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The Company's input pipes contained microplastics, per the preliminary test findings. While the water yield produced by PDAM Tirta Daroy contains 150 particles/L, the Tirta Daroy Drinking Water Area has 275 particles/L. Microplastics found in the water pose a major risk to living beings if they are consumed. This work aims to characterize the properties, flux, and polyethersulfone (PES) membrane rejection coefficient, which were made utilizing the phase inversion technique with a solvent and additives called N,N-dimethylformamide (DMF). In Sungai Krueng Aceh, titanium dioxide (TiO2) is utilized to filter out microplastics from the water. Results of Scanning Electron Microscopy (SEM) examination of Membrane Morphology demonstrate that the resulting membrane is an asymmetrical membrane of two layers, the upper layer relatively thin and the lower layer porous. When compared to the PES membrane when it was 15% DMF/TiO2, the 20% DMF/TiO2 membrane exhibits a finger-like cross-sectional structure called a macrovoid) with more and larger numbers. Analysis of the microplastic rejection coefficients proved the effectiveness of PES, DMF, and TiO2 membranes in removing microplastics. Results of tests on the effectiveness of rejecting microplastics after undergoing process filtration with a microplastic rejection coefficient of 94% and 14.2 particles/L utilizing a 20% PES/DMF/TiO2 membrane Performance of PES membranes: The PES membrane with 20% DMF/TiO2 has a water flux of 0.467 L/m2.hour compared to 15% DMF/TiO2 0.733 L/m2.hour. This study's findings on membrane Ultrafiltration have the potential to be used as a water filter standard in PDAM.

ABSTRAK Seiring dengan semakin pesatnya pertumbuhan industri tentunya akan mempengaruhi kondisi lingkungan dikarenakan semakin banyak limbah buangan hasil industri yang dibuang ke lingkungan, salah satunya adalah limbah cair industri penyamakan kulit dengan kandungan kromium (Cr) yang tinggi antara 40 – 25000 mg.l-1. Perlu adanya pengolahan limbah terlebih dahulu sebelum di buang ke lingkungan. Salah satu teknologi yang dapat digunakan adalah menggunakan membran. Pada penelitian ini membran yang digunakan adalah membran komposit kitosan-selulosa. Tujuan penelitian ini yaitu mengkaji karateristik fisik dari membran kitosan-selulosa dan mengkaji pengaruhnya dalam merejeksi Cr pada limbah industri penyamakan kulit. Pembuatan membran menggunakan metode pembalikan fasa, dimana kitosan dalam bentuk padatan atau serbuk akan dilarutkan menggunakan asam asetat dengan konsentrasi yang beragam. Pada penelitian ini menggunakan Rancangan Acak Lengkap (RAL) yang disusun secara factorial dengan menggunakan 2 variasi faktor yaitu Asam Asetat (CH3COOH) (1%, 2%, 3%) dan konsentrsi massa kitosan (1.5 g, 2 g, dan 2.5 g). Kandungan krom awal sebesar 10.87 mg.l-1. Berdasarkan pengujian anova, variasi konsentrasi asam asetat dan konsentrasi kitosan memiliki pengaruh nyata terhadap penurunan Cr pada limbah cair. Koefisien rejeksi terbesar sebesar 85% dengan variasi terbaik pada membran dengan konsentrasi 2.5 g – 3%. Kata kunci : filtrasi, koefisien rejeksi ABSTRACT Along with the rapid growth of the industry will certainly affect the environmental conditions because the increasing amount of industrial waste disposal that is discharged into the environmen, for example is liquid waste from the tanning industry with chromium (Cr) content between 40 – 25000 mg.l-1. One of the technologies that can be used is to use membrans. In this study membran used was the cellulose-chitosan composite membran. The purpose of this research is to examine physical characteristics of chitosan-cellulose membrans and their filtration influence to rejection Cr in the tanning industry. The method of membran making is by using phase reversal method, in which chitosan in the form of solid or powder will be dissolved using acetic acid with various concentration. Completely Randomized Design was used in this research with 2 factorial which is cariation of acetate (CH3COOH) (1%, 2%, and 3%), and variations of chitosan mass (1.5 g, 2g, 2.5 g). The chromium content before treatment is 10.87 mg.l-1. Based on the anova test, the variation of acetic acid concentration has a significant effect on the decrease of chromium. The largest rejection coefficient is 85% with best variation on membran with concentration 2.5g – 3%. Keywords : filtration, rejection coefficient

