Ultrafiltration Tests Research Articles

Homogeneous CaAlg/PES hybrid ultrafiltration membranes prepared with in situ ionic crosslinking and phase inversion method

Calcium alginate hydrogel/polyethersulfone (CaAlg/PES) hybrid membranes were synthesized via combining in situ ion crosslinking with phase conversion method. Once the Sodium alginate (NaAlg) uniformly dispersed in the casting solution contacted with Ca2+ dissolved in coagulation bath solution in the phase conversion membrane formation process, nanoscale CaAlg hydrogel was in situ formed through ion exchange and evenly dispersed in the membrane matrix. FT-IR and XPS were adopted to confirm the formation of CaAlg hydrogel distributed in PES membrane matrix. SEM, AFM, BET analysis and contact Angle analyzer were all used to characterize the surface changes of morphology, roughness and hydrophilicity in detail. Specific separation performance was also evaluated and compared by cross-flow ultrafiltration tests. Comprehensive analysis of the measured properties of all obtained membranes, when the content of NaAlg was 1.5 wt%, the CaAlg/PES hydrogel membrane M32 had the most excellent performance. The pure water flux increased from 1967 to 2193 L/m2hMPa, rejection rate of BSA was up to 99.87 %, and RFR value was almost 76.83 % after 4 cycles BSA filtration. XPS characterization of the membrane after filtration for 72 hours showed that the retention rate of Ca (2 P) reached 95 %, which further proved the stability of the membrane operation.

Fast and efficient chromium(VI) extraction by colloidal Mg/Al layered double hydroxide nanoparticles

Due to the constraints associated with diffusion and mixing time, traditional kinetic and thermodynamic approaches were inadequate for probing the true mechanism of interaction between chromate and Layered Double Hydroxide (LDH). To circumvent these limitations, colloidal suspensions of Mg/Al-NO3 LDH, characterized by a positively charged surface (approximately +50 mV) in ultrapure water and a mean average diameter of 140 nm, allowing the formation of stable suspensions for days, were swiftly mixed with Cr(VI) suspensions at both pH = 4 and 9 using a stopped flow technique. This rapid mixing, accomplished in <5 milliseconds, enabled the examination of the initial stages of interaction between the toxic anion and the host compound. Two distinct steps in the adsorption process were identified: a very fast step (completed in <5 ms), representing up to 80% of the measured variation, and a slower step lasting up to 100 s. The fast step assumed to be driven by electrostatic interaction (ζ ∼ +50 mV) with the surface, and sites close to the surface are easily accessible to the chromate anions. The slower step corresponded to a diffusion process close or inside the particles. Chromate extraction efficiency was investigated through ultrafiltration tests, varying the LDH and chromate amounts, indicating that 2 nitrate ions are exchanged for 1 chromate, regardless of the pH considered, and a total exchange can be fulfilled with 0.1 g L−1 of LDH within the explored concentration range.

Investigating the impact of the sulfonation degree in sulfonated polyphenylsulfone (sPPSU) on PES/sPPSU polymer blend membranes

Polyethersulfone (PES) has widespread applications due to its excellent processability, mechanical strength, and chemical resistance. Nevertheless, its hydrophobic nature often leads to severe fouling and permeance decline. To improve the hydrophilicity of PES membranes, polymer blending is one of the most common methods. In this work, a series of sulfonated polyphenylene sulfones (sPPSU) with 1.9, 4.5, 8.2, 12.7, 19 degrees of sulfonation (DS) were synthesized and used to blend with PES. The PES/sPPSU blends were found to be compatible by calculating their theoretical enthalpy of mixing and measuring their glass transition temperatures (Tg's) at a blend weight ratio of 1:1. Ultrafiltration (UF) membranes were cast using the nonsolvent-induced phase separation (NIPS) method. It was found that 50/50 PES/sPPSU blend membranes with a DS equaling to or exceeding 8.2 eliminated finger-like macrovoids, resulting in a thinner and tight cross-sectional structure. A higher DS of sPPSU rendered the blend membranes with more hydrophilicity and oleophobicity as well as a more negatively charged surface. The unmodified PES membrane had rejections of 87.47 % and 91.5 % in ultrafiltration tests using feed solutions containing BSA and oil/water emulsion, respectively. The rejections could be further increased to 99.37 % and 97.17 % respectively by the blend membranes. The blend membranes consisting of a higher DS of sPPSU also exhibited a higher permeance, lower BSA absorption and better anti-fouling properties than the PES membrane.

