Degradation of Polyacrylamide Molecules in Aqueous Solutions by High-speed Stirring

Nagashiro, Waichi; Tsunoda, Teruo; Tanaka, Makoto; Oikawa, Mitsuru

doi:10.1246/bcsj.48.2597

Cited by 14 publications

(8 citation statements)

References 2 publications

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“…When exposed to a shear environment, high molecular weight formulations typically see an initial steep decline in viscosity which plateaus as the smaller remaining molecules flow around the source of shear more easily. Nagashiro et al (1975) saw viscosity drop quickly as molecular weight fell from 5 to 3 Mg mor 1 . PAM solutions or PAM applied to targets can also experience gradual (e. g., weeks) reduction of molecular weight due to environmental exposure, particularly UV light, or through gradual unfolding of the macromolecule (Molyneux, 1983).…”

Section: Pam Properties Affecting Efficacymentioning

confidence: 99%

Polyacrylamide in Agriculture and Environmental Land Management

Sojka

Bjorneberg

Entry

et al. 2007

Advances in Agronomy

351

240

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Section: Pam Properties Affecting Efficacymentioning

confidence: 99%

Polyacrylamide in Agriculture and Environmental Land Management

Sojka

Bjorneberg

Entry

et al. 2007

Advances in Agronomy

351

240

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“…It was reported that a shearing hydrodynamic field induced chain bond scissions leading to a decrease in the molecular weight of the polyacrylamide and then to a decrease in intrinsic viscosity of PAM solutions (Paterson and Abernathy 1970;Abdel-Alim and Hamielec 1973;Nagashiro et al 1975;Povkh and Chernyuk 1986;Nguyen and Boger 1998;Avadiar et al 2013). In particular, mechanical degradation of polymers used for drag reduction in a turbulently flowing liquid has been studied by several authors (Rho et al 1996;Vlachogiannis et al 2003;Pereira and Soares 2012).…”

Section: Mechanical Degradationmentioning

confidence: 99%

Transfer and degradation of polyacrylamide-based flocculants in hydrosystems: a review

Guézennec

Michel²,

Bru³

et al. 2014

Environ Sci Pollut Res

120

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The aim of this review was to summarize information and scientific data from the literature dedicated to the fate of polyacrylamide (PAM)-based flocculants in hydrosystems. Flocculants, usually composed of PAMs, are widely used in several industrial fields, particularly in minerals extraction, to enhance solid/liquid separation in water containing suspended matter. These polymers can contain residual monomer of acrylamide (AMD), which is known to be a toxic compound. This review focuses on the mechanisms of transfer and degradation, which can affect both PAM and residual AMD, with a special attention given to the potential release of AMD during PAM degradation. Due to the ability of PAM to adsorb onto mineral particles, its transport in surface water, groundwater, and soils is rather limited and restricted to specific conditions. PAM can also be a subject of biodegradation, photodegradation, and mechanical degradation, but most of the studies report slow degradation rates without AMD release. On the contrary, the adsorption of AMD onto particles is very low, which could favor its transfer in surface waters and groundwater. However, AMD transfer is likely to be limited by quick microbial degradation.

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“…In the PAM-treated soil, the effect of PAM solution-based adhesion and adsorption on soil is that small soil particles become aggregated, which enhances the overall stability of soil aggregates and limits crust formation at the soil surface, resulting in an increase in the infiltration rate and decrease in runoff. However, excess dissolved PAM could clog soil pores 35 – 37 , thus forming a sealed layer on the surface soil similar to surface crust resulting from the impact of raindrops. Therefore, runoff rates were reduced with 1 and 2 g·m −2 PAM application rates but increased with4 g·m −2 PAM application rates.…”

Section: Resultsmentioning

confidence: 99%

“…The overland-flow depth on the sloped land is very thin, approximately0.1–0.5 mm 35 . Therefore, the ponding water was neglected, and the runoff can be expressed as follows: Substituting Eq.…”

Section: Methodsmentioning

confidence: 99%

Mathematical model of ammonium nitrogen transport with overland flow on a slope after polyacrylamide application

Yang

Ren

et al. 2018

Sci Rep

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The nutrient loss caused by soil erosion is the main reason for soil degradation and environmental pollution, and polyacrylamide (PAM) as a common soil amendment has a great influence on runoff and erosion processes at the slope. In order to investigate the mechanism of nutrient transport with runoff, a field experiment was conducted and a simple mathematical model was developed in this study. Four PAM application rates (0, 1, 2, and 4 g·m−2) and two rainfall intensities (50 and 80 mm·h−1) were applied in the field experiment. The results revealed that runoff rate of 2 g·m−2 PAM application treatments decreased by 5.3%-10.6% compared with the control groups, but it increased by10.9%-18.7% at 4 g·m−2 PAM application treatments. Polyacrylamide application reduced ammonium nitrogen concentrations of runoff by 10.0% to 44.3% relative to the control groups. The best performance with correlation coefficient (R2) and Nash–Sutcliffe efficiency (NSE) showed that the ammonium transport with runoff could be well described by the proposed model. Furthermore, the model parameter of the depth of the mixing layer (hm) linearly increased with an increase in flow velocity, but exponentially decreased with an increase in PAM application rate.

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Degradation of Polyacrylamide Molecules in Aqueous Solutions by High-speed Stirring

Cited by 14 publications

References 2 publications

Polyacrylamide in Agriculture and Environmental Land Management

Polyacrylamide in Agriculture and Environmental Land Management

Transfer and degradation of polyacrylamide-based flocculants in hydrosystems: a review

Mathematical model of ammonium nitrogen transport with overland flow on a slope after polyacrylamide application

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