Sieving Capacity Research Articles

Unveiling the Mystery: How TR precursors lead to exceptional gas separation performance in CMSMs

One of the main issues with membrane-based gas separation lies in the unexplored relationship between the precursors and their derived carbon molecular sieve membranes (CMSMs). Herein, we designed a series of TR polymers with gradient PBO content as precursors to investigate the carbonization mechanisms of PBO structure. The process of transforming the polymer precursor into carbon structure throughout pyrolysis involves utilizing an array of characterization techniques along with pyrolysis simulation. Results indicated that a higher PBO content leads to stronger molecular sieving effect of the resulting CMSM. The TR-CMS-50 membrane demonstrated exceptional gas separation performance with high permeability (PH2 = 3154 and PCO2 = 1495 Barrer) as well as ultra-high H2/CH4 (384) and CO2/CH4 (166) selectivity, which far exceeded the newest Upper bound line, showing significant potential for practical applications. This may can be attributed to “delayed effect” of the PBO structure which requires pyrolysis at higher temperatures, leading to more intense pyrolysis and the release of nitrogen-containing substances. Meanwhile, PBO has a cyclic system with a strong aromatic structure that closely resembles a carbon strand, which probably facilitates aromatization and enables it to more easily integrate into CMS structure, resulting in a more orderly arrangement in the Langmuir phase and generating higher concentration of pyrrolic-N (58.7 % vs. 44.1 %) as well as graphitic-N (31.6 % vs. 17.2 %). Thus, increasing the PBO content makes the derived CMS denser and significantly enhances its molecular sieving capacity. This study offers new insights into the development of precursor structures that creates high-performance CMSMs.

Polyelectrolyte intercalated two-dimensional covalent organic framework membranes for efficient desalination

Two-dimensional covalent organic frameworks (2D COFs) have been proven to be ideal membrane materials for highly efficient separation. However, synergistic manipulation of the in-plane pores and interlayer channel structures of 2D COF membranes (COFMs) to acquire both high permeability and selectivity has rarely been reported. In this work, we synthesized TbTG COF nanosheets with intrinsic sub-nanometer pores, which were assembled with polyelectrolytes to form intercalated 2D COFMs. The sub-nanometer in-plane pores of the COF nanosheets endowed the COFM with size sieving capacity toward hydrated multivalent ions. The polyelectrolyte introduces numerous charged groups to the interlayer channels, enhancing the Donnan effect for desalination and also enlarging the interlayer distance to facilitate permeability. Accordingly, the in-plane pores and interlayer channels of the 2D COFM were synergistically engineered to simultaneously enhance the selectivity and permeability of COFMs. By adjusting the polyelectrolytes with different charged groups, the intercalated COFMs exhibited a high Na2SO4 rejection of 97.5 % and MgCl2 rejection of 99.4 %, respectively, as well as about a fourfold increase in permeability. Compared with the pure COFM. This work highlights the significance of interlayer channel structure of 2D COFMs for precise separations, providing new guidelines on the design and construction of advanced COFMs.

Emerging 3D-printed zeolitic gas adsorbents

The development of zeolitic adsorbents is an essential subject of interest in the realm of green chemistry, especially in the aspect of gas adsorption. The intrinsic molecular sieving capacity of zeolites allows them to be widely adopted as effective gas adsorbents. As a layer-by-layer deposition technology, three-dimensional (3D) printing can achieve more complex zeolitic gas adsorbent structures than conventional manufacturing methods by offering flexible freeform construction and controllable 3D structural design. This review article focuses on the recent development of 3D-printed zeolitic gas adsorbents, which integrate advanced zeolitic structures and emerging additive manufacturing technologies for gas absorption. A description of zeolites and their conventional fabrication methods is given for a basic understanding of zeolitic gas adsorbents. 3D printing technologies are also introduced and discussed for the fabrication of zeolitic adsorbents such as monoliths. Next, the recent progress in the fabrication of zeolitic gas adsorbents using 3D printing is illustrated and summarized, which boosts the application of 3D-printed zeolite absorbents in different fields of gas adsorption. Conclusions are given with an outlook on opportunities ahead for future research. It is expected that the development of advanced zeolitic materials and structures for gas adsorption purposes will be significantly accelerated through 3D printing technologies.

