scholarly journals Effects of Impurities from Sugar Excipient on Filtrate Flux during Ultrafiltration and Diafiltration Process

Membranes ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 775
Author(s):  
Jieun Lee ◽  
Jiwon Na ◽  
Youngbin Baek
Keyword(s):  
Sucrose Solution ◽  
Membrane Surface ◽  
Solution Viscosity ◽  
Sugar Solution ◽  
Good Correspondence ◽  
Sem Image ◽  
Flux Decline ◽  
Filtration System ◽  
Flow Filtration ◽  
The One

Sugar excipients such as sucrose and maltose are widely used for biopharmaceutical formulation to improve protein stability and to ensure isotonicity for administration. However, according to recent literature, pharmaceutical-grade sucrose contained nanoparticulate impurities (NPIs) that result in protein aggregation and degradation. The objective of this study was to evaluate the filtrate flux behavior of sugar solution during ultrafiltration (UF) and diafiltration (DF). Filtrate flux data were obtained using either a tangential flow filtration (TFF) system for DF experiments or a normal flow filtration system for UF experiments. In diafiltration experiments, which were performed using 7 g/L of human immunoglobulin G in a 20 mM histidine buffer with the 100 mM sucrose or maltose, the filtrate flux with sucrose solution decreased significantly. In contrast, the one with maltose solution was in good correspondence with the calculated filtrate flux accounting for the effects of solution viscosity. This large decline in the flux was also observed during UF experiments, in which the presence of NPIs was identified by dynamic light scattering analysis and by capturing an SEM image of the membrane surface after filtration. In addition, highly purified sucrose resulted in a much lower flux decline in TFF in the absence of NPIs. These results provide important insights into the factors governing the optimization of the UF/DF process using appropriate excipients for biopharmaceutical formulation.

Low-pressure membrane filtration with unconventional coagulation regimes

2005 ◽  
Vol 5 (5) ◽  
pp. 1-8 ◽  
Author(s):  
K.Y. Choi ◽  
B.A. Dempsey
Keyword(s):  
Activated Carbon ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Cross Flow ◽  
Chemical Cleaning ◽  
Sand Filters ◽  
Charge Neutralization ◽  
Floc Size ◽  
Filtration System ◽  
Pre Treatment

The objective of the research was to evaluate in-line coagulation to improve performance during ultrafiltration (UF). In-line coagulation means use of coagulants without removal of coagulated solids prior to UF. Performance was evaluated by removal of contaminants (water quality) and by resistance to filtration and recovery of flux after hydraulic or chemical cleaning (water production). We hypothesized that coagulation conditions inappropriate for conventional treatment, in particular under-dosing conditions that produce particles that neither settle nor are removed in rapid sand filters, would be effective for in-line coagulation prior to UF. A variety of pre-treatment processes for UF have been investigated including coagulation, powdered activated carbon (PAC) or granular activated carbon (GAC), adsorption on iron oxides or other pre-formed settleable solid phases, or ozonation. Coagulation pre-treatment is often used for removal of fouling substances prior to NF or RO. It has been reported that effective conventional coagulation conditions produced larger particles and this reduced fouling during membrane filtration by reducing adsorption in membrane pores, increasing cake porosity, and increasing transport of foulants away from the membrane surface. However, aggregates produced under sweep floc conditions were more compressible than for charge neutralization conditions, resulting in compaction when the membrane filtration system was pressurized. It was known that the coagulated suspension under either charge-neutralization or sweep floc condition showed similar steady-state flux under the cross-flow microfiltration mode. Another report on the concept of critical floc size suggested that flocs need to reach a certain critical size before MF, otherwise membranes can be irreversibly clogged by the coagulant solids. The authors were motivated to study the effect of various coagulation conditions on the performance of a membrane filtration system.

An index for back pain risk assessment in nursery activities

2005 ◽  
Vol 4 (4) ◽  
pp. 281-290
Author(s):  
Silvia Taloni ◽  
Giovanni Carlo Cassavia ◽  
Giuseppe Luca Ciavarro ◽  
Giuseppe Andreoni ◽  
Giorgio Cesare Santambrogio ◽  
...  
Keyword(s):  
Back Pain ◽  
Biomechanical Model ◽  
Risk Level ◽  
Individual Risk ◽  
Industrialized Countries ◽  
Good Correspondence ◽  
Gold Standard Method ◽  
Trunk Inclination ◽  
Leg Flexion ◽  
The One

