Synthesizing Hypercrosslinked Polymers with Deep Eutectic Solvents to Enhance CO2/N2 Selectivity.

Hypercrosslinked polymers (HCPs) are widely used in ion exchange, water purification, and gas separation. However, HCP synthesis typically requires hazardous halogenated solvents e. g., dichloroethane, dichloromethane and chloroform which are toxic to human health and environment. Herein we hypothesize that the use of halogenated solvents in HCP synthesis can be overcome with deep eutectic solvents (DES) comprising metal halides-FeCl3, ZnCl2 that can act as both the solvent hydrogen bond donor and catalyst for polymer crosslinking via Friedel Crafts alkylation. We validated our hypothesis by synthesizing HCPs in DESs via internal and external crosslinking strategies. [ChCl][ZnCl2]2 and [ChCl][FeCl3]2 was more suitable for internal and external hypercrosslinking, respectively. The specific surface areas of HCPs synthesized in DES were 20-60 % lower than those from halogenated solvents, but their CO2/N2 selectivities were up to 453 % higher (CO2/N2 selectivity of poly-α,α'-dichloro-p-xylene synthesized in [ChCl][ZnCl2]2 via internal crosslinking reached a value of 105). This was attributed to the narrower pore size distributions of HCPs synthesized in DESs.

The influence of palm oil additives on the pour point and wax deposition tendencies of Chenor crude oil.

One of the major concerns during the production of crude oil especially in tropical waters is the deposition of wax on to the walls of the pipeline. This is due to the low seabed temperatures which can be below the wax appearance temperature (WAT) which leads to wax depositing out through molecular diffusion. Currently, there are many methods to prevent and remedy wax deposition but most of these solutions pose a serious environmental threat and are expensive to produce. Hence, this research investigated the use of an organic and cheaper alternative by utilizing synthetic fatty acid esters such as oleic acid which has shown promising results in reducing the pour point of waxy crude oils. The solution that was used was of palm oil origin, crude palm oil (CPO) and crude palm kernel oil (CPKO) and was subsequently compared with the pour point depressant and wax inhibition efficiency of the current industry used inhibitors utilizing the SETA Pour Point and Cloud Point as well as the cold finger apparatus. It was observed that the palm oil inhibitors were highly effective at 1 wt.% due to the high composition of oleic acid present portraying a similar result to Triethanolamine (TEA) while Ethylene Vinyl Acetate (EVA) performed best at low concentration of 0.1 wt.% but deteriorates significantly as the concentration increases due to the polar end agglomerating among itself.

Hyper-Cross-Linked Polymer-Decorated Surfaces with Ultrahigh Efficiency for Oil/Water Emulsion Separation and Recovery.

A novel superhydrophobic/superoleophilic surface has been developed by direct surface condensation of dichloroxylene that results in a controlled coating of hyper-cross-linked polymers. Specifically, the coating was successfully applied to a melamine formaldehyde sponge and optimized by fine-tuning the reaction variables. The resulting hierarchical porous sorbents stabilized by polydimethylsiloxane exhibited an increased surface area, good physiochemical stability, high selectivity, and adsorption capacities for a variety of oils and solvents. The composite can separate oil in water emulsions with ultrahigh separation efficiency >99% over 10 cycles in liter-scale experiments, wherein the highest separation efficiency was as low as 2 ppm even with a short period of filtration, suggesting strong potential for oil/water separation and recovery.

Further Insights into the Performance of Silylated Polyacrylamide-Based Relative Permeability Modifiers in Carbonate Reservoirs and Influencing Factors.

