Morphological controlling of CTA forward osmosis membrane using different solvent-nonsolvent compositions in first coagulation bath

Cellulose triacetate (CTA) membranes were fabricated via a modified nonsolvent induced phase separation (NIPS) method. Different solvent-nonsolvent compositions in first coagulation bath (FCB) were introduced to optimize CTA membrane structures. The effects of FCB compositions, immersion time and mass ratio of solvent (N-methyl-2-pyrrolidone, NMP) and nonsolvent (water, ethanol, ethylene glycol and glycerol) on membrane morphology and performance were systematically investigated. Prospective membranes with a dense bottom layer and a scaffold-like top layer were obtained under room temperature, owing to the low relative energy difference (RED) between nonsolvent and polymer as well as the high viscosity of FCBs. A high water flux J_v (12.6 L m^?2 h^?1) and a low reserve salt flux J_s (1.32 g m^?2 h^?1) were obtained in the optimized membrane, with a structural parameter S of 119 μm. Compared with membranes prepared via conventional NIPS method and commercial CTA forward osmosis (FO) membranes, a remarkable improvement of J_s/J_v value and S value was achieved, indicating membranes with single dense-layer structure might suffer less from internal concentration polymerization (ICP) which is the main obstacle for the development of FO process. This study might help us pave the way to design superior CTA membrane structures for forward osmosis application.     

Electrochemically mediated atom transfer radical polymerization of iminodiacetic acid-functionalized poly(glycidyl methacrylate)grafted at carbon fibers for nano-nickel recovery from spent electroless nickel plating baths

In this work, iminodiacetic acid-functionalized poly(glycidyl methacrylate)grafted carbon fibers (CCFs) were prepared by electrochemically mediated atom transfer radical polymerization (eATRP) for nano-nickel recovery from spent electroless nickel (EN) plating baths. The adsorption behaviors of Ni²⁺ were investigated at CCFs in the spent EN plating baths. The adsorption kinetics perfectly fitted pseudo-second order model with a chemisorption process. The thermodynamic parameters suggested that adsorption was feasible, spontaneous, and endothermic. The adsorption maximum capacity was 0.908 mM g^?1 under optimum conditions (pH 5.2, 50 °C and 40 min). The present materials were carefully characterized by the Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscope, and electrochemical techniques. Experimental results showed that CCFs were successfully prepared, which were efficient adsorbent and support for nano-nickel recovery from the spent EN plating baths.     

Advanced FO membranes from newly synthesized CAP polymer for wastewater reclamation through an integrated FO‐MD hybrid system

A new cellulose acetate propionate (CAP) polymer has been synthesized and used to prepare high‐performance forward osmosis (FO) membranes. With an almost equal degree of substitution of acetyl and propionyl groups, the CAP‐based dense membranes show more balanced physicochemical properties than conventional cellulose acetate (CA)‐based membranes for FO applications. The former have a lower equilibrium water content (6.6 wt. %), a lower salt diffusivity (1.6×10¹⁴ m² s^?1) and a much lower salt partition coefficient (0.013) compared with the latter. The as‐prepared and annealed CAP‐based hollow fibers have a rough surface with an average pore radius of 0.31 nm and a molecular weight cut off of 226 Da. At a transmembrane pressure of 1 bar, the dual‐layer CAP‐CA hollow fibers show a pure water permeability of 0.80 L m^?2 h^?1 bar^?1 (LMH/bar) and a rejection of 75.5% to NaCl. The CAP‐CA hollow fibers were first tested for their FO performance using 2.0 M NaCl draw solution and deionized water feed. An impressive water flux of 17.5 L m^?2 h^?1 (LMH) and a reverse salt flux of 2.5 g m^?2 h^?1 (gMH) were achieved with the draw solution running against the active CAP layer in the FO tests. The very low reverse salt flux is mainly resulting from the low salt diffusivity and salt partition coefficient of the CAP material. In a hybrid system combining FO and membrane distillation for wastewater reclamation, the newly developed hollow fibers show very encouraging results, that is, water production rate being 13–13.7 LMH, with a MgCl₂ draw solution of only 0.5 M and an operating temperature of 343 K due to the incorporation of bulky propionyl groups with balanced physiochemical properties. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1245–1254, 2013     

