Search

The mutations of bacteria due to the excessive use of antibiotics, and generation of antibiotic-resistant bacteria have made the development of new antibacterial compounds a necessity. MXenes have emerged as biocompatible transition metal carbide structures with extensive biomedical applications. This is related to the MXenes' unique combination of properties, including multifarious elemental compositions, 2D-layered structure, large surface area, abundant surface terminations, and excellent photothermal and photoelectronic properties. The focus of this review is the antibacterial application of MXenes, which has attracted the attention of researchers since 2016. A quick overview of the synthesis strategies of MXenes is provided and then summarizes the effect of various factors (including structural properties, optical properties, surface charges, flake size, and dispersibility) on the biocidal activity of MXenes. The main mechanisms for deactivating bacteria by MXenes are discussed in detail including rupturing of the bacterial membrane by sharp edges of MXenes nanoflakes, generating the reactive oxygen species (ROS), and photothermal deactivating of bacteria. Hybridization of MXenes with other organic and inorganic materials can result in materials with improved biocidal activities for different applications such as wound dressings and water purification. Finally, the challenges and perspectives of MXene nanomaterials as biocidal agents are presented.

Extreme nanoconfinement has been shown to significantly affect the properties of materials. Here we demonstrate that extreme nanoconfinement can significantly improve the thermal stability of polystyrene (PS) and reduce its flammability. Capillary rise infiltration (CaRI) is used to infiltrate PS into films of randomly packed silica nanoparticles (NPs) to produce highly confined states. We demonstrate that as the NP size is decreased, increasing the degree of confinement, the isothermal degradation time is dramatically increased, by up to a factor of 30 at 543 K for PS confined in ∼3 nm pores. The activation energy of PS degradation is also increased, by 50 kJ/mol in the most confined state (∼3 nm pores). We demonstrate that the degradation proceeds through the film surface and from the center of large holes toward NP surfaces, indirect evidence that the process is diffusion limited. The surface-driven process dramatically reduces char formation even in large NP packings that show no significant changes in their dynamics and glass transition temperature (

In this study, a polyamide forward osmosis membrane was functionalized with zwitterions followed by the in situ growth of metal-organic frameworks with silver as a metal core (Ag-MOFs) to improve its antibacterial and antifouling activity. First, 3-bromopropionic acid was grafted onto the membrane surface after its activation with N,N-diethylethylenediamine. Then, the in situ growth of Ag-MOFs was achieved by a simple membrane immersion sequentially in a silver nitrate solution and in a ligand solution (2-methylimidazole), exploiting the underlying zwitterions as binding sites for the metal. The successful membrane functionalization and the enhanced surface wettability were verified through an array of characterization techniques. When evaluated in forward osmosis tests, the modified membranes exhibited high performance and improved permeability compared to pristine membranes. Static antibacterial experiments, evaluated by confocal microscopy and colony-forming unit plate count, resulted in a 77% increase in the bacterial inhibition rate due to the activity of the Ag-MOFs. Microscopy micrographs of the Escherichia coli bacteria suggested the deterioration of the biological cells. The antifouling properties of the functionalized membranes translated into a significantly lower flux decline in forward osmosis filtrations. These modified surfaces displayed negligible depletion of silver ions over 30 days, confirming the stable immobilization of Ag-MOFs on their surface.

An approach combining molecular dynamics simulations and laboratory experiments was applied to provide new theoretical insights into the chemical structure of polyamide (PA) thin-film composite (TF...

Sustainable and energy-efficient molecular separation requires membranes with high gas permeability and selectivity. This work reports excellent CO2 separation performance of self-standing and thin-film mixed matrix membranes (MMMs) fabricated by embedding 2D Ti3C2Tx MXene nanosheets in Pebax-1657. The CO2/N2 and CO2/H2 separation performances of the free-standing membranes are above Robeson's upper bounds, and the performances of the thin-film composite (TFC) membranes are in the target area for cost-efficient CO2 capture. Characterization and molecular dynamics simulation results suggest that the superior performances of the Pebax-Ti3C2Tx membranes are due to the formation of hydrogen bonds between Ti3C2Tx and Pebax chains, leading to the creation of the well-formed galleries of Ti3C2Tx nanosheets in the hard segments of the Pebax. The interfacial interactions and selective Ti3C2Tx nanochannels enable fast and selective CO2 transport. Enhancement of the transport properties of Pebax-2533 and polyurethane when embedded with Ti3C2Tx further supports these findings. The ease of fabrication and high separation performance of the new TFC membranes point to their great potential for energy-efficient CO2 separation with the low cost of $29/ton separated CO2.

