Photocatalytic Degradation of Poly(Acrylamide-co-acrylic Acid)

Spotlight on the Life Cycle of Acrylamide-Based Polymers Supporting Reductions in Environmental Footprint: Review and Recent Advances

Humankind is facing a climate and energy crisis which demands global and prompt actions to minimize the negative impacts on the environment and on the lives of millions of people. Among all the disciplines which have an important role to play, chemistry has a chance to rethink the way molecules are made and find innovations to decrease the overall anthropic footprint on the environment. In this paper, we will provide a review of the existing knowledge but also recent advances on the manufacturing and end uses of acrylamide-based polymers following the "green chemistry" concept and 100 years after the revolutionary publication of Staudinger on macromolecules. After a review of raw material sourcing options (fossil derivatives vs. biobased), we will discuss the improvements in monomer manufacturing followed by a second part dealing with polymer manufacturing processes and the paths followed to reduce energy consumption and CO2 emissions. In the following section, we will see how the polyacrylamides help reduce the environmental footprint of end users in various fields such as agriculture or wastewater treatment and discuss in more detail the fate of these molecules in the environment by looking at the existing literature, the regulations in place and the procedures used to assess the overall biodegradability. In the last section, we will review macromolecular engineering principles which could help enhance the degradability of said polymers when they reach the end of their life cycle.

Investigating the effects of polymer plugging mechanism of liquid production decrease and improvement by the cross-linked gel performance

Polymer flooding, as the most successful and well-known chemical EOR method was broadly applied around the world. Mostly, contrasted with Waterflooding, the production rate decrease during polymer flooding is smaller based on field application. Nevertheless, the production liquid rate decreased critically in the middle phase to late phase due to plugging, which could lead the way to poor flooding performance and fewer cumulative oil. In this work, first, we approached the affecting polymer plugging mechanism model on liquid production decrease to investigate the parameters such as; solid-phase concentration (SOLIDMIN), reacting frequency factor (FREQFAC) and others affecting components are all investigated consecutively. Secondly the model approached by cross-linked gel for the improvement of production liquid rate. The physical work was designed by a physical model, and then the polymer adsorption that generating blockage emerging in permeability diminish assessed by a mathematical model. The outcomes specify that the existence of this debris, excessive assemblage of solid-phase and the excessive reactant frequency factor has major mechanical and physical parameters effects on the reservoir throughout polymer flooding. Polymer flood model base case liquid ratio loss is 11.15 m³/day between the years 2014-08-01 to 2020-03-04. Comparing with the polymer flood model case 1, liquid ratio loss ranging to 1.97 m³/day between the years 2014-08-02 to 2020-03-03. While the oil ratio loss of the polymer flood base case model between the years 2015-07-08 to 2020-03-04 attained 12.4 m³/day contrasting with the polymer flood model case 1 oil ratio increase to 0.37 m³/day between the years 2014-08-04 to 2019-04-02. The cross-linked gel model base case liquid ratio loss is 2.09 m³/day between the years 2015-01-02 to 2020-02-03, while the oil ratio lost reached 9.15 m³/day between the years 2015-09-01 to 2020-02-03. Contrasting with the cross-linked gel model case 2 liquid ratio recovered from the loss and attained 25.43 m³/day in the year 2020-12-01, while the oil ratio is reached 15.22 m³/day in the year 2020-12-01. Polymer flood model examined through cross-linked gel model performed reliable outcomes by taking out the plugging, which also occasioned the reservoir production rate to decrease. With the application of cross-linked gel the affected parameters and the production rate have achieved an improvement.