Ceramic and polymeric membrane systems were compared at the pilot scale for separating agave fructans into different molecular weight fractions that help to diversify them into more specific industrial applications. The effect of the transmembrane pressure of ultrafiltration performance was evaluated through hydraulic permeability, permeate flux and rejection coefficients, using the same operating conditions such as temperature, feed concentration and the molecular weight cut-off (MWCO) of membranes. The fouling phenomenon and the global yield of the process were evaluated in concentration mode. A size distribution analysis of agave fructans is presented and grouped by molecular weight in different fractions. Great differences were found between both systems, since rejection coefficients of 68.6% and 100% for fructans with degrees of polymerization (DP) > 10, 36.3% and 99.3% for fructooligosaccharides (FOS) and 21.4% and 34.2% for mono-disaccharides were obtained for ceramic and polymeric membrane systems, respectively. Thus, ceramic membranes are better for use in the fractionation process since they reached a purity of 42.2% of FOS with a yield of 40.1% in the permeate and 78.23% for fructans with DP > 10 and a yield of 70% in the retentate. Polymeric membranes make for an efficient fructan purification process, eliminating only mono-disaccharides, and reaching a 97.7% purity (considering both fructan fractions) with a yield of 64.3% in the retentate.

In this article, we report the removal of a reactive dye, viz. sunset yellow, from the aqueous solution using micellar media of two cationic surfactants, viz. cetyltrimethylammonium bromide and ethyl hexadecyldimethyl ammonium bromide (. The values of rejection coefficient (R%) and permeate flux (J) have been calculated using membranes with different pore sizes, viz. 10,000 (10k) molecular weight cutoff (MWCO) and 30,000 (30k) MWCO at 1.5 bar transmembrane pressure. The membrane of 30k MWCO was found to be more suitable in order to retain the dye molecules incorporated in the micelles. [ABSTRACT FROM AUTHOR]

The possibility of intensifying the ultrafiltration concentrating of food substance solutions by the separation of the near-membrane flow part that comprises the concentration boundary layer (or diffusion layer) enriched by a useful component has been investigated in this study. A mathematical model of the longitudinal development of polarization on a membrane with consideration of its selectivity (rejection coefficient) has been proposed. The efficiency of the separation of the near-membrane layer has theoretically been estimated on the basis of this model. Some constructions of membrane modules with the separation of the near-membrane layer have been proposed. Experiments have shown that the proposed method allows the concentrate to be enriched in the continuous-flow module by 9-10%, which is much higher than for the traditional concentrating process. The calculated concentration coefficients are in good agreement with experimental values.

Membrane fouling has been investigated by using a polysulfone ultrafiltration membrane with the molecular weight cutoff of 20 kDa to treat crushed coal pressurized gasification wastewater. Under the conditions of different feed pressures, the permeate flux declines and rejection coefficients of pollutants referring to three parameters (total organic carbon (TOC), chroma and turbidity) were studied. The membrane fouling mechanism was simulated with three classical membrane fouling models. The membrane image and pollutants were analyzed by scanning electron microscopy and gas chromatography-mass spectrography (GC-MS). The results indicate that the permeate flux decreases with volume reduction factor before reaching a constant value. The rejection coefficients were also measured: f = 70.5%, f = 84.9% and f = 91%. Further analysis shows that the higher the feed pressure is, the sooner the permeate flux reaches constant value and the more sharply the permeate flux declines. Constant flux indicates a nonlinear growth with feed pressure ( P ): when P equals 1.2 bar, the mark for the critical flux, slight membrane fouling occurs; when P exceeds 1.2 bar, cake layer pollution aggravates. Also the rejection coefficients of global pollutant increases slightly with P , suggesting the possibility of cake compression when P exceeds 1.2 bar. Through regression analysis, the fouling of polysulfone ultrafiltration membrane could be fitted very well by cake filtration model. The membrane pollutants were identified as phthalate esters and long-chain alkenes by GC-MS, and a certain amount of inorganic pollutants by X-ray photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]