When aged below the glass transition temperature, [Formula: see text] , the density of a glass cannot exceed that of the metastable supercooled liquid (SCL) state, unless crystals are nucleated. The only exception is when another polyamorphic SCL state exists, with a density higher than that of the ordinary SCL. Experimentally, such polyamorphic states and their corresponding liquid–liquid phase transitions have only been observed in network-forming systems or those with polymorphic crystalline states. In otherwise simple liquids, such phase transitions have not been observed, either in aged or vapor-deposited stable glasses, even near the Kauzmann temperature. Here, we report that the density of thin vapor-deposited films of N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD) can exceed their corresponding SCL density by as much as 3.5% and can even exceed the crystal density under certain deposition conditions. We identify a previously unidentified high-density supercooled liquid (HD-SCL) phase with a liquid–liquid phase transition temperature ([Formula: see text]) [Formula: see text] 35 K below the nominal glass transition temperature of the ordinary SCL. The HD-SCL state is observed in glasses deposited in the thickness range of 25 to 55 nm, where thin films of the ordinary SCL have exceptionally enhanced surface mobility with large mobility gradients. The enhanced mobility enables vapor-deposited thin films to overcome kinetic barriers for relaxation and access the HD-SCL state. The HD-SCL state is only thermodynamically favored in thin films and transforms rapidly to the ordinary SCL when the vapor deposition is continued to form films with thicknesses more than 60 nm.

High-temperature polymerization of acrylates involves numerous reactions. A reliable quantitative understanding of these reactions allows for producing high quality polymers and for reliably design...

Cyclodextrin molecules are cyclic oligosaccharides that display a unique structure including an inner side and two faces on their outer sides. Each face and the inner core can be selectively functionalized with polymers so that nanoscale materials with complex structures can be formed. Materials based on cyclodextrin with controlled architectures can be synthesized by taking advantage of the flexibility, simplicity, and availability of reagents of the atom transfer radical polymerization (ATRP) technique. Combining supramolecular chemistry enabled by cyclodextrins and ATRP yields polymers with a unique macromolecular architecture such as star polymers with large numbers of branches. Herein, we describe the preparation and properties of cyclodextrin initiators, cyclodextrin monomers, and polymers attached to cyclodextrin via the “grafting to” method or host–guest interactions. The strategies for pre-functionalizing cyclodextrins, subsequent ATRP, and self-assembly of the obtained polymers are compared and discussed. This class of polymers has found applications in various biomedical areas, as templates for fabricating inorganic nanoparticles, and for separating chiral organic molecules.

This paper presents a study on control of nanoparticles dispersion in the hard and soft segments of a polyurethane (PU) membrane, via adjusting surface groups of the nanoparticles. The dispersion control allows for tailoring physical and transport properties of the membrane. PU-based mixed-matrix membranes (MMMs) embedded with cyanuric chloride and its derivatives, melamine, and 2,4,6-trihydazino-1,3,5-triazine (THDT) nanoparticles, are prepared. The MMMs are characterized using FTIR, XRD, TGA, DSC, and SEM analyses, and tensile strength tests. Peak assignment of the bonded carbonyl, crystallinity change, mechanical properties of the membranes, possible hydrogen-bonding of the PU backbone and the nanoparticles, and permeation tests indicate that cyanuric chloride nanoparticles are dispersed in the hard segments, whereas melamine and the THDT nanoparticles are distributed in the soft domains. As the cyanuric chloride nanoparticle concentration of the MMMs increases, the gas permeabilities and O 2 /N 2 , CO 2 /CH 4 and CO 2 /N 2 selectivities of the membranes increase. In the case of THDT and melamine, as the filler loading increases, the permeabilities of the gases decrease, whereas O 2 /N 2 , CO 2 /CH 4 and CO 2 /N 2 selectivities increase. A 10 wt% incorporation of THDT into the PU increases CO 2 /N 2 and CO 2 /CH 4 selectivities by 92% and 75%, respectively. These results point to the potential of cyanuric chloride nanoparticles for simultaneous improvement of gas permeability and selectivity, and the potential of melamine and THDT nanoparticles for preparation of highly selective nanocomposite membranes for CO 2 removal.

