Polysulfonamide Membranes Research Articles

Highly permeable benzene-trisulfonyl chloride-based polysulfonamide membranes fabricated by interfacial polymerization for acid-resistant nanofiltration

The fabrication of highly acid-resistant nanofiltration (NF) membranes with excellent separation performance via interfacial polymerization remains challenging due to the lack of precise pore architecture manipulation. Herein, novel acid-resistant nanofiltration membranes were fabricated based on benzene-1,3,5-trisulfonyl chloride (BTSC), which holds the characteristic resonant π-backbonding structure and high steric hindrance, by interfacial polymerizing with polyethyleneimine (PEI) and piperazine (PIP) on the polyethersulfone (PES) substrate. The as-prepared PIP-BTSC/PES and PEI-BTSC/PES membranes displayed sub-nanometer pore sizes of 0.62 and 0.65 nm, respectively, with much narrower pore size distribution than the conventional acid-resistant NF membranes. Notably, the PEI-BTSC-H/PES membrane exhibited an MgCl2 rejection of 95.5 % and a high permeance of 43.5 L h-1 m−2 bar−1. Besides, the PEI-BTSC/PES membrane exhibited excellent acid-resistance in the 72-day static acid soaking test and dynamic acid permeation experiment. Density functional theory calculation revealed that the outstanding acid-resistance of BTSC was ascribed to the much higher hydrolyzation energy barrier of the polysulfonamide than conventional polyamide.

Recent developments in the preparation of improved nanofiltration membranes for extreme pH conditions

• Substantial R&D efforts have been devoted to preparing improved pH stable membranes. • Polyamine and polyurea membranes are more acid stable than polyamide membranes. • Specific polyelectrolyte multilayer membranes (PEM) are acid and alkaline stable. • PEM show better permeance than commercial NF membranes at extreme pH conditions. • Further R&D is needed before developed membranes can be widely applied in industry. Conventional commercially available nanofiltration (NF) membranes show limited stability at extreme pH conditions, whereas commercially available NF membranes that can cope with these conditions often show (too) low permeance or are relatively open. Since NF applications in many industrial sectors require pH stable NF membranes with a range of molecular weight cut-offs (MWCO), including tight NF membranes, substantial research and development efforts are being devoted to the research and development of these membranes. This review discusses these developments as reported in open literature, with a focus on the period between 2016 and 2021. Most developments relate to the use of interfacial polymerization to produce thin film composite membranes. Polyamine and polyurea membranes with good chemical stability for extreme pH conditions have been prepared. For polysulfonamide membranes indications for good chemical stability at low pH have been shown. These membrane types show improved stability compared to developed poly(aryl cyanurate), polyesteramide, poly(amide-sulfonamide), and polyamide membranes, which are more susceptible to hydrolysis and therefore less chemically stable at extreme pH. Furthermore, layer-by-layer coating using strong cation - and anion polyelectrolytes has led to new pH stable NF membranes. Despite the extension of the pH stable NF membrane portfolio, most of the developed membranes still do not meet the performance characteristics of the best commercially available NF membranes applicable for the common pH range between 2 and 11. Only a few layer-by-layer coated polyelectrolyte membranes combine high permeance, relatively low MWCO and stability at extreme pH. However, these membranes are not yet commercially available for full-scale applications requiring high pressure operation. Consequently, there is still room for research and development to further improve pH stable NF membranes.

Correlation between membrane surface properties, polymer nature and fouling in skim milk ultrafiltration

The fouling of the membranes in skim milk ultrafiltration with the nominal molecular weight cut-off (MWCO) of 100 kDa fabricated from different polymers (polysulfone (PSF), polysulfonamide (PSA), aromatic polyamide (PA), polyacrylonitrile (PAN), cellulose acetate (CA) and regenerated cellulose (RC)) was studied. The membrane structure and physical-chemical properties of the selective layer were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), water contact angle (θ, °) measurements, free surface energy measurements and bovine serum albumin (BSA) adsorption. Additionally, the flux of the skim milk at the constant product concentration, protein adsorption, resistance of the gel layer of the membranes were determined. It was found that according to the decrease in water contact angle of the membrane selective layers membranes can be arranged in the series as follows: PSF > PSA > PA > PAN > CA > RC. It was revealed that there was no direct correlation between the membrane hydrophilicity and the protein adsorption. It was noted, that the studied membranes featured significantly different hydraulic resistances of the protein gel-layer, which can be considered as a secondary dynamic membrane. Comparison of the parameters – water contact angle and polar component of the free surface energy of the membrane selective layer, and normalized dipole moment of the membrane polymers - with the adsorption values of the proteins during ultrafiltration proves that the protein adsorption to the membrane surface increases with an increase in hydrophobicity and polarity of the membrane. The high protein adsorption by the moderately hydrophilic PAN membrane is due to the contribution of the high normalized dipole moment of the polymer. In the case of the polar RC-100 membrane, the influence of the membrane polarity was shown to be counter-balanced by its high hydrophilicity. The study highlights the impact of the physical-chemical properties and structure of the membrane on the protein gel-layer and thus their importance in membrane fouling control in dairy applications.