Fabrication of fullerenol-incorporated thin-film nanocomposite forward osmosis membranes for improved desalination performances

Development and use of novel membranes for forward osmosis (FO) applications have gained popularity throughout the world. To enhance FO membrane performance, a novel thin-film nanocomposite membrane was fabricated by interfacial polymerization incorporating Fullerenol (C₆₀(OH)_n) nanomaterial, having n in the range of 24–28 into the active layer. Different concentrations of fullerenol loading (100, 200, 400, and 800 ppm) were added to the top skin layer. The structural and surface properties of the pure thin-film composite membrane (TFC) and fullerenol-incorporated thin-film nanocomposite (FTFC) membranes, were characterized by ATR-FTIR, SEM, and AFM. FO performance and separation properties were evaluated in terms of water flux, reverse salt flux, antifouling propensity, water permeability and salt permeability for all TFC and FTFC membranes. Osmotic performance tests showed that FTFC membranes achieved higher water flux and reverse salt flux selectivity compared with those of TFC membranes. The FTFC membrane with a fullerenol loading of 400 ppm exhibited a water flux of 26.1 L m^?2 h^?1 (LMH), which is 83.03% higher than that of the TFC membrane with a specific reverse salt flux of 0.18 g/L using 1 M sodium chloride draw solution against deionized water in FO mode. The fullerenol incorporation in FTFC membranes also contributed to a decreased fouling propensity.     

Influence of metal salts in reaction medium on performance enhancement of novel aliphatic–aromatic-based polyamide thin-film composite osmosis membranes

In this study, we report an easy and novel way to develop high flux aliphatic–aromatic-based thin-film composite (TFC) polyamide osmosis membranes by addition of inorganic metal salts with amine reactants in the reaction system of polyethylene imine (PEI) and 1,3-benzene dicarbonyl chloride. Inorganic metal salts like CuSO₄, NiSO₄, MgSO₄, and Al₂(SO₄)₃ added to block some of the amine groups of PEI through complexation which in turn changes the polycondensation reaction kinetics of amine acid chloride reaction. The prepared membranes were characterized using water contact angle and atomic force microscopy studies and the performances were evaluated both in reverse osmosis and forward osmosis mode. In presence of metal salts in reaction interface, the performance of TFC membranes was greatly enhanced and the optimum metal salt concentration was identified for individual metal salts for maximum performance enhancement. The effects of different anions for same metal ion and different molecular weight of PEI were evaluated on composite polyamide membrane performances. Water permeability (flux) of 63.48 L m^?2 h^?1 was achieved upon inorganic salt addition compared to the unmodified TFC membranes with flux of 42.1 L m^?2 h^?1 at similar salt rejection of ~95%. Based on the new findings, a conceptual model was proposed to explain the role of metal ion in amine solution on the resulting characteristics of aromatic–aliphatic type polyamide–polysulfone composite membrane.     

High Flux Layer by Layer Polyelectrolyte FO Membrane: Toward Enhanced Performance for Osmotic Microbial Fuel Cell

Combination of microbial fuel cell (MFC) and forward osmosis (FO) is called an osmotic microbial fuel cell (OMFC). Because of the high cost of FO membranes, for the first time laboratory made FO membrane has been used in OMFC. This study investigates the performance of FO membrane in OMFC treating glucose as substrate and 2M NaCl as draw solution. The FO membrane was able to achieve 18.43 lm^?2 h^?1 (LMH) and for fouled FO membrane it was 15.26 lm^?2 h^?1. The OMFC constantly produced bioelectricity and achieved maximum current density 139.52 A/m³ and power density 27.38 W/m³. The energy production of OMFC was 0.438 kWh/m³.     

