119 results found
Mohd Azmi LH, Williams D, Ladewig B, 2020, Can metal organic frameworks outperform adsorptive removal of harmful phenolic compound 2-chlorophenol by activated carbon?, Chemical Engineering Research and Design, Vol: 158, Pages: 102-113, ISSN: 0263-8762
Removal of persistent organic compounds from aqueous solutions is generally achieved using adsorbent like activated carbon (AC) but it suffers from limited adsorption capacity due to low surface area. This paper describes a pioneering work on the adsorption of an organic pollutant, 2-chlorophenol (2-CP) by two MOFs with high surface area and water stability; MIL-101 and its amino-derivative, MIL-101-NH2. Although MOFs have higher surface area than AC, the latter was proven better having the highest equilibrium 2-CP uptake (345 mg g−1), followed by MIL-101 (121 mg g−1) and MIL-101-NH2 (84 mg g−1). Used MIL-101 could be easily regenerated multiple times by washing with ethanol and even showed improved adsorption capacity after each washing cycle. These results can open the doors to meticulous adsorbent selection for treating 2-CP-contaminated water.
Hunter-Sellars E, Tee JJ, Parkin IP, et al., 2020, Adsorption of volatile organic compounds by industrial porous materials: Impact of relative humidity, MICROPOROUS AND MESOPOROUS MATERIALS, Vol: 298, ISSN: 1387-1811
Hakim Mohd Azmi L, Williams DR, Ladewig BP, 2020, Polymer-Assisted Modification of Metal-Organic Framework MIL-96 (Al): Influence on Particle Size, Crystal Morphology and Perfluorooctanoic Acid (PFOA) Removal
<jats:p><div><b>Abstract</b></div><div>A new synthesis method was developed to prepare an aluminum-based metal organic framework (MIL-96) with a larger particle size and different crystal habits. A low cost and water-soluble polymer, hydrolyzed polyacrylamide (HPAM), was added in varying quantities into the synthesis reaction to achieve >200% particle size enlargement with controlled crystal morphology. The modified adsorbent, MIL-96-RHPAM2, was systematically characterized by SEM, XRD, FTIR, BET and TGA-MS. Using activated carbon (AC) as a reference adsorbent, the effectiveness of MIL-96-RHPAM2 for perfluorooctanoic acid (PFOA) removal from water was examined. The study confirms stable morphology of hydrated MIL-96-RHPAM2 particles as well as a superior PFOA adsorption capacity (340 mg/g) despite its lower surface area, relative to standard MIL-96. MIL-96-RHPAM2 suffers from slow adsorption kinetics as the modification significantly blocks pore access. The strong adsorption of PFOA by MIL-96-RHPAM2 was associated with the formation of electrostatic bonds between the anionic carboxylate of PFOA and the amine functionality present in the HPAM backbone. Thus, the strongly held PFOA molecules in the pores of MIL-96-RHPAM2 were not easily desorbed even after eluted with a high ionic strength solvent (500 mM NaCl). Nevertheless, this simple HPAM addition strategy can still chart promising pathways to impart judicious control over adsorbent particle size and crystal shapes while the introduction of amine functionality onto the surface chemistry is simultaneously useful for enhanced PFOA removal from contaminated aqueous systems.<br></div></jats:p>
Martinez-Ahumada E, Lopez-Olvera A, Jancik V, et al., 2020, MOF Materials for the Capture of Highly Toxic H2S and SO2, ORGANOMETALLICS, Vol: 39, Pages: 883-915, ISSN: 0276-7333
Duralliu A, Matejtschuk P, Stickings P, et al., 2020, The Influence of Moisture Content and Temperature on the Long-Term Storage Stability of Freeze-Dried High Concentration Immunoglobulin G (IgG)., Pharmaceutics, Vol: 12, ISSN: 1999-4923
High protein concentration products for targeted therapeutic use are often freeze-dried to enhance stability. The long-term storage stability of freeze-dried (FD) plasma-derived Immunoglobulin G (IgG) from moderate to high concentrations (10-200 mg/mL) was assessed. Monomer content, binding activity and reconstitution times were evaluated over a 12-month period under accelerated and real-term storage conditions. In the first case study it was shown that FD IgG from 10 to 200 mg/mL had minimal monomer/activity losses at up to ambient temperature after 12 months of storage. However, at 45 °C the sucrose-to-protein ratio played a significant impact on IgG stability above 50 mg/mL. All IgG concentrations witnessed moisture ingress over a 12-month period. The impact of moisture ingress from environmental exposure (between 0.1% and 5% w/w moisture) for IgG 50 mg/mL was assessed, being generated by exposing low moisture batches to an atmospheric environment for fixed time periods. Results showed that at -20 °C and 20 °C there was no significant difference in terms of monomer or antigen-binding activity losses over 6 months. However, at 45 °C, there were losses in monomer content, seemingly worse for higher moisture content samples although model binding activity indicated no losses. Finally, the difference between a low moisture product (0.1-1% w/w) and a moderately high moisture (3% w/w) product generated by alternative freeze-drying cycles, both stoppered under low oxygen headspace conditions, was evaluated. Results showed that at -20 °C and 20 °C there was no difference in terms of binding activity or monomer content. However, at 45 °C, the low moisture samples had greater monomer and binding activity losses than samples from the highest moisture cycle batch, indicating that over-drying can be an issue.