Confined intercalating sulfonated graphene quantum dots into GO laminates for fast alkali recovery

Graphene oxide (GO) membranes with uniform sub-nanometer interlayer channels have shown great promise in the ion sieving field. However, the lack of ion-transporting sites on the GO nanosheets usually leads to inferior ion permeation and selectivity. Although the intercalation of molecules with ionic groups into GO laminates is easily achieved to incorporate ion exchange sites, this approach inevitably enlarges the interlayer spacing, reducing the ionic sieving capacity. Thus, current methods are limited in breaking the permeation and selectivity “trade-off”. Herein, we report a confined intercalation strategy to inject ample sulfonic acid groups into GO laminates using sulfonated graphene quantum dots (SGQD) as intercalators. SGQD with abundant ion exchange sites assembles on the sp2 domains of GO via π-π interactions and confers the GO membranes with continuous ion conduction pathways. Meanwhile, benefiting from the ultra-small size SGQD as well as its sheet morphology, it can well accommodate in the GO laminates. This strategy fulfills the incorporation of ionic sites without expanding channel width and destructing the two-dimensional (2D) regularity for GO laminates, resulting in simultaneous improvements in ion permeability and selectivity. Correspondingly, the resulting membranes show synergistically improving OH- dialysis coefficients of 3.5 × 10−3-8.2 × 10−3 m h−1 and OH-/WO42- separation factors of 56–116 compared with the GO membrane (0.9 × 10−3 m h−1 and 8.4) for separating simulated NaOH/Na2WO4 alkaline effluents. We believe the confined intercalating regulation can act as a versatile and fine way to modify 2D membranes for intensifying ion separation.

A novel dynamic coating medium for single stranded DNA separation in capillary electrophoresis: Thermosensitive hydrogel nanoparticles

Nowadays, research on single-stranded DNA (ssDNA) requires a quick, effective and easy operation method to separate small ssDNA fragments from the organism and ssDNA production process to realize their application in gene therapy and drug diagnosis. Herein, a novel separation matrix of thermosensitive hydrogel nanoparticles (NPs) was proposed, which has been successfully applied to the isolation of biomacromolecules such as enzymes, peptides and proteins, based on the desirable properties of various monomers and advantages, such as high sieving capacity, tunability of hydrophilic and hydrophobic performance and non-toxicity. The flexible particles were prepared by precipitation polymerization method in aqueous solution while N-isopropylacrylamide (NIPAm), acrylic acid (AAc) and N-t-butyl acrylamide (TBAm) was performed as co-monomer, which were first used as the dynamic coating to separate small fragments of ssDNA in capillary electrophoresis (CE). The synthesized NPs were bound to the inner wall of the capillary through non-covalent interactions forming stable dynamic coating to affect the electroosmotic flow and improve the separation reproducibility of ssDNA fragments. Based on the formulation design of NPs and condition optimization of electrophoresis, the running buffer TG (25 mM Tris, 192 mM glycine, pH 8.3) was modified by 4 mg·mL−1 optimized NPs aqueous suspension addition while its molar feed ratio of NIPAm /AAc /TBAm /BIS was 83/5/10/2 and particle size was about 214 nm. Both the formulation design and temperature sensitivity of hydrogel nanoparticles contributed to the DNA separation efficiency. The designed NPs with low viscosity provide an approach to increase their capability as the separation medium for small fragment DNA with important physiological functions great potential and promise.