Poly(ether imide) membranes modified with charged surface‐modifying macromolecule—Its performance characteristics as ultrafiltration membranes

Modification of poly (ether imide) (PEI) ultrafiltration (UF) membranes was attempted by blending charged surface modifying macromolecule (cSMM). Compared to the pure PEI membrane, blending of PEI with cSMM resulted in blend membranes with enhanced UF characteristics such as lower hydraulic resistance (R_m) and higher pure water flux (PWF) coupled with higher water content (WC). Among the various modified membranes, blend membranes with 5 wt % cSMM concentration exhibited higher PWF (60.38 L m^?2 h^?1), WC (73.6%), protein permeate flux (27.12 L m^?2 h^?1) and lower flux decline rate (R_fd) (55.1%), R_m (5.21 kPa/L m^?2 h^?1), bovine serum albumin (BSA) rejection (87.1%). Meanwhile, the fouling resistant ability was studied by flux recovery ratio (FRR) after water and alkali cleaning, irreversible and reversible fouling rate. Higher FRR after water cleaning (95.07%), FRR after alkali cleaning (97.1%), reversible fouling rate (50.14%) and lower irreversible fouling rate (5%) exhibited by 5 wt % cSMM membranes showed its better antifouling ability compared to pure PEI and other blend membranes because of its higher hydrophilic nature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40320.     

Poly(ethylene glycol) crosslinked sulfonated polysulfone composite membranes for forward osmosis

Forward osmosis (FO) membranes were prepared by a coating method with poly(ethylene glycol) crosslinked sulfonated polysulfone (SPSf) as a selective layer. The poly(ether sulfone)/SPSf substrate was prepared by phase inversion. The composite membranes were characterized with respect to membrane chemistry (by attenuated total reflectance/Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy), hydrophilicity (by static contact angle measurement), and surface morphology (by scanning electron microscopy and atomic force microscopy). The FO performance was also characterized. The effects of the crosslinker concentration on the hydrophilicity and FO performance were investigated. The crosslinked membrane exhibited a high hydrophilicity with a lowest contact angle of 15.5°. Under FO tests, the membranes achieved a higher water flux of 15.2 L m^?2 h^?1 when used against deionized water as the feed solution and a 2 mol/L sodium chloride (NaCl) solution as the the draw solution. The membranes achieved a magnesium sulfate rejection of 96% and an NaCl rejection of 55% when used against a 1 g/L inorganic salt solution as the feed solution and a 2 mol/L glucose solution as the draw solution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43941.     

Cellulose triacetate/LUDOX-SiO2 nanocomposite for synthesis of pervaporation desalination membranes

A series of cellulose triacetate/Ludox-silica nancomposite pervaporation membranes was successfully prepared via solution casting, aiming to improve the performance of cellulose triacetate membranes for desalination. The fabricated nanocomposite membranes were characterized to study the membrane morphology, chemical composition, mechanical properties, and surface hydrophilicity. Furthermore, the desalination performance was investigated as a function of silica (SiO₂) loading (ranging from 1 to 4 wt%) and feed concentration at 30 and 60 g/L of sodium chloride (NaCl). Pervaporation experiments showed that incorporating 4 wt% SiO₂ into a cellulose triacetate (CTA) membrane increased the water flux by a factor 2.5 compared with pristine CTA (from 2.2 to 6.1 kg m⁻² h⁻¹) for a 30 g/L NaCl feed solution at 70°C, while the salt rejection remained above 99%. The CTA/4 wt% SiO₂ membrane was found to have only 21% flux reduction when tested with a 60 g/L NaCl feed solution, without changes in membrane selectivity. This suggests that the developed CTA/Ludox-SiO₂ nanocomposite pervaporation membrane is suitable for desalination.     

