| HS Code | 890013 |
| Name | Deinking Enzymes |
| Category | Industrial Enzyme |
| Enzyme Class | Hydrolases (e.g., cellulases, xylanases, lipases, esterases) |
| Primary Composition | Bacterial or fungal enzyme blends with stabilizers and carriers |
| Function | Selectively hydrolyze ink-carrying surface fibers and binders, facilitating ink release from recycled paper pulp |
| Application | Recycled paper and pulp deinking processes |
| Optimal Ph | 6.0–8.5 |
| Optimal Temperature | 40–60°C |
| Dosage | 30–300 g per ton of dry pulp depending on pulp grade and ink load |
| Appearance | Light yellow to brown liquid or fine powder |
| Solubility | Fully dispersible in water |
| Packaging | Drums, IBC totes, or bulk containers |
| Storage Conditions | Keep sealed in cool, dry, well-ventilated area away from direct sunlight |
| Shelf Life | 6–12 months from date of manufacture under recommended storage |
| Safety Profile | Non-toxic, biodegradable; avoid inhalation of dust and prolonged skin contact; use personal protective equipment |
As an accredited Deinking Enzymes factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Deinking Enzymes are supplied in 25 kg sealed drums with inner liners, ensuring safe handling, stability, and efficient storage. |
| Container Loading (20′ FCL) | Container loading of deinking enzymes in 20′ FCL involves palletized, secured packaging to ensure safe, efficient transport. |
| Shipping | Deinking enzymes ship as non-hazardous liquid concentrates in drums or IBC totes. To preserve enzyme activity, maintain temperatures between 5–25°C, avoiding freezing or excessive heat. Ensure containers are sealed, labeled, and protected from moisture. Standard freight with temperature-controlled options is recommended for optimal performance. |
| Storage | Store deinking enzymes in a cool, dry, well-ventilated area, away from direct sunlight, heat sources, and moisture. Keep containers tightly sealed to prevent contamination and humidity absorption. Optimal storage temperature is typically 5–25°C (41–77°F). Avoid freezing and excessive heat. Under recommended conditions, shelf life is generally six to twelve months. Always follow manufacturer guidelines. |
| Shelf Life | Deinking enzymes generally have a shelf life of 6–12 months when stored properly in cool, dry conditions away from sunlight. |
A recovered-fibre mill processing sorted office paper printed with electrophotographic toners typically encounters fused styrene-acrylate particles bound to alkaline-sized woodfree fibres. The bond is not solely surface adhesion; heat-fused toner penetrates surface fibrils and fines. An endoglucanase-rich cellulase preparation from Trichoderma reesei is dosed at 0.08–0.25 U/g oven-dry fibre after high-consistency pulping at 30–35% consistency. Pulping temperature is held at 45–50 °C for 30–45 min. Initial pH is adjusted to 6.5–7.0 with sodium hydroxide or acetic acid. The enzyme is introduced into the dump chest only after residual pulper hydrogen peroxide has fallen below 0.05 g/L, because peroxide oxidation of catalytic methionine residues reduces activity. The enzyme hydrolyses β-1,4-glycosidic linkages in accessible surface microfibrils, releasing toner-carrying fines; it does not solubilise the toner polymer itself. Flotation follows in three-stage primary cells at air-to-stock ratio 0.8–1.2. Accepts brightness is measured by ISO 2470-1. Effective residual ink concentration is quantified by ISO 22754. Dirt count is measured by TAPPI T 437. Recycled copy paper typically requires ERIC after flotation below 150 ppm and brightness above 88%; final copy paper with optical brightener addition is targeted at 90–92% ISO brightness. Ash content measured by ISO 1762 must be controlled below 5% to avoid reduced runnability. The deinked stock is refined in disc refiners to 35–45 °SR before forming. The end product is 70–80 g/m² recycled copy paper, with tensile strength measured by ISO 1924-2 and internal sizing alkyl ketene dimer addition adjusted because residual cellulose fines affect size retention.