Retention of Virus Versus Surrogate, by Ultrafiltration in Seawater: Case Study of Norovirus Versus Tulane.

In the field of chemical engineering and water treatment, the study of viruses, included surrogates, is well documented. Often, surrogates are used to study viruses and their behavior because they can be produced in larger quantities in safer conditions and are easier to handle. In fact, surrogates allow studying microorganisms which are non-infectious to humans but share some properties similar to pathogenic viruses: structure, composition, morphology, and size. Human noroviruses, recognized as the leading cause of epidemics and sporadic cases of gastroenteritis across all age groups, may be mimicked by the Tulane virus. The objectives of this work were to study (i)the ultrafiltration of Tulane virus and norovirus to validate that Tulane virus can be used as a surrogate for norovirus in water treatment process and (ii) the retention of norovirus and the surrogate as a function of water quality to better understand the use of the latter pathogenic viruses. Ultrafiltration tests showed significant logarithmic reduction values(LRV) in viral RNA: around 2.5 for global LRV (i.e., based on the initial and permeate average concentrations) and between 2 and 6 for average LRV(i.e., retention rate considering the increase of viral concentration in the retentate), bothfor norovirus and the surrogate Tulane virus. Higher reduction rates (from 2 to 6 log genome copies) are obtained for higher initial concentrations (from 101 to 107 genome copies per mL) due to virus aggregation in membrane lumen. Tulane virus appears to be a good surrogate for norovirus retention by membrane processes.

#4202 FLUID OVERLOAD AT THE BEGINNING OF PERITONEAL DIALYSIS: A CROSS-SECTIONAL STUDY TO DETERMINE ITS ASSOCIATION WITH SERUM BIOMARKERS

Abstract Background and Aims Volume management in peritoneal dialysis (PD) patients is of major importance as fluid overload has been associated with cardiovascular and non-cardiovascular morbidity and mortality. Clinical examination itself has a poor diagnostic accuracy for minor deviations from normohydration, highlighting the need of additional tools. The aim of this study was to evaluate the association between serum biomarkers (CA-125 and NT-proBNP) and volume status, evaluated by clinical and bioimpedance analysis, at the initiation of PD technique. Method Single-center cross-sectional study including PD patients that started technique between 2017 and 2022. Demographic and clinical data were collected from the electronic records. Parameters evaluated were clinical examination, serum biomarkers, bioimpedance and dialysis adequacy. Results A total of 79 patients (51 male) were included with a mean age of 57±15 years. All of them started with CAPD and 52% were under icodextrin. Hypertension, cardiovascular disease and diabetes were present in 94%, 51% and 34%, respectively. The great majority were under renin-angiotensin-aldosterone system inhibitors (91%), beta-blockers (48%) and diuretic therapy (94%). Baseline PET showed that 77% were high or high-average transporters. Mean weekly Kt/V was 2.4±15. The mean residual renal function (RRF) and residual diuresis were 6.7±15 mL/min/1.73 m2 and 1.6±0.8 L (4% anuric), respectively, and 11% had ultrafiltration failure. Median nPCR was 0.9 g/Kg/day (IQR 0.3). Median NT-proBNP and CA-125 were 1337 pg/mL (IQR 3401) and 14.6 U/mL (IQR 17.6), respectively. NT-proBNP was positively associated with overhydration (OH &amp;gt;2 L) (r = 0.31; p = 0.009), CA-125 (r = 0.28; p = 0.01) and icodextrin use (p = 0.002). It was negatively associated with weekly Kt/V (r = -0.35; p = 0.003), RRF (r = -0.36; p = 0.002), ultrafiltration test (UFT) (r = -0.35; p = 0.003) and nPCR (r = -0.28; p = 0.001). CA-125 was positively associated with higher overhydration (OH &amp;gt; 3.6 L), D/P creatinine (r = 0.3; p = 0.004) and icodextrin use (p = 0.001). It was negatively associated with weekly Kt/V (r = -0.3; p = 0.01), UFT (r = -0.25; p = 0.03) and nPCR (r = -0.23; p = 0.04). NT-proBNP was still associated with overhydration in a multivariable analysis, adjusted to diabetes, icodextrin use, RRF and CA-125 (p = 0.024). Conclusion Serum NT-proBNP and CA-125 seem to be good markers of overhydration at PD baseline. They were also associated with worse dialytic efficacy and ultrafiltration, lower residual renal function and an early need of icodextrin use. Malnourished patients were associated with higher NT-proBNP and CA-125. Early and effective management of hydration may improve clinical outcomes, allowing personalized dialysis prescription and nutritional support.