Room-temperature in situ fabrication of ultrathin undulating layered hydroxide salt membranes for efficient H2/CO2 separation

Two-dimensional (2D) materials have demonstrated their superiorities as molecular sieve membranes for strategic gas separations. The promotion of these 2D membranes is confronted with great challenges such as elaborate fabrication procedures and expensive raw materials. Layered hydroxide salts (LHSs) are a kind of lamellar material involving economical ingredients and are quite easy-to-fabricate. However, they have yet to be developed into gas separation membranes and their separation potential has not been investigated, despite their merits. Here, we report the successful fabrication of ultrathin Zn5(OH)8(NO3)2·2H2O membranes by using a rapid and facile in situ growth strategy at room temperature. By virtue of the few-layered membrane thickness, the obtained membranes exhibited intriguing surface undulations, which endowed the membranes with extremely tortuous interlayer channels and therefore an auspicious molecular sieving ability. Consequently, these membranes showed an optimal H2/CO2 mixture separation selectivity of 792 ± 38 and a remarkable H2 permeance of 1607 ± 99 GPU. Moreover, with a demonstration of a gentle framework dehydration, the molecular sieving capacity of the LHS membrane was further sharpened at 150 °C owing to the narrowed interlayer channels. This work introduced a low-cost 2D membrane and manifested the advantages of fabricating few-layered 2D membranes, opening a new avenue for membrane future scale-up.

Covalent organic framework membrane with sub-nano pores for efficient desalination

Covalent organic frameworks (COFs) have emerged as advanced membrane materials for molecular separations, but it is rarely used for desalination due to the mismatch between the COFs pore size (1−5 nm) and the diameter of hydrated ions (<1 nm). Herein, we designed and fabricated an imide-linked TbTG COF membrane (COFM) with intrinsic sub-nano pores. The TbTG nanosheets were prepared by interfacial polymerization, and then self-assembled into COFMs on the porous PAN substrate. The sub-nano pore size (∼0.4 nm by simulation) conferred excellent size sieving capacity to the TbTG COFM with the molecular weight cut-off of only 180 Da, which was the lowest among COFMs ever reported. Moreover, the positive charge on the skeleton of TbTG COFM greatly fortified the Donnan effect. The TbTG COFM exhibits excellent salt rejections of 98.7% to Na2SO4, 99.1% to MgSO4, 99.5% to MgCl2 and 93.3% to NaCl, respectively. The TbTG COFM also maintained high salt rejections under both high salt concentration up to 10000 ppm and high pH value of 9.4, showing great potential in seawater desalination applications.

Nanoengineered ZIF fillers for mixed matrix membranes with enhanced CO2/CH4 selectivity

Zeolitic-imidazolate frameworks (ZIFs) are considered as promising nanoporous solids for the development of membranes with exceptional gas separation properties. In this work, we show how molecular-scale modifications can lead to ZIF variants, which can greatly enhance the CO2/CH4 separation performance of mixed-matrix membranes (MMMs) when used as additives. First the permeabilities of CO2 and CH4 in ZIF-8 are estimated with the help of molecular simulations. Based on these results and a macroscopic model, the performance of MMMs with ZIF-8 as fillers is deduced. The validity of this approach is confirmed through experiments by developing flat-sheet ZIF-8 based nanocomposite membranes with two typical polymers (rubbery Pebax® MH1657 and glassy 6FDA-DAM) having different permeability properties. In a subsequent step, we design computationally new ZIF crystals, by changing the original metal, organic linker and functional group of ZIF-8, and the CO2/CH4 separation performance of MMMs with the new ZIF variants is predicted. Our results reveal that some of these MMMs exhibit an unprecedented CO2/CH4 separation performance, which surpasses any reported MMM and is directly attributed to the enhanced sieving capacity of the modified ZIF fillers. In conclusion, this work highlights the effectiveness of ZIF nanoengineering as a means to develop highly selective CO2 membranes.