With sorted old newsprint and coated magazine stock, the binder system contains mineral oil, alkyd resins, and calcium carbonate coating pigments. Traditional deinking relies on sodium hydroxide and fatty acid soaps to saponify the offset binder. An alkaline-tolerant xylanase is added to the pulper at 0.1–0.5 IU/g dry furnish at pH 7.5–8.5 and temperature 45–55 °C for 20–40 min. Pulping consistency is 10–15%. The enzyme cleaves xylan in the fibre surface, releasing coating fines and promoting ink agglomeration while reducing fibre swelling energy. The stock is then sent to coarse screening and two-stage flotation. Calcium ion concentration is maintained at 100–200 mg/L as CaCO₃ to support soap-based ink collection. Residual ink is measured by ISO 22754; target values for newsprint are typically 200–350 ppm after deinking, and ISO 2470-1 brightness of 58–62% for standard newsprint. Dirt speck count per TAPPI T 437 is held below 25 mm²/m². The deinked pulp is refined and formed on a twin-wire former into 42–48 g/m² newsprint. Because coated magazine stock contributes calcium carbonate, ash content by ISO 1762 is often 10–18%; high ash can stabilize colloidal ink and reduce flotation efficiency. The enzyme step is positioned before peroxide bleaching because residual hydrogen peroxide above 0.5 g/L can denature the xylanase within 10–15 min.
| Recovered paper grade | Enzyme type | Dosage | pH | Temperature | Time | Critical output |
|---|---|---|---|---|---|---|
| Mixed office waste toner-printed paper | Endoglucanase-rich cellulase | 0.08–0.25 U/g | 6.5–7.0 | 45–50 °C | 30–45 min | ERIC < 150 ppm; brightness > 88%; dirt 5–15 mm²/m² |
| ONP/OMG offset and letterpress stock | Alkaline-tolerant xylanase | 0.1–0.5 IU/g | 7.5–8.5 | 45–55 °C | 20–40 min | ERIC 200–350 ppm; brightness 58–62% |
| Recovered office paper for tissue/towel | Neutral cellulase | 0.05–0.15 U/g | 6.0–7.5 | 45–50 °C | 30–60 min | ERIC shift 20–50 ppm; plate count < 10⁴ CFU/g |
| Recovered mechanical pulp for SC/LWC | Hemicellulase/xylanase | 0.05–0.2 IU/g | 6.5–7.5 | 50–60 °C | 30 min | Freeness gain 15–30 mL CSF |
| Deinked top ply for white-top linerboard | Xylanase, protease-free | 0.03–0.08 U/g | 6.0–7.0 | 45–50 °C | 20–30 min | Dirt 5–10 mm²/m²; brightness 65–80% |
| Recovered printed sheets for molded fibre packaging | Neutral cellulase | 0.04–0.10 U/g | 6.5–7.0 | 40–50 °C | 45–60 min | Dirt < 20 mm²/m² |
In the production of tissue and towel from sorted recovered office paper, the deinking enzyme dose is shifted toward the lower end of the cellulase range because residual enzyme protein can interfere with wet-strength resin adsorption and Yankee coating chemistry. A neutral cellulase is applied at 0.05–0.15 U/g oven-dry fibre in a low-consistency chest at 8–12% consistency, pH 6.0–7.5, and temperature 45–50 °C for 30–60 min. The furnish is pulped in a drum pulper at 15–20% consistency, then screened through slotted baskets with slot width 0.15–0.25 mm. Flotation is followed by washing on a twin-wire press to 25–30% consistency. The washed stock is heated to 80 °C in the machine chest to denature residual enzyme before addition of polyamidoamine-epichlorohydrin wet-strength resin. Microbiological control is monitored by ISO 8784-1; heterotrophic plate counts above 10⁴ CFU/g in stock after enzyme treatment require biocide adjustment because enzyme hydrolysis releases low-molecular-weight carbohydrates that support microbial growth. Final tissue base sheet of 14–40 g/m² is formed on a crescent former with Yankee dryer creping. Compliance for food-contact tissue and towel is assessed under FDA 21 CFR 176.170 and EN 643 recovered paper sourcing; enzymes used in the stock must be listed under national food-contact substance inventories where applicable. Batch-to-batch variation in recovered office paper means that the same enzyme dose can shift the post-flotation ERIC by 20–50 ppm, measured by ISO 22754, because toner fusion severity and fibre damage vary with printer type and storage conditions.