The effect of nanoporous confinement on the glass transition temperature (Tg) strongly depends on the type of porous media. Here, we study the molecular origins of this effect in a molecular glass, N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine (TPD), highly confined in concave and convex geometries. When confined in controlled pore glass (CPG) with convex pores, TPD's vibrational spectra remained unchanged and two Tg's were observed, consistent with previous studies. In contrast, when confined in silica nanoparticle packings with concave pores, the vibrational peaks were shifted due to more planar conformations and Tg increased, as the pore size was decreased. The strong Tg increases in concave pores indicate significantly slower relaxation dynamics compared to CPG. Given TPD's weak interaction with silica, these effects are entropic in nature and are due to conformational changes at molecular level. The results highlight the role of intramolecular degrees of freedom in the glass transition, which have not been extensively explored.

In this work, nanorods with high antibacterial properties were synthesized with silver acetate as the metal source and 2-aminoterephthalic acid as the organic linker and were then embedded into thin-film composite (TFC) membranes to amend their performance as well as to alleviate biofouling. Silver metal-organic framework (Ag-MOF) nanorods with a length smaller than 40 nm were incorporated within the polyamide thin selective layer of the membranes during interfacial polymerization. The interaction of the synthesized nanorods with the polyamide was favored because of the presence of amine-containing functional groups on the nanorod's surface. The results of X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and atomic force microscopy characterizations proved the presence of Ag-MOF nanorods in the selective layer of thin-film nanocomposite (TFN) membranes. TFN membranes demonstrated improved water permeance, salt selectivity, and superior antibacterial properties. Specifically, the increased hydrophilicity and antibacterial potential of the TFN membranes led to a synergetic effect toward biofouling mitigation. The number of live bacteria attached to the surface of the neat TFC membrane decreased by more than 92% when a low amount of Ag-MOF nanorods (0.2 wt %) was applied. Following contact of the TFN membrane surface with Escherichia coli and Staphylococcus aureus, full inactivation, and degradation of bacteria cells were observed with microscopy, colony-forming unit tests, and disc inhibition zone analyses. This result translated to a negligible amount of the biofilm formed on the active layer. Indeed, the incorporation of Ag-MOF nanorods decreased the metal-ion release rate and therefore provided prolonged antibacterial performance.

The synthesis of nanostructures with tunable antibacterial properties using green solvents at room temperature is of environmental interest, and antibacterial nanomaterials are used in the fabricat...

Biofouling is a major challenge for desalination, water treatment, and water reuse applications using polymer-based membranes. Two classes of novel silver-based metal azolate frameworks (MAF) are proposed to decorate polyamide (PA) forward osmosis membranes and to improve numerous aspects of fouling and transport. Membranes functionalized with two concentrations of each MAF are compared with a pristine control material, with results that clearly highlight their tunability and bio-inhibitory effects. We report for the first time PA membranes yielding near complete suppression of a robust biofilm-forming bacterium (Pseudomonas aeruginosa) and inactivation of planktonic bacteria, while maintaining high selectivity. These features improve the long-term water flux performance of the membranes, tested during 24 hours of accelerated biofouling and organic fouling conditions, and showing lower than 10% and 20% decline in water flux. These enhancements were achieved with only 0.03% to 0.06% mass of additives and little generation of hazardous waste products, indicating that low-cost and environmentally benign functionalization can prevent biofouling growth while maintaining selectivity and transport for high-performance desalination, water treatment and reuse.

