Solvent Filtration Research Articles

Functionalized boron nitride membranes with ultrafast solvent transport performance for molecular separation

Pressure-driven, superfast organic solvent filtration membranes have significant practical applications. An excellent filtration membrane should exhibit high selectivity and permeation in aqueous and organic solvents to meet increasing industrial demand. Here, we report an amino functionalized boron nitride (FBN) based filtration membrane with a nanochannel network for molecular separation and permeation. This membrane is highly stable in water and in several organic solvents and shows high transport performance for solvents depending on the membranes’ thickness. In addition, the FBN membrane is applicable for solute screening in water as well as in organic solvents. More importantly, the FBN membranes are very stable in acidic, alkaline and oxidative media for up to one month. The fast-flow rate and good separation performance of the FBN membranes can be attributed to their stable networks of nanochannels and thin laminar structure, which provide the membranes with beneficial properties for practical separation and purification processes.

The effects of filamentary Ni, graphene and lithium amide (LiNH2) additives on the dehydrogenation behavior of mechano-chemically synthesized crystalline manganese borohydride (Mn(BH4)2) and its solvent filtration/extraction

Dehydrogenation properties of mechano-chemically synthesized crystalline Mn(BH4)2 hydride without and with ultrafine filamentary carbonyl nickel (Ni), graphene and LiNH2 were investigated. It is reported for the first time that all additives suppressed the release of B2H6 with the filamentary Ni additive being the most effective suppressor of B2H6. In DSC, the decomposition peak of Mn(BH4)2 was endothermic. The estimated apparent activation energy for isothermal dehydrogenation was dramatically reduced to 44.9 ± 4.3 kJ/mol for the 5 wt.% LiNH2 additive from about 76–81 kJ/mol range for the additive-free sample and 5 wt.% filamentary Ni and graphene additives. The most striking finding, that has never been reported in the literature, is that the process of solvent filtration and extraction of the mechano-chemically synthesized (Mn(BH4)2/LiCl) sample, resulted in the crystallization of a dimetallic borohydride solvate [{Li(Et2O)2}Mn2(BH4)5] instead of crystalline Mn(BH4)2. Its dehydrogenation behavior was investigated isothermally and by TGA/DSC.

The Effects of Additives on the Dehydrogenation of Amorphous Manganese Borohydride and Its Crystalline Form after Solvent Filtration/Extraction

A non-stoichiometric, amorphous a-Mn(BH4)(2x) hydride, accompanied by a NaCl-type salt, was mechanochemically synthesized from the additive-free mixture of (2NaBH4 + MnCl2), as well as from the mixtures containing the additives of ultrafine filamentary carbonyl nickel (Ni), graphene, and LiNH2. It is shown that both graphene and LiNH2 suppressed the release of B2H6 during thermal gas desorption, with the LiNH2 additive being the most effective suppressor of B2H6. During solvent filtration and extraction of additive-free, as well as additive-bearing, (Ni and graphene) samples from diethyl ether (Et2O), the amorphous a-Mn(BH4)(2x) hydride transformed into a crystalline c-Mn(BH4)2 hydride, exhibiting a microstructure containing nanosized crystallites (grains). In contrast, the LiNH2 additive most likely suppressed the formation of a crystalline c-Mn(BH4)2 hydride during solvent filtration/extraction. In a differential scanning calorimeter (DSC), the thermal decomposition peaks of both amorphous a-Mn(BH4)(2x) and crystalline c-Mn(BH4)2 were endothermic for the additive-free samples, as well as the samples with added graphene and Ni. The samples with LiNH2 exhibited an exothermic DSC decomposition peak.

