Advantages of polydimethyl diallylammonium chloride (PDADMAC; PolyDADMAC; PDDA) and instructions for use
Advantages and instructions for use of polydimethyldiallylammonium chloride (PDADMAC)
With the implementation of polymer flooding technology in major domestic oil fields, the use of some oil displacement agents has gradually increased the concentration of residual polyacrylamide and surfactants in the oil field production fluid, and a large number of 0/w emulsions have formed. Negatively charged colloidal particles are greatly increased. Cationic polymer flocculants are widely used in oilfield wastewater treatment due to their large molecular weight and large chain extension, which can neutralize electricity, adsorb and bridge, and destabilize and coalesce particles in the system. Currently in oil fields, cationic polyacrylamide and polydimethyl diallyl chloride (PDADMAC) are the most commonly used flocculants.
The results of many experiments show that:
1. When cationic polyacrylamide (CPAM) is used in sewage treatment, it is greatly affected by the stirring speed and stirring time. The flocs adhere to the wall of the vessel and are difficult to separate, corrode equipment and pipelines, are expensive, and their degradation products have relatively high Strong carcinogenicity, seriously affecting the treatment effect of sewage and practical application on site; and polydimethyldiallylammonium chloride (PDADMAC) flocculant has a unique quaternary ammonium group, extremely water-soluble, high positive charge density, It has good stability, low cost, high efficiency and non-toxicity, and is easy to operate and apply on site.
2. The optimal flocculation temperatures of polydimethyldiallylammonium chloride (PDADMAC) are 30°C and 33°C respectively; the optimal dosage range is related to the concentration of partially hydrolyzed polyacrylamide in sewage; the residual polymer content is low , when the cationicity is high, the flocculation effect is better; the combination with polyaluminum chloride (PAC) can complement each other's advantages and achieve an ideal polymer flooding sewage treatment effect.
3. In order to overcome the shortcomings of a single flocculant, from the perspective of molecular structure and performance, polydimethyl diallyl ammonium chloride (PDADMAC, solid content 40%, homopolymer molecular weight 500,000) is combined with flocs to produce light flocs. , the low-priced inorganic flocculant polyaluminum chloride (PAC) is used in combination.
In the experiment, polydimethyldiallyl ammonium chloride (PDADMAC), which has good treatment effect, stable and dense floc, and widely used polyaluminum chloride (PAC) were mixed at a ratio of 20:1, and the water temperature was 30°C. The best flocculation effect can be achieved when treating simulated sewage containing 100 mg/L polyacrylamide at 33°C.
The experimental results show that the flocculation effect of the compound flocculant is significantly better than that of a single flocculant, with the highest light transmittance of 98.0%. At this time, the oil content in the water is 6.8 mg/L, and the flocs are large and stable. , and basically floats, making post-processing easier and reaching the index of water injection back into the oil field. Therefore, when applying on site, appropriate consideration should be given to compounding flocculants with different molecular structures and properties to give full play to their respective strengths to achieve the ideal polymer flooding sewage treatment effect.
Summary
1. For simulating oil field polymer flooding wastewater, polydimethyldiallyl ammonium chloride (PDADMAC) has good flocculation effect.
2. The content of partially hydrolyzed polyacrylamide has a significant impact on the flocculation effect of sewage. When the content is low, the light transmittance of the treated sewage is higher; when the content is high, it is difficult to achieve better results even if the dosage is increased. processing effect.
3. Mixing polydimethyldiallylammonium chloride (PDADMAC) and polyaluminum chloride (PAC) in a certain amount has good results, is easy to operate and apply on site, is economical and efficient, and is environmentally friendly. It is worthy of vigorous promotion and use.