Forward osmosis (FO) has applications in desalination, water purification, and wastewater treatment. A major problem in FO is membrane fouling (especially biofouling), which affects adversely the flux efficiency, operating costs, and membrane lifespan. Here, this work addresses this problem via incorporating graphene quantum dots (GQDs) in the active polyamide layer of thin film composite (TFC) membranes. The incorporation of GQDs leads to the development of thin film nanocomposite (TFN) membranes that have improved surface hydrophilicity, antimicrobial activity, and FO performance. The functionalization of the polyamide layer by GQDs is verified by XPS and ATR-FTIR. The properties and FO performance evaluation of the TFN membranes are compared with those of the TFC membranes, in terms of membrane morphology, structural properties, permeability, separation ability, and antifouling properties. The TFN membranes exhibited considerable antibacterial activity (about 90–95% reduction in the proliferation of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) as attached live bacteria). This significant antimicrobial activity is due to the unique structure of GQD-functionalized polyamide selective layer (i.e., its higher number of active edges representing oxidation stress). The TFN membranes also exhibited improved water flux in a range of GQD loading, and satisfactory long term stability due to strong covalent interactions between the GQDs and the polyamide active layer. The higher antibacterial activity, better antifouling properties, and the same transport properties of the TFN membranes point to the great FO potential of this new generation of membranes.

Antibacterial properties of two-dimensional (2D) nanomaterials are of great interest in fields such as environmental engineering, biomedical engineering, and medicine. Ti3C2Tx MXene, a novel 2D nan...

This paper presents new mixed-matrix membranes (MMMs) synthesized via incorporating hexamethylenetetramine dicyanamide cadmium nanoparticles, a metal organic framework (MOF), into the polysulfone (PSF) matrix. The MMMs are characterized using FTIR and SEM analyses, and their gas permeation properties are evaluated at different MOF loadings and various pressures. The results show that the nanoparticle is compatible with the polymer and distributes homogenously in the matrix. Compared to the pristine PSF membrane, the MMM with 2.5 wt. % of the MOF nanoparticles has lower CO2, CH4, N2 and O2 permeabilities but significantly higher CO2/CH4, CO2/N2 and O2/N2 gas pair selectivities (i.e., 41.66, 20.08 and 5.09, respectively, which are 42.6, 61.6 and 60.02 % higher). As the total pressure increases, the gas permeabilities of the pristine PSF membrane and the MMMs decrease, but their sieving abilities increase. These results suggest that gas selectivities of high free-volume polymers with poor sieving abilities can be improved by incorporating the MOF into the polymer.

Industrial deactivated Ag/alumina catalysts contain an appreciable amount of silver. As silver is a precious metal, it is of great economic and environmental interest to recover silver from the catalysts before disposing them. This paper introduces a novel hybrid process for efficient silver recovery from deactivated catalysts. The process combines leaching and emulsion liquid membrane (ELM) techniques. Leaching first transfers silver from catalyst particles to an aqueous solution. An ELM then extracts silver ions from the leach solution in a single separation step. To prevent emulsion instability in the ELM, a new surfactant, a relatively low number-average-molecular-weight (

This work shows that incorporating highly compatible polyrhodanine nanoparticles (PRh-NPs) into a polyamide (PA) active layer allows for fabricating forward osmosis (FO) thin-film composite (TFC)-PRh membranes that have simultaneously improved antimicrobial, antifouling, and transport properties. To the best of our knowledge, this is the first reported study of its kind to this date. The presence of the PRh-NPs on the surface of the TFC-PRh membranes active layers is evaluated using FT-IR spectroscopy, SEM, and XPS. The microscopic interactions and their impact on the compatibility of the PRh-NPs with the PA chains were studied using molecular dynamics simulations. When tested in forward osmosis, the TFC-PRh-0.01 membrane (with 0.01 wt % PRh) shows significantly improved permeability and selectivity because of the small size and the high compatibility of the PRh-NPs with PA chains. For example, the TFC-PRh-0.01 membrane exhibits a FO water flux of 41 l/(m2·h), higher than a water flux of 34 l/(m2·h) for t...

Extensive experimental results (measurements of the monomer conversion in the absence of any external initiators) indicating the occurrence of the self-initiation reaction of methyl acrylate (MA) a...