Back pain is one of the most significant socioeconomic problem in industrialized countries. Its origin is multifactorial, including physical, psychosocial and individual risk factors. Among the working population, nursery teachers are highly exposed to back pain diseases, but not many studies have dealt with this problem. So a suitable quantitative index is proposed, based on an unobtrusive video-analysis of established motor-tasks. In particular five nursery teachers were asked to perform lifting and lowering movements placing their feet at two different distances from a weight (a toy pet loaded with 8 kg, simulating a child) with different strategies (flexed, partially flexed and extended legs). The index is based on the idea that a greater trunk inclination angle determines increased loads on the lumbar spine, and so an augmented probability of spinal disorders. To validate our protocol, the same data were analyzed through a 3D biomechanical model (gold standard method), which computes the loads on L3-L4 intervertebral disc. Data show a good correspondence between the risk level suggested by the index and the one indicated by the mechanical loads: the antero-posterior shearing forces and the values of index coherently increase with the reduction of leg flexion.

scholarly journals Influence of bulk concentration on the organisation of molecules at a membrane surface and flux decline during reverse osmosis of an anionic surfactant

2016 ◽  
Vol 499 ◽  
pp. 257-268 ◽  
Author(s):  
Zhaohuan Mai ◽  
Vincent Butin ◽  
Mohammed Rakib ◽  
Haochen Zhu ◽  
Murielle Rabiller-Baudry ◽  
...  
Keyword(s):  
Reverse Osmosis ◽  
Anionic Surfactant ◽  
Membrane Surface ◽  
Bulk Concentration ◽  
Flux Decline

Electroflocculation as potential pretreatment in colloid ultrafiltration

2006 ◽  
Vol 6 (1) ◽  
pp. 69-78 ◽  
Author(s):  
T. Harif ◽  
M. Hai ◽  
A. Adin
Keyword(s):  
Membrane Fouling ◽  
Colloidal Suspension ◽  
Membrane Surface ◽  
Constant Current ◽  
Permeate Flux ◽  
Batch Mode ◽  
Membrane Behavior ◽  
Flux Decline ◽  
Stainless Steel Cathode ◽  
Marginal Improvement

Electroflocculation (EF) is a coagulation/flocculation process in which active coagulant species are generated in situ by electrolytic oxidation of an appropriate anode material. The effect of colloidal suspension pretreatment by EF on membrane fouling was measured by flux decline at constant pressure. An EF cell was operated in batch mode and comprised two flat sheet electrodes, an aluminium anode and stainless steel cathode, which were immersed in the treated suspension, and connected to an external DC power supply. The cell was run at constant current between 0.06–0.2A. The results show that pre-EF enhances the permeate flux at pH 5 and 6.5, but only marginal improvement is observed at pH 8. At all pH values cake formation on the membrane surface was observed. The differences in membrane behavior can be explained by conventional coagulation theory and transitions between aluminium mononuclear species which affect particle characteristics and consequently cake properties. At pH 6.5, where sweep floc mechanism dominates due to increased precipitation of aluminium hydroxide, increased flux rates were observed. It is evident that EF can serve as an efficient pretreatment to ultrafiltration of colloid particles.

scholarly journals Efficient filtration system for paraffin-catalyst slurry separation

2013 ◽  
Vol 19 (2) ◽  
pp. 295-301 ◽  
Author(s):  
Mohammad Khodagholi ◽  
Mohammad Hemmati ◽  
Ali Pour
Keyword(s):  
Bubble Column ◽  
Liquid Paraffin ◽  
Cylindrical Tube ◽  
Filtration Efficiency ◽  
Filter Element ◽  
Bubble Column Reactor ◽  
Sem Image ◽  
Sintered Metal ◽  
Filtration System ◽  
Spherical Alumina

The filtration efficiency for separating liquid paraffin (or water) from a slurry consisting of 25 weight% spherical alumina in a Slurry Bubble Column Reactor (SBCR) comprised of a cylindrical tube of 10 cm diameter and 150 cm length was studied. Various differential pressures (?P) were applied to two separate tubular sintered metal stainless steel filter elements with nominal pore size of 4 and 16?m. The experimental results disclosed that the rate of filtrations increased on applying higher differential pressure to the filter element. Albeit this phenomenon is limited to moderate ?Ps and for ?P more than 1 bar is neither harmful nor helpful. The highest filtration rates at ?Ps higher than 1 bar were 170 and 248 ml/minute for 4 and 16?m respectively. Using water as the liquid in slurry the rate of filtration enhanced to 4 folds, and this issue reveals impact of viscosity on filtration efficiency clearly. In all situations, the total amount of particles present in the filtrate part never exceeded a few parts per million (ppm). The statistical analysis of the SEM image of the filtrate indicated that by applying higher pressure difference to the filter element the frequency percent of larger particle size increases. The operation of filter cake removing was performed with back flashing of 300 ml of clean liquid with pressures of 3-5 bar of N2 gas.