Niederdruckumkehrosmose mit modifizierten polyacrylnitril-ultrafiltrationsmembranen

The chemical modification of polyacrylonitrile ultrafiltration (PAN-UF) membranes by hydroxylamine yields low-pressure reverse-osmosis (LP-RO) membranes containing amidoxime and hydroxamic acid groups besides nitrile groups. These membranes are positively charged at pH values of 4.0 to 6.5. The water permeability of the membranes decreases from 400 L h^?1 m^?2 to 15 L h^?1 m^?2 (p = 0.3 MPa) by this modification. A comprehensive characterization was carried out by retention curves, IR and NMR spectra, Hg porosimetry, measurement of membrane potentials and separation performance regarding different metal salts. Due to the Donnan exclusion these membranes have a retention of 88% at a filtrate flux of 8 L h^?1 m^?2(p = 0.3 MPa) regarding bivalent metal ions like Ca²⁺ and Mg²⁺ which cause the water hardness. Regarding heavy metal ions like Cu²⁺ and In³⁺ much higher filtrate fluxes from 90 to 100 L h^?1 m^?2 (p = 0.3 MPa) are possible. In water medium without any heavy metal ions the amidoxime and hydroxamic acid groups are hydrolysed to carboxylic acid groups which are able to reject multivalentanions. By this the water softening ability remains.     

Charged membranes prepared by SPEEK of very low degree of sulfonation

Novel charged membranes were prepared with sulfonated poly(ether ether ketone) (SPEEK). Methylsulfonic acid was used as solvent to accommodate the very low degree of sulfonation of the SPEEK. Membranes were prepared by immersion phase inversion method, using coagulation baths of different composition and temperature. Low molecular weight and negatively charged dye molecules were used as model solutes to test the nanofiltration (NF) performance of the membranes. Higher than 93% rejection of the two dye molecules, Rose Bengal and Reactive Brilliant Red, was observed at normal operating temperature. A permeate flux as high as 497 L m^?2 h^?1 and higher than 90% of solute rejection at 80°C was achieved in the NF of Reactive Brilliant Red aqueous solution, in contrast to a flux of 226 L m^?2 h^?1 and about 78% of solute rejection at the same temperature in the case of Rose Bengal solute. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

电渗析法再生化学镀镍老化液的实验研究

应用电渗析技术,再生化学镀镍老化液以降低镀液成本,减少环境污染。在采用非均相离子交换膜条件下,考察了4种工艺条件对电渗析的选择去除效果的影响,得出了优化工艺条件,在去除副产物的同时限制了有效物质的流失。     

Influence of nickel ions for electroless Ni–P plating on polyester fabric

Properties of electroless Ni–P plated polyester fabric mainly depend on the plating bath constituents/conditions. The effects of NiSO₄ concentration of the plating bath on the deposition rate, phosphorus content, surface morphology, and crystal structure of the electroless Ni–P plated polyester fabric were investigated. The study revealed that phosphorus content in the deposits decreased at higher NiSO₄ concentration. SEM micrographs showed that nodule size of the Ni–P deposits increased. All the Ni–P deposits had an amorphous structure. The electromagnetic interference (EMI) shielding effectiveness (SE) of electroless Ni–P plated polyester fabric was evaluated. With the rise of nickel ion in the solution, the EMI SE of the Ni–P plated polyester fabric increased.     

Synthesis and characterization of PES/PSF/PEG by immersion precipitation for Mediterranean seawater desalination by FO membrane

In the present study, a simple, inexpensive, nontoxic, and environmentally friendly polyethylene glycol (PEG) polymer was used to enhance the hydrophilicity of the forward osmosis (FO) membrane using various PEG concentrations as a pore forming agent in the casting solution of polyethersulfone/polysulfone (PES/PSF) blend membranes. A nonwoven PES/PSF FO blend membrane was fabricated via the immersion precipitation phase inversion technique. The membrane dope solution was cast on polyethylene terephthalate (PET) nonwoven fabric. The results revealed that PEG is a pore forming agent and that adding PEG promotes membrane hydrophilicity. The membrane with 1 wt% PEG (PEG1) had about 27% lower contact angle than the pristine blend membrane. The PEG1 membrane has less tortuosity (which reduces from 3.4–2.73), resulting in a smaller structure parameter (S value) of 277 μm, due to the presence of open pores on the bottom surface structure, which results in diminished ICP. Using 1 M NaCl as the draw solution and distilled water as the feed solution, the PEG1 membrane exhibited higher water flux (136 L m⁻² h⁻¹) and lower reverse salt flux (1.94 g m⁻² h⁻¹). Also, the selectivity of the membrane, specific reverse salt flux, (J_s/J_w) showed lower values (0.014 g/L). Actually, the PEG1 membrane has a 34.6% higher water flux than the commercial nonwoven-cellulose triacetate (NW-CTA) membrane. By means of varied concentrations of NaCl salt solution (0.6, 1, 1.5, and 2 M), the membrane with 1 wt% PEG showed improved FO separation performance with permeate water fluxes of 108, 136, 142, and 163 L m⁻² h⁻¹. In this work, we extend a promising gate for designing fast water flux PES/PSF/PEG FO blend membranes for water desalination.     