Recovered mechanical pulp from newsprint and magazine grades contains high lignin-rich fines and a surface xylan layer that restricts water removal. In mills producing supercalendered or light-weight coated grades, a hemicellulase/xylanase preparation is dosed before the post-deinking dispersion stage at 0.05–0.2 IU/g dry pulp. pH is buffered to 6.5–7.5 and the mixture held at 50–60 °C for 30 min in a plug-flow retention tower. The enzyme partially hydrolyses the fibre surface xylan, lowering water retention and improving dewatering on the wire. Freeness is measured by ISO 5267-2; typical Scandinavian mill data show freeness gains of 15–30 mL CSF for enzyme-treated recovered mechanical pulp at constant refining energy, but published data for this specific configuration is limited due to furnish heterogeneity. Zeta potential of the stock is tracked by electrophoretic mobility; xylan hydrolysis tends to reduce the negative surface charge of lignin-rich fines, which alters retention aid demand in the short circulation loop. Dosing of cationic polyacrylamide may need reduction by 5–15% to avoid over-cationization and foam generation. The deinked stock is used in a SC furnish to reach final sheet brightness of 68–72% by ISO 2470-1, with filler clay or ground calcium carbonate added to 20–30% ash by ISO 1762. Equipment includes high-temperature dispersers and low-pulsation fan pumps. Process water temperature above 65 °C should be avoided before the enzyme stage because irreversible enzyme unfolding occurs within minutes. The final sheet basis weight is 39–60 g/m² for SC and LWC base stock.
| Parameter | Standard or method | Application context | Typical acceptance or control window |
|---|---|---|---|
| Diffuse blue reflectance brightness | ISO 2470-1 | All deinked grades | 58–92% depending on end product |
| Effective residual ink concentration | ISO 22754 | Flotation accept stock | < 150–350 ppm depending on furnish |
| Dirt count | TAPPI T 437 | Printing, tissue, packaging | 5–25 mm²/m² |
| Ash content | ISO 1762 | Coated recovered furnish | 5–30% |
| Drainability | ISO 5267-2 | Mechanical recovered pulp | Reported freeness gain 15–30 mL CSF |
| Microbial enumeration | ISO 8784-1 | Tissue and food-contact stock | < 10⁴ CFU/g post-treatment |
| Tensile properties | ISO 1924-2 | Recycled copy paper | Report for spec compliance |
| Food-contact paper components | FDA 21 CFR 176.170 | Tissue and towel | Enzyme and stabiliser listing required |
White-top linerboard uses a deinked recovered printing paper top ply over unbleached kraft or recovered baseboard. The top ply must have low visible dirt content rather than high brightness. A cellulase/protease-free xylanase is dosed into the top-ply furnish at 0.03–0.08 U/g oven-dry fibre. The lower dose is chosen because the brightness margin does not support high chemical cost. The deinking sequence includes high-consistency pulping at 25–30%, slotted screening, and a single-stage flotation cell. pH is held at 6.0–7.0, temperature 45–50 °C, and retention time 20–30 min. After flotation, the stock is washed and lightly refined to 28–35 °SR. Dirt count is measured by TAPPI T 437; typical acceptance for white-top linerboard is 5–10 mm²/m² in the top ply. Brightness of the top ply by ISO 2470-1 is typically 65–80%; printed graphics accept lower brightness but reject large visible specks. The top ply is formed at 40–70 g/m² over a 100–160 g/m² brown baseboard on a multi-ply fourdrinier. If the top-ply deinked stock contains residual pressure-sensitive adhesive particles, a subsequent hot dispersion at 90–110 °C is required because the enzyme does not hydrolyse synthetic adhesive polymers. Final combined board is tested for ply bond strength by ISO 16260. Use of deinked top ply reduces reliance on bleached virgin fibre but increases sensitivity to wet-end bacterial growth, controlled by residual biocide dosing based on ISO 8784-1 counts.
