Nonionic polyacrylamide (NPAM) is a water-soluble high molecular polymer or polyelectrolyte. Because its molecular chain contains a certain number of groups, it has the functions of flocculation, dispersion, thickening, bonding, film formation, gelation, and colloid stabilization. It can a
Non ionic polyacrylamide is a water-soluble polymer or polyelectrolyte. Due to the presence of a certain number of polar groups in its molecular chain, it can adsorb solid particles suspended in water, bridging between particles or causing particle aggregation to form large flocs through charge neutralization. So, it can accelerate the settling of particles in the suspension, significantly improve solution clarification, and promote filtration. Mainly used for flocculation, sedimentation, and clarification treatment of various industrial wastewater. Such as wastewater treatment for papermaking and pulp processing, wastewater treatment for mineral processing and metal smelting processes, wastewater treatment for steel and stone processing plants, etc.
The mechanism of action of non-ionic polyacrylamide is mainly based on the following characteristics:
1. Hydrogen bond adsorption and bridging
The amide group (- CONH ₂) adsorbs onto the surface of particles (such as sediment and organic colloids) through hydrogen bonding, and long-chain molecules act as "bridges" to connect multiple particles, forming a network structure of particle polymer particle, allowing small particles to aggregate into large flocs.
Features: Not dependent on charge neutralization, suitable for neutral or low charge particles (such as proteins, starch colloids).
2. Physical wrapping and roll scanning
When the concentration of NPAM is high, polymer chains intertwine with each other in the solution to form a three-dimensional network structure, and suspended particles are wrapped and settled through physical capture, especially suitable for high turbidity and low viscosity wastewater (such as river raw water and sand washing wastewater).
3. Dehydration and floc reinforcement
The hydrophilicity of amide groups can capture the hydration film on the surface of particles, making them easier to contact and aggregate; At the same time, the internal structure of the formed flocs is loose and porous, with low moisture content, which facilitates subsequent dewatering (such as sludge conditioning).
1. Non ionic properties, wide acid-base adaptability
The molecular chain is electrically neutral and not affected by the pH value of the solution. It can stably function under strong acidic to strong alkaline conditions (pH 1-14), especially suitable for water with large pH fluctuations or complex water quality (such as chemical wastewater and acidic mineral water).
2. Strong adsorption bridging ability
Amide groups (- CONH ₂) can adsorb onto particle surfaces through hydrogen bonding (regardless of particle charge properties), and long-chain molecules can effectively connect multiple particles to form large and loose flocs, suitable for low surface charge suspension systems (such as organic colloids and sediment particles).
3. Excellent dispersibility and thickening properties
After dissolving in water, it forms a high viscosity solution with both dispersion stability and thickening effect:
Dispersion: prevents particle aggregation of pigments, fillers, and other materials (such as coatings and ceramic slurries);
Thickening: improve the viscosity of the system (such as oilfield drilling fluid and daily chemical lotion), and the thickening efficiency is higher than that of the anionic type.
4. Outstanding salt tolerance
Due to the absence of ionic groups, it is not easily affected by calcium, magnesium, and sodium ions, and its flocculation effect in high salt wastewater (such as papermaking black liquor and oilfield produced water) is significantly better than that of anionic and cationic types.
5. Mild and efficient, low toxicity and environmentally friendly
Low dosage (usually 0.1-5ppm) and low residual monomer content (≤ 0.05%) meet environmental standards and can be used in scenarios with high safety requirements such as food processing and medicine.
6. Significant synergistic effect
Often used in combination with inorganic flocculants (such as polyaluminum chloride PAC): first reduce the surface charge of particles through PAC, and then strengthen bridging with NPAM to improve flocculation speed and floc strength.
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