Cherukupally P, Sun W, Wong APY, et al., 2020, Surface-engineered sponges for recovery of crude oil microdroplets from wastewater (vol 321, pg 784, 2019 ), NATURE SUSTAINABILITY, Vol: 3, Pages: 161-161, ISSN: 2398-9629
Ngeow YW, Williams DR, Chapman AV, et al., 2020, Surface Energy Mapping of Modified Silica Using IGC Technique at Finite Dilution, ACS Omega
© 2020 American Chemical Society. The reinforcing silica filler, which can be more than 40% of an elastomer composite, plays a key role to achieve the desired mechanical properties in elastomer vulcanizates. However, the highly hydrophilic nature of silica surface causes silica particle aggregation. It remained a challenge for many tire manufacturers when using silica-filled elastomer compounds. Here, the silica surface energy changes when the surface is modified with coupling or noncoupling silanes; coupling silanes can covalently bond the silica to the elastomers. The surface energy of silica was determined using inverse gas chromatography (IGC) at finite dilution (FD-IGC) and found to be reduced by up to 50% when the silica surface was silanized. The spatial distribution of silica aggregates within the tire matrix is determined by transmission electron microscopy (TEM) and a direct correlation between aggregate size (silica microdispersion) and work of cohesion from IGC is reported, highlighting surface energy and work of cohesion being excellent indicators of the degree of dispersion of silica aggregates.
Cherukupally P, Sun W, Wong APY, et al., 2019, Surface-engineered sponges for recovery of crude oil microdroplets from wastewater, Nature Sustainability, ISSN: 2398-9629
In the United States, the oil industry produces over 15 billion barrels of wastewater contaminated with crude oil microdroplets annually. Current methods are ineffective for the removal of these microdroplets at the variable pH conditions commonly found in wastewater. Here, an innovative surface-engineered sponge (SEnS) that synergistically combines surface chemistry, charge and roughness, provides a solution to this problem. Over broad pH conditions, the SEnS rapidly adsorbed oil microdroplets with 95–99% removal efficiency, predominantly facilitated by Lifshitz–van der Waals forces. At the optimum pH, 92% of the oil was adsorbed within 10 min. The oil was subsequently recovered by solvent extraction under ambient conditions, and the cleaned SEnS was reused for oil microdroplets adsorption ten times. The combined efficacy and reusability can enable large-scale removal and recovery of crude oil microdroplets from wastewater.