Nanofiltration performance of lead solutions: effects of solution pH and ionic strength

2010 ◽  
Vol 10 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Wuthikorn Saikaew ◽  
Supatpong Mattaraj ◽  
Ratana Jiraratananon
Keyword(s):  
Ionic Strength ◽  
Membrane Surface ◽  
Aromatic Polyamide ◽  
Solution Chemistry ◽  
Lead Ion ◽  
Solution Ph ◽  
Dead End ◽  
Flux Decline ◽  
Charged Membrane ◽  
Double Layer Thickness

Nanofiltration performance (i.e. rejection and flux decline) of lead solutions was investigated using a dead-end test cell at room temperature. An aromatic polyamide NF-90 membrane was chosen to determine the impacts of solution chemistry. The experimental results revealed that solution flux decline was dependent on solution pH, ionic strength, and type of lead solutions. Solution flux conducted with different types of lead solutions (i.e. PbCl2 and Pb(NO3)2) decreased with increased solution pH. Solutions having high pH exhibited greater flux decline than those having low solution pH, while lead ion rejections were relatively high. Increased ionic strengths resulted in a greater flux decline, while lead ion rejections decreased with decreasing solution pH and increasing ionic strengths. Such results were related to low solution pH, suggesting an increase in fixed charge of proton (H+), decreasing electrical double layer thickness within membrane, thus allowing increased lead concentration passing through the membrane surface. Solution flux and rejection decreased further at higher ionic strengths, which caused a reduced negatively charged membrane, and thus decreased rejections. It was also found that lead ion for PbCl2 solution exhibited higher rejections than that of Pb(NO3)2 solution.

scholarly journals A Modified HYDRUS Model for Simulating PFAS Transport in the Vadose Zone

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2758 ◽  
Author(s):  
Jeff Allen Kai Silva ◽  
Jiří Šimůnek ◽  
John E. McCray
Keyword(s):  
Vadose Zone ◽  
Unsaturated Flow ◽  
Transport Model ◽  
Solid Phase ◽  
Interfacial Area ◽  
Solution Viscosity ◽  
Transient Nature ◽  
Unsaturated Transport ◽  
The One ◽  
Groundwater Source

The HYDRUS unsaturated flow and transport model was modified to simulate the effects of non-linear air-water interfacial (AWI) adsorption, solution surface tension-induced flow, and variable solution viscosity on the unsaturated transport of per- and polyfluoroalkyl substances (PFAS) within the vadose zone. These modifications were made and completed between March 2019 and May 2019, and were implemented into both the one-dimensional (1D) and two-dimensional (2D) versions of HYDRUS. Herein, the model modifications are described and validated against the available literature-derived PFAS transport data (i.e., 1D experimental column transport data). The results of both 1D and 2D example simulations are presented to highlight the function and utility of the model to capture the dynamic and transient nature of the temporally and spatially variable interfacial area of the AWI (Aaw) as it changes with soil moisture content (Θw) and how it affects PFAS unsaturated transport. Specifically, the simulated examples show that while AWI adsorption of PFAS can be a significant source of retention within the vadose zone, it is not always the dominant source of retention. The contribution of solid-phase sorption can be considerable in many PFAS-contaminated vadose zones. How the selection of an appropriate Aaw(Θw) function can impact PFAS transport and how both mechanisms contribute to PFAS mass flux to an underlying groundwater source is also demonstrated. Finally, the effects of soil textural heterogeneities on PFAS unsaturated transport are demonstrated in the results of both 1D and 2D example simulations.

Investigation of membrane fouling by synthetic and natural particles

2004 ◽  
Vol 50 (12) ◽  
pp. 279-285 ◽  
Author(s):  
J.H. Kweon ◽  
D.F. Lawler
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Research Articles ◽  
Clay Material ◽  
Dramatic Effect ◽  
Flux Decline ◽  
Scanning Electron

The biggest impediment for applying membrane processes is fouling that comes from mass flux (such as particle and organic matter) to the membrane surface and its pores. Numerous research articles have indicated that either particles or natural organic matter (NOM) has been the most detrimental foulant. Therefore, the role of particles in membrane fouling was investigated with two synthetic waters (having either particles alone or particles with simple organic matter) and a natural water. Membrane fouling was evaluated with flux decline behavior and direct images from scanning electron microscopy. The results showed that the combined fouling by kaolin and dextran (a simple organic compound selected as a surrogate for NOM) showed no difference from the fouling with only the organic matter. The similarity might stem from the fact that dextran (i.e., polysaccharide) has no ability to be adsorbed on the clay material, so that the polysaccharide behaves the same with respect to the membrane with or without clay material being present. In contrast to kaolin, the natural particles showed a dramatic effect on membrane fouling.

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