Effect of Unipolar Corona Discharge Parameters on the Surface Characteristics of Polysulfonamide Membranes and Their Separation Efficiency for Water-in-Oil Emulsions

Ultrafiltration polysulfonamide (PSA) membranes with a molecular weight cutoff of 100 kDa have been treated in a unipolar corona discharge field in an air atmosphere at varying voltage (5, 15, 25, and 35 kV) and corona discharge treatment times (1, 3, and 5 min). Using instrumental methods of analysis, it has been revealed that the treatment leads to changes in the surface structure of the membrane, namely, an increase in the roughness and hydrophilicity and, as a consequence, in the flux and separation efficiency for a model water-in-oil emulsion. It has been found that the maximum efficiency (89.3%) is exhibited by a PSA membrane treated with a corona discharge at a voltage of 35 kV for 5 min.

Polysulfonamide coating layer polymerized by1,3-disulfonyl chloride and polyethylenimine to achieve acid resistant TFC membranes

In this work polysulfonamide membranes are presented that are prepared by the interfacial polymerization of polyethylenimine (PEI) and benzene-1,3-disulfonyl chloride (BDSC) on porous polyvinylidenefluorid support membrane. The thin film composite (TFC) polysulfonamide membranes show superior acid stability as compared to conventional polysulfonamide membranes that are derived from monomeric amine and benzene-1,3-disulfonyl chloride. The polysulfonamide membranes show exceptionally strong resistance towards nucleophilic attack induced by extreme acidic conditions. This is verified by the dyes rejection performance in 20%(w/v) H2SO4 and 2.5%(w/v) HNO3 aqueous solution at 70 ± 5 °C for 24 h. PEI-PSA and PEI/PIP-PSA membranes were considerably stable in two acids. In contrast, the durability of PEI/MPD-PSA was lower than the other two. The changes in CV and MO dye rejection were −3.15% and −2.19%, and −1.11%, −5.6% for PEI-PSA and PEI/PIP-PSA, respectively after H2SO4 soaking while they were −20% and −15.9% for PEI/MPD-PSA. Moreover, the changes in CV and MO dye rejection were −15.7% and −14.3%, and −7.8%, −5.7 % for PEI-PSA and PEI/PIP-PSA, respectively after HNO3 soaking while they were −17.7% and −10.2% for PEI/MPD-PSA.

Effect of Radiofrequency Plasma Treatment on the Characteristics of Polysulfonamide Membranes and the Intensity of Separation of Oil-in-Water Emulsions

Polysulfonamide membranes with a molecular weight cutoff of 20 kDa (pore size of 0.01 μm) have been treated with a flow of a radiofrequency (RF) capacitively coupled low-pressure glow discharge plasma in an argon and nitrogen atmosphere at an anode voltage of Ua = 1.5 kV and τ = 1.5 min. Instrumental methods of analysis have revealed the following changes in the structure of the membrane surface as a consequence of plasma treatment at the above parameters: a decrease in roughness, a decrease in the contact angle from 59.6° to 47.9°, and the formation of oxygen-containing functional groups. Experiments on the membrane separation of a 3% oil-in-water emulsion have been conducted; the results have shown that the use of plasmatreated polysulfonamide membranes leads to an intensification of the process.

Enhancement of Separation of Water–Oil Emulsion Using Unipolar Corona-Treated Polysulfonamide Membranes

The influence of unipolar-corona discharge treatment on the efficiency of separation of a model oil-in-water emulsion using polysulfonamide membranes with a molecular weight cut-off of 20 kDa (pore size ≈ 0.01 μm) has been investigated. It has been shown that the corona discharge treatment of the membranes leads to the intensification of the separation of water–oil emulsions and the process parameters depend on the processing time and the voltage applied to the corona electrode. The maximum value of the efficiency (95.4%) is noted in the case of the membrane treated in a corona discharge for 5 minutes at a voltage of 5 kV applied onto the electrode. The trends observed have been explained. It has been shown that the corona treatment promotes the hydrophilization of the membrane surface: the contact angle of water is α = 55° for the initial membrane and α = 50° after the corona treatment. Atomic force microscopy has shown a change in the structure of the membrane surface by the corona treatment—an increase in the roughness. A small decrease in the crystallinity of polysulfonamide by its treatment in a unipolar corona discharge has be been revealed.