Peptide-functionalized iron oxide magnetic nanoparticle for gold mining

Here, we present our work on preparing a novel nanomaterial composed of inorganic binding peptides and magnetic nanoparticles for inorganic mining. Two previously selected and well-characterized gold-binding peptides from cell surface display, AuBP1 and AuBP2, were exploited. This nanomaterial (AuBP-MNP) was designed to fulfill the following two significant functions: the surface conjugated gold-binding peptide will recognize and selectively bind to gold, while the magnetic nano-sized core will respond and migrate according to the applied external magnetic field. This will allow the smart nanomaterial to mine an individual material (gold) from a pool of mixture, without excessive solvent extraction, filtration, and concentration steps. The working efficiency of AuBP-MNP was determined by showing a dramatic reduction of gold nanoparticle colloid concentration, monitored by spectroscopy. The binding kinetics of AuBP-MNP onto the gold surface was determined using surface plasmon resonance (SPR) spectroscopy, which exhibits around 100 times higher binding kinetics than peptides alone. The binding capacity of AuBP-MNP was demonstrated by a bench-top mining test with gold microparticles.Graphical abstract

Synthesis of amorphous manganese borohydride in the (NaBH4–MnCl2) system, its hydrogen generation properties and crystalline transformation during solvent extraction

The mixture of (2NaBH4 + MnCl2) was ball milled in a magneto-mill. No gas release was detected. The XRD patterns of the ball milled mixture exhibit only the Bragg diffraction peaks of the NaCl-type salt which on the basis of the present X-ray diffraction results and the literature is likely to be a solid solution Na(Cl)x(BH4)(1−x), possessing a cubic NaCl-type crystalline structure. No presence of any crystalline hydride was detected by powder X-ray diffraction which clearly shows that NaBH4 in the initial mixture must have reacted with MnCl2 forming a NaCl-type by-product and another hydride that does not exhibit X-ray Bragg diffraction peaks. Mass spectrometry (MS) of gas released from the ball milled mixture during combined MS/thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC) experiments, confirms mainly hydrogen (H2) with a small quantity of diborane gas, B2H6. The Fourier transform infra-red (FT-IR) spectrum of the ball milled (2NaBH4 + MnCl2) is quite similar to the FT-IR spectrum of crystalline manganese borohydride, c-Mn(BH4)2, synthesized by ball milling, which strongly suggests that the amorphous hydride mechano-chemically synthesized during ball milling could be an amorphous manganese borohydride. Remarkably, the process of solvent filtration and extraction at 42°C, resulted in the transformation of mechano-chemically synthesized amorphous manganese borohydride to a nanostructured, crystalline, c-Mn(BH4)2 hydride.

How Much Do Ultrathin Polymers with Intrinsic Microporosity Swell in Liquids?

As synthetic membrane materials, polymers with intrinsic microporosity (PIMs) have demonstrated unprecedented permeation and molecular-separation properties. Here, we report the swelling characteristics of submicron-thick supported films of spirobisindane-based PIMs, PIM-1 and PIM-6FDA-OH, for six organic solvents and water using in situ spectroscopic ellipsometry. Surprisingly, PIMs swell significantly in most organic solvents, with swelling factors (SF = hswollen/hdry) as high as 2.5. This leads to the loss of the ultrarigid character of the polymer and produces equilibrated liquid-like swollen films. Filling of the excess frozen-in fractional free volume with liquid was discovered next to swelling-induced polymer matrix dilation. Water hardly swells the polymer matrix, but it penetrates into the intrinsic microporous structure. This study is the first to provide fundamental swelling data for PIMs, leading to better comprehension of their permeation properties. Such an understanding is indispensable for applications such as solvent filtration, natural-gas separation, and ion retention in flow batteries.

ECTFE membranes produced by non-toxic diluents for organic solvent filtration separation

A new grade of ethylene-chlorotrifluoroethylene, low melting point HALAR® ECTFE (LMP ECTFE), was studied and used as a polymer for the preparation of solvent-resistant flat-sheet membranes.

