Organic Solvent Separation Research Articles

Modelling and Scaling-Up of a Supercritical Fluid Extraction of Emulsions Process

Supercritical CO2 (scCO2) is utilized in the supercritical fluid extraction of emulsions (SFEE) to swiftly extract the organic phase (O) from an O/W emulsion. The dissolved substances in the organic phase precipitate into small particles and remain suspended in the water (W) with the aid of a surfactant. The process can be continuously conducted using a packed column in a counter-current flow of the emulsion and scCO2, at moderate pressure (8–10 MPa) and temperature (37–40 °C). To ensure the commercial viability of this technique, the organic solvent must be separated from the CO2 to facilitate the recirculation of both streams within the process while minimizing environmental impact. Thus, the aim of this work was to design a plant to produce submicron materials using SFEE, integrating the recovery of both solvents. First, experimental equilibrium data of the ternary system involved (CO2/ethyl acetate/water) were fitted with a proper thermodynamic model. Then, simulations of the whole integrated process at different scales were carried out using Aspen Plus®, along with economical evaluations. This work proposes the organic solvent separation with a distillation column. Thus, the two solvents can be recovered and recycled to the process in almost their entirety. Furthermore, the particles in the aqueous raffinate are produced free of solvents and sterilized for further safe use. The costs showed an important economy scale-up. This work could ease the transfer of the SFEE technology to the industry.

Defect engineering on zeolitic imidazolate framework membrane via thermal annealing for organic solvent nanofiltration

Zeolitic imidazolate frameworks (ZIFs) have been attracting intensive attention in membrane separation fields because of their ultrahigh specific surface areas, well-defined apertures, and variable topological characteristics. However, the aperture sizes of ZIFs are smaller than the kinetic diameters of most organic solvent molecules, which impedes their applications in organic solvent separation. Herein, we develop a thermal annealing-derived methodology for defect engineering on the ZIF-67 membrane. This post-synthetic modification not only expanded the aperture size of ZIF-67 but also repaired intercrystalline cracks in the polycrystalline ZIF-67 layer. By controlling the thermal annealing conditions, the permeability of the polycrystalline ZIF-67 membrane toward organic solvent nanofiltration was enhanced by two times. Moreover, the annealed ZIF-67 membrane showed a high rejection of more than 99.6% for dyes (Evans blue) and pharmaceutical molecules (tetracycline, vitamin B12). This work provides an avenue for the controllable modification of ZIFs membranes to broaden their applications.

Electrospinning organic solvent resistant preoxidized poly(acrylonitrile) nanofiber membrane and its properties

A high performance O-PAN nanofiber with excellent solvent resistance, thermal stability and flexibility was fabricated. • O-PAN nanofiber membrane with excellent thermal stability and also flexibility was fabricated by the preoxidation of electrospun PAN nanofiber membrane. • In SiO 2 particle and DMAc suspension, O-PAN nanofiber membrane showed excellent organic solvent resistance and separation performance. • The O-PAN membrane after hydrophobic treatment showed excellent hydrophobicity and good oil/water separation performance. A high performance preoxidized poly(acrylonitrile) (O-PAN) nanofiber membrane with excellent solvent resistance, thermal stability and flexibility was fabricated by the preoxidation of electrospun PAN nanofiber membrane. The performance of resultant O-PAN nanofiber membrane was optimized by altering the PAN concentration and preoxidation temperature. The results showed that the O-PAN nanofiber membrane which made from PAN concentration of 14% (mass) and preoxidation temperature of 250.0 ℃ have a more optimal comprehensive performance. In the long-term separation test of SiO 2 particle (1 μm) in DMAc suspension, the permeate flux of O-PAN nanofiber membrane stabilized at 227.91 L·m −2 ·h −1 (25 ℃, 0.05 MPa) while the SiO 2 rejection above 99.6%, which showed excellent solvent resistance and separation performance. In order to further explore the application of the O-PAN nanofiber membrane, the O-PAN nanofiber membrane was treated with fluoride and used in oil/water separation process. The O-PAN nanofiber membrane after hydrophobic treatment showed excellent hydrophobicity and good oil/water separation performance with the permeate flux about 969.59 L·m −2 ·h −1 while the separation efficiency above 96.1%. The O-PAN nanofiber membrane exhibited a potential application prospect in harsh environment separation.