Efficient removal of bovine serum albumin from water by cellulose acetate membranes modified with clay and titania nano particles.

Modified cellulose acetate membranes with bentonite clay (CA/bent) and TiO2 nanoparticles (CA/TiO2) using the phase inversion method are successfully prepared and characterized. These Membranes are favored due to their high salt rejection properties and recyclability. The IR and EDX spectral data indicate the formation of modified membranes. The Scan Electron Microscope micrographs show that the modified membranes have smaller particle sizes with higher porosity than the neat membrane. The average pore diameter is 0.31µm for neat cellulose acetate membrane (CA) and decreases to 0.1µm for CA/0.05bent. All modified membranes exhibit tensile strengths and elongation percentages more than the neat membrane. The higher tensile strength and the maximum elongation% are 15.3N/cm2 and 11.78%, respectively, for CA/0.05bent. The thermogravimetric analysis of modified membranes shows higher thermal stability than the neat membrane. The modified membranes exhibit enhanced wettability and hydrophilicity compared with cellulose acetate, by measuring the contact angle which decreases from 60° (CA) to 40° (CA/0.1bent). The ultrafiltration tests indicated that the CA/bent and CA/TiO2 are better than CA. The most efficient nanocomposite membrane is CA/0.05bent with 100% removal of (BSA) from industrial water with a flux equal to 9.5mL/min under an applied pressure of 20bar. Thus, this study introduces a novel ultrafiltration membrane (CA/0.05bent) that can be used effectively to completely remove bovine serum albumin from contaminated water.

Potential Difference-Modulated Synthesis of Self-Standing Covalent Organic Framework Membranes at Liquid/Liquid Interfaces.

Covalent organic framework (COF) membranes with tailored functionalities hold great promise in diverse applications, but the key to realize their full advantages of highly ordered pore structures is the development of membrane fabrication approaches. In this work, we report a potential difference-modulated biphasic strategy to fabricate large-area, self-standing COF membranes under ambient conditions. The fabrication was conducted at the polarized water/1,2-dichloroethane (water/DCE) interface, where HCl was dissolved in water as a catalyst and monomers (both amine and aldehyde) were added to DCE. The external polarization of the water/DCE interface by cyclic voltammetry can continuously pump H+ from water to DCE to boost the Schiff base reaction of monomers and the growth of COF membranes. Moreover, the growth process can be real-time-monitored by interfacial double-layer capacitance measurement, and the permeability of COF membranes can be in situ-examined by heterogeneous ion transfer voltammetry. Given that the potential difference across the water/DCE interface can be also facilely modulated by dissolving proper electrolyte ions in two phases, the fabrication of large-area COF membranes is made possible in beakers. Using this strategy and different monomers, three types of centimeter-scale, free-standing COF membranes with tunable pore size and surface functionality were prepared, and their defect-free structure was proved by the molecular permeance and ultrafiltration test. We believe that this biphasic strategy offers a controllable and scalable way to fabricate COF membranes and sheds light on development of novel self-supporting membranes with unique functions.