Nickel hydroxide nanosheet membranes with fast water and organics transport for molecular separation

Two-dimensional nanosheets of late show great promise as novel materials for size-selective separation membranes of high efficiency. Herein, we demonstrate a novel laminated nanofiltration membrane for fast water purification and organic solvent nanofiltration using the 1 nm-thick and 50 nm-wide nickel hydroxide nanosheets that are facilely prepared by a green chemistry method. The resulting membranes exhibit uniform and flectional two-dimensional laminated structure. With about 1 nm high laminated channels, they allow super-fast transport of water and organic solvents. The water and organic fluxes are three orders of magnitude higher than commercially available polymeric nanofiltration membranes. In addition, the membranes have high retention for organic dyes in aqueous and organic solutions. Typically, the 3.18 μm-thick membrane with the molecular weight cut-off of 328 g mol-1 has an outstanding pure water flux of 99 L m-2 h-1 bar-1 and up to 97% rejection for direct yellow dye molecules. The newly developed nickel hydroxide nanosheets and the subsequent membranes have great potential application in water purification, organic solvent filtration and electronic devices.

An automatic and sensitive method for simultaneous determination of sixteen polycyclic aromatic hydrocarbons and four derivatives by online solid-phase extraction coupled with ultra-high performance liquid chromatography with online solvent filtration

An automatic and sensitive method for simultaneous determination of 16 PAHs and 4 derivatives by online SPE-UHPLC with online solvent filtration.

Poly(arylene sulfide sulfone) hybrid ultrafiltration membrane with TiO2‐g‐PAA nanoparticles: Preparation and antifouling performance

Poly(arylene sulfide sulfone) (PASS) is a kind of newly developed polymeric membrane material which has excellent mechanical strength, thermal stability, and solvent resistance. And, it would be a potential material for high temperature ultrafiltration and organic solvent filtration. In this article, PASS hybrid ultrafiltration membrane with improved antifouling property was prepared by mixing TiO2 nanoparticles which were grafted with polyacrylic acid (PAA). These membranes were prepared by a phase inversion technique and their separation performance and antifouling property of the prepared membranes were investigated in detail by SEM, FTIR, EDS, contact angle goniometry, filtration experiments of water, and BSA solution. The results shown that the TiO2‐g‐PAA nanoparticles dispersed well in membrane matrix, the hydrophilicity of the membranes prepared within TiO2‐g‐PAA nanoparticles have been improved and these membranes exhibited excellent water flux and antifouling performance in separation than that of the pure PASS membranes and PASS membranes with TiO2 nanoparticles. More specifically, among membrane sample M0, M1.5, and MP1.5, MP1.5 which contained 1.5 wt% TiO2‐g‐PAA exhibited the highest water permeation (190.4 L/m2 h at 100 kPa), flux recovery ratio, and the lowest BSA adsorption amount. POLYM. ENG. SCI., 55:2829–2837, 2015. © 2015 Society of Plastics Engineers

Solvent permeation behavior of PDMS grafted γ-alumina membranes

Solvent permeability in polymer grafted ceramic membranes was described by incorporating solvent sorption terms into the Hagen–Poiseuille equation. Two types of ceramic membranes grafted with a relative short or long PDMS chain (n=10 and n=39), which differed in pore size, were examined. Sorption was measured “ex situ” using a pure PDMS phase. The results show that curves of flux versus transmembrane pressure were identical for all solvents studied if flux values are corrected for viscosity as well as sorption of the solvent. It is suggested that the permeable volume of the membrane reduces by swelling of the grafted organic moiety by the solvent used. This model provides a way to predict the performance of grafted porous membranes for solvent filtration.