Ultrafast organic solvent nanofiltration in C[sbnd]C bonded conjugated microporous membrane-based nanochannels by space-confined polymerization

Organic solvent nanofiltration is a new membrane technology for separation of organic solvents with low energy consumption and environmental compatibility. However, commercial ultrafiltration membranes are unsuitable for organic solvents separation owing to their low retention and poor solvent resistance. CC bonded conjugated microporous polymer (CCMP) membranes consisting of all-rigid conjugated systems feature well-developed microporosity and excellent organic resistance. Herein, we report a strategy to prepare solvent-resistant CCMP@PTFE composite membrane by portioning channels in polytetrafluoroethylene (PTFE) ultrafiltration membrane by space-confined polymerization. Owing to intrinsic micropores from crosslinking of multifunctional rigid building units and the robustness of PTFE substrate, three CCMP@PTFE membranes exhibit outstanding separation performance, solvent resistance and high flexibility, which rival against the best of those reported membranes. This strategy inspires the design of OSN membranes with high performance.

Tannic acid/Fe3+ interlayer for preparation of high-permeability polyetherimide organic solvent nanofiltration membranes for organic solvent separation

Organic solvent nanofiltration (OSN) membranes have a great application prospect in organic solvent separation, but the development of OSN membranes is mainly restricted by trade-off between permeability and rejection rate. In this work, a TA/Fe3+ polymer was introduced into polyetherimide (PEI) ultrafiltration membranes crosslinked with hexamethylene diamine as the intermediate layer, and OSN membranes with high separation performance and solvent permeability were obtained through interfacial polymerization and solvent activation. The interlayer with high surface hydrophilicity and a fixed pore structure controlled the adsorption/diffusion of the amine monomer during interfacial polymerization, forming a smooth (average surface roughness < 5.5 nm), ultra-thin (separation layer thickness reduced from 150 to 16 nm) and dense surface structure polyamide (PA) layer. The PA-Fe33+-HDA/PEI membrane retained more than 94% of methyl blue (BS) in 0.1 g·L−1 BS ethanol solution at 0.6 MPa, and the ethanol permeation reached 28.56 L−1·m−2·h−1. The average flux recovery ratio (FRR) of PA-Fe33+-HDA/PEI membrane was found to be 84%, which has better fouling resistance than PA-HDA/PEI membrane, and it was found to have better stability performance through different solvent immersion experiments and continuous operation in 0.1 g·L−1 BS ethanol solution. Compared with thin-film composite nanofiltration membranes, the PA-Fe33+-HDA/PEI membrane can be manufactured from an economical and environment-friendly method and overcomes the trade-off between permeability and rejection rate, showing great application potential in organic solvent separation systems.

The Physicochemical Structure of Inorganics in PIM-1/Alox Hybrid Membranes Synthesized Via Vapor Phase Infiltration (VPI)