Inclusion of various polymeric chains with different lengths and functionalities (such as hydrophobic, ionic, acidic, basic, etc) into polysaccharide backbones leads to new polymeric materials with interesting properties that may self-assembled into different aggregations and have the potential to for use in a variety of applications. This review highlights the application of various ATRP techniques (such as “grafting-from” and “grafting-to”) to modify non-cellulosic polysaccharides under homogenous condition. Chemical modification of chitosan, pullulan, dextran, agarose, hyaluronic acid (hyaluronan), starch, glycogen, heparin, chitin, guar gum, locust bean gum, and dextrin using ATRP are described. Pre-functionalization or protection of some functional groups in the polysaccharide backbone required in some cases to prepare a precursor with higher solubility in organic solvents is illustrated. For each polymerization, the strategy for synthesis of the copolymer and the condition of the polymerization is described in detail along with the properties of the prepared copolymers. Furthermore, examples that produced materials with the potential for use in a specific application are reviewed in summary.

The ease of producing two-dimensional (2D) structure, tunable surface chemistry, and interlayer spacing of MXenes have created innumerable opportunities for researchers to prepare such novel emergent materials as energy-efficient membranes in a variety of engineering separations. In this review, various methods used for the synthesis of MXenes, their functionalization and membrane fabrication are discussed with potential examples. The engineering as well as the design of atomically thin 2D MXene membranes developed over the past decade have played a major role in high-throughput separation areas. The fascinating features of MXenes in terms of ultrathin structure, tunable interlayer distance, versatile chemistry, and appealing physiochemical properties render themselves to be developed as membranes for use in numerous applications, such as in gas separation, liquid separation, and desalination. These applications are critically discussed in this review in terms of their current challenges and future directions as effective emergent membranes in industrial separation processes.

This work investigates the use of a silver-based metal-organic framework (MOF) for mitigating biofouling in forward-osmosis thin-film composite (TFC) membranes. This is the first study of the use of MOFs for biofouling control in membranes. MOF nanocrystals were immobilized in the active layer of the membranes via dispersion in the organic solution used for interfacial polymerization. Field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) characterization results showed the presence of the MOF nanocrystals in the active layer of the membranes. The immobilization improved the membrane active layer in terms of hydrophilicity and transport properties without adversely affecting the selectivity. It imparted antibacterial activity to the membranes; the number of live bacteria attached to the membrane surface was over 90% less than that of control membranes. Additionally, the MOF nanocrystals provided biocidal activity that lasted for 6 months. The immobilization improved biofouling resistance in the membranes, whose flux had a decline of 8% after 24 h of operation in biofouling experiments, while that of the control membranes had a greater decline of ∼21%. The better biofouling resistance is due to simultaneous improvement of antiadhesive and antimicrobial properties of the membranes. Fluorescence microscopy and FE-SEM indicated simultaneous improvement in antiadhesive and antimicrobial properties of the TFN membranes, resulting in limited biofilm formation.

To improve the hydrophilicity and antifouling properties of polysulfone (PS) ultrafiltration membranes, we studied the use of salicylate-alumoxane (SA) nanoparticles as a novel hydrophilic additive. The effects of SA nanoparticles on the membrane characteristics and performance were investigated in terms of membrane structure, permeation flux, solute rejection, hydrophilicity, and antifouling ability. The new mixed-matrix membranes (MMMs) possess asymmetric structures. They have smaller finger-like pores and smoother surfaces than the neat PS membranes. The embedment of SA nanoparticles in the polymer matrix and the improvement of surface hydrophilicity were investigated. Ultrafiltration experiments indicated that the pure-water flux of the new MMMs initially increases with SA nanoparticles loading followed by a decrease at high loadings. Higher BSA solution flux was achieved for the MMMs compared to the neat PS membranes. Membranes with 1 wt.% SA nanoparticles exhibit the highest flux recovery ratio of 87% and the lowest irreversible fouling of 13%.

Modified TiO2 nanoparticles were successfully embedded into Pebax-1657 as a polymer matrix. The resulting mixed-matrix membranes are highly efficient for CO2 removal especially at high pressures. Nanofiller grafting with 3-aminopropyl-diethoxymethylsilane (silane agent) and surface modification with carboxymethyl chitosan led to Pebax-modified-TiO2 composite membranes with 50–60% increase in CO2 permeability and 30–33% in CO2/N2 selectivity compared to the pristine Pebax. The performance of the nanocomposite membranes is favorably above the 2008 Robeson upper bound. Stability analyses of the prepared membranes showed acceptable durability of the membranes in permeation experiments. Characterization techniques such as FT-IR, DSC, TGA, and SEM showed the compatibility of the nanoparticles and the polymer, better thermal stability of the nanocomposite membranes, and satisfactory dispersion of nanofillers into the polymer.