Effect of ionic liquid on formation of copolyimide ultrafiltration membranes with improved rejection of La3+

Ultrafiltration (UF) as a widely used industrial separation method with optimal selection of membrane materials can be applied to extract rare earth metals from dilute solutions formed during the processing of electronic waste by hydrometallurgical methods. In the present work, promising UF copolyimide membranes were prepared using [hmim][TCB] ionic liquid (IL) co-solvent which can be considered as an environmentally friendly alternative to conventional solvents. The membranes were characterized by ATR-FTIR, TGA, SEM and quantum chemical calculations. A significant difference in morphology of these membranes was revealed by SEM of membrane cross-sections; the P84 membrane has finger-like structure of porous substrate in contrast to spongy structure of substrate for the P84/IL membrane due to a higher dynamic viscosity of the casting solution. The transport parameters were determined in ultrafiltration tests with pure water and an aqueous solution of bovine serum albumin. The addition of ionic liquid to the P84 casting solution increases the performance of the membrane. The rejection capacity was evaluated with respect to La3+ in the form of a lanthanum alizarin complex (LAC) in aqueous acetone solution. The P84 membrane prepared using IL showed a high rejection (98.5%) with respect to LAC, as well as a significant productivity.

Application of Cyclized Polyacrylonitrile for Ultrafiltration Membrane Fouling Mitigation.

In this study, novel composites were produced by blending partially cyclized polyacrylonitrile (cPAN) and poly(amide-imide) (PAI) in N-methylpyrrolidone in order to fabricate asymmetric membranes via phase inversion method. The compatibility of PAI and cPAN through possible intermolecular interaction was examined by quantum chemical calculations. The composite membranes were characterized by FTIR, SEM, contact angle measurements, etc. A considerable reduction in the contact angles of water and ethylene glycol (EG) was observed after adding cPAN to the PAI membrane, which is evidence of improved membrane hydrophilicity. Membrane transport properties were investigated in ultrafiltration tests by measuring the pure water flux, rejection of proteins, and flux recovery ratio (FRR). The best properties were found for the membrane containing 5 wt% cPAN; an increase in BSA rejection and a remarkable increase in FRR were observed, which can be explained by the hydrophilization of the membrane surface provided by the presence of cPAN.

New Facility for Membrane Fouling Investigations under Customizable Hydrodynamics: Validation and Preliminary Experiments with Pulsating Cross-Flow.

Flux reduction induced by fouling is arguably the most adverse phenomenon in membrane-based separation systems. In this respect, many laboratory-scale filtration studies have shown that an appropriate use of hydrodynamic perturbations can improve both performance and durability of the membrane; however, to fully understand and hence appropriately exploit such effects, it is necessary to understand the underpinning flow processes. Towards this end, in this work we propose and validate a new module-scale laboratory facility with the aim of investigating, at very well-controlled flow conditions, how hydrodynamics affects mass transport phenomena at the feed/membrane interface. The proposed facility was designed to obtain a fully developed and uniform flow inside the test section and to impose both steady and pulsating flow conditions. The walls of the facility were made transparent to grant optical accessibility to the flow. In this paper, we discuss data coming from particle image velocimetry (PIV) measurements and preliminary ultrafiltration tests both under steady and pulsating flow conditions. PIV data indicate that the proposed facility allows for excellent flow control from a purely hydrodynamic standpoint. Results from filtration tests provide promising results pointing towards pulsating flows as a viable technique to reduce fouling in membrane systems.

Enhanced anti-fouling performance in Membrane Bioreactors using a novel cellulose nanofiber-coated membrane

• The fouling of TFNC-CNF membranes is reversible when filtering wastewater. • Enhanced flux was achieved in the submerged TFNC-CNF membrane bioreactor. • TFNC-CNF membranes showed higher rejection potential of bio-foulants. • Air scouring enhanced the flux of TFNC-CNF membranes when filtering wastewater. The filtration performance, fouling and flux recovery efficiency of a novel thin film nanofibrous composite-cellulose nanofiber (TFNC-CNF) coated membrane was studied and compared with polyvinylidene fluoride (PVDF) membranes treating domestic wastewater. The enhanced anti-fouling property of the TFNC-CNF membrane was associated with the super-hydrophilic nature and negative charge on the membrane surface. The dead-end cell filtration tests demonstrated the TFNC-CNF membrane recovered more than 90% of the initial flux after mechanical cleaning, compared with 26–43% recovery by PVDF membranes. Continuous wastewater ultrafiltration tests with mechanical air scouring confirmed the outstanding permeability (71.3–138.9 LMH/bar) and the superior anti-fouling characteristics (59.2–86.8% recovery of the initial flux) of the TFNC-CNF membrane. Furthermore, higher total organic carbon rejection rates were also observed in the TFNC-CNF membrane (>83.2%) than the PVDF membrane (<69.8%). Collectively, the superior flux recovery and high permeability makes the TFNC-CNF membrane a promising material for membrane bioreactors.