High-purity molded fibre for electronics packaging is produced from recovered printed sheets that must be deinked to remove conductive carbon black particles from newspaper and toner. A neutral cellulase is dosed at 0.04–0.10 U/g dried furnish in a batch pulper at 12–15% consistency, pH 6.5–7.0, temperature 40–50 °C, and residence time 45–60 min. The enzyme step precedes high-pressure screening and a conservative flotation stage; because the end product is a moulded three-dimensional body rather than a flat paper sheet, drainage and formation are less controlling than residual ink contamination. The stock is then refined in a low-intensity conical refiner and vacuum-formed into shapes of 1.5–3.0 mm wall thickness. A residual ink speck count above 20 mm²/m² by TAPPI T 437 is ground for rejection in high-purity molded fibre because visually clean surfaces are specified for instrument packaging. Surface resistivity of the dried molded fibre is tested according to IEC 61340-5-1 when antistatic cushioning is required; typical static-dissipative packaging targets fall between 1×10⁶ Ω and 1×10⁹ Ω. The deinked fibre must be free of wax and polyethylene coating residuals because these materials create surface voids and interfere with vacuum formation. Regulatory compliance includes REACH registration for enzyme stabilizers and absence of intentionally added per- and polyfluoroalkyl substances from the furnish chain. The application is sensitive to over-dosing because cellulase can lower fibre length beyond the acceptable forming range for deep-draw molded parts if the dose exceeds 0.15 U/g or retreatment time exceeds 90 min.
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Deinking Enzymes are supplied as a blended enzyme preparation designed for repulping recovered paper and board in neutral-to-slightly-acidic stock preparation lines. Representative product designations within the DE-500 series are DE-500 L, DE-500 G, and DE-500 HT. DE-500 L is a standardized amber liquid with specific gravity 1.05–1.15 and an as-supplied pH of 4.8–6.2. DE-500 G is a cream-colored granulate with bulk density 0.45–0.65 g/cm³, intended for dust-controlled metering and dry-handling areas. DE-500 HT is a thermostable grade screened for activity retention at 65 °C for 60 min. The preparation combines cellulase, xylanase, lipase, and esterase fractions corresponding to IUBMB designations EC 3.2.1.4, EC 3.2.1.8, EC 3.1.1.3, and EC 3.1.1.1. Minimum declared activities are cellulase 2,500 U/g, xylanase 800 U/g on birchwood xylan, and lipase 120 U/g on tributyrin, where one unit releases 1 µmol of reducing sugar or fatty acid per minute at pH 5.0 and 50 °C using the dinitrosalicylic acid reducing-sugar method. Storage at 4–10 °C preserves at least 90 % activity over 12 months. Actual release values are lot-specific and accompany each Certificate of Analysis.
Two activity axes define the product specification. The endoglucanase-rich fraction controls fiber-surface activation and ink release, while the esterolytic fraction controls binder hydrolysis and stickies conversion. This two-axis standardization separates the product from commodity cellulase-only formulations. Liquid stabilization is achieved with 20–35 wt% glycerol or sorbitol, and granular stabilization uses cornstarch or dextrin at 20–40 wt%. Microbiological limits for the liquid grade are below 1,000 CFU/g, and heavy-metal limits are below 20 mg/kg each for lead, cadmium, and mercury as measured by ICP-MS according to ISO 17294-2, with arsenic below 5 mg/kg. Batch-to-batch variation in enzyme activity is typically controlled to ±5–10 % of the declared value; production lines compensate by adjusting dosing-pump stroke based on the activity certificate rather than on volume alone. This reduces shifts in post-pulping freeness and strength properties when changing lots.