Performance of Grignard functionalized ceramic nanofiltration membranes

A new generation of membranes modified by using Grignard reactions was recently introduced. These alkyl modified membranes have an enhanced hydrophobicity, and a potential for organic solvent nanofiltration (OSN). In this work, the solvent filtration performance and application potential of these Grignard functionalized membranes were further explored. To this purpose, the retention of model solutes using a variety of grafted and ungrafted membranes was investigated in 5 different solvent/solute test mixtures. Experiments were performed with two different solvents, acetone with intermediate polarity and toluene as an apolar solvent, and 3 different solute classes, namely polyethylene glycol, polystyrene and a well-known catalyst ligand. The varying retention behavior can be explained by the changing affinity of solvents and solutes for the modified and unmodified membrane surfaces. Results of sorption tests confirm this conclusion. Subsequently, filtration of a phosphine mixture in isopropanol containing different solutes with similar size but varying polarity, showed the clear potential of affinity-based separations with Grignard modified membranes. A filtration test during four days revealed that the grafted groups are sufficiently stable. As a conclusion, Grignard functionalization of ceramic membranes allows to tune solvent–membrane–solute interactions in OSN in a controlled way for specific separations, without the extra complexity of swelling.

Organic solvent nanofiltration with Grignard functionalised ceramic nanofiltration membranes

In this paper the use of functionalised ceramic nanofiltration membranes in solvent filtration is described. The membranes were grafted using a novel method for surface modification based on Grignard chemistry. Commercially available 1nm TiO2 membranes were differently functionalised with a series of alkyl groups (methyl, pentyl, octyl, dodecyl) in order to generate a more hydrophobic membrane surface.The properties of the modified membranes were examined by physico-chemical characterisation (contact angle measurements, micro-ATR/FTIR-spectroscopy) in addition to performance characterisation (flux measurements for solvents ranging from highly polar to non-polar, next to polyethylene glycol retentions in water and polystyrene retentions in acetone). All observations for modified membranes are consistent with the assumed partial replacement of the OH-groups on the membrane surface and the consequent amphiphilic character of the modified membrane surface.The retentions of modified and unmodified membranes in acetone confirm the recent findings in organic solvent nanofiltration (OSN): an increase in the hydrophobicity of the membrane leads to an increase in the retentions.A comparison with reference polymeric membranes shows that the newly developed membranes are a good alternative, having the advantage of the absence of effects of swelling. This new grafting technique for ceramic membranes allows to further explore solvent–membrane–solute interactions in OSN in a controlled way without the extra complexity of swelling.

Using electrospray laser desorption ionization mass spectrometry to rapidly examine the integrity of proteins stored in various solutions

Electrospray laser desorption ionization mass spectrometry (ELDI/MS) allows the rapid desorption and ionization of proteins from solutions under ambient conditions. In this study, we have demonstrated the use of ELDI/MS to efficiently examine the integrity of the proteins stored in various solutions before they were further used for other biochemical tests. The protein standards were prepared in the solutions containing buffers, organic salts, inorganic salts, strong acid, strong base, and organic solvents, respectively, to simulate those collected from solvent extraction, filtration, dialysis, or chromatographic separation. Other than the deposit of a drop of the sample solution on the metallic sample plate in an ELDI source, no additional sample pretreatment is needed. The sample drop was then irradiated with a pulsed laser; this led to desorption of the analyte molecules, which subsequently entered the ESI plume to undergo post-ionization. Because adjustment of the composition of the sample solution is unnecessary, this technique appears to be useful for rapidly evaluating the integrity of proteins after storage or prior to further biochemical treatment. In addition, when using acid-free and low-organic-solvent ESI solutions for ELDI/MS analysis, the native conformations of the proteins in solution could be detected.

Identification of Non-Volatile Components and Volatile Organic Compounds in Wet Building Materials

The major volatile components in two solvent-based paints, two thinners, and four adhesives have been identified by a method involving pre-treatment by solvent dilution, filtration, and gas chromatography-mass spectrometry. The non-volatile components in these wet building materials have been determined by infrared spectroscopy. The results have shown the major volatile organic compounds in one-component polyurethane varnish and alkyd paint thinner to be nonane, decane, undecane, xylene, ethylbenzene and ethyltoluene. The main film-forming matter in cement floor paint has been identified as styrenated acrylic emulsion, with the volatile components being mainly butyl acetate, decane and benzene series. The basic substances in these adhesives were polychloroprene, styrene butadiene carboxylated latex, or polyvinyl acetate emulsion. The primary volatile compounds in two adhesives were methyl acetate, and many branched-chain and normal alkanes, while those in the other two adhesives were toluene and benzene.