Combined strategy of blending and surface modification as an effective route to prepare antifouling ultrafiltration membranes

Ultrafiltration (UF) membranes blended with hydrophilic nanomaterials usually exhibit preferable overall performance including the membrane permeability and antifouling capability. However, the improvement in antifouling performance may be not outstanding due to the small amount of nanomaterial distributed near the membrane surface and the limited improvement in membrane hydrophilicity. Notably, excess addition of nanomaterials may lead to the decline in membrane permeability. In order to solve the above problem, we integrated the strategy of blending and surface modification to construct novel hybrid UF membranes. Novel nanohybrid was prepared via tannic acid (TA) coating on hydroxyapatite nanotubes (HANTs) and the subsequent grafting of zwitterionic polyethylenimine (ZPEI). The prepared nanohybrid (HANTs@TA-ZPEI) was incorporated with the polysulfone containing tertiary amine groups to fabricate hybrid membranes via the solution blending and the subsequent immersion-precipitation phase inversion process. Then the matrix was modified with zwitterions via the reaction of tertiary amine group with 1, 3-propane sultone. UF tests were conducted using the bovine serum albumin (BSA) and humic acid (HA) as the representative foulants. Results showed that both the permeability and the antifouling performance of the membranes achieved favorable promotion. Thereinto, the water flux of M-B0.4-Z membrane (pre blended with 0.4 wt% HANTs@TA-ZPEI in the casting solution and post-surface modified) exhibited 2.6 times that of the pristine membrane and the flux recovery ratio (FRR) for BSA and HA attained 93.4% and 96.1%, respectively. By the combination of blending and surface modification, both the membrane permeability and fouling resistant properties could attain remarkable promotion, which exerted the advantages of two methods and made up the deficiency of single blending method.

Fabrication of polycarbonate ultrafiltration mixed matrix membranes including modified halloysite nanotubes and graphene oxide nanosheets for olive oil/water emulsion separation

In this study, ultrafiltration polycarbonate mixed matrix membranes (MMMs) were synthesized to remove the olive oil from the aqueous solution. To characterize the synthesized membranes in terms of surface morphology, functional groups, hydrophilicity, and mechanical strength, various analyses such as FESEM, FTIR, contact angle, and tensile strength were carried out, respectively. Modified halloysite nanotubes and graphene oxide nanosheets with the loading of 0.25, 0.5, and 0.75 wt% were added to the blank membrane. Membranes including modified halloysite nanotubes exhibited better hydrophilicity and higher pure water flux due to the presence of amphiphilic sodium dodecyl sulfate surfactant at higher nanoparticle loadings, while the agglomeration of graphene oxide nanosheets in the membrane polymeric matrix resulted in the lower pure water flux compared to the blank PC membrane. Moreover, the pure water flux data were modeled by Design-Expert software, and the highest pure water flux of 1340 L/m2 h was reported for PC-MHNT0.75 MMM. Then, the optimized membranes based on the output of the design expert software were used in the ultrafiltration tests for olive oil removal. All the selected membranes reached 100% rejection efficiency of olive oil; however, they were different based on the time to reach this efficiency and the permeate flux. Performance evaluation of membranes in ultrafiltration tests at different feed concentrations showed that the PC-MHNT0.75 mixed matrix membrane possessed the lowest time (165 min at 100 ppm feed concentration) to reach 100% rejection efficiency and subsequently selected as the optimal membrane. The regeneration process using 20% (v/v) acetone solution was implemented for the optimal membrane and the obtained membrane water flux after three cycles of regeneration was more than 96%, introducing the fabricated MMMs as suitable candidates for olive oil separation.