Polymers of intrinsic microporosity (PIMs) represent a unique class of polymer membranes defined by their inherent microporosity, leading to excellent separations ability. However, the poor solvent stability of these organic membranes limits their use for organic solvent separations. Vapor phase infiltration (VPI) is an emerging technique adapted from atomic layer deposition (ALD) processes that infiltrates inorganic clusters into polymeric materials, generating hybrid organic-inorganic materials with improved chemical stability. VPI treated polymer of intrinsic microporosity 1 (PIM-1) has shown dramatically improved resistance to solvent dissolution while maintaining its microporosity, making it a much more robust membrane. However, the lack of clarity around the structure of the inorganic clusters within VPI synthesized hybrid materials limits the ability to design these hybrid membranes to optimize potential trade-offs between chemical stability, permeance, and separation performance.Currently, most VPI literature refers to the inorganic components within the hybrid as “metal oxides” or “MOx”. This oversimplification does not fully describe the possible cluster structure or inorganic-to-organic bonding characteristics likely present in these hybrid structures. Moreover, the atomic-scale and long-range disorder of these inorganic clusters make them difficult to describe with traditional methods used for inorganic crystals or polymeric solids. Thus, a more sophisticated understanding of the inorganic structure is needed to inform both process and function design of these hybrid materials. This talk will discuss combined experimental and computational efforts to clarify the structure of inorganic clusters in VPI treated PIM-1/AlOx membranes. XPS and FTIR in conjunction with DFT calculations indicate that the final inorganic species is an oxyhydroxide species. Further, solid state NMR suggests the final inorganic cluster is a 6-coordinate species that is at least dimerized, with water molecules coordinating to the structure to fill out the coordination sphere. DFT calculations validate this claim as the lowest energy structure compared to the monomer form as well as other aluminum oxyhydroxide species. This interdisciplinary work explores the structural characteristics of PIM-1/AlOx hybrid membranes and its impact on the VPI treated material properties such as solvent stability.

Nanocomposite membranes for organic solvent nanofiltration: Recent advances, challenges, and prospects

Organic solvent nanofiltration (OSN) is an emerging technology for the separation of organic solvents that are relevant to the petrochemical, pharmaceutical, food and fine chemical industries. The separation performance of OSN membranes has continued to push the boundary up through advanced membrane fabrication techniques and novel materials for fabricating the membranes. Despite the many advantages, OSN membranes still face such challenges as low solvent permeability and durability in harsh organic solvent conditions. To overcome these limitations, attempts have been made to incorporate nanomaterial fillers into OSN membranes to improve their overall performance. This review analyzes the potential and use of nanomaterials for OSN membranes, including covalent organic frameworks (COFs), metal-organic frameworks (MOFs), metal oxides (MOs) and carbon-based materials (CBMs). Recent advances in the state-of-the-art nano-based OSN membranes, in the form of thin-film nanocomposite (TFN) membranes and mixed matrix membranes (MMMs), are reviewed. Moreover, the separation mechanisms of OSN with nano-based membranes are discussed. The challenges faced by these OSN membranes are also elaborated, and recommendations for further research in this field are provided.

Fluorinated graphene nanosheet supported halloysite nanoarchitectonics: Super-wetting coatings for efficient and recyclable oil sorption

Designing selective oil sorption and recovery systems to tackle oil/organics spills in water bodies by using special-wetting property are gaining huge attention. In the present work, we develop a coating material based on functionalized halloysite nanotubes (HNT) supported over fluorinated graphene (FG) nanosheets displaying super-wetting functions. The HNTC-FG hybrids were methodically analysed by various spectroscopic, microscopic and solvent wetting studies. The water contact angle (145 ± 2°) for HNTC-FG hybrids with a surface free energy of 18.1 mJ/m2 significantly affects the solvent wettability. To carry out oil–water separation, the HNTC-FG dispersion was imbibed on polyurethane (PU) sponge via dip-coating method. The HNTC-FG-PU sponges were probed towards the remediation of oil/organics spill under static, turbulent and continuous modes. The sorption capacity of HNTC-FG-PU sponges for various oils and organics falls in the range of 38–62 g/g with excellent recyclability under static and turbulent conditions besides remarkable corrosive, thermal and mechanical stabilities. Furthermore, the HNTC-FG-PU sponges were effectively used in the selective continuous separation of organic solvents by vacuum pump-assisted process over 10 cycles with flux ranging from 1593 and 4690 L.m−2.h−1 for kerosene and mesitylene respectively. The stable hydrophobicity, chemical stability and remarkable recyclability of these HNTC-FG-PU sponges drive the oil/organics recovery prototypes.