“Chemistry in a spinneret” to fabricate hollow fibers for organic solvent filtration

Organic solvent filtration (OSF) is a very efficient separation technique with high potential in many branches of industry. Currently the choice of the commercial membranes is limited only to a few flat sheet membranes and spiral wound modules. It is generally known that a membrane in hollow fiber form has several advantages, over a flat configuration, such as high surface to volume ratio and no need of spacers. Consequently more compact and simpler modules and easy to scale up can be built.In this work we explore a new technique called “chemistry in a spinneret”, to fabricate a hollow fiber (HF) for OSF. This technique combines the membrane formation and crosslinking reaction into a single step process. P84 polyimide was chosen as a membrane forming polymer and poly(ethylene imine) (PEI), dissolved in the bore liquid, as a crosslinking agent. In order to obtain a membrane with the best stability and low membrane MWCO, the composition of the bore liquid was systematically varied, including solvent/non-solvent ratio and PEI concentration.The crosslinked membranes have MWCO in the range of 2500–3500gmol−1 and toluene permeance in the range of 0.2–1.1lm−2h−1bar−1. The most stable crosslinked membrane maintains 80% of its mass after 11days immersion in N-methyl-2-pyrrolidinone. Due to crosslinking, the HFs become more hydrophilic and therefore attractive for separations in alcohol systems. Preliminary results are in fact presented here using an ethanol/polyethylene glycol model system.

Composition of Floccules Formed in Hydrotreated Base Oil

The composition of the floccules formed in hydrotreated base oil was investigated in detail. First, a method of solvent dilution and filtration at low temperature was employed to perform the separation of the floccules in the oil. Second, n-paraffins in the floccules were separated with urea, and carbon number distribution of the floccules was obtained by gas chromatography (GC). Finally, the composition and structure between the floccules and filtrated oils were investigated using gas chromatography–mass spectrometry (GC-MS) and infrared spectroscopy (IR), and their average molecular weights were also measured. The results indicate that the floccules were caused by some hydrocarbon compounds with large average molecular weight, high paraffinic carbon content, and high freezing point. The floccules were composed of a large amount of naphthenes and some paraffins. The naphthenes had longer side branches and lower ring numbers, and the paraffins had longer chains and lower degrees of branching. During slow cooling under static conditions, these hydrocarbon compounds formed a colloidal network, which embodied the oil and dispersed throughout the oil and formed the floccules.

A rapid capillary gas chromatographic method for the determination of propionic acid and propionates in bread and bread products.

A rapid method for the determination of propionic acid and propionates in bread and bread products is reported. The method employs solvent extraction, filtration and quantification by capillary gas chromatography using an internal standard. The limit of determination was 10 mg kg-1 propionic acid. The mean recovery rates for spiked bread samples were 108% at approximately 1,000 mg kg-1 (range of 106-110%, coefficient of variation 1.1%), 97% at approximately 2,000 mg kg-1 (range 96-98%, coefficient of variation 0.7%) and 98% at approximately 3,000 mg kg-1 (range of 97-100% and coefficient of variation of 1.1%). The method offers improved sensitivity, precision, chromatographic resolution and a wider sample analyte concentration range over a previously reported packed-column gas chromatographic method and has been applied to the analysis of bread, rolls, pitta breads and hamburger buns.

Use of Adsorption Columns in the Analysis of Soap and Detergent-stabilized Emulsions

METHODS at present available for the determination of the total materials in aqueous emulsions involve cracking the emulsion, separating the non-aqueous phase by solvent extraction or filtration, and weighing the products prior to analytical investigation. The need for a rapid means of isolating the components of such systems has led to the development of a technique employing adsorbents containing an ion-exchange resin, whereby the separation of an oil-in-water emulsion (for example, wool-scouring liquors) can be achieved. This has been suggested previously1 as being applicable to large-scale cracking and recovery of emulsified grease from industrial effluents.