Mesoporous silica filled smart super oleophilic fibers of triblock copolymer nanocomposites for oil absorption applications

Super oleophilic fibers of styrene-isoprene-styrene (SIS) block copolymer/mesoporous silica (MS) nanocomposites are fabricated by electrospinning, and their oil absorption efficiency is monitored by following two different approaches. The first way is by using the fibers as tubular packing materials for oil absorption, whereas the second approach uses the fibers as filtration membrane after deposition on the commercial polyethersulfone (PES) support. All composites are made by adding inorganic MS in different concentrations (2, 4, and 7 wt.%) to SIS block copolymer. The addition of MS increases the fiber diameters and leads to enlarged and bead-like appearances, especially at higher filler concentrations. The oil absorption efficiency is explored based on the oil absorption capacity of the samples as well as with the gravity-driven oil filtration experiments. The best oil absorption efficiency is achieved by the 4 wt.% SIS-MS composite (150% higher oil absorption capacity compared to the neat SIS), and it is used to spin on the PES mechanical support of different pore sizes (0.2 μ and 8 μ). Ultrafiltration tests conducted on those coated membranes observe improved oil rejection performance as the fibrous SIS-MS are layered on the commercial mechanical support.

Impacts of composite flocculant in coagulation/ultrafiltration hybrid process for treatment of humic acid water: the role of basicity

ABSTRACT The effects of the composite flocculant, polyaluminium chloride and poly dimethyldiallylammonium chloride (PACl-PDMDAAC) in comparison with PACl on coagulation efficiencies and membrane fouling in coagulation-ultrafiltration (C-UF) process were analysed, which was conducted in the conditions of different basicity (B) values and the presence of Mg2+. Results showed that PACl-PDMDAAC enhanced the ability of charge neutralization and absorption bridging, and improved the coagulation efficiency. When B value was 1.5, the flocculant hydrolyzed to form more Alb morphology and effectively removed HA molecules. The presence of Mg2+ could improve the coagulation performance through bridging ability. The results of the ultrafiltration test showed that the flux reduction for PACl was 70%, while the flux reduction for PACl-PDMDAAC was 60% in C-UF process. PACl-PDMDAAC could effectively reduce membrane fouling mainly by reducing strongly attached cake/gel layer. When B value was 1.5, the Alb content of the flocculant was higher and the ability of adsorption charge neutralization was strong, resulting in forming a stable cake layer. Therefore, the membrane fouling was the lightest. In addition, the presence of Mg2+ in raw water reduced the membrane fouling.

High-flux and antifouling polyethersulfone nanocomposite membranes incorporated with zwitterion-functionalized graphene oxide for ultrafiltration applications

Polyethersulfone (PES) membranes containing cysteine-functionalized graphene oxide (CGO) were prepared to enhance the ultrafiltration performance such as water flux and antifouling property. The synthesis of CGO was achieved through a simple thiol-ene click reaction between graphene oxide and cysteine. Since CGO has a zwitterionic moiety, it was observed to improve the hydrophilicity and negative charge of the membranes. The results of the ultrafiltration test showed that the separation performance of the prepared CGO/PES nanocomposite membranes was much better than that of the pristine PES membrane. For example, the CGO/PES nanocomposite membrane with 0.5wt.% CGO content has the pure water flux and BSA rejection values of 82.6Lm−2h−1 and 99.8%, respectively, while the pristine PES membrane has these values of 51.7Lm−2h−1 and 96.7%, respectively, indicating that the addition of CGO successfully improves the separation performance of PES-based membrane by overcoming the intrinsic trade-off relationship between permeability and selectivity. Furthermore, CGO/PES nanocomposite membranes also showed much better antifouling property than the pristine PES membrane. For example, the flux recovery ratio of the CGO/PES nanocomposite membrane with 0.5wt.% CGO content is 92.1%, while that of the pristine PES membrane is only 47.5%.

