2PL-C Formulation for High-Turbidity Deinked Pulp Streams
Molecular Mass and Anionic Charge Design of 2PL-C for Selective Adsorption in High-Turbidity Deinked Pulp
In recycled fiber lines, dissolved and colloidal substances (DCS) from mechanical pulping and deinking—hemicelluloses, extractives, lignans—create a high-turbidity environment that competes for brightener adsorption. The 2PL-C formulation (CAS 4193-55-9) is engineered with a moderate molecular mass and a strong anionic charge density, enabling selective affinity for cellulose fibers even when wash water carries 500–1500 NTU of suspended solids. Unlike cationic fixatives that aggregate DCS, this anionic brightener relies on hydrogen bonding and van der Waals forces to anchor onto fiber surfaces, minimizing quencher interference. Our process engineers have observed that in closed water loops where conductivity exceeds 3000 µS/cm, the sulfonated stilbene backbone of 2PL-C maintains a zeta potential below -25 mV, resisting flocculation with cationic trash. This behavior is critical when mills run high percentages of old corrugated containers (OCC) or mixed office waste, where stickies and pitch elevate turbidity. For a deeper dive into dryer section performance, see how Optical Brightening Agent 2Pl-C In High-Speed Fourdrinier Dryer Sections retains brightness under thermal stress.
Technical Specifications and COA Parameters for 2PL-C in Recycled Fiber Brightening
Procurement managers evaluating drop-in replacement options for incumbent OBAs will find 2PL-C aligns with standard liquid brightener dosing systems. The typical certificate of analysis includes:
| Parameter | Specification | Test Method |
|---|---|---|
| Appearance | Clear, amber liquid | Visual |
| Ionic nature | Anionic | Zeta potential |
| pH (1% solution) | 8.5 – 10.5 | pH meter |
| Density (20°C) | 1.10 – 1.20 g/cm³ | Densitometer |
| Viscosity (25°C) | ≤ 50 mPa·s | Brookfield |
| Fluorescence intensity | ≥ 95% vs. standard | Spectrofluorometer |
| Solubility in water | Miscible in all proportions | Visual |
Please refer to the batch-specific COA for exact values. The product is classified as C.I. 113 and functions as a fluorescent whitening agent that absorbs UV light and re-emits in the blue region, compensating for the yellowish hue of recycled fibers. When benchmarking against a performance benchmark like BBU, 2PL-C shows equivalent brightness gain at 0.2–0.5% on dry fiber weight, with the advantage of lower sensitivity to residual peroxide from bleaching stages. For mills transitioning from BBU, our Drop-In Replacement For Bbu Optical Brightener In Alkaline Sizing article details the substitution protocol.
Bulk Packaging and Supply Chain Reliability for 2PL-C in Pulp and Paper Mills
NINGBO INNO PHARMCHEM supplies liquid optical brightener 2PL-C in standard industrial packaging: 210L HDPE drums, 1000L IBC totes, and isotanks for bulk shipments. Each container is nitrogen-blanketed to prevent oxidative yellowing during storage. Our logistics network ensures lead times of 4–6 weeks to major ports, with safety stock held in Rotterdam and Houston for just-in-time delivery. For mills running continuous DIP lines, we offer vendor-managed inventory with real-time tank monitoring. The product is classified as non-hazardous for transportation, though we recommend storage between 5–35°C to avoid viscosity shifts. In sub-zero conditions, the formulation may exhibit a reversible increase in viscosity up to 200 mPa·s; gentle warming to 20°C restores pumpability without affecting fluorescence yield. This field observation is critical for mills in northern climates where unheated warehouses can cause dosing pump cavitation.
Field Performance of 2PL-C in Variable Feedstock Quality: Non-Standard Parameters and Edge Cases
Real-world deinked pulp streams present challenges beyond standard lab conditions. One non-standard parameter we track is the trace iron content from mill water, which can quench fluorescence. In a Southeast Asian mill using 100% recycled newsprint, iron levels of 3–5 ppm caused a 2-point ISO brightness drop. Pre-treatment with 0.1% EDTA on fiber weight restored full 2PL-C performance. Another edge case involves crystallization handling: if the product is accidentally frozen, thawing without agitation can lead to localized concentration gradients. Our recommendation is to recirculate the IBC for 30 minutes before drawing. Additionally, when mills switch from virgin pulp to high-ash recycled furnish, the ash content can exceed 15%, requiring a dosage increase of 0.1–0.2% to maintain target brightness. These adjustments are part of our formulation guide provided during technical onboarding. As a global manufacturer, we maintain application labs to simulate your specific water chemistry and furnish composition, ensuring the equivalent performance of 2PL-C as a paper brightener.
Frequently Asked Questions
What is the recommended dosage of 2PL-C for high-turbidity deinked pulp?
Start at 0.3% on dry fiber weight and adjust based on brightness targets. In streams with turbidity above 1000 NTU, a 0.1% increase may be needed to compensate for DCS adsorption. Jar tests with actual process water are essential.
How does 2PL-C maintain brightness consistency when recycled content varies?
The anionic charge and molecular mass are tuned to minimize competitive binding from anionic trash. Consistent brightness is achieved by monitoring zeta potential and adjusting dosage to maintain a fiber surface charge of -15 to -20 mV.
Can 2PL-C be used in closed water loops without buildup?
Yes, 2PL-C is designed for high solubility and low foaming. In closed systems, we recommend regular purge of the clear filtrate to prevent accumulation of non-adsorbed brightener, which can cause greening at high concentrations.
What salts are used in bleaching wood pulp that might interfere with 2PL-C?
Residual hydrogen peroxide and sodium silicate from bleaching can quench fluorescence if not properly washed. 2PL-C shows good tolerance to peroxide levels up to 50 ppm; above that, a catalase pretreatment is advised.
How to remove turbidity in process water to improve brightener efficiency?
While 2PL-C is robust, reducing turbidity through dissolved air flotation or ultrafiltration lowers DCS and improves first-pass retention. This is a mechanical pretreatment, not a chemical function of the brightener.
What is the difference between turbidity and suspended solids in this context?
Turbidity measures light scattering by colloidal and fine particles, while suspended solids are filterable matter. High turbidity often correlates with DCS that can adsorb brightener, reducing efficiency. 2PL-C's anionic nature helps it preferentially target fibers over these colloids.
Sourcing and Technical Support
As a dedicated global manufacturer of optical brightening agents, NINGBO INNO PHARMCHEM provides comprehensive technical support from lab trials to full-scale implementation. Our team assists with COA interpretation, dosage optimization, and troubleshooting in high-turbidity environments. We understand the bulk price sensitivity of paper mills and offer competitive contracts with quarterly price adjustments tied to raw material indices. For custom synthesis requirements or to validate our drop-in replacement data, consult with our process engineers directly.