The structure and local mechanical properties of the surface of polysulfone(PS-100)- and polyacrylonitrile( PAN-100)-based source ultrafiltration membranes and ones modified with thin films of polyvinylpyridine (PVPyr) or latex particles applied by the Langmuir-Blodgett (LB) method and by the formation of a PVPyr/sodium polystyrene sulfonate polyelectrolyte complex have been studied using atomic force microscopy. It has been found that the application of a PVPyr layer on the PS-100 membrane results in a twofold decrease in the membrane pure water flux from 250-360 L/(m h), while a substantial increase in the rejection coefficient is observed: the nominal molecular weight cut-off limit is reduced from 100000 to 10000 Da. For the PAN membrane a 10% increase in water permeability was found, and the rejection coefficient for PVP K-30 increases from 55 to 65%. Modification with latex particles results in a sharp decrease in the membrane performance. Comparative analysis of the topography and the local elasticity modulus of the samples indicates almost complete blocking of the porous structure of the source membranes in the case of their modification with latex particles, as well as the destruction of the PVPyr layer with the formation of globular structures upon contact with water. The surface energy of the samples after the modification increases. Layer-by-layer applying of PVPyr and sodium polystyrene sulfonate results in a twofold decrease in the pure water flux of the PAN-100 membrane and in an increase in the rejection coefficient due to the formation of a polyelectrolyte complex. In addition, for the PAN/PVPyr/PSS membrane a substantial decrease in the degree of fouling after filtration of a model calibrant solution was detected. It was shown that depending on the type of the source matrix and the polymer used for the surface modification by the horizontal precipitation (LB) method, it is possible to produce membranes with a predetermined pore size, mechanical and transport properties; at the same time, the density and permeability of the modifying layer are determined by the physicochemical properties and the surface structure of the source membrane. [ABSTRACT FROM AUTHOR]

The results of a pilot study of the structure and properties of cellulose diacetate filtration membranes with solid fillers are reported; thermally treated millet thresh waste (millet glume) was used as a filler. The porosimetric parameters of the initial polymer and solid fillers, the rheological properties of molding solutions, and the operational characteristics of the resulting composite membranes were determined. [ABSTRACT FROM AUTHOR]

To explore the potential of micellar enhanced ultrafiltration (MEUF) process for the treatment of industrial effluent, herein, we report the surfactant-based separation of a metal ion [Ni(II)] from the aqueous solution using two different anionic surfactants viz. dioctyl sodium sulfosuccinate (DSS) and sodium dodecyl sulfate (SDS). By following a systematic investigation, we utilized two membranes with different pore sizes viz. 10,000 MWCO (molecular weight cutoff) and 30,000 MWCO and determined the rejection coefficient and permeate flux of the Ni(II) from aqueous at 1.5 bar transmembrane pressure. The experimental results showed higher percentage of Ni(II) retention upon using the micellar solution of SDS compared with the solution containing DSS surfactant. In addition, the retention of Ni(II) ions incorporated in the micelles of surfactants was also found to be higher upon using 10,000 MWCO membrane compared with 30,000 MWCO membrane. Hence, we suggest that the combination of SDS surfactant and 10,000 MWCO membrane is a potent solution for the removal of metal ions from aqueous solutions via MEUF process. [ABSTRACT FROM AUTHOR]

The present study reports the surfactant-based separation of a reactive dye (reactive blue 19 (RB-19), from aqueous solution containing two cationic surfactants (cetyltrimethylammonium bromide (CTAB) and ethyl hexadecyldimethyl ammonium bromide (EHAB)). Three membranes of different pore size (5000, 10,000, and 30,000 molecular weight cutoff (MWCO)) were used for the determination of rejection coefficient and permeate flux of the solution at 1.5 bar transmembrane pressure (TMP). The membrane of 10,000 MWCO was found to be the most suitable in regard to retaining the dye molecules incorporated in the micelles. [ABSTRACT FROM PUBLISHER]