Cellulase EC 3.2.1.4 cleaves β-1,4-glycosidic bonds at accessible amorphous cellulose zones, producing controlled surface fibrillation that releases mechanically bonded ink particles without extensive fiber shortening. Xylanase EC 3.2.1.8 hydrolyzes xylan and arabinoxylan in the outer fiber wall, increasing permeability of the ink-bearing lamellae. Lipase EC 3.1.1.3 and esterase EC 3.1.1.1 hydrolyze ester linkages in vegetable-oil-derived offset vehicles and resin/alkyd binders. Detachment is monitored by ERIC at 950 nm and by TAPPI T 437 om-21 residual ink counts. In a 30 m³ batch pulper running at 12 % consistency and 50 °C, addition of 0.15 kg/t oven-dry fibre reduces ERIC by 55–75 % for offset-printed old newsprint after 45 min of pulping. The same furnish under alkaline chemical deinking at pH 10.5 commonly yields ERIC reductions of 40–60 %. The comparison is furnish-dependent, and published data for heavily UV-cured or inkjet-printed mixed office waste are limited.
The rate-limiting step in mixed recovered paper is not always esterolysis. For water-based flexographic inks and laser-printed toner, the cellulose/xylanase surface-cleavage effect determines release because the binder is not oil-based. Mills processing flexographic old newsprint report lower residual ink counts when xylanase activity is present at a cellulase-to-xylanase activity ratio of 3:1 to 5:1. Residual shive content measured by ISO 5267-2 can decline from 8 % to 3 % under optimized conditions, but screen configuration remains a cofactor. Temperature governs reaction rate; the practical maximum for standard DE-500 L is 55 °C, while DE-500 HT remains active up to 65 °C. At 70 °C, standard-grade cellulase loses more than 50 % of initial activity within 20 min. Therefore, thermostable grade selection is mandatory when high-yield recovered paper is pulped at elevated temperatures. The enzyme does not function as a dispersing collector in the manner of fatty-acid soap; it requires a subsequent flotation or washing stage to remove detached ink particles from the stock, because enzymatic activity alone leaves ink particles suspended but not separated.
Effective application in stock preparation requires controlled pH, residence time, and metering. The recommended dosage window is 0.05–0.50 kg/t oven-dry furnish, with mixed office waste typically at 0.15–0.25 kg/t and old newsprint at 0.10–0.20 kg/t. The pH is adjusted with 0.1 M citrate or acetate buffer to 6.5–7.5; below pH 5.0, cellulase activity falls below 40 % of maximum, and above pH 8.5, lipase and esterase fractions drop below 50 %. Pulping consistency of 6–15 % is acceptable, but uniform dispersion requires either a high-consistency batch pulper with rotor tip speed 12–18 m/s or a drum pulper at 14–18 rpm. At consistencies above 15 %, diffusion path length increases and enzyme access to the fiber-ink interface declines because the enzyme is bound first by cellulosic fines.
Post-pulping residence of 30–75 min is typical before flotation or washing. The enzyme is added after any high-alkali swelling stage or peroxide stabilization stage, because residual hydrogen peroxide above 0.2 % by weight in filtrate causes rapid oxidative denaturation. In closed water loops, calcium hardness of 80–250 mg/L as CaCO₃ supports fatty-acid soap function, but values above 400 mg/L can form calcium soaps that precipitate onto fibers and increase ash content as measured by ISO 1762. Flotation after enzymatic treatment is commonly performed with an air-to-stock ratio of 0.25–0.40 in a multi-cell flotation bank, and wash deinking uses multistage washers with 60–100 µm wire openings. The equipment selection does not alter enzyme dosage but determines final brightness, measured by ISO 2470-1, and ash retention.
Metering hardware should use 316L stainless steel or inert polymer wetted parts. Copper, bronze, and brass fittings are incompatible because cupric ions at 5 mg/L can inhibit cellulase activity by approximately 25 % in standard activity assay. Dosing pumps are typically peristaltic or progressive-cavity units rated for 1–20 L/h per 100 t/d production line, configured to inject into the pulper dilution water or into the pulper stock at moderate shear. Direct injection into the flotation cell is not recommended because residence time is too short for measurable enzyme action. Batch-to-batch variation in the mill furnish is addressed by running a rapid freeness check before and after enzyme addition; a post-pulping Schopper-Riegler drop of 2–6 °SR at ISO 5267-1 is a practical indicator of surface fibrillation on a specific line.