Waste to treasure: Superwetting foam enhanced by bamboo powder for sustainable on-demand oil-water separation

Low-cost and sustainable superwetting materials are urgently required for oily wastewater treatment. Many poly(vinylidene fluoride) (PVDF)-based materials have been designed for oil-water separation. However, their fabrication processes frequently require toxic organic solvents and high-cost materials (e.g., carbon tubes and graphene). In this study, a highly porous and superhydrophobic bamboo powders (BP)-enhanced PVDF foam (SBPF) was fabricated via an organic solvent-free process. The SBPF exhibits efficient adsorption and recovery for various oils and organic solvents. Moreover, the SBPF shows high adsorption and separation performance under ultraviolet exposure and turbulent environments. It can also be used for water-in-oil emulsions separation, with a high separation efficiency more than 99.3 % under gravity. Interestingly, the amphiphilic PVDF-BP foam (ABPF) shows underwater superoleophobicity and underoil superhydrophobicity after delignification of SBPF. Owing to the conversion of wettability, it presents a high performance in treatment of both surfactant-stabilied water-in-oil and oil-in-water emulsions with the high separation efficiency achieving more than 99.6 % and 99.5 % respectively under gravity. In addition, the ABPF shows a high separation performance even after ten cycles. Hence, this fabricated organic solvent-free foams are promising candidates for sustainable on-demand separation of oils or organic solvents and water in complex environments.

A microgel-structured cellulose nanofibril coating with robust antifouling performance for highly efficient oil/water and immiscible organic solvent separation

Recently, superhydrophilic-underwater superoleophobic hydrogel coatings with excellent antifouling performance have attracted increased attention for oily wastewater purification. However, the antifouling performance of hydrogel coatings is destroyed when they are exposed to air or oily conditions without prewetting. In addition, their application in industry is limited by toxic crosslinking agents, poor adhesion to substrates, and complex synthesis processes, among other factors. Herein, a versatile cellulose nanofiber microgel coating is developed via a strategy of catechol-amine chemistry that can be simply applied on various substrates through a layer-by-layer method without any additional toxicant crosslinking agents or nanoparticles. Consequently, the resultant coating, which has underwater superoleophobic and underoil superhydrophilic properties, exhibits long-term stable antifouling performance without prehydration. In addition, it displays ultrahigh physical durability and chemical stability, even with exposure to various harsh conditions, e.g., acidic, alkaline, salt and UV light environments, as well as mechanical attrition. Moreover, under gravity, coated stainless steel mesh can rapidly separate various oil/water and immiscible organic solvents (with a water flux of 139556 ± 3733 L m−2 h−1). Even coated melamine sponges can efficiently separate surfactant-stabilized oil-in-water and water-in-oil emulsions. Thus, this study provides a general method for preparing a robust microgel coating and discusses prospective applications in on-demand multitype liquid separation in practical hazardous water purification applications.

Co-transport of water and p-xylene through carbon molecular sieve membranes

Carbon molecular sieve (CMS) materials are a potential candidate for scalable and high-performance reverse osmosis membranes due to their impressive chemical and thermal stabilities. Moreover, they have the potential to enable impressive rejections of small neutral solutes from water based on their known ability to separate small organic molecules. CMS has been extensively examined for gas and organic solvent separations, but the transport of organic and aqueous mixtures through CMS microstructures is poorly understood. In this work, we investigated the sorption, diffusion, and permeation behavior of organic compounds and water in poly(vinylidene fluoride)(PVDF)-derived CMS (PVDF-CMS). Experimental observations of diffusion, sorption, and permeation shows how the properties of penetrants such as polarity and molecular size affect the transport rates and selectivity. These basic transport and sorption parameters are utilized in sorption-diffusion models to permeation rates of water-organic mixtures in CMS membranes. The transport of water and p-xylene in CMS was experimentally confirmed to follow the sorption-diffusion mechanism. The sorption-diffusion model ideal permselectivity indicates that the CMS is p-xylene selective over water. Water/p-xylene mixture permeation experiments revealed an increased selectivity of p-xylene over water, thus providing tentative evidence for a competitive sorption-selective separation mechanism. This work suggests that CMS membranes exhibit organic-permeable separation properties in water/organic separations. The results presented here highlight the potential for the removal of dilute organics in water via CMS pervaporation membranes.