A novel approach for the recovery of the proteins contained in the effluent formed during production of surimi-like material from mechanically recovered poultry meat was proposed, using an integrated membrane process comprising microfiltration, ultrafiltration and vacuum membrane distillation. Additionally, the possibility of using the integrated membrane process to achieve high-quality water for reuse was also investigated. Using cross-flow membrane techniques, it was found that the total recovery of soluble proteins as well as the average degree of concentration amounted to 84 % and 9.3, respectively. Moreover, using this process, the total recovery of water was 70 % and the percentage reduction in COD, TOEM and TSS in the permeate obtained using vacuum membrane distillation exceeded 99 %. As a result, the water recovered by the integrated membrane process could be reused in the manufacture of surimi-like material from mechanically recovered poultry meat. [ABSTRACT FROM AUTHOR]

This work was focused on the investigation of the temperature- and pH-responsive polyurethane (PU) membranes and their permeability to amino-acids in response to environmental stimuli. The PU membrane was prepared from a wet phase inversion method and a two-step solution polymerization from polycaprolactone diols (PCL), 4,4'-diphenylmethane diisocyanate (MDI), dimethylol propionic acid (DMPA), etc. The chemical structure, phase state, morphology and surface wettability of the membrane were characterized with Fourier transform infrared (FTIR) spectrometer, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and contact angle tester, respectively. The temperature and pH responses of the membrane were investigated by means of an amino-acid permeate experiment. The L-phenylalanine (L-Phe) was chosen as model amino-acids. The permeation of the L-Phe was measured using a dead-end flow filtration at varied temperatures and pH, and characterized by the permeate flux ( J) and rejection coefficient ( R). J of the L-Phe across the PU membrane increased with increasing temperature and showed a sharp increase when temperature was raised to the crystalline melting temperature ( T) of the soft segment of PU, while decreased with increasing pH and having a sharp decrease when pH reached the dissociation constant (p K) of DMPA contained in PU macromolecules. While, the R behavior of L-Phe was just opposite from the results of J, which decreased with increasing temperature and increased with increasing pH, also showing the temperature and pH responses. Hopefully, the PU membrane with temperature- and pH-controllable permeability has promising prospects in water treatment, membrane separation, drug delivery system, etc. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Highlights: [•] Navier–Stokes and continuity equations were used to model fluxes in hollow fibres. [•] Solvent flux and solute flux through the membrane were modelled. [•] Increases of inlet velocity or decreases of MW resulted in rejection increases. [•] Observed rejection can either increase or decrease as a function of pressure. [•] For concentration dependent viscosity, observed and true rejection decreased. [Copyright &y& Elsevier]

The effect of the concentration boundary layer on the pressure-driven membrane separation like nanofiltration or ultrafiltration is well-known and extensively discussed in the literature. In most of these studies, the effect of the boundary layer and that of the membrane layer on the separation efficiency are discussed separately. This paper presents a general model to describe the convective and diffusive mass transport taking into account the simultaneous effect of both the concentration boundary layer and the membrane layer. The advantage of this model that the mass transport can be correctly described under all mass transfer conditions, independently that the effect of the boundary layer can or not be neglected. [ABSTRACT FROM AUTHOR]

Abstract: This study investigates and compares the performance of two different types of ultrafiltration (UF) membranes in the recovery of water from secondary treated wastewater. Filtration experiments were carried out on a pilot scale cross-flow unit using synthetic wastewater similar to the quality of secondary treated wastewater by varying the operating parameters such as transmembrane pressure (TMP), feed composition and membrane configuration. The filtration experiments demonstrated that the flux recovery through spiral polymeric UF membrane was more sensitive to the variation in TMP compared to the tubular ceramic UF membrane over the range of TMP studied. The resistance in series model was used for the evaluation of the resistance to the permeate flux. The fouling resistance, particularly irreversible resistance compared to reversible resistance plays a major role in the total resistance for the tubular ceramic membrane. In contrast clean membrane resistance is the major contributor for the total resistance of the spiral polymeric membrane. Finally, the effectiveness of the filtration treatment was determined by evaluating the rejection coefficients for various pollution indices of the wastewater. Significant differences in the performance of the membrane types were observed which are likely to impact on the selection, operation and maintenance of the membrane system. [Copyright &y& Elsevier]

