) cartridge production line. The carbon is used as the primary filtration media in household and commercial drinking water filter cartridges — the type you find inside under-sink purifiers, refrigerator filters, and point-of-use water dispensers.
Here's how we handled this order from specification to delivery.
CTO stands for Chlorine, Taste, and Odor — the three things these cartridges are designed to remove from tap water. Unlike loose GAC (granular activated carbon) filters where carbon granules sit loosely inside a housing, CTO cartridges are solid carbon blocks made by mixing fine carbon powder with a polyethylene (PE) binder and sintering them under heat and pressure.
The result is a dense, uniform block with no channeling, no carbon fines in your water, and significantly better chlorine removal performance than loose GAC at the same contact time.
Why carbon powder is required:
The sintering process needs particles fine enough to create a homogeneous mixture with PE powder. If the carbon is too coarse, the block has voids, weak spots, and inconsistent filtration. Standard CTO production requires 80×325 mesh carbon powder — particles between 0.044mm and 0.177mm.
This manufacturer produces approximately 3 million CTO cartridges per year for both their own brand and OEM customers across Europe and the Middle East. Their spec:
| Parameter | Client specification | What we supplied |
|---|---|---|
| Raw material | Coconut shell | Sri Lanka origin coconut shell |
| Particle size | 80×325 mesh (≥90% within range) | 93.5% within 80×325 mesh |
| Iodine number | ≥1100 mg/g | 1150 mg/g |
| Ash content | ≤3% | 2.4% |
| Moisture | ≤5% | 3% |
| pH | 6.5–8.0 | 7.2 |
| Apparent density | 0.45–0.55 g/mL | 0.48 g/mL |
| Iron content | ≤0.05% | 0.02% |
| Acid-soluble matter | ≤1% | 0.6% |
| Water extract conductivity | ≤80 μS/cm | 52 μS/cm |
| Chlorine reduction capacity | ≥12,000 gallons (per NSF 42 at 0.5 gpm) | Verified by client's in-house test |
Why these specs matter for CTO production:
Not all activated carbon is suitable for CTO cartridge production. Here's why coconut shell dominates the drinking water filter market:
| Factor | Coconut shell | Coal-based | Wood-based |
|---|---|---|---|
| Ash content | 3% | 8–12% | 3–7% |
| Taste/odor of carbon itself | Neutral | Slight smoky note possible | Possible woody note |
| Micropore ratio | Very high (>90%) | Medium (60–70%) | Low (40–50%) |
| Chlorine removal efficiency | Excellent | Good | Fair |
| NSF 42/61 certification path | Standard | Requires more washing | Possible but less common |
| Food safety profile | Excellent | Acceptable with washing | Good |
| Cost per ton | Higher | Lower | Medium |
The micropore advantage: Chlorine molecules are small. They're captured in micropores (<2nm diameter). Coconut shell carbon has the highest micropore ratio of any activated carbon type — meaning more of its internal surface area is actually useful for chlorine removal. This translates directly to longer cartridge life.
Food safety: Drinking water cartridges must pass extractables testing — hot water is passed through the carbon and the extract is analyzed for heavy metals, PAHs, and other contaminants. Low-ash coconut shell carbon passes these tests more easily than coal-based alternatives.
For context on why our specs matter, here's the basic CTO manufacturing process:
What happens if carbon quality is wrong:
This is why CTO manufacturers are the most demanding activated carbon buyers — every parameter directly affects whether the final cartridge works or gets scrapped.
Huamei Carbon factory warehouse: 1-ton jumbo bags (FIBC) of coconut shell activated carbon stacked on wooden pallets, ready for container loading and export shipment
| Item | Detail |
|---|---|
| Packing | 1-ton jumbo bags (FIBC), double PE inner liner |
| Bags per container | 28 bags per 40'HQ |
| Total containers | 2 × 40'HQ |
| Loading | Fork-loaded, secured with dunnage bags |
| Moisture protection | Double PE liner + silica gel sachets inside each jumbo bag |
| Port of loading | Xiamen |
| Port of discharge | Mersin, Turkey |
| Transit time | 22 days |
Why double PE liner for carbon powder:
Carbon powder is hygroscopic — it absorbs moisture from air. During the 22-day sea transit through the Suez Canal (high humidity), unprotected carbon can gain 3–5% moisture. Double PE liner keeps moisture gain below 0.5% during transit. This matters because excess moisture causes sintering defects in CTO production.
After running our carbon through their CTO production line (first batch = 5 tons for validation):
They've confirmed a supply agreement for 56 tons per quarter (224 tons/year).
If you're a CTO cartridge manufacturer sourcing activated carbon, here are the key specs to look for:
| Parameter | Minimum for CTO | Ideal range | Why it matters |
|---|---|---|---|
| Raw material | Coconut shell | Coconut shell | Lowest ash, best micropore ratio |
| Mesh size | 80×200 minimum | 80×325 | Proper block density and flow rate |
| Iodine number | ≥1000 mg/g | 1100–1200 mg/g | Cartridge lifespan |
| Ash | ≤5% | ≤3% | Extractables testing |
| Iron | ≤0.1% | ≤0.05% | Prevents discoloration and metallic taste |
| pH | 6–9 | 6.5–8.0 | Neutral water output |
| Moisture | ≤8% | ≤5% | Sintering quality |
| Conductivity (water extract) | ≤150 μS/cm | ≤80 μS/cm | Low ionic leaching |
| Apparent density | 0.40–0.60 g/mL | 0.45–0.55 g/mL | Consistent block weight and density |
CTO (Carbon Block) cartridges use coconut shell activated carbon powder in 80×325 mesh size. The powder is mixed with polyethylene binder and sintered into a solid block. Coconut shell is preferred because of its high micropore content (best for chlorine removal), low ash (passes food-safety extractables tests), and neutral taste profile. Coal-based carbon is rarely used in drinking water cartridges due to higher ash and potential taste issues.
80×325 mesh (0.044–0.177mm particle size) is the standard for most 10-inch CTO cartridges. Some manufacturers use 100×325 for tighter blocks with slower flow, or 50×200 for faster flow but slightly lower chlorine removal. The exact size depends on your target flow rate and pressure drop specifications.
A standard 10-inch × 2.5-inch CTO cartridge contains approximately 300–450 grams of activated carbon (60–70% of total block weight, remainder is PE binder). A 10-inch × 4.5-inch "big blue" cartridge contains approximately 1,200–1,500 grams. One ton of carbon powder produces approximately 2,200–3,300 standard cartridges.
The carbon itself doesn't carry NSF certification — the finished cartridge does. However, the carbon must be produced to a standard that allows the cartridge to pass NSF 42 (aesthetic effects — chlorine, taste, odor) and NSF 61 (health effects — extractables). Key requirements: low heavy metals, low ash, low conductivity of water extract, no PAH contamination. We supply carbon that has been validated by multiple NSF-certified cartridge manufacturers.
Typically 6–12 months or 1,000–3,000 gallons depending on inlet water quality and cartridge size. The carbon's iodine number directly determines cartridge life — higher iodine (1100+) gives 20–30% longer life compared to standard 900 iodine carbon. Our 1150 iodine number coconut shell carbon helps manufacturers deliver longer-rated cartridges as a competitive advantage.
Huamei Activated Carbon Co., Ltd.
Website: www.huameicarbon.com