We have previously used surface chemistry analysis techniques to optimize the functionalization of carbonate rocks with a silylated polyacrylamide-based relative permeability modifier (RPM). The RPM is expected to selectively reduce the permeability to water in a hydrocarbon reservoir setting, resulting in a reduction in the amount of produced water while maintaining the production of oil/gas. This study will focus on using core flooding techniques with brine/crude oil under reservoir conditions (i.e., 1500 psi pore pressure and 60 °C temperature) to understand the impact of a silylated polyacrylamide-based RPM on the fluid transport properties in carbonate rocks. The effects of RPM concentration, brine salinity, rock permeability, and pore structure on permeability characteristics were studied. Scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDX) provided visual images of the polymer adsorbed onto the rock surfaces and confirmed the attachment of the polymer on the surface of the rock pore space after treatment. The relative percentage of Si increased from 1.65 to 13.55%, and the relative percentage of N increased to 4.54%. Core flooding showed that increasing the PAM-co-AA (poly acrylamide-co-acrylic acid partial sodium salt) concentration resulted in residual resistance factors for oil (RRFoil) and brine (RRFbrine) that were greater than 1. However, there was a modest decrease in the disproportionate permeability reduction (DRP) ratio (RRFbrine/RRFoil) from 1.75 to 1.60 when the polymer concentration was increased from 0.05 to 0.1 wt %. Furthermore, the RRFbrine values decreased slightly from 120 to 62 with increasing salinity (i.e., 1-10% NaCl) because of electrostatic shielding caused by charged ions in brine and the RPM. The cross-over points of relative permeability in these four samples shifted to the right because of the larger decrease in relative water permeability compared with relative oil permeability. End-point relative permeability to water in sample C-5 decreased by 80%, showing a reduction greater than that in the sample C-2 (i.e., 74%). Kr curves indicated a stronger formation damage in sample C-1, C-2, and C-4 than in sample C-5. Rock samples with a higher initial permeability exhibited a higher RRFbrine to RRFoil ratio (i.e., 3.05) under similar test conditions. This can be attributed to a larger pore radius, which was verified by nuclear magnetic resonance (NMR) measurements. Furthermore, a detailed mechanism has been proposed to understand the effects of the RPM on fluid transport in porous carbonate cores. In this study, SEM-EDX and NMR measurements combined with core flooding tests provide insights into the performance of silylated polyacrylamide-based RPMs and benefit its future implementation in carbonate reservoirs.

Effects of Crude Palm Oil and Crude Palm Kernel Oil Upon Wax Inhibition.

The ever-increasing demand for the finite source of oil has led oil production companies to produce and transport the produced crude oil as efficiently and economically as possible. One of the major concerns especially in waters like the South China Sea is the deposition of wax on the walls of the pipeline or wellbore, constricting and hindering the hydrocarbon flow. This is due to the low seabed temperatures, which can be below the wax appearance temperature (WAT), leading to the deposition of wax out of waxy crude oil through the molecular dispersion mechanism. Currently, many prevention and remedy methods are in place to overcome the problem, but most of the additives possess environmental threat, as most of the chemical solutions used are toxic, nonorganic, and costly. Hence, this paper aims to provide some insights into the effect of palm oil derivatives such as crude palm oil (CPO) and crude palm kernel oil (CPKO) on wax inhibition. The effect of aging time (i.e., immersion time) was also evaluated. A comparison was made between paraffin inhibition efficiency results (PIE %) obtained by CPO, CPKO, poly(ethylene-co-vinyl acetate) (EVA), and triethanolamine (TEA). It was observed that the average efficiency of 81.67% was obtained when 1% CPO was added to heavy crude oil. The wax inhibition performance reached a plateau after 1.5 h of aging time for all of the investigated samples.

Mercury-bearing wastes: Sources, policies and treatment technologies for mercury recovery and safe disposal.