Synergetic activation of persulfate by heat and Fe(II)-complexes for hydrolyzed polyacrylamide degradation at high pH condition: Kinetics, mechanism, and application potential for filter cake removal during cementing in CO2 storage wells

The long-term integrity of the interface between cement and formation rock in CO₂-capture and storage wells is crucial to avoid leakage of CO₂ in/along wells. However, the interface can be easily damaged by the filter cake, which is a compressed composite of bentonite, polymers such as hydrolyzed polyacrylamide (HPAM), and barite, on the wellbore rock. Therefore, removing the filter cake during the cementing process by degrading HPAM in an efficient way is essential. In this study, chelated-Fe²⁺ activated potassium persulfate (KPS) was used for HPAM degradation and filter-cake removal. Ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA-2Na) and diethylenetriaminepentaacetic acid (DTPA) were adopted to control the precipitation of Fe²⁺/Fe³⁺. A mixture of 0.4 mM Fe²⁺, 0.8 mM DTPA, and 4 mM KPS at a pH of 10.0 at 70 °C reduced the molecular weight of HPAM significantly from 3.0 × 10⁶ to (3.6-10) × 10⁴ Da. Electron paramagnetic resonance (EPR) analysis suggested that HO was the dominant radical and that SO₄^- and O₂^- were responsible for the degradation. The reactions conformed to continuous distribution kinetics with an activation energy of 38.36 kJ mol^-1. A possible degradation pathway was proposed based on analyses via infrared spectroscopy (IR) and time-of-flight liquid chromatography-mass spectrometry (TOF-LC/MS). >90 wt% of the filter cake was removed by the system. The results suggest that the proposed DTPA-Fe²⁺ activated KPS system exhibits promising potential for in situ degradation of high molecular weight HPAM and for the removal of filter cake in downhole wells.

Delayed Crosslinking Amphiphilic Polymer Gel System with Adjustable Gelation Time Based on Competitive Inclusion Method

Delayed crosslinking polymer gel systems are widely utilized in deep profile control processes for water production control in oilfields. In this paper, a kind of delayed crosslinking amphiphilic polymer gel system with adjustable gelation time based on competitive inclusion was prepared and its delayed crosslinking gelling properties were studied. The amphiphilic polymer of P(acrylamide (AM)⁻sodium acrylate (NaA)⁻N-dodecylacrylamide (DDAM)) was synthesized and it showed much better salt resistance, temperature resistance, and shear resistance performance compared with hydrolyzed polyacrylamide (HPAM). Phenol can be controlled released from the the cavity of β-cyclodextrin (β-CD) ring in the presence of the hydrophobic group used as the competitive inclusion agent in the amphiphilic polymer backbone. Accordingly, the gelation time of the delayed crosslinking amphiphilic polymer gel system is closely related to release rate of the crosslinker from the the cavity of β-CD ring. This study screened an amphiphilic polymer with good salt resistance and temperature resistance performance, which can be used in high temperature and high salinity reservoirs, and provided a feasible way to control the gelation time of the polymer gel system by the competitive inclusion method.

Effect of BMP-2 from matrices of different stiffnesses for the modulation of stem cell fate

Stem cells cultured on extracellular matrix (ECM) with different stiffnesses have been shown to engage into different lineage commitments. However, in vivo, the components of the ECM are known to bind and strongly interact with growth factors. The effect, on the stem cell fate, of the cooperation between the mechanical properties and the growth factor in the same microenvironment has not yet been investigated. Here, we propose a protocol for mimicking this stem cell microenvironment with an in vitro system. This system consists in grafting (without using a spacer) biomolecules that contain N-termini groups onto hydrogel (poly(acrylamide-co-acrylic acid)) surfaces of various stiffnesses ranging from 0.5 to 70 kPa. First, we demonstrate that the commitment of mesenchymal stem cell populations changes in response to the substrate's rigidity, with myogenic differentiation occurring at 13-17 kPa and osteogenic differentiation at 45-49 kPa. Chemical grafting of soft and stiff matrices with an osteogenic factor (BMP-2(mimetic peptide)) results only in osteogenic differentiation. Also, when grafted on even softer gels (0.5-3.5 kPa), the BMP-2(mimetic peptide) had no effect on the stem cell differentiation. We prove that correct organization of F-actin cytoskeleton due to the mechanical properties of the microenvironment is necessary for BMP-induced smad1/5/8 phosphorylation and nuclear translocation. These results suggest that stem cell differentiation is dictated mechanically, but in the presence of a biochemical factor, the effect of the mechanical factor on stem cell commitment is modified. This can explain the diversity of stem cell behaviors in vivo where different growth factors are sequestrated on the ECM.