Reactive black 5 (RB-5) dye was removed from a water stream using two cationic surfactants, cetyltrimethylammonium bromide (CTAB) and cetylpyridinium chloride (CPC), via micellar enhanced ultrafiltration. Three membranes with different pore size were used for the determination of rejection coefficient and permeate flux of the solution at 1.5 bar trans-membrane pressure (TMP). The two surfactants (CPC and CTAB) played an almost negligible role in rejection efficiency with 5000 and 10,000 molecular weight cut-off membrane (MWCO), respectively. In this case, high rejection and low permeate flux was the result of a larger molecular size of RB-5 DYE being retained by comparatively smaller sized pores of membrane via ultrafiltration. However, CPC and CTAB surfactants showed 83% and 98% rejection coefficient, respectively, at a concentration greater than their CMC values against 30,000 MWCO. Permeate flux remained low and constant in presence of 5000 and 10,000 MWCO with a small variation against 30,000 MWCO for the two surfactants, thereby no appreciable effect on both surfactant concentrations on concentration polarization was estimated. Thus, RB-5 dye alone was determined to be responsible for membrane plugging or concentration polarization and ultimately for low permeate flux. The effect of trans-membrane pressure was also investigated during this study. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the concentration boundary layer on the pressure-driven membrane separation like nanofiltration or ultrafiltration is well-known and extensively discussed in the literature. In most of these studies, the effect of the boundary layer and that of the membrane layer on the separation efficiency are discussed separately. This paper presents a general model to describe the convective and diffusive mass transport taking into account the simultaneous effect of both the concentration boundary layer and the membrane layer. It has been demonstrated how the Peclet number of the membrane, the ratio of diffusive mass transfer coefficient of the membrane to that of the polarization layer and the product of the steric partition coefficient and the convection hindrance factor affect the permeate concentration or the rejection coefficient. Comparing the measured and calculated data, it has been proven that the effect of the polarization layer can significantly affect the separation efficiency during practical nanofiltration of uncharged compounds. The model developed gives a general treatment method to evaluate pressure-driven membrane separation processes. [ABSTRACT FROM AUTHOR]

Abstract: Increasingly stringent regulations for drinking water quality have stimulated the ultrafiltration (UF) to become one of the best alternatives replacing conventional drinking water treatment technologies. However, UF is not very effectively to remove humic acid due to the comparatively larger pore size compared to the size of humic acid. Fouling issue is another factor that restricts its widespread application. In this study, rejection of humic acid and flux decline were compared with essentially neutral, negatively charged version of a regenerated cellulose membrane, in which electrostatic interaction was explored for a better humic acid removal and less fouling. Solution environment, including ionic strength, pH and calcium ion concentration, affecting humic acid removal and flux decline on negatively charged and neutral membranes was also compared. Results indicated that the appropriate charge modification on the neutral UF membrane could be an effective way for better removal of NOM and reduction of the membrane fouling due to the electrostatic interactions with the combination effect of membrane pore size. Electrostatic interactions are significant important to achieve high humic acid removal and less fouling, and to improve the water quality and protect people’s health. [ABSTRACT FROM AUTHOR]