Conventional deinking of offset-printed recovered paper uses sodium hydroxide, sodium silicate, hydrogen peroxide, and fatty-acid collectors in an alkaline loop at pH 10.0–11.5. That system swells fiber, saponifies oil-based vehicles, and suspends ink through collector aggregation. It also darkens lignin-rich mechanical pulp, raises chemical oxygen demand in process water, and requires downstream neutralization. The blended enzyme system operates at pH 6.5–7.5, minimizing alkali darkening and reducing COD load by 20–40 % in published mill-scale comparisons when measured by ISO 6060. Single-enzyme cellulase products detach ink by surface fibrillation but can reduce tensile index by 5–12 % at 0.20 kg/t dosage when measured by ISO 1924-2. The three-enzyme formulation limits tensile index loss to below 7 % at the same dosage because xylanase and lipase fractions allow lower cellulase exposure times. This difference is critical for recycled containerboard and sack paper where strength retention is controlled by the final converting operation.
| Property | Test method | Alkaline surfactant deinking | Cellulase-only enzymatic | DE-500 blended enzyme |
|---|---|---|---|---|
| Process pH | Direct pH electrode | 10.0–11.5 | 5.5–7.0 | 6.5–7.5 |
| Operating temperature | Thermocouple in pulper | 45–55 °C | 45–55 °C | 50–65 °C |
| Residual ink area reduction | TAPPI T 437 om-21 | 40–60 % | 45–65 % | 55–75 % |
| ISO brightness gain | ISO 2470-1 | 4–8 points | 5–9 points | 7–11 points |
| COD load in process water | ISO 6060 | 60–120 kg/t | 35–70 kg/t | 25–55 kg/t |
| Tensile index loss at 0.20 kg/t | ISO 1924-2 | 0–5 % | 5–12 % | 1–7 % |
Range endpoints in the table are derived from pilot-scale trials and published mill water-loop data. Furnish composition, water-loop closure, and screening configuration shift the observed values. Published data for this specific configuration is limited for toner-heavy office waste, and laboratory-scale brightness gains should not be extrapolated to full-scale lines without extended stock-preparation trials. The table is intended as a comparative decision aid, not as a guaranteed process prediction.
Formulation boundaries must be observed when integrating the enzyme into existing recovered-fiber lines. The liquid grade should not be frozen; freeze-thaw cycling reduces activity by 10–15 % per cycle as determined by tributyrin hydrolysis. Granular DE-500 G must be predispersed in 10 volumes of water at 25–35 °C for 15 min before pulper addition; direct dry addition at consistency above 12 % can create localized viscosity gradients and uneven ink release. Cationic coagulants and strongly cationic retention aids should not be added within 10 min of enzyme dosing, because cationic demand can reduce enzyme adsorption onto fiber by 30–50 % and suppress the surface fibrillation needed for ink detachment. Nonionic alcohol-ethoxylate deinking surfactants at 0.05–0.15 % by weight can improve enzyme access, but anionic sulfonate collectors above 0.5 % may strip calcium from the suspension and reduce lipase/esterase activity by 20–40 %.
In closed-loop mill water with conductivity above 5,000 µS/cm, enzyme activity is partly inhibited by accumulated dissolved solids. This is visible in zero-discharge deinking mills where salt concentration rises between bleaching and pulper stages. The operational response is to dilute with fresh water to conductivity below 3,000 µS/cm or to increase dosage to the upper end of the recommended band, with verification by standard activity assay. Because enzyme performance is pH-, temperature-, and shear-sensitive, production lines with heavy deinking post-bleach towers using residual hypochlorite above 0.05 % active chlorine must neutralize the residual before enzyme addition; otherwise oxidative inactivation occurs within minutes. These are the reported operational incompatibilities that govern placement of Deinking Enzymes in stock preparation.
Handling follows protein-dust and liquid-enzyme safety protocols. Liquid DE-500 L is classified under GHS for respiratory sensitisation; dust extraction and containment should conform to EN 1822-1 filter class H13 or equivalent. For food-contact recycled paper, the formulation can be used within liners that comply with FDA 21 CFR 176.170 and EU Framework Regulation EC 1935/2004 when migration testing is completed on the finished article. REACH registration and CLP classification are lot-specific, and the safety data sheet is the controlling document.