Metal scavenging resin tethered with catechol or gallol binders via reversible addition–fragmentation chain transfer polymerisation

Resin-supported metal scavengers are interesting in the separation and purification of target organic compounds and solvents because they avail a suitable and facile material platform for the adsorption of metal ions, thus enabling successive recycling. Here, a mussel-inspired catechol-functionalised or tunicate-inspired gallol-functionalised polymer, which was tethered to the Merrifield resin containing self-reducing hydroxyl groups that could bind well with metal ions, was synthesised via reversible addition–fragmentation chain transfer polymerisation. The number of functional groups on the surface of the resin was quantitatively controlled by modulating the ratio of the monomer to the resin-attached chain transfer agent. The metal ion adsorption capacity, as well as removal ability of the resin in an aqueous solution, which increased with the increasing number of the dihydroxy and trihydroxy groups, was investigated employing silver, copper, zinc, magnesium, lead, and iron ions. The polytrihydroxystyrene-bearing resin exhibited better metal ion-scavenging performance compared with the polydihydroxystyrene-incorporated resin at the same grafting degree in an aqueous solution owing to the tridentate structure of the gallol group, which acted as a ligand in the synthesis of the metal complex. The developed resins demonstrated that the residual metal catalyst that was derived from synthesising the conjugated polymer can be successfully removed. • Polydihydroxystyrene (PDHS) or polytrihydroxystyrene (PTHS) was incorporated into microbeads. • Reversible addition-fragmentation chain transfer agents afforded mussel-inspired catechol or tunicate-inspired gallol groups. • Hydroxyl group-containing polymers were synthesised on commercial resins to avail many metal-ion-binding sites. • The successive adsorption/desorption of metals from the PDHS or PTHS-immobilised resins demonstrated its reusability. • The metal scavenger resin was used to remove the Cu catalyst after the click reaction of the block copolymers.

Highly hydrophobic and superoleophilic agar/PVA aerogels for selective removal of oily substances from water

In this study, low-cost, environmentally friendly and porous agar/PVA aerogel sorbent materials with highly hydrophobic property were fabricated for the selective separation of oily substances and organic solvents from water by (i) the cross-linking reaction, (ii) freeze drying process and (iii) surface coating treatment. The characterization of agar/PVA aerogels was performed by water solubility, contact angle, SEM, EDX, mapping and XPS measurements. SEM and porosity results revealed that the increase of PVA amount within aerogel matrix led to a decrease in the pore structure of aerogel material. Agar/PVA (100:0) aerogel had good absorption capacity values (19.0–48.1 g·g−1) for various oily substances and organic solvents. All aerogels had excellent separation efficiency (≥99.3%) for chloroform-water mixture. For chloroform-water mixture and emulsion, the flux value of agar/PVA (100:0) aerogel was found to be 4273 L·m−2·h−1 and 3094 L·m−2·h−1, respectively. New agar/PVA aerogels are promising materials for the effective separation of oil-water or organic solvent-water mixtures and the cleaning of oil-spills from water.

2D Polymer Nanosheets for Membrane Separation.