Abstract: Sugar beet press water is one of the main wastewater in the sugar industry, which presently returned to the diffuser with no further treatment. Some form of treatment, such as pretreatment with membrane may however, improved the output efficiency of sugar plants. In this study, nanofiltration membrane (AFC80) were used to investigate the permeate flux, fouling percent and rejection percent of most important molassogenic ions (sodium and potassium) and sucrose. Sugar beet press water was provided by Abkoh sugar beet factory. The effect of operating parameters such as temperature (at levels of 25,40and 55°C), trans membrane pressure (at levels of 10,15and 20bar) on nanofiltration performance (permeate flux, fouling and rejection) were investigated. The results show that maximum permeate flux is obtained at 55°C and 20bar, while the average value is 49.27 kgm-2h-1. The minimum permeate flux is obtained at 25°C and 10bar, and the average value in this conditions is 14.63 kgm-2h-1. Maximum and minimum fouling are reached at 55°C and 20bar and 25°C and 15bar, respectively. Furthermore maximum rejection of sodium and potassium (84.3% and 72.5% respectively) is obtained at 25°C and 20bar, and minimum of rejection of sodium and potassium (74.3% and 69.05% respectively) is obtained on 55°C and 10bar. For all operating conditions, sucrose rejection was exceeded 95%. Variation in operating conditions had no significant effect on sucrose rejection. [Copyright &y& Elsevier]

Abstract: Filtration characteristics and membrane fouling in BSA/dextran binary suspension cross-flow microfiltration is studied. An increase in cross-flow velocity or transmembrane pressure leads to higher pseudo-steady filtration flux due to less membrane fouling or higher driving force. The fouled membrane pore size and fouled layer thickness under various conditions are estimated using a theoretical model based on the Hagen–Poiseuille law. The fouled membrane pore size decreases with increasing transmembrane pressure due to ever increasing fouling. The fouled layer thickness becomes thicker and invariant with operating conditions under a lower pressure drop through the fouled membrane. Molecular adsorption occurs on the pore walls until a specific wall shear stress is reached in the membrane pores. However, the fouled layer becomes thinner when the pressure drop exceeds a critical value. An increase in cross-flow velocity results in a larger fouled membrane pore size and a thicker fouled layer in such condition. The dextran molecular deformation under higher transmembrane pressure causes a thinner fouled layer and an ultimate equilibrium adsorption in the membrane pores. Furthermore, an increase in cross-flow velocity leads to higher BSA and dextran rejection due to the sweeping effect on the membrane surface. The BSA rejection increases with transmembrane pressure due to the reduction in membrane pore size, while the decrease in dextran rejection under higher transmembrane pressure is attributed to the molecular deformation. The “coil-stretched” deformation of dextran molecules can be indicated using the Deborah number. The fouled membrane pore size and dextran rejection decrease with increasing Deborah number and remain constant as the Deborah number exceeds a critical value. Taking the filtration flux and solute rejection into consideration, operating a cross-flow microfiltration system under lower cross-flow velocity and higher transmembrane pressure is more efficient from the selectivity and mean dextran mass flux view points. [Copyright &y& Elsevier]

Abstract: The operating condition effects on the cross-flow microfiltration performance of dilute macromolecular suspension were studied. Track-etched membranes of different pore sizes were used to filter blue dextran with a molecular weight of 2000kDa. Increasing the membrane pore diameter results in higher filtration flux but decreases the dextran rejection coefficient. For filtration using 0.2-μm membrane, an increase in cross-flow velocity or filtration pressure leads to higher filtration flux, but the impact of cross-flow velocity is more significant. A membrane fouling model based on force analysis and membrane pore size reduction caused by dextran adsorption at pseudo-steady state is proposed. The effective membrane pore diameter and pseudo-steady filtration flux under various conditions can then be estimated. On the other hand, the pseudo-steady dextran rejection coefficient increases with increasing cross-flow velocity or decreasing filtration pressure when cross-flow velocity is lower than 0.3m/s. This can be reasonably explained by the sweeping effect of tangential flow or using the modified gel-polarization model. However, a contrary trend occurs under the conditions with higher cross-flow velocity. This result is attributed to the dextran molecular deformation. The “coil-stretched” deformation of blue dextran molecules can be indicated using the Reynolds number in the permeating flow direction or Deborah number for macromolecular flow through porous media. [Copyright &y& Elsevier]