Duralliu A, Matejtschuk P, Williams DR, 2019, Measuring the specific surface area (SSA) of freeze-dried biologics using inverse gas chromatography, EUROPEAN JOURNAL OF PHARMACEUTICS AND BIOPHARMACEUTICS, Vol: 142, Pages: 216-221, ISSN: 0939-6411
Hedberg SHM, Brown LG, Meghdadi A, et al., 2019, Improved adsorption reactions, kinetics and stability for model and therapeutic proteins immobilised on affinity resins, Adsorption, Vol: 25, Pages: 1177-1190, ISSN: 0929-5607
Protein adsorption on solid state media is important for the industrial affinity chromatography of biotherapeutics and for preparing materials for self-interaction chromatography where fundamental protein solution thermodynamic properties are measured. The adsorption of three model proteins (lysozyme, catalase and BSA) and two antibodies (a monoclonal and a polyclonal antibody) have been investigated on commercial affinity chromatography media with different surface functionalities (Formyl, Tresyl and Amino). Both the extent of protein immobilised (mg protein/ml media) and the reaction kinetics are reported for a range of reaction conditions, including pH, differing buffers as well as the presence of secondary reactants (glutaraldehyde, sodium cyanoborohydride, EDC and NHS). Compared to the reaction conditions recommended by manufacturers as well as those reported in previous published work, significant increases in the extent of protein immobilisation and reaction kinetics are reported here. The addition of glutaraldehyde or sodium cyanoborohydride was found to be especially effective even when not directly needed for the adsorption to happen. For mAb and pIgG, immobilisation levels of 50 and 31 mg of protein/ml of resin respectively were achieved, which are 100% or more than previously reported. Enhanced levels were achieved for lysozyme of 120 mg/ml with very rapid reaction kinetics (< 1 h) with sodium cyanoborohydride. It can be concluded that specific chromatography resins with Tresyl activated support offered enhanced levels of protein immobilisation due to their ability to react to form amine or thio-ether linkages with proteins. Additionally, glutaraldehyde can result in higher immobilisation levels whilst it can also accelerate immobilisation reaction kinetics.
Duralliu A, Matejtschuk P, Dubey S, et al., 2019, The influence of the closure format on the storage stability and moisture content of freeze-dried influenza antigen, VACCINE, Vol: 37, Pages: 4485-4490, ISSN: 0264-410X
Antonio Zarate J, Sanchez-Gonzalez E, Williams DR, et al., 2019, High and energy-efficient reversible SO2 uptake by a robust Sc(III)-based MOF, JOURNAL OF MATERIALS CHEMISTRY A, Vol: 7, Pages: 15580-15584, ISSN: 2050-7488
Ngeow YW, Chapman AV, Heng JYY, et al., 2019, Characterization of silica modified with silanes by using thermogravimetric analysis combined with infrared detection, Rubber Chemistry and Technology, Vol: 92, Pages: 237-262, ISSN: 0035-9475
Tire treads with reduced rolling resistance and increased wet grip can be achieved by coupling hydrophilic silica to hydrocarbon rubber by using an alkoxysilane. The silica surface was modified by reaction with a wide range of coupling and non-coupling silanes. The chemistry and extent of these silanizations were elucidated using thermogravimetric analysis (TGA) combined with infrared detection. The silane grafting efficiencies were typically 52–72%, but efficiencies were lower in the bulkier [3-(di-(tridecyloxypenta(ethyleneoxy))ethoxysilyl]propyl mercaptan. However, the silica surface coverage increases with increasing size of the silane. Grafting efficiencies were lower with higher silane loadings. In the TGA, ethoxy and methoxy groups are displaced from the grafted silanes mainly at moderate temperatures (up to about 495 °C) to form siloxane bridges. Over a similar temperature range, the weaker S–S bonds present in bis(3-triethoxysilylpropyl) tetrasulfide (TESPT)- or bis[3-(triethoxysilyl)propyl] disulfide (TESPD)-modified silica are cleaved, leading to weight losses from TESPT or TESPD bound at one end to the silica and from TESPT bound at both ends. The remaining weight losses from bound silanes occurred mainly at higher temperatures. In the commercial silanized silica Coupsil 8113, TGA indicates that about two of three ethoxy groups in each triethoxysilane were lost during the silanization process.
Kondor A, Mautner A, Lee K-Y, et al., 2019, Challenges on specific surface area analysis of cellulosic materials, National Meeting of the American-Chemical-Society (ACS), Publisher: AMER CHEMICAL SOC, ISSN: 0065-7727
Ngeow YW, Heng JYY, Williams DR, et al., 2019, TEM observation of silane coupling agent in silica-filled rubber tyre compound, Journal of Rubber Research, Vol: 22, Pages: 1-12, ISSN: 1511-1768
The microdispersion of silica in filled elastomer vulcanisates was evaluated by transmission electron microscopy (TEM)—network visualisation analysis. In this study, the silica is modified with a wide range of coupling and non-coupling silanes. The silica-filled elastomer samples were microtomed using a glass knife. The resulting TEM micrographs were interpreted and characterised based on aggregates with a cross-sectional area larger than 100 nm2. The study showed that silica surface modification has reduced the silica aggregate size by approximately 30–40% compared to an untreated silica-filled elastomer vulcanisate. The TEM micrographs showed evidence of coupling between silica and the elastomer phase and demonstrated a good estimation of silica microdispersion in the elastomer phase. This study has shown that the presence of different surface functionalities has an effect on the silica microdispersion.