Preparation of mesh-reinforced cellulose acetate forward osmosis membrane with very low surface roughness

Mesh-reinforced cellulose acetate (CA)-based membranes were prepared for forward osmosis (FO) by immersion precipitation. Casting compositions such as CA percent and 1, 4-dioxane/acetone ratio and also preparation conditions such as evaporation time, coagulation bath and annealing temperatures were tested for membranes’ performance. The results were compared with commercially CTA membranes. The best membrane (17.9% polymer and 1, 4-dioxane/acetone ratio of 1.89) showed water flux of 9.3 L/m²h (LMH) and RSF of 0.536 mol NaCl/m²h. Moreover, the membrane structure was reinforced by a polyester mesh, which created micro pores in the back of the membrane. This caused higher water flux and RSF compared to membranes without mesh. FO membrane prepared under best conditions, had a smoother surface than commercial ones. This feature enhances the fouling properties of the membrane, which can be appropriate for wastewater treatment applications.     

Effect of pore characteristics on permeability of sintered diatomite filter for microfiltration

Diatomite, because it is inherently porous and irregular, presents an interesting opportunity to investigate how the processing conditions of green bodies and the incorporation of spherical pores affect the final properties of a sintered ceramic filter. The water flux of a diatomite filter sintered at 1200°C was 6·3×10⁴ L m^?2 h^?1 bar^?1, which is higher than the water fluxes of typical ceramic filters such as spherical fly ash (1·6×10⁴ L m^?2 h^?1 bar^?1), γ-alumina (～1·0×10³ L m^?2 h^?1 bar^?1) and zirconia (1·6×10³ L m^?2 h^?1 bar^?1) filters. The results obtained in this study show that the pressure applied during the processing of green bodies and the incorporation of spherical pores directly affect pore characteristics and accordingly determine the permeability of the sintered diatomite filters.     

Ultraviolet‐ray treatment of polysulfone membranes on the O2/N2 and CO2/CH4 separation performance

UV irradiation on polysulfone (PSF) membranes was studied to improve their gas‐separation properties. Membranes with 19–25% PSF contents were prepared by the phase‐inversion method, and the membrane surface was modified with UV rays with a wavelength of 312 nm and a power of 360 µw/cm². Measurements of gas permeation were conducted with pure carbon dioxide (CO₂), methane (CH₄), oxygen (O₂), and nitrogen (N₂) gases under 3–8 bar pressure at 25°C. Fourier transform infrared spectrometry revealed that the polar functional groups of hydroxyl and carbonyl were introduced by UV irradiation. The water contact angle of the treated membrane was reduced from 70–75° to 10–12° after 12 h of UV exposure. Scanning electron microscopy observation showed that the dense skin layer increased as the polymer concentration increased. After UV treatment, the permeation of O₂ decreased from 0.4–3.4 to 0.2–2.3 m³ m^?2 h^?1 bar^?1, whereas that of N₂, CO₂, and CH₄ increased for all of the pressures used from 0.1–1.7 m³ m^?2 h^?1 bar^?1 to about 0.1–3.4 m³ m^?2 h^?1 bar^?1; this depended on the applied pressure and the PSF content. As a result, the selectivity ratio of O₂/N₂ decreased from 1.9–7.8 to 0.6–1.5, whereas that of CO₂/CH₄ increased from 0.9–2.6 to 1.1–6.1. Moreover, the O₂/N₂ and CO₂/CH₄ of the untreated and the treated membranes decreased with increasing pressure and increased with increasing polymer concentration. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42074.     