Effect of the pH of emulsion on ultrafiltration of oil products and nonionic surfactants

The structure and properties of a water–oil emulsion have been studied. The ultrafiltration of the water–oil emulsion has been performed with the use of spiral wound and hollow fiber membranes to separate the emulsion into a filtrate and a concentrate. The effect of pH on the following performance characteristics of the ultrafiltration process has been studied: the efficiency and the degree of separation of oil products and nonionic surfactants. It was found that an increase in the pH value of the emulsion decreased the efficiency of membranes and the degree of separation of nonionic surfactants. It has been found that a Raifil UF membrane effectively rejects oil products from acidic emulsion and, on the contrary, an EMU 45-300 membrane is effective in an alkaline medium. This behavior has been associated with to a positive surface charge of the EMU 45-300 membrane. The maximum efficiencies and degrees of separation of oil products and nonionic surfactants from emulsions with the use of the Raifil UF ultrafiltration membrane and the EMU 45-300 membrane have been attained in the pH ranges from 2.1 to 2.9 and from 2.2 to 2.5, respectively. After ultrafiltration, the size of particles in the filtrate increased by a factor of about 18 due to the coalescence of oil particles in the near-membrane layer because of polarization effects. The increase in the particle size of the dispersed phase in the filtrate can also be explained by a positive surface charge of polysulfonamide membranes.

Intensification of separation of oil-in-water emulsions using polysulfonamide membranes modified with low-pressure radiofrequency plasma

Effect of low-pressure radiofrequency capacitively-coupled plasma parameters on the separation of model “oil-in-water” emulsions using UPM-20 polysulfonamide membranes with a pore size of 0.01 μm has been studied. Atmospheric air has been used as a plasma gas. The plasma treatment time is 1, 5, 4, and 7 min at a plasma torch anode voltage of U a = 1.5–7.5 kV. The separated medium is a 3% emulsion based on the industrial oil I-20A; the stabilizer is the surfactant Kosintol-242. The highest performance is observed in the case of membranes treated with plasma for 7 min. It is found that plasma treatment leads to an increase in the emulsion separation efficiency from 90 to 99%. It has been shown that the plasma treatment contributes to the surface hydrophilization of the membranes owing to the formation of oxygen-containing functional groups. The membrane exhibits a contact angle of water of α = 59.6° before treatment and α = 19.5° after a 4-min plasma treatment at U a = 7.5 kV. Atomic force microscopy reveals that the plasma treatment leads to a change in the surface structure of the membranes, namely, to a decrease in their roughness. The internal structure of the membranes also undergoes changes which result in an increase in their crystallinity.

Static and dynamic assessments of polysulfonamide and poly(amide-sulfonamide) acid-stable membranes

Polysulfonamide (PSA) and poly(amide-sulfonamide) (PASA) thin film composite (TFC) membranes as the novel acid-stable membranes have been prepared by two aromatic and cycloaliphatic diamines. The acid-stable membranes were synthesized by interfacial polymerization of the diamines with benzene-1,3-disulfonyl chloride (BDSC) and/or trimesoyl chloride (TMC) on PES support membrane and their structures and performance were compared with polyamide (PA) TFC membranes. The stability of the TFC membranes in acids were studied by static acid soaking tests in two strong acids of 2.5% (w/w) HNO3 and 10% (w/w) H2SO4 at high temperature of 55 °C for 24 h. The dynamic permeation experiments were also done by 500 ppm MgSO4 at 0.5 MPa in deionized water and in 5% (w/w) H2SO4 solution. The acid retention in all of the membranes was very low. In contrast, the salt rejection was high in both water and acid solutions. The salt rejection was enhanced in acid solution filtration test because of the positive surface charge of the membranes in very low acidic pHs. The PSA membranes showed very good stability in high temperature acids while the PA membranes were completely degraded after acid soaking tests. Despite of the MPD-PA membranes which showed higher salt rejections than PIP-PA, the MPD-PSA membranes had lower rejections of 32% compared to PIP-PSA one (46%). The percent changes of salt rejection in water were −54%, −71%, −9.6% and −22% in H2SO4 and −29%, −54%, −2.1% and −13% in HNO3 for PIP-PASA, MPD-PASA, PIP-PSA and MPD-PSA membranes, respectively. The high molecular weight PSA polymers with improved acid stability and salt rejection were obtained from aliphatic diamine of PIP compared to aromatic MPD.