Hedberg SHM, Devi S, Duralliu A, et al., 2019, Mechanical behavior and structure of freeze-dried cakes, Methods in Pharmacology and Toxicology, Pages: 327-351
© 2019, Springer Science+Business Media, LLC, part of Springer Nature. Freeze-drying or the lyophilization of biopharmaceuticals is a standard method for product manufacture in order to increase product shelf-life and minimize the tendency of re-constituted products to aggregate. However, the physical and or mechanical stability of freeze-dried cakes can be problematic, which can directly result in financial losses due to unusable or damaged products. Currently, there is very limited systematic knowledge of the relationship between lyophilization process conditions and the cake-specific physical structure, mechanical performance, and stability. This Chapter reviews the detailed mechanical properties and structure of freeze-dried cakes formed from aqueous solutions with concentrations from 1 to 40% w/v of common excipients, mannitol, sucrose, and trehalose in some detail. In addition, the mechanical properties of commercial freeze-dried products as well as effects of moisture content and ingress into freeze-dried cakes are also reported. Both experimentally measured Young’s moduli and yield stress data scale well with reduced cake density, in line with theoretical predictions from classical cellular solids theory. A novel compressive indentation method is reviewed which can accurately determine a cake’s Young’s modulus and yield stress within 1 min, allowing the potential future use of these mechanical cake attributes as Critical Quality Attributes (CQAs).
Hedberg S, Rapley J, Haigh JM, et al., 2018, Cross-interaction chromatography as a rapid screening technique to identify the stability of new antibody therapeutics, European Journal of Pharmaceutics and Biopharmaceutics, Vol: 133, Pages: 131-137, ISSN: 0939-6411
Protein aggregation can be a major problem in the manufacturing of new biopharmaceuticals and there is a desirability for development of techniques that can predict the behaviour of new biopharmaceuticals early on in the development process. A technique that can be used to predict aggregation is self-interaction chromatography that is used to determine the second virial coefficient, B22, but one of the limitations includes the need to immobilise every protein of interest. In this study a related technique, cross interaction chromatography (CIC), is evaluated which overcomes this limitation. Three antibodies were studied across a range of NaCl concentrations with each antibody being studied as both a mobile phase and as the stationary phase - in total 6 different stationary-mobile phase combinations. The B22 values obtained for all three proteins correlated strongly with the B23 results obtained for the same protein in the mobile phase, and were significantly independent of the protein immobilised on the stationary phase. This observation allows the use of pre-prepared columns with known immobilised model proteins such as a polyclonal antibody or mAb, with other unknown monoclonal antibodies in the mobile phase. Preliminary experiments using a series of known immobilised mAbs columns with an unknown mAb in the mobile phase resulted in at least a 50 fold reduction in the amount of unknown protein needed and a rapid semi-quantitative assessment of aggregation propensity. CIC can speed up the screening process with minimum preparation time and therefore more rapidly be able to identify the aggregation stability of new antibody formulations.
Sadeek SA, Williams DR, Campbell KLS, 2018, Using sodium thiosulphate for carbon steel corrosion protection against monoethanolamine and 2-amino-2-methyl-1-propanol, INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 78, Pages: 125-134, ISSN: 1750-5836
Ali N, Marsh J, Godfrey S, et al., 2018, Aqueous MEA and Ammonia Sorption-Induced Damage in Keratin Fibers, ACS OMEGA, Vol: 3, Pages: 14173-14180, ISSN: 2470-1343
Sadeek SA, Williams DR, Campbell KLS, 2018, Using sodium thiosulphate for carbon steel corrosion protection against monoethanolamine and methyldiethanolamine, INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 74, Pages: 206-218, ISSN: 1750-5836
Williams DR, Mapping the mAb Aggregation Propensity Using Self-InteractionChromatography as a Screening Tool, Analytical Chemistry, ISSN: 0003-2700
Duralliu A, Matejtschuk P, Williams DR, 2018, Humidity Induced Collapse in Freeze Dried Cakes: A Direct Visualization Study using DVS., European Journal of Pharmaceutics and Biopharmaceutics, Vol: 127, Pages: 29-36, ISSN: 0939-6411
Maintaining low moisture content is seen as crucial to sustaining long term stability in freeze dried (FD) cakes as higher moisture could lead to cake collapse, degradation and loss in biological potency. Using a combination of gravimetric data and video images captured from a Dynamic Vapour Sorption instrument the onset humidity Collapse Point (RHcp), the humidity Onset Crystallisation (RHc) and Onset Glass Transition (RHg) points for a series of freeze dried cakes at 10, 25 and 40°C have been determined. The moisture sorption behavior with respect to cake collapse and other morphological phase transitions are reported for a two freeze drying excipients and one product formulation; sucrose, trehalose (both 5% w/w) and an influenza antigen (A/Wisconsin/15/2009 H3N2 NYMCX-183, formulated with 1.1% w/w sucrose). Stability maps for all three formulations tested were reported as a function of %RH and temperature using the methods described in this work, thus direct visualization of collapse behavior for any FD cake can now be standardized and routinely determined, facilitating the formulation of FD products with improved stability and storage performance.
