Dual polarization interferometric analysis on the interaction between fullerene grafted polymer and nonionic surfactants

Synthesis and flocculation of a novel flocculant for treating wastewater produced from polymer flooding

Preparation of a flocculant which can have high-oil removal and no viscous flocs production for treating oily wastewater produced from polymer flooding (OWPF) is meaningful work. In this paper, a novel flocculant (denoted as PDC₁₂DM) for treating OWPF was prepared by copolymerization of dodecyl dimethylallyl ammonium chloride (C₁₂DM) and dimethyl aminopropyl methacryamide (DMAPMA). By using oil removal and viscous floc production as indexes, the synthesis condition of PDC₁₂DM was optimized. The optimum PDC₁₂DM had an oil removal of 98.8% and a viscous floc production decrease of 62.86% compared with commercial cationic flocculant. Measurement of zeta potential, surface tension, interfacial tension, interfacial film strength and dual polarization interferometry tests were carried out for investigating the flocculation mechanism of PDC12DM. The results showed that PDC₁₂DM can destroy oil droplet stability by electrostatic charge neutralization and demulsification together. Especially, demulsification mechanism is helpful for reducing the viscous floc.

Preparation of a selective flocculant for treatment of oily wastewater produced from polymer flooding and its flocculant mechanism

There are residual polymers in the oily wastewater produced from polymer flooding (OWPF); keeping the residual polymer in the water during the flocculation is meaningful and challenging. In this paper, a selective flocculant (denoted as PDC10) which can remove the oil while keeping partially hydrolyzed polyacrylamide (HPAM) in water was prepared by copolymerization of decyl two methyl vinylbenzyl ammonium chloride (C10MVBA) and dimethyl aminopropyl methacryamide (DMAPMA). By using oil removal and HPAM retention as evaluation indexes, the synthesis condition of PDC10 was optimized. The optimum PDC10 exhibited oil removal of 98.0% and HPAM retention of 80.5%. Its HPAM retention is much higher than that of a regular cationic flocculant. Measurements of zeta potential, interfacial tension, interfacial dilational modulus and a dual polarization interferometry (DPI) test were carried out for investigating the flocculation mechanism of PDC10. The mechanism of PDC10 was that it can bridge and flocculate oil droplets by electrostatic interaction and hydrophobic interaction. It also preferred to distribute at the interface, and its interaction with HPAM in bulk water was weak, which confirms its selective flocculation properties.

Multi-tunable self-assembled morphologies of stimuli-responsive diblock polyampholyte films on solid substrates

Intelligent polymers, due to their sensitive stimuli response to changes in the environment, have gained increasing amounts of attention over recent years and have become a popular topic in polymer materials science. In this study, the aggregation behaviors and stimuli responses of the stimuli-responsive diblock polyampholyte poly(2-(dimethylamino)ethyl methacrylate)-b-poly(acrylic acid) (PDMAEMA-b-PAA) are conveniently tunable by introducing pH changes, temperature changes, salt addition and surfactant neutralization. Under different pH values, either globular or fractal self-assemblies can be observed in which the latter have crystal properties. Salts and alkalis can promote the fractal aggregation growth because their deposited crystals can act as nucleation sites for the polyampholyte chains. A combination of fluorescence spectroscopy, atom force microscopy and transmission electron microscopy revealed that the presence of anionic surfactants in the PDMAEMA-b-PAA solutions promoted the solubility of the polyampholyte, consequently leading to a more homogeneous distribution of the polymer chains on the solid substrate upon drying the mixtures. The fractal formation was suppressed for the studied Gemini surfactants, and a higher surfactant hydrophobicity results in an earlier start of the formation of the fractal pattern.