Design and Development of a Low Cost Laterite Sieving Machine

Sieving has been an essential process in the use of laterite for building, agriculture, etc. However, manual laterite sieving results to drudgery, fatigue, and time wastage during the processing. The method of laterite sieving is still being done manually in some parts of the country and therefore labour intensive. This is because a lot of Small and Medium Scale Entrepreneurs cannot afford the existing sieving machines because of their cost implications and availability. The simple aim of this paper is to develop a laterite sieving machine that will enhance the efficient sieving of laterite sand to be used in the construction/housing sector and also to reduce drudgery. This paper presents the design of an efficient laterite sieving machine that was developed with locally sourced materials with ease of maintenance amongst other advantages. The machine motion was designed with the concept of crank and slider mechanism. The machine is powered with a 2.43kW, 2600 RPM diesel engine and with the appropriate pulley ratio, the machine operated at a speed of 440RPM with an operating rate of 300kg/hour. The machine component parts include prime mover, Hopper, driving/driven pulley, belt guard, sieving unit and the machine frame. Several fabrication techniques such as welding, machining, etc. are adopted for the fabrication of the machine. Dry laterite sample was tested with the machine for operational effectiveness and the result shows that the machine has a sieving capacity of 300kg/hr and sieving efficiency ranging from 92 - 97%. The fabricated laterite sieving machine performed well with high sieving efficiency, reliability, durability with an estimated cost of 646, 684.00 Nigerian Naira.&#x0D; The study was carried out in Akure, Ondo State, Nigeria. A performance evaluation was carried out on the machine and the sieving efficiency is 96% was achieved.

PH-regulated interfacially polymerized nanofiltration membranes to achieve high separation of NOM and moderate desalination for purifying ground water

Highly permeable nanofiltration (NF) membranes with efficient natural organic matter (NOM) removal yet preserving essential minerals are of great significance for purifying ground water. In this work, a novel pH-regulated interfacial polymerization (PRIP) strategy was proposed to fabricate ultra-low pressure NF membranes. This strategy was achieved by changing the aqueous solution pH (5, 7, 9, and 11) during IP process. The effects of pH-regulated processes on the structure, chargeability, and physicochemical properties of NF membranes were systematically investigated. Tailored NF membranes under acidic conditions (TFC-pH 5) achieved the ultrahigh permeability of 42.9 L m−2 h−1 bar−1 and 83.3 % moderate rejection of Na2SO4. For the NF membranes prepared under alkaline conditions (TFC-pH 11), the sieving capacity was obviously improved with fewer defects, and 99.4 % rejection of Na2SO4 was observed. In addition, the purification performance of NF membranes in ground water treatment was further studied. Modified NF membranes showed significant removal of NOM and retain moderate amounts of mineral salts. Finally, the mechanism of the pH-regulated influence on the polyamide active layer formation process was proposed. This study provides a feasible and facile design idea for ultralow-pressure NF membranes in purifying ground water.

Surface modification of bilayer structure on metal-organic frameworks towards mixed matrix membranes for efficient propylene/propane separation

Rational matching of filler-matrix in mixed matrix membranes (MMMs) is crucial but challenging for highly efficient gas separation. Herein, we propose a bilayer structure modification strategy on metal-organic frameworks (MOFs) to design various MOF-based MMMs for efficient propylene/propane separation. The octadecylphosphonic acid-lecithin-cholesterol bilayer structure grafted onto the surface of MOFs strengthens their sieving capacity under the premise of maintaining good interfacial compatibility, and promotes the formation of holes in the cross-linked poly(ethylene oxide) (XLPEO) polymer matrix. This allows for the simultaneous enhancement of gas permeability (∼266 Barrer) and C3H6/C3H8 selectivity (40.5). We briefly investigated the effect of the modified bilayer structure on the gas separation performance. More importantly, this constructing strategy is also effective for other MOF fillers in MMMs; thus this design of bilayer modification at a molecular level opens new insights into optimizing MOF-based MMMs in the challenging olefin/paraffin separation.