Cherukupally P, Li B, Williams D, et al., 2018, Mining value from oil sands tailings ponds
© 2018 Society of Plastics Engineers. All rights reserved. Regeneration Methods: 1. Mechanical Compression 2. pH-Swing method 3. Chemical wash method. Findings: Simple and environmental friendly Effective for absorbed oil recovery Ineffective for adhered oil recovery New technique of oil recovery Effective for 2 cycles only but in 3rd cycle the efficiency dropped to ~70% Advanced exploratory work required New technique of oil recovery Effective for all cycles and materials are reusable Advanced formulation of solvents required to improve environmental benefits.
Cherukupally P, Williams D, Bilton A, et al., 2018, Mining the value from oil sands tailings ponds: Addressing the energy, environmental, and economic challenges of oil sands industry
© 2018 Society of Plastics Engineers. All rights reserved. In the US, over 7 billion gallons of the contaminated water generated each day by steam-based oil extraction processes. One of the biggest challenges in treating these effluents is the removal of crude oil droplets due to its high temperature and salinity. Current materials, membranes and adsorbents are ineffective due to fouling, thermal instability, or slow response. Alternatively, sponges have high thermally stable and adsorb oil droplets effectively. This research focuses on the fundamental properties required for usage of sponges as filter separation media. The oil field effluents are enriched with both positive and negative ions due to its high salt concentration. Thus, the oil droplets and the acid-base polymers attract ions of opposite charge. This phenomenon results in attraction between the droplets and the sponges. In this work, an acid-base surface engineered sponge (SEnS) was evaluated for its thermal stability and surface charge properties to show its potential as a practical adsorbent. The SEnS effectively adsorbed the crude oil droplets under various salt concentrations. As the salt concentration increased, the time of removal dramatically declined, resulting in over 99% of oil removal within 5 minutes. Furthermore, the sponge was regenerated and reused multiple times for oil adsorption. Also, in the regeneration process, the crude oil was recovered from the mixture. In conclusion, the SEnS was shown to be effective and reusable, resulting in recovered crude oil. Thus, the SEnS filter has the great potential to be disruptive in remediation of oil field effluents and generate value from otherwise unusable waste.
Sadeek SA, Williams DR, Sedransk Campbell KL, 2017, Use of green inhibitors and pre-treated carbon steel for reduced corrosion in post-combustion capture infrastructure, EUROCORR 2017
© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. All rights reserved. Development of strategies to implement carbon steel (CS) infrastructure in lieu of stainless steel (SS) in post-combustion CO2 capture plants will advance wide-scale deployment of this technology. Herein two proposed techniques were investigated: 1) pre-treatment of CS with 5 M methyldiethanolamine (MDEA), 2) green (i.e. low-toxicity) inhibitors: sodium thiosulphate (STS), copper carbonate (CC), and 2-mercaptobenzimidazole (MBI). Coupons (CS) were immersed for seven days in industry standard solvent 5 M monoethanolamine (MEA) to test these proposals. Pre-treated coupons demonstrated good corrosion protection with the development of a dense layer of siderite crystals, significantly reducing oxidation of the underlying Fe substrate. Copper carbonate exhibited good inhibition performance with no surface change evident after immersion. The inhibitor STS provided some corrosion protection through surface adsorption, while MBI proved least effective. The combination of a siderite layer (generated by MDEA pre-treatment) with each inhibitor was also tested. However, the integrity of the protective siderite layer was compromised in the presence of an inhibitor, ranging from nearly complete removal to some destruction.