Separation efficiency and stability of thin-film composite nanofiltration membranes in long-term filtration of copper sulphate and sulphuric acid mixture

Separation efficiency and stability of two lab-fabricated polysulfonamide (PSA) and polypiperazineamide (PA) thin-film composite nanofiltration membranes in long-term filtration of copper sulphate and sulphuric acid mixture were evaluated and compared in this study. The PSA and PA membranes were fabricated through interfacial polymerization process and 60-day long-term filtration tests were carried out with an acidic aqueous solution containing 2.5% (w/v) CuSO4 and 8.0% (w/w) H2SO4 under 25.0°C and 10.0 bar. The separation efficiency was studied in terms of permeate flux and retentions to copper and acid. The change of separation efficiency with filtration time was investigated to evaluate the performance stability of the membranes studied. Attenuated total reflectance Fourier transform infrared, field emission scanning electron microscopy, streaming potential analyzer, and contact angle analyzer were also adopted to characterize the change of membrane surface property during filtration. It was found that the PSA membrane maintained its separation efficiency during the 60-day continuous filtration, exhibiting a copper retention of about 83.5% and a sulphuric acid retention of less than 5.0%. The PA membrane began to lose its selectivity after 20 days of filtration due to the deterioration of its skin layer, which was confirmed by the change of membrane surface property.

Wastewater treatment for removal of dyes by coagulation and membrane processes

The development of effective wastewater treatment means and processes is one of the most important problems of textile dyeing-and-finishing plants. Textile dyeing wastewater contains large amounts of chemically different synthetic dyes, surfactants, and mineral substances, which are responsible for a serious chemical load on municipal wastewater treatment facilities. In this study using wastewater from direct and reactive dyeing processes at the Svitanak dye-works (Zhodino, Belarus) as an example, a comparative analysis has been performed of the efficiency of wastewater treatment by the following two processes: reagent coagulation with the use of aluminum hydroxychloride and anionic and cationic flocculants and ultrafiltration with the use of polyacrylonitrile, polysulfone, aromatic polyamide, and polysulfonamide membranes and experimental membrane samples with additionally modified surfaces.

Adsorption and Surface Properties of Vladipor Cellulose Acetate and Polysulfonamide Membranes

Surface and adsorption characteristics of porous cellulose acetate (UAM) and polysulfonamide (UPM) membranes with pore diameters from 0.015 to 0.1 µm are compared. The specific surface areas of UPM membranes are 130 and 150 cm2/cm2, whereas those of UAM membranes vary from 80 to 360 cm2/cm2 of the membrane area. The density of negative charges on the pore surface is 5 × 10− 8 and about 20 × 10−8 C/cm2 for UAM and UPM membranes, respectively. The adsorption of basic and acidic substances, proteins (cytochrome C and ovalbumin) and dyes (rhodamine 6G and Acid Orange), from aqueous solutions is studied. Far stronger hydrophobic interactions are observed for the UPM than for UAM membranes. The adsorption of basic substances is markedly higher than that of acidic substances because of acidic properties of the membrane surface. The distribution constants for the adsorption of Acid Orange and cytochrome C on the UPM membrane with a pore diameter of 0.1 µm are 50- and 100-fold higher than for the UAM membrane of the same pore diameter and specific surface area.

The development of polysulfonamide membrane and its application in treating chromium plating wastewater

This paper presents the method of preparation of polysulfonamide (PSA) membranes and discusses their properties. It shows that PSA membranes have a very high resistance to acid oxidation and heat making them suitable for treating electroplating wastewater over a wide pH range.

Reinforced and dry polysulfonamide membranes

Reinforced polysulfonamide membranes were prepared by the method of continually casting membrane on a polyester web. The variables for the process of making membranes, such as casting rates, evaporation periods, compositions and temperature of gelation bath were discussed. The membranes could be dried without changing their properties. The ranges of average pore radius could be controled from 200 to 1200 Å by changing compositions of casting solution and conditions of preparation of membranes, the corresponding membrane fluxes were 300 to 800 ml/cm 2.hr. at the pressure of 2.5 kg/cm 2 and with distilled water as feed. The pore sizes of the membranes were changed only a little after the treatment in boiling water and even the heat-treatment under vapor pressure of 0.5 kg/cm 2, but the fluxes were increased. The membranes are also stable in solutions of PH 1 to 12, and resistant to solvents and oxidation. The membranes can be used as ultrafiltration membranes and supporting membranes for composite membranes.