High-performance porous graphene oxide hollow fiber membranes with tailored pore sizes for water purification

Though graphene oxide (GO) membranes hold a good promise for water purification, their performance is restricted by permeation through long and tortuous diffusional pathways, leading to lower water permeance. In this study, we proposed a mild chemical etching approach to create nano-scale pores on the basal plane of GO nanosheets to make hollow fiber (HF) porous GO (PGO) membranes with improved water permeance and good dye rejection performance. Various characterization techniques were performed to monitor the pore generation and structural and compositional changes of synthesized PGO nanosheets. Results revealed that by controlling the etching time, PGO nanosheets with tunable pore size and surface chemistry as well as good solution processability were synthesized. The fabricated PGO HF membranes showed a well-stacked laminar morphology with uniform structures. The membrane made of PGO nanosheets etched for 5h (named PGO_5h) exhibited a 23-fold enhancement in pure water permeance from 0.129 LMHBar −1 for pristine GO membrane to 2.98 LMHBar −1 . Rejection tests with dyes in the molecular weights range between 200 and 900 g mol −1 were performed to prob the sieving capacity of the membranes on dye-containing wastewaters. The PGO_5h membrane showed molecular weight cut-off (MWCO) about 500 g mol −1 , demonstrating the great potential of PGO HF membranes for nanofiltration applications. • Porous graphene oxide (PGO) synthesis using mild chemical etching technique. • Controlling the pore sizes on the PGO by altering treatment times. • Processing the synthesized PGO into membranes on alumina hollow fibre support. • 23-folds enhancement in water permeation compared to pristine GO membranes. • Reject molecular of size larger than around 500 g mol −1 .

Rice sort machine design to improve rice granules quality

To produce quality rice, improvement in rice production management must begin at the farmer level (on-farm) by using high-quality seeds and good plant maintenance. Good quality rice is rice grains that don't break or crumble. To urge good quality rice, rice producers usually sort it manually. This method leads to long work processes and low productivity. Efforts to beat this problem are by designing a rice sorting machine which will separate whole rice and broken rice so on lighten the workload, improve rice quality, and increase prices. The results of the study obtained that the look specifications of the rice sieving machine were a). The sieving capacity is 10 kg of rice, the most drive is an electrical motor of 0.25 HP, a V-belt transmission, and an angled iron frame. Machine dimensions: length 120 cm, width 70 cm and height 90 cm). Machine testing the standard of rice grains employing a sorting machine can improve the standard of rice grains by reducing the presence of broken rice (size p=0.30 mm and below) a mean of 0.2 kg for 10 kg of sorted rice or increasing the standard by 1.91%. Machine testing from the ergonomic aspect.

A review on recent advances in CO2 separation using zeolite and zeolite-like materials as adsorbents and fillers in mixed matrix membranes (MMMs)

Anthropogenic emissions have developed the environmental demands for proficient carbon dioxide (CO2) separation technologies. Adsorption and membrane technologies are widely used to separate CO2 from other light gases due to their multiple technological benefits, including but not limited to factors such as energy efficiency and low environmental footprint. In this context, zeolites are often used due to their intrinsic molecular sieving capacity. This review initially addresses recent technological advances to enhance the gas separation performance of zeolite materials. Current trends directed toward improving CO2 adsorption capacity of zeolites include amine, silica, and ion-exchange modifications. Other promising efforts to improve the adsorption performance of zeolites involve processing zeolite nanoparticles, nanofibers, and zeolite-based foams. The second part of the review deals with pristine and modified zeolites beneficial properties for designing polymer-based mixed matrix membranes (MMMs), which enable to adapt a desirable gas separation performance. The gas transport mechanisms and morphological properties of MMMs are essential. This review addresses the most current strategies used to improve interfacial adhesions between zeolite particulates and polymer matrices to overcome the trade-off between gas selectivity and permeability faced by pure polymeric membranes. Filler shape and size play vital roles in determining the filler and polymer matrix's interfacial adhesions. New structures of inorganic fillers have been designed to fabricate MMMs with excellent gas transport properties. Hollow zeolite spheres (HZSs) are particularly interesting as they effectively minimize agglomeration and improve filler dispersion in the polymer matrix. Furthermore, approaches that employ nanoporous layered fillers, including AMH-3 and Jilin-Davy-Faraday, layered solid No. 1 (JDF-L1), have been reviewed to overcome the limitation of incorporating high contents of zeolites, which are required to improve the gas transport properties of MMMs. Furthermore, this review explores implementing zeolitic imidazolate frameworks (ZIFs) in MMMs because of their tunable pore structure and remarkably high adsorption capacity and surface area as well as excellent chemical and thermal properties. Lastly, we address the prospects and future developments in gas separation applications.