Due to the lenient environmental policies in developing economies, mercury-containing wastes are partly produced as a result of the employment of mercury in manufacturing and consumer products. Worldwide, the presence of mercury as an impurity in several industrial processes leads to significant amounts of contaminated waste. The Minamata Convention on Mercury dictates that mercury-containing wastes should be handled in an environmentally sound way according to the Basel Convention Technical Guidelines. Nevertheless, the management policies differ a great deal from one country to another because only a few deploy or can afford to deploy the required technology and facilities. In general, elemental mercury and mercury-bearing wastes should be stabilized and solidified before they are disposed of or permanently stored in specially engineered landfills and facilities, respectively. Prior to physicochemical treatment and depending on mercury's concentration, the contaminated waste may be thermally or chemically processed to reduce mercury's content to an acceptable level. The suitability of the treated waste for final disposal is then assessed by the application of standard leaching tests whose capacity to evaluate its long-term behavior is rather questionable. This review critically discusses the main methods employed for the recovery of mercury and the treatment of contaminated waste by analyzing representative examples from the industry. Furthermore, it gives a complete overview of all relevant issues by presenting the sources of mercury-bearing wastes, explaining the problems associated with the operation of conventional discharging facilities and providing an insight of the disposal policies adopted in selected geographical regions.

Direct air capture (DAC) of CO2 using polyethylenimine (PEI) "snow": a scalable strategy.

We have developed a cross-linked polyethyleneimine non-porous material (PEI "snow") for direct air capture (DAC) of CO2. This new hydrogel is green, inexpensive, readily scalable and can be fabricated through simple crosslinking of PEI with triglycidyl trimethylolpropane ether (TTE) in 10 minutes. It demonstrates outstanding DAC performance (overall CO2 uptake efficiency of approximately 50 mg g-1 of sorbent) at lab scale (sorbent weight roughly 60 g, air flow rate 2000 ml min-1) and the CO2 can be desorbed using low-grade waste steam.

Preventing Hydrate Adhesion with Magnetic Slippery Surfaces.

Hydrate formation is a common challenge in the oil and gas industry when natural gas is transported under cold conditions in the presence of water. Coatings are one of the solutions that have shown to be a promising approach to address this challenge. However, this strategy suffers from the intrinsic existence of a solid-liquid interface causing a high rate of hydrate nucleation and high hydrate adhesion strength. This proof-of-concept study highlights the performance of a magnetic slippery surface to prevent hydrate adhesion at atmospheric pressure using tetrahydrofuran hydrates. The coating consisted of a hydrocarbon-based magnetic fluid, which was applied to a metal surface to create an interface that lowered the hydrate adhesion strength on the surface. The performance of these new surfaces under static and dynamic (under fluid flow) conditions shows that the magnetic coating gel can be a potential inhibitor for hydrate adhesion as it reduced the torque value after the formation of hydrates.

Polyethylenimine "Snow": An Emerging Material for Efficient Carbon Removal.

Amine-functionalized solid adsorbents are one of the most promising alternatives to the conventional "amine scrubbing" for carbon capture with a number of prominent examples being reported. However, their widespread application in industry is unfulfilled due to their overall performance and complex fabrication, which relies on a porous support. In this "proof of concept" study, we report an approach for generating a new type of material called polyethylenimine (PEI) 'snow', which can be prepared for use in under 15 min. The material does not require a support, and the resulting CO2 uptake is the highest reported to date for PEI-functionalized materials. This was achieved through a rigorous material program that identified conditions where a material with the requisite properties could be generated. From experimental measurements, the virtual dryness of the PEI snow results in fast CO2 absorption kinetics, which is comparable to conventional solid adsorbents, but its CO2 uptake (451.5 mg CO2/g PEI) is the highest reported so far. Breakthrough curves demonstrate the outstanding CO2 selectivity over N2 and CH4 (above 1000), with the potential for post-combustion capture and natural gas sweeting. This strategy can be applied in affordable and efficient gas treatment for various large point sources.

Scalable synthesis of core-shell microgel particles using a 'dry water' method.

This proof-of-concept study demonstrates a facile and scalable 'dry water' method for producing micrometer-sized microgel particles by use of 'water-in-air' droplets as micro-reactors. Solid microgel particles could be easily produced by this method with no further purification. The microgel particles comprise of porous hydrophobic shells and hydrophilic cores and could absorb both oil and water. The swelling of the particles could be triggered by a surfactant under a wide range of conditions.

Solvation Effects on the Permeation and Aging Performance of PIM-1-Based MMMs for Gas Separation.