Campbell KLS, Yu LCY, Williams DR, 2017, Using pre-treated carbon steel for post-combustion carbon capture infrastructure, 13th International Conference on Greenhouse Gas Control Technologies (GHGT), Publisher: ELSEVIER SCIENCE BV, Pages: 1991-1997, ISSN: 1876-6102
The reduction of capital cost in building post-combustion CO2 capture is necessary to realize its widespread use. Cheaper steels, e.g. carbon steel, are attractive but lack the necessary corrosion resistance. To protect from corrosion, one approach is to implement a protective coating on the surface. Particularly, a coating like siderite (FeCO3) is appealing because it can be formed by amines and therefore could be regenerated. This study investigates the formation, over seven days at 40 and 80 °C, of such siderite layers formed in methyldiethanolamine (MDEA), 2-amino-2-methyl-1-propanol (AMP), and a K2CO3 solution. When tested against 2.5 M monoethanolamine for 28 days, the coatings formed at 80 °C in MDEA and AMP appear the most resilient. There is a substantial siderite crystal layer remaining on the surface and only minimal weight loss.
Yu LCY, Sadeek S, Williams DR, et al., 2017, Investigating the corrosion due to high capacity and uptake promoter amine blends on carbon steel, 13th International Conference on Greenhouse Gas Control Technologies (GHGT), Publisher: ELSEVIER SCIENCE BV, Pages: 1998-2008, ISSN: 1876-6102
The continued development of amine solvents for post-combustion CO2 capture is essential to the large-scale success of this technology, with particular interest in high capacity and uptake promoter blends. Some of these solutions also show reduced corrosive tendencies in the presence of carbon steel, a significantly cheaper alternative to the stainless steels generally employed. Optimization of the solution composition and reduced corrosion could yield both a decrease in capital and operating costs. Solutions (30% by weight) of monoethanolamine (MEA) or piperazine (PZ) were blended with either methyldiethanolamine (MDEA) or 2-amino-2-methyl-1-propanol (AMP). At 120 °C, Solutions containing PZ outperformed those with MEA showing the formation of good protective siderite (FeCO3) crystal layers, reducing continued oxidation of Fe from the surface and therefore corrosion.
Campbell KLS, Yu LCY, Williams DR, 2017, Siderite corrosion protection for carbon steel infrastructure in post-combustion capture plant, INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 58, Pages: 232-245, ISSN: 1750-5836
Cheung PCW, Williams DR, Kirk DW, 2017, Comments on: "Encapsulation in ceramic material of the metals Cr, Ni, and Cu contained in galvanic sludge via the solidification/stabilization method. J. Environ. Chem. Eng. 5 (2017) pp. 3834-3843, Journal of Environmental Chemical Engineering
Yu LCY, Campbell KLS, Williams DR, 2016, Carbon steel corrosion in piperazine-promoted blends under CO2 capture conditions, International Journal of Greenhouse Gas Control, Vol: 55, Pages: 144-152, ISSN: 1750-5836
Aqueous amine promoter blends have improved CO2 absorption capacity and uptake. Tertiary (3°) and sterically-hindered (SH) amines are favoured for their molar absorption ratio, (i.e. CO2 absorption capacity). With a promoter, namely piperazine (PZ), the ordinarily slow reaction kinetics of a 3°/SH amine is accelerated. Amine blends of 30 and 50% by weight, MDEA + PZ and AMP + PZ, were tested using immersion corrosion techniques at 120 °C. In all cases, a siderite (FeCO3) product layer was formed on the surface of the carbon steel coupons. Aqueous PZ solutions produced thin layers with comparatively lower Fe ion concentrations than blended solutions. The fast CO2 capture kinetics of PZ, and therefore carbonate formation, makes the rapid reaction possible due to readily available Fe ions oxidised on the surface. The replacement of PZ content in a blend, by MDEA or AMP, resulted in slower formation of siderite and variably poorer corrosion protection. Critically, the use of AMP in the blend offers better protection against corrosion, shown by lower concentration of Fe ions in the bulk solution than parallel MDEA solutions. This can be attributed to the faster formation of carbonate species by AMP, as a SH amine, which also results in more imperfect crystals.
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