Loose nanofiltration membranes, which have a loose selective layer and desired surface charge, provide high water flux and significant retention of low molecular weight molecules. In this study, a thin film of copper (II)-benzene-1,3,5-tricarboxylate (Cu-BTC) clusters was anchored on the surface of a chitosan (CS)-coated polyethersulfone (PES) membrane to improve the surface properties as well as performance (permeability, heavy metal removal efficiency, and antifouling activity) of the membrane. Characterization techniques, such as FE-SEM, EDX, XPS and AFM, zeta potential and water contact-angle measurements, verified that Cu-BTC was successfully anchored on the CS layer. The Cu-BTC/CS membrane exhibited higher surface hydrophilicity and roughness compared to the pristine one. It also demonstrated a water flux of 44 L m−2h−1 and a manganese removal efficiency of 86%, while the membrane coated only with CS had an average water flux of 39 L m−2h−1 and a manganese removal efficiency of 78%. Compatibility and interfacial interactions between the Cu-BTC clusters and the CS layer were investigated using molecular dynamics (MD). MD simulations indicated that the Cu-BTC clusters increased the affinity of the membrane for water molecules. The anchored Cu-BTC clusters also improved the antibacterial activity of the membrane; the Cu-BTC/CS membrane inactivated 83% of Escherichia coli bacteria, while the pristine CS membrane 47% of the bacteria. The Cu-BTC/CS membrane also demonstrated interesting anti-fouling properties against both organic and biological foulants.

Polymers of intrinsic microporosity (PIMs) with high free volumes have been synthesized by incorporating contorted rigid moieties into polymers backbones. Despite their many appealing properties, membranes made of these polymers have not been used industrially because of their fast physical aging. The unprecedented CO2 permeability and satisfactory CO2/N2 and CO2/CH4 selectivity of PIMs have led to establishing the new 2019 upper bounds for the gas mixtures. This article reviews recent advances in the field of PIM-based membranes. It discusses polymer synthesis strategies to modify PIM structures such that the resulting membranes have improved CO2 separation performance and lower physical aging. The strategies include the use of monomers with suitable side chains, kinked moieties, and stable structures.

Membrane adsorbents have emerged as powerful and attractive tools for the removal of hazardous materials such as dyes and heavy metal ions, mainly in trace amounts, from water resources. Among membrane adsorbents, those prepared from or modified with chitosan biopolymer and its derivatives are cases of interest because of chitosan advantages including biocompatibility, biodegradability, nontoxicity, reactivity, film and fiber forming capacity and favorable hydrophilicity. This review is oriented to provide a framework for better insight into fabrication methods and applications of chitosan-based adsorptive membranes. Critical aspects including thermokinetic analyses of adsorption and regeneration capacity of the membrane adsorbents have been also overviewed. Future of chitosan-based adsorptive membranes might include efforts for the improvement of mechanical stability and reusability and also most targeted application of appropriate copolymers as well as nanostructures in preparing high performance adsorptive membranes.

Mixed Matrix Membrane (MMM) recently has shown a great potential for separation of CO 2 from CH 4 as the main part of a gas sweetening process for natural gas treatment. The main objective of this study is to develop novel nanocomposite membranes of TiO 2 as inorganic nano-filler incorporated into poly (ether- b -amide) Pebax 1657 as the polymer matrix. Considerable improvement of permeation and selectivity was achieved for synthesized membranes for separation of CO 2 and CH 4 over a range of operating variables. The scanning electron microscopy (SEM) was used to characterize nanocomposite membranes which images showed high degree of agglomeration in high loadings of TiO 2 in polymer matrix. Defect free organic/inorganic membranes showed the best performance at TiO 2 loading concentration of 3% at 30 °C and 15 bar. The CO 2 permeability increased from 129 Barrer for Pebax to 167 Barrer and a remarkable enhancement in the related CO 2 /CH 4 selectivity was observed from 37 to 51.