Light FCC gasoline olefin oligomerization over a magnetic NiSo4/γ‐Al2o3 catalyst in a magnetically stabilized bed

Magnetic NiSO₄/γ‐Al₂O₃ catalysts were prepared by impregnating NiSO₄ solutions onto the γ‐Al₂O₃ support containing a magnetic material of Fe₃O₄. Characterization by XRD, NH₃‐TPD, and thermal analysis showed that the magnetic NiSO₄/γ‐Al₂O₃ catalyst with a nickel content of 7.0% by weight had a monolayer dispersion of NiSO₄ and the largest number of moderate strength acid sites, and a high specific saturation magnetization. The magnetic catalyst was evaluated for light FCC gasoline olefin oligomerization in both fixed‐bed and magnetically stabilized bed (MSB) reactors. Comparing with that in the fixed‐bed reactor, the optimal reaction temperature in the MSB lowered to 443 K, and its space velocity ranged broadly from 2.0 to 6.0 h^?1. The sulfur‐free diesel distillate produced by operation of the MSB for 100 h had higher cetane number and good low‐temperature flow property, which illuminates a promising application of the MSB to manufacture clean diesel fuels with high productivity and flexibility. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Effects of K<Subscript>4</Subscript>Fe(CN)<Subscript>6</Subscript> on electroless copper plating using hypophosphite as reducing agent

K₄Fe(CN)₆ was used to improve the microstructure and properties of copper deposits obtained from hypophosphite baths. In electroless copper plating solutions using hypophosphite as the reducing agent, nickel ions (0.0038 M with Ni²⁺/Cu²⁺ mole ratio 0.12) was used to catalyze hypophosphite oxidation. However, the color of the copper deposits was dark or brown and its resistivity was much higher than that obtained in formaldehyde baths. The effects of K₄Fe(CN)₆ on the deposit composition, resistivity, structure, morphology and the electrochemical reactions of hypophosphite (oxidation) and cupric ion (reduction) have been investigated. The deposition rate and the resistivity of the copper deposits decreased significantly with the addition of K₄Fe(CN)₆ to the plating solution and the color of the deposits changed from dark-brown to copper-bright with improved uniformity. The nickel and phosphorus content in the deposits also decreased slightly with the use of K₄Fe(CN)₆. Smaller crystallite size and higher (111) plane orientation were obtained by addition of K₄Fe(CN)₆. The electrochemical current–voltage results show that K₄Fe(CN)₆ inhibited the catalytic oxidation of hypophosphite at active nickel sites and reduced the reduction reaction of cupric ions on the deposit surface by adsorption on the electrode. This results in lower deposition rate and a decrease in the mole ratio of NaH₂PO₂/CuSO₄ consumed during plating.     

Taurine as an additive for improving the fouling resistance of nanofiltration composite membranes

A hydrophilic compound, taurine, was investigated as an additive in the interfacial polymerization between piperazine (PIP) and trimesoyl chloride (TMC) to prepare thin‐film composite (TFC) membranes. The resulting membranes were characterized by X‐ray photoelectron spectroscopy and attenuated total reflectance–Fourier transform infrared spectroscopy. The morphology and hydrophilicity of the membranes were investigated through scanning electronic microscopy and water contact angle measurements. The separation performance of the TFC membranes was investigated through water flux and salt rejection tests. The protein‐fouling resistance of the films was evaluated by water recovery rate measurements after the treatment of bovine serum albumin. The membrane containing 0.2 wt % taurine showed the best performance of 92% MgSO₄ rejection at a flux of 31 L m^?2 h^?1 and better antifouling properties than the PIP–TMC membranes. An appropriately low concentration of taurine showed the same MgSO₄ rejection as the PIP–TMC membranes but a better fouling resistance performance. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41620.