Since the discovery of single‐layer graphene in 2004, the family of 2D inorganic nanosheets is considered as ideal membrane materials due to their ultrathin atomic thickness and fascinating physicochemical properties. However, the intrinsically nonporous feature of 2D inorganic nanosheets hinders their potential to achieve a higher flux to some extent. Recently, 2D polymer nanosheets, originated from the regular and periodic covalent connection of the building units in 2D plane, have emerged as promising candidates for preparing ultrafast and highly selective membranes owing to their inherently tunable and ordered pore structure, light weight, and high specific surface. In this review, the synthetic methodologies (including top–down and bottom–up methods) of 2D polymer nanosheets are first introduced, followed by the summary of 2D polymer nanosheets‐based membrane fabrication as well as membrane applications in the fields of gas separation, water purification, organic solvent separation, and ion exchange/transport in fuel cells and lithium‐sulfur batteries. Finally, based on their current achievements, the authors’ personal insights are put forward into the existing challenges and future research directions of 2D polymer nanosheets for membrane separation. The authors believe this comprehensive review on 2D polymer nanosheets‐based membrane separation will definitely inspire more studies in this field.

High flux thin film composite (TFC) membrane with non-planar rigid twisted structures for organic solvent nanofiltration (OSN)

Organic solvent nanofiltration (OSN) has become an emerging green and efficient technique for the separation and purification of organic solvents. The key of the industrial application of this technique is OSN membrane. Till now, current OSN membranes still have relatively low solvent permeance due to the high hydraulic resistance of the dense structure of the OSN barrier layer. Herein, a thin-film composite (TFC) polyamide-polyarylate OSN membrane containing polymers of intrinsic microporosity (PIMs) structure was successfully prepared via interfacial polymerization (IP) using a kind of hydrophilic monomer with rigid twisted structure as aqueous co-monomer together with m-phenylenediamine (MPD). The added co-monomer remarkably enhanced the perm-selectivity of the prepared OSN membrane, with an increase of more than 1.5 times for ethanol permeance, while maintaining the rejection of rhodamine B (RDB, 479 Da) above 99% under the optimal conditions. Moreover, the prepared OSN membrane has a much high permeance to polar solvents, e.g., 110.5, 112.6 and 95.8 L m−2h−1 MPa−1, for ethyl acetate, methanol and DMF, respectively. The most exciting aspect of the prepared OSN membrane is its superior solvent resistance in strong polar organic solvent. It maintained an essentially unchanged solute rejection during 63 d immersion in DMF at 80 °C, and during 120 h continuous cross-flow filtration of the RB-DMF solution at room temperature, which is superior over most of the state-of-the-art literature works, indicating its broad application prospects for separation and purification of polar organic solvent systems.

Mussel-Inspired and In Situ Polymerization-Modified Commercial Sponge for Efficient Crude Oil and Organic Solvent Adsorption.

Oil spills and pollution of oily wastewater from the industrial field have not only caused serious economic losses but also imposed a huge threat to human beings. To solve these issues, the development of advanced materials and technologies for the purification of oily wastewater has garnered great concern and become a central topic. Hence, a superhydrophobic polyurethane (PU) sponge adsorbent is designed via mussel-inspired coatings by double bonds to PU sponge, followed by in situ polymerization with 1-hexadecene. The prepared PU sponge adsorbent (PU@DB@16ene sponge) showed outstanding mechanical properties including low density, high porosity, and compression recovery ability. Moreover, the prepared PU@DB@16ene sponge showed excellent adsorption of oils and organic solvents (up to 187 g g-1) and exhibited superior recyclability. Particularly, when the PU@DB@16ene sponge was applied in the continuous and rapid separation of oils and organic solvents, it still showed desired properties at a rapid velocity of 8.3 L m-3 s-1. Additionally, the PU@DB@16ene sponge could not only adsorb organic solvents in laboratories but also adsorb crude oil and industrial waxy oil in practice. Therefore, we proposed a simple and convenient method to construct PU sponge absorbents with great application prospects, which would be highly valuable for crude oil and organic solvents cleanup.