Achieving realistic gastric emptying curve in an advanced dynamic in vitro human digestion system: experiences with cheese-a difficult to empty material.

Nowadays, in vitro digestion models have received growing interest in recent years to track the digestive fate of foods in the gastrointestinal tract. A major challenge in the development of more physiologically relevant in vitro gastric models is to simulate realistic gastric emptying. In this study, an advanced dynamic in vitro human gastric system was investigated for its potential in achieving the above. The mechanisms for controlling the gastric emptying rate by modulations of the peristaltic moving distance, the pylorus opening size/frequency, and the stomach tilting angle in relation to time are illustrated. With solid cheese, a difficult food material for emptying, different combinations of the operational parameters of the stomach system were evaluated. The system was steered to attain consistent gastric emptying curve with the theoretical data by optimizing operational parameters. By fitting the gastric retention data with a power-exponential model, which is a common approach for describing gastric emptying, the total meal achieved an average emptying half-time (t1/2) of 84.5 min and a curve shape coefficient (β) of 1.69, similar to the theoretical data reported in the literature, where the values of t1/2 and β were 85 min and 1.8, respectively (p > 0.05). Furthermore, the mean median particle size was significantly decreased from the initial 2.80 mm (cheese cubes) to the final 1.35 mm (p < 0.05). There are few particles greater than 2 mm observed in the emptied cheese digesta throughout the digestion process. These suggest the powerful gastric grinding and sieving capacity exhibited by the in vitro system. The current study demonstrates that a well-considered in vitro system can offer a reasonable approach for tracking the structural and physicochemical changes of foods during digestion in the stomach, which is practically meaningful.

Proširena hemodijaliza - osnovni principi i klinički značaj

Expanded hemodialysis is a method of treatment to replace kidney function, which effectively removes uremic toxins of middle molecular weight from the blood of the patients with the end stage of chronic kidney disease. Two basic principles of removing uremic toxins during an expanded hemodialysis session are diffusion and convection. The basis of diffusion is the concentration gradient, and the basis of convection is internal filtration (covective transport). Increased MCO membrane sieving capacity and high internal filtration provide high clearance of middle molecular weight uremic toxins. Expanded hemodialysis prevents the development of microinflammation, malnutrition, resistance to the action of erythropoietin, amyloidosis, accelerated atherosclerosis and atherosclerotic cardiovascular diseases in the population of patients treated with regular dialysis. The task of the nephrologist is to evaluate different dialysis modalities that are available and to select the optimal dialysis modality for the treatment of each patient individually, i.e., the individualization of dialysis treatment.

Performance Evaluation of A Developed Dewatered Cassava Mash Sifter

A cassava pulp sifter for grated and dewatered cassava was developed and evaluated. The machine was evaluated at three operating speeds of 260rpm, 350rpm and 530rpm and masses of 1kg, 2kg and 3kg. It was observed that increase in the speed of operation increased both sieving capacity and sieving efficiency of the machine. Increase in mass, increased sieving capacity and decreased sieving efficiency. The average maximum sifting efficiency and capacity were 95.32% and 613.16kg/hr respectively. All the materials used for the fabrication were obtained locally and the machine has low labour requirements which can be adopted in gari processing industries. Keywords: Cassava, Dewatered, Mash, Performance Evaluation, Shifter DOI: 10.7176/FSQM/99-04 Publication date: July 31 st 2020