Abstract: This paper describes the transport process, rejection curve and molecular weight cut-off (MWCO) of ultrafiltration membranes by using a log-normal distribution, Poiseuille flow and steric interaction between solute molecules and pores. The rejection coefficient of membranes was expressed with an analytical function of D */a (the ratio of geometric mean diameter to solute diameter) and σ (geometric standard deviation). For ultrafiltration membranes with different MWCO, the pore size distribution can be divided into three zones by σ: Zone I, long tail-effect of big pores (σ >1.55); Zone II, linearization of pore size distribution parameters (D *, σ) (1.15≤ σ ≤1.55); Zone III, sieving effect (1≤ σ <1.15). The relationship between D */D MWCO (D MWCO is the diameter of solute molecule at R =0.9) and σ was described by the Extreme model: For any rejection coefficient, the relationship between D */a and σ can also be described using the Extreme model. A method to predict the pore size distribution and MWCO of ultrafiltration membranes by two points was first presented and verified by hollow fiber membranes spun at different shear rates. The shear rate in the spinning of hollow fiber membranes dominated the pore size distribution parameters (D *, σ), which played an important role in membrane performance. With an increase in shear rate, the geometric standard deviation (σ) was strongly suppressed, which resulted in hollow fiber membranes with low MWCO. [Copyright &y& Elsevier]

Abstract: Acetyl cellulose nanofiltration membrane (NF) was manufactured by a dry/wet phase inversion process and studied on its performance characteristics for the electrolyte solutions NaCl, MgCl2, Na2SO4 with a concentration range of 10−3–10−2 N at various pH values. It was shown that the multivalent cation Mg2+ or sulfate anion present in non-symmetrical electrolytes makes the membrane more positively or negatively charged as a result of their adsorption on the amphoteric pore surface, which greatly increases the membrane selectivity up to 85–95% for these electrolyte solutions. Meanwhile, with respect to 1:1 electrolyte solution NaCl the rejection capacity is low (R=30–40%) because there is essentially no adsorption on the membrane surface. For a feed source made of the RO retentate the experimental data showed that the fabricated membrane possesses high rejection capacity for multivalent ions such as (R=85.7%) and Mg2+ (R=93.5%) and low selectivity for monovalent salts such as NaCl (R=33.7%). The following salts rejection sequence with respect to symmetric and non-symmetric electrolyte solutions has been set up: R Na2SO4>R NaCl>R MgCl2 and R MgCl2>R Na2SO4>R NaCl at pH≥7 and pH≤7, respectively. The fact that at pH values above 7 rejection of sodium chloride is higher than that of magnesium chloride, although its ion size is smaller than that of the latter, can be explained only by charge exclusion effect. From these results it can be concluded that Donnan exclusion effect is the predominant mechanism for salt removal by NF membranes. [Copyright &y& Elsevier]

Ceramic and polymeric membrane systems were compared at the pilot scale for separating agave fructans into different molecular weight fractions that help to diversify them into more specific industrial applications. The effect of the transmembrane pressure of ultrafiltration performance was evaluated through hydraulic permeability, permeate flux and rejection coefficients, using the same operating conditions such as temperature, feed concentration and the molecular weight cut-off (MWCO) of membranes. The fouling phenomenon and the global yield of the process were evaluated in concentration mode. A size distribution analysis of agave fructans is presented and grouped by molecular weight in different fractions. Great differences were found between both systems, since rejection coefficients of 68.6% and 100% for fructans with degrees of polymerization (DP) > 10, 36.3% and 99.3% for fructooligosaccharides (FOS) and 21.4% and 34.2% for mono-disaccharides were obtained for ceramic and polymeric membrane systems, respectively. Thus, ceramic membranes are better for use in the fractionation process since they reached a purity of 42.2% of FOS with a yield of 40.1% in the permeate and 78.23% for fructans with DP > 10 and a yield of 70% in the retentate. Polymeric membranes make for an efficient fructan purification process, eliminating only mono-disaccharides, and reaching a 97.7% purity (considering both fructan fractions) with a yield of 64.3% in the retentate. [ABSTRACT FROM AUTHOR]