The experimental results for the solvent extraction of silver ions from acidic aqueous media with bis(2,4,4-trimethylpentyl) monothiophosphonic acid (Cyanex 302) and a mixture of mono and di(2-ethylhexyl) phosphoric acid and di(2-ethylhexyl)phosphoric acid (MEHPA) as the ligand, diluted with an industrial paraffinic solvent are presented. The effects of the influential parameters such as pH, contact time, extractant type, extractant concentration and temperature were investigated. The results of the solvent extraction of silver ions from the solutions showed that extraction of the silver ions increased with increasing pH, extractant concentration and temperature. The stoichiometry of the extracted metal species by Cyanex 302 and MEHPA with silver ions was 1.0:1.5 and 1.0:4.0, respectively. The results of solvent extraction showed that a quantitative extraction of silver ions was feasible in a single stage within 3 min only at the condition of O/A = 1, silver ions concentration of 0.035 mol L − 1 , pH eq = 7.0 for [MEHPA] = 0.4 M and pH eq = 6.5 for [Cyanex 302] = 0.05 M, respectively. The stripping of silver from the loaded organic carried out with nitric acid showed quantitative stripping for MEHPA (97.2%). The composition of the extracted species in the organic phase was proposed to be AgL ( HL ) (4 x − 1)( org ) and AgL ( HL ) (1.5 x − 1)( org ) , for MEHPA and Cyanex 302, respectively. The thermodynamic analysis of the temperature effects showed that the extraction processes were endothermic and standard enthalpy change for both extractants were positive.

The extraction of manganese from sulfate solution using mixture of mono and di (2-ethylhexyl) phosphoric acid (MDEHPA) as extractant was experimentally studied in this work. The effect of various parameters including MDEHPA concentration, aqueous phase pH, phase ratio of organic/aqueous, aqueous and organic phases contact time, kind of diluent and temperature on the manganese extraction were investigated. Simultaneously, stripping of manganese from the manganese-loaded organic phase using a sulfuric acid solution as stripping reagent was studied. The results revealed that an extraction of 97.5 % was obtained with the extraction system composed of 0.4 M MDEHPA in diluent at a phase ratio of 1, pH 3.5, and contact time = 15 min. The stoichiometry of the extracted species as an appropriate design parameter was determined based on slope analysis approach. Results also revealed the capability of this system in manganese recovery.

This study investigates the effect of surface functionalization of a thin-film composite forward osmosis membrane with zwitterions and silver-based metal organic frameworks (Ag-MOFs) to improve the antifouling, anti-biofouling, and antimicrobial activity of the membrane. Two types of zwitterions, namely, 3-bromopropionic acid and 1,3-propane sultone, are chemically bonded, with and without incorporation of Ag-MOFs, over the surface of a polyamide membrane. Spectroscopy measurements indicate successful grafting of the modifying agents on the membrane surface. Contact angle measurements demonstrate a notable improvement in surface wettability upon functionalization. The performance of the membranes is evaluated in terms of water and salt fluxes in forward osmosis filtrations. The transport data show demonstrably increased water flux of around 300% compared to pristine membranes, with similar or slightly reduced salt reverse flux. The antifouling and anti-biofouling properties of the modified membranes are evaluated using sodium alginate and E. coli, respectively. These experiments reveal that functionalized membranes exhibit significant antifouling and anti-biofouling behavior, with high resilience against flux decline.

This experimental and theoretical study deals with the thermal spontaneous polymerization of n-butyl acrylate (n-BA). The polymerization was carried out in solution (n-heptane as the solvent) at 200 and 220 °C without adding any conventional initiators. It was studied with the five different n-BA/n-heptane volume ratios: 50/50, 70/30, 80/20, 90/10, and 100/0. Extensive experimental data presented here show significant monomer conversion at all temperatures and concentrations confirming the occurrence of the thermal self-initiation of the monomer. The order, frequency factor, and activation energy of the thermal self-initiation reaction of n-BA were estimated from n-BA conversion, using a macroscopic mechanistic model. The estimated reaction order agrees well with the order obtained via our quantum chemical calculations. Furthermore, the frequency factor and activation energy estimates agree well with the corresponding values that we already reported for bulk polymerization of n-BA.