Polybenzimidazoles (PBIs) and state-of-the-art PBI hollow fiber membranes for water, organic solvent and gas separations: a review

A comprehensive overview of the recent progress toward polybenzimidazole hollow fiber membranes, including material chemistry, molecular structure modification, spinning chemistry and process protocols, is presented with challenges and perspectives.

Development of polydimethylsiloxane composite membrane for organic solvent separation

Membrane processes have proven to be energy-efficient technologies for separation of various substances, including organic solvents. In this study, crosslinked polydimethylsiloxane (PDMS) composite membranes were developed for organic solvent separation. Precursor solutions containing double-ended vinyl PDMS with four different molecular weights were spin-coated onto a polyethersulfone membrane substrate, and the crosslinking reaction was accelerated by heat treatment to produce PDMS composite membranes. The influence of the PDMS molecular weight and crosslinking on the membrane properties and performance was tested. It was shown that less swelling, more selective hexane absorption, and increased separation coefficient was observed with decreasing PDMS molecular weight. The trade-off relationship between the permeance and the separation coefficient was observed as the membranes prepared with lower molecular weights of PDMS showed lower permeability and higher separation coefficient. The separation coefficient showed a maximum value at a supplied ethanol concentration of 50 wt%. In addition, various solvent mixtures containing hexane and alcohols were used for organic solvent separation performance test using the PDMS composite membranes. A correlation was observed between the separation coefficient and the difference of χ parameters between alcohol/PDMS and hexane/PDMS. The mechanisms for solvent permeation and separation were discussed based on the interaction parameters, membrane swelling and solvent dissolution. The results of this study could be used as guidelines for the development of solvent-resistant PDMS composite membranes.

Thermally Induced Silane Dehydrocoupling: Hydrophobic and Oleophilic Filter Paper Preparation for Water Separation and Removal from Organic Solvents.

Organic solvents with high purity are essential in various fields such as optical, electronic, pharmaceutical, and chemical areas to prevent low-quality products or undesired side-products. Constructing methods to remove impurities such as water residue in organic solvents has been a significant challenge. Within this article, we report for the first time a new method for the preparation of hydrophobic and oleophilic filter paper (named OCFP), based on thermally induced silane dehydrocoupling between cellulose-based filter paper and octadecylsilane. We comprehensively characterized OCFP using various characterization techniques (FTIR, XPS, XRD, and EDS). OCFP showed super-hydrophobic and oleophilic properties as well as remarkable water separation and removal efficiency (>93%) in various organic solvents with sustained reusability. In addition, the analytical results both before and after filtration of an NMR solvent using OCFP indicated that OCFP has an excellent solvent drying efficiency. This work presents a new strategy for the development of super-hydrophobic cellulose-based filter paper, which has great potential for solvent drying and water separation.

Hydrophobic modification of sintered glass filters for the separation of organic solvents and gasoline from water as well as emulsified water

Sintered glass filters are used in chemical plants and laboratories to separate particulate matter from liquids. This paper reports their hydrophobic modification to render an additional function: the separation of water-immiscible organic liquids (oils) from water as well as emulsified water. To coat the filters, chlorodimethyloctadecylsilane and a 5 kDa poly(dimethyl siloxane) sample bearing an epoxy end group, PDMS-Ep, are covalently grafted onto the filter pore walls. Investigated are how varying the hydrophobic coating agent, its solution concentration, water content in the emulsion, and the filter pore size affects oil separation. While the oil flux increases with the filter pore size and pressure drop across the filter, the tilting of a filter from its horizontal position or the stirring of the feed emulsion also increases the separation flux presumably due to reduced pore blockage by the settling water. Based on the knowledge gained through this study, a prototype funnel for the household purification of wet gasoline is constructed. Such a funnel is shown to completely remove water droplets from wet gasoline, which contrasts with the inadequate performance of a commercial funnel sold specifically for this application. The developed filter should have applications in the treatment of wet gasoline and in the separation of organic phases from water in chemical laboratories and plants.