Membranes are particularly attractive for lowering the energy intensity of separations as they eliminate phase changes. While many tantalizing polymers are known, limitations in selectivity and stability slightly preclude further development. Mixed-matrix membranes may address these shortcomings. Key to their realization is the intimate mixing between the polymer and the additive to eliminate nonselective transport, improve selectivity, and resist physical aging. Polymers of intrinsic microporosity (PIMs) have inherently promising gas transport properties. Here, we show that porous additives can improve transport and resist aging in PIM-1. We develop a simple, low-cost, and scalable hyper-cross-linked polymer (poly-dichloroxylene, pDCX), which was hydroxylated to form an intimate mixture with the polar PIM-1. Solvent variation allowed control of physical aging rates and improved selectivity for smaller gases. This detailed study has allowed many interactions within mixed matrix membranes to be directly elucidated and presents a practical means to stabilize porous polymers for separation applications.

A Highly Tunable Approach to Enhance CO2 Capture with Liquid Alkali/amines.

A diverse range of alkali/amine infused hydrogels (AIHs) were generated by incorporating the liquids into a hydrogel particle for carbon capture application. As a consequence, the CO2 uptake was significantly enhanced owing to the increased contact area. This AIHs technique was highly tunable as it could be applicable to varying species of alkali chemicals and it was found that their molecular structure and architectures could impact the CO2 uptake. Compared to stirred bulk alkali/amine solutions, the CO2 absorption capacity of AIHs was increased by 400% within 30 min with a low hydrogel loading (10 w/w%). In addition, the recyclability of various AIHs was assessed and was found to be extremely encouraging. The effect of salinity on the performance of AIHs was also investigated and high salinity was found to have a minimal effect on CO2 absorption. Most importantly, the preparation of AIHs is fast and straightforward with few wastes and byproducts formed in the preparation process. In all, extensive investigations were presented and the AIHs were found to be a highly tunable and effective approach to enhance CO2 capture with liquid alkali/amines.

Hyper-Cross-Linked Additives that Impede Aging and Enhance Permeability in Thin Polyacetylene Films for Organic Solvent Nanofiltration.

Membrane materials with high permeability to solvents while rejecting dissolved contaminants are crucial to lowering the energy costs associated with liquid separations. However, the current lack of stable high-permeability materials require innovative engineering solutions to yield high-performance, thin membranes using stable polymers with low permeabilities. Poly[1-(trimethylsilyl)-1-propyne] (PTMSP) is one of the most permeable polymers but is extremely susceptible to physical aging. Despite recent developments in anti-aging polymer membranes, this research breakthrough has yet to be demonstrated on thin PTMSP films supported on porous polymer substrates, a crucial step toward commercializing anti-aging membranes for industrial applications. Here we report the development of scalable, thin film nanocomposite membranes supported on polymer substrates that are resistant to physical aging while having high permeabilities to alcohols. The selective layer is made up of PTMSP and nanoporous polymeric additives. The nanoporous additives provide additional passageways to solvents, enhancing the high permeability of the PTMSP materials further. Through intercalation of polyacetylene chains into the sub-nm pores of organic additives, physical aging in the consequent was significantly hindered in continuous long-term operation. Remarkably we also demonstrate that the additives enhance both membrane permeability and rejection of dissolved contaminants across the membranes, as ethanol permeability at 5.5 × 10-6 L m m-2 h-1 bar-1 with 93% Rose Bengal (1017.6 g mol-1) rejection, drastically outperforming commercial and state-of-the-art membranes. These membranes can replace energy-intensive separation processes such as distillation, lowering operation costs in well-established pharmaceutical production processes.

Organic Microporous Nanofillers with Unique Alcohol Affinity for Superior Ethanol Recovery toward Sustainable Biofuels.