A new superior competitor for exceptional propylene/propane separations: ZIF-67 containing mixed matrix membranes

Recently, the ZIF-67 molecular sieve has emerged as an excellent substitute for the ZIF-8 counterpart due to its potentially high C3H6/C3H8 separation performance. Here, for the first time, we investigated the effect of ZIF-67 in mixed matrix membranes (MMMs) for C3H6/C3H8 separations by integrating them into 6FDA-DAM polymer matrix. The 6FDA-DAM/ZIF-67 (80/20wt/wt) MMMs achieved an ideal selectivity of 29.9 and a separation factor of 19 under single and equimolar mixed gas conditions, respectively, at 35°C. The intrinsic C3H6/C3H8 separation performance of ZIF-67 was estimated from our experimental transport results based on the Maxwell model. The calculation demonstrated its superior C3H6/C3H8 selectivity of 251, which is twice of that of ZIF-8, supporting the high molecular sieving capacity of ZIF-67 containing MMMs. Moreover, a thorough investigation on the temperature-dependent gas transports elucidated that the energetic selectivity is a major contributor for the high C3H6/C3H8 diffusivity selectivity in ZIF-67 containing MMMs. However, the minimum aperture size of ZIF-67 (4.5 Å), derived by the cuboid dimensions of C3H6 and C3H8, substantially sacrificed the C3H6/C3H8 entropic selectivity of ZIF-67 containing MMMs. Lastly, the defect-free incorporation of ZIF-67 nanoparticles into 6FDA-DAM polymer matrix effectively retarded physical aging process, maintaining the excellent separation performance of the associated MMMs for 75 days.

Impact of sodium hypochlorite (NaClO) on polysulfone (PSF) ultrafiltration membranes: The evolution of membrane performance and fouling behavior

Abstract This paper presents a study on the impact of sodium hypochlorite (NaClO) on the performance and fouling behavior of polysulfone (PSF) membranes. The performance of aged PSF membranes was studied under different transmembrane pressures (TMPs), and three critical TMPs including the pressure corresponding to critical flux (P C ), the pressure corresponding to critical filtration efficiency (P V ), and the pressure corresponding to the greatest retention ability (P R ) were innovatively proposed. In terms of an aged membrane, the filtration efficiency (η v ) and retention ability (R) were decreased, while, the enhanced sieving capacity (η s ) were experimentally proved. These are strongly related to modified surface properties and enlarged pore diameters of aged PSF membranes. The fitting results of Hermia’s model and critical flux analysis mutually verified that the formation of cake layer fouling on an aged PSF membrane surface was delayed. However, the specific fouling results indicated the aged membrane suffered a more severe pore block fouling. Moreover, the target plot also implied that the critical parameters (P C , P V and P R ) can serve as indicators of the evolution of membrane performance and fouling behaviors.

Anti-Biofouling Isoporous Silica-Micelle Membrane Enabling Drug Detection in Human Whole Blood

Direct electrochemical detection in human whole blood remains challenging due to electrode surface fouling and passivation by abundant biological substances. In this work we report that the isoporous silica-micelle membranes (designated as iSMM) can effectively function as antibiofouling layer for electrochemical detection of drug molecules in human whole blood without pretreatment. The iSMM possesses molecular sieving capacity, charge/lipophilicity selectivity, and preconcentration ability. Only small and neutral/lipophilic analytes can permeate the iSMM, be concentrated, and subsequently be detected at the underlying electrode. It is however impermeable to big sized substances and those small but charged and hydrophilic. We first investigated the molecular permeability of iSMM by electrochemical impedance spectroscopy (EIS) and then demonstrated its application in the quantitative determination of chloramphenicol (CAP) in the unprocessed human whole blood. The analytical sensitivity and long-term stability of iSMM based electrochemical sensors are apparently better than bare electrodes.