Performance of ultrafiltration as a pre-concentration stage for the treatment of oxyfluorfen by electrochemical BDD oxidation

The present work deals with the use of ultrafiltration as a pre-concentration stage in the electrochemical degradation of a non-polar organochlorine compound (oxyfluorfen) with boron-doped diamond (BDD) anodes. The first stage of the work consisted in evaluating the performance of a pilot scale ultrafiltration unit to concentrate a solution of a commercial formulation of oxyfluorfen (Barre®) at total recirculation mode. The ultrafiltration membrane exhibited a total rejection of oxyfluorfen, around 70% rejection of TOC and a permeate flux of 285.1 L h−1 m−2 at 4 bar and 25 °C. The rejection of oxyfluorfen is higher than expected due to the presence of surfactant compounds in the commercial formulation selected, which promotes a mechanism of micellar enhanced ultrafiltration. Next, a discontinuous ultrafiltration test was performed, maintaining this high rejection of oxyfluorfen and observing a limited contribution of fouling mechanisms, according to the adjustment of the data to fouling models. Regarding the electrochemical oxidation of the concentrate with BDD anodes, it was observed an increase in the specific power consumption from 590 kWh kg−1 for the raw solution to 882 kWh kg−1 for the concentrate. This unexpected result can be explained due to the limited rejection of the soluble fraction in the ultrafiltration stage, what produced a lower concurrence of oxidants in the electrochemical oxidation step. According to these results, it can be stated that it is worth using ultrafiltration as a concentration stage for commercial formulations of non-polar organochlorines with both high rejection and flux, although it should be combined with degradation technologies different from electrochemical oxidation.

The performance of bovine serum albumin filtration by using polyethersulfone-Tetronic 304 blend Ultrafiltration Membrane.

Background: Membrane technology has been widely applied for protein purification. In applications for protein separation, a membrane with stable filtration performance is necessary. In this work, two types of hollow fiber membranes with different characteristic were used to study the filtration profile of bovine serum albumin. Methods: A single piece of hollow fiber module was used for ultrafiltration testing using UF0 and UFT304 membranes. Flux and rejection of BSA solution were collected based on a pressure-driven inside filtration model. Results: Ultrafiltration experiments showed that the flux of UFT304 membrane was higher than that of UF0 membrane in all applied pressure condition. Solute rejection reaches 90 and 88% for ultrafiltration of BSA solution on the operating pressure of 0.5 atm using UF0 and UFT304 membranes, respectively. Conclusion: In general, UFT304 membranes has better ultrafiltration performance for BSA separation than UF0 membranes. The UFT304 membrane has a more stable flux for up to two hours of filtration.

The performance of bovine serum albumin filtration by using polyethersulfone-Tetronic 304 blend Ultrafiltration Membrane

Background: Membrane technology has been widely applied for protein purification. In applications for protein separation, a membrane with stable filtration performance is necessary. In this work, two types of hollow fiber membranes with different characteristic were used to study the filtration profile of bovine serum albumin. Methods: A single piece of hollow fiber module was used for ultrafiltration testing using UF0 and UFT304 membranes. Flux and rejection of BSA solution were collected based on a pressure-driven inside filtration model. Results: Ultrafiltration experiments showed that the flux of UFT304 membrane was higher than that of UF0 membrane in all applied pressure condition. Solute rejection reaches 90 and 88% for ultrafiltration of BSA solution on the operating pressure of 0.5 atm using UF0 and UFT304 membranes, respectively. Conclusion: In general, UFT304 membranes has better ultrafiltration performance for BSA separation than UF0 membranes. The UFT304 membrane has a more stable flux for up to two hours of filtration.

Selective separation of copper and zinc and regeneration of polymer from electroplating effluent using shear induced dissociation coupling with ultrafiltration

Shear-induced dissociation coupling with ultrafiltration (SID-UF) was used to remove and separate copper and zinc from both simulative effluent and real electroplating effluent using polyacrylate sodium (PAAS) as complex-ant. The effects of pH and the mass ratio of polymer on metal ions (P/M) on the removal of copper and zinc were investigated in the ultrafiltration tests, and the optimum pH and P/M were 7.0 and 25, respectively. The shear rate distributions on the membrane surface at various rotating speeds were simulated by CFD software. The shear stabilities of the polymer-metal complexes studied at various pHs indicated that the complexes would dissociate when the shear rate exceeded the critical shear rates (γc), and the order of critical shear rate was PAA-Zn>PAA-Cu at the same pH. The contrast between these two complexes shear stabilities was used to separate copper and zinc and recovery complexant from electroplating effluent by SID-UF. The results show that copper and zinc can be separated at 1.06×105 s-1 1.58×105 s-1. Compared to conventional complexation-ultrafiltration, SID-UF is a green and efficient method for the separation of metals and the regeneration of complexant.