To minimize energy consumption and carbon footprints, pervaporation membranes are fast becoming the preferred technology for alcohol recovery. However, this approach is confined to small-scale operations, as the flux of standard rubbery polymer membranes remain insufficient to process large solvent volumes, whereas membrane separations that use glassy polymer membranes are prone to physical aging. This study concerns how the alcohol affinity and intrinsic porosity of networked, organic, microporous polymers can simultaneously reduce physical aging and drastically enhance both flux and selectivity of a super glassy polymer, poly-[1-(trimethylsilyl)propyne] (PTMSP). Slight loss in alcohol transportation channels in PTMSP is compensated by the alcohol affinity of the microporous polymers. Even after continuous exposure to aqueous solutions of alcohols, PTMSP pervaporation membranes loaded with the microporous polymers outperform the state-of-the-art and commercial pervaporation membranes.

Hypercrosslinked Additives for Ageless Gas-Separation Membranes.

The loss of internal pores, a process known as physical aging, inhibits the long-term use of the most promising gas-separation polymers. Previously we reported that a porous aromatic framework (PAF-1) could form a remarkable nanocomposite with gas-separation polymers to stop aging. However, PAF-1 synthesis is very onerous both from a reagent and reaction-condition perspective, making it difficult to scale-up. We now reveal a highly dispersible and scalable additive based on α,α'-dichloro-p-xylene (p-DCX), that inhibits aging more effectively, and crucially almost doubles gas-transport selectivity. These synergistic effects are related to the intimately mixed nanocomposite that is formed though the high dispersibility of p-DCX in the gas-separation polymer. This reduces particle-size effects and the internal free volume is almost unchanged over time. This study shows this inexpensive and scalable polymer additive delivers exceptional gas-transport performance and selectivity.

Hierarchical Porous Polystyrene Monoliths from PolyHIPE.

Hierarchical porous polystyrene monoliths (HCP-PolyHIPE) are obtained by hypercrosslinking poly(styrene-divinylbenzene) monoliths prepared by polymerization of high internal phase emulsions (PolyHIPEs). The hypercrosslinking is achieved using an approach known as knitting which employs formaldehyde dimethyl acetal (FDA) as an external crosslinker. Scanning electron microscopy (SEM) confirms that the macroporous structure in the original monolith is retained during the knitting process. By increasing the amount of divinylbenzene (DVB) in PolyHIPE, the BET surface area and pore volume of the HCP-PolyHIPE decrease, while the micropore size increases. BET surface areas of 196-595 m(2) g(-1) are obtained. The presence of micropores, mesopores, and macropores is confirmed from the pore size distribution. With a hierarchical porous structure, the monoliths reveal comparable gas sorption properties and potential applications in oil spill clean-up.

High surface area amorphous microporous poly(aryleneethynylene) networks using tetrahedral carbon- and silicon-centred monomers.

Poly(aryleneethynylene) networks prepared from tetrahedral monomers are highly microporous and exhibit apparent Brunauer-Emmett-Teller surface areas of up to 1213 m2 g(-1).

Synthetic control of the pore dimension and surface area in conjugated microporous polymer and copolymer networks.

A series of rigid microporous poly(aryleneethynylene) (PAE) networks was synthesized by Sonogashira-Hagihara coupling chemistry. PAEs with apparent Brunauer-Emmet-Teller surface areas of more than 1000 m(2)/g were produced. The materials were found to have very good chemical and thermal stability and retention of microporosity under a variety of conditions. It was shown that physical properties such as micropore size, surface area, and hydrogen uptake could be controlled in a "quantized" fashion by varying the monomer strut length, as for metal-organic and covalent organic frameworks, even though the networks were amorphous in nature. For the first time, it was demonstrated that these properties can also be fine-tuned in a continuous manner via statistical copolymerization of monomer struts with differing lengths. This provides an unprecedented degree of direct synthetic control over micropore properties in an organic network.

Conjugated microporous poly(phenylene butadiynylene)s.

High surface area porous poly(phenylene butadiynylene) networks were obtained (BET surface area up to 842 m(2) g(-1)) by the palladium-catalyzed homocoupling of 1,3,5-triethynylbenzene and 1,4-diethynylbenzene.