Reverse Osmosis Separation Research Articles

Vapor Phase Infiltration of Metal Oxides into Nanoporous Polymers for Organic Solvent Separation Membranes

Membrane-based organic solvent separations promise a low-energy alternative to traditional thermal separations but require materials that operate reliably in chemically aggressive environments. While inorganic membranes can withstand demanding conditions, they are costly and difficult to scale. Polymeric membranes, such as polymer of intrinsic microporosity 1 (PIM-1), are easily manufactured into forms consistent with large-scale separations (e.g., hollow fibers) but perform poorly in aggressive solvents. Here, a new postfabrication membrane modification technique, vapor phase infiltration (VPI), is reported that infuses PIM-1 with inorganic constituents to improve stability while maintaining the polymer’s macroscale form and nanoporous internal structure. The atomic-scale metal oxide networks within these hybrid membranes protect PIM-1 from swelling or dissolving in solvents. This stability translates to improved separation performance in a variety of solvents, including solvents capable of dissolving PIM-1. The infiltrated inorganic phase also appears to give new control over solute sorption in organic solvent nanofiltration (OSN). These hybrid membranes further show promising performance for organic solvent reverse osmosis (OSRO) separations in challenging solvents, even at small-molecular-weight differentials (14 Da). Because the VPI process can be integrated with state-of-the-art membrane modules, this treatment could be readily adopted into the large-scale manufacturing of advanced membranes.

Study and Method of Calculating the Efficiency of Roll-Type Devices, Taking Into Account the Hydrodynamics of Flow

Hydrodynamics of flow of a solution in a membrane channel were investigated and a criterion equation was obtained to determine the structural coefficients of flow. A method was developed that takes into account the hydrodynamics of flow, which allows to determine the technological parameters of the membrane installation. A quantitative calculation was performed to determine the working area, the number of elements, pressure losses and pump head for roll-type elements ERO-e-6.5/900А and ERO-K-92-475 in reverse osmosis separation of different industrial solutions.

Reverse osmosis separation of particular organic solvent mixtures by a perfluorodioxole copolymer membrane

Reverse osmosis (RO) separation of organic solvent mixtures where solvent molecular weights are < 100 Da is challenging especially for powerful solvents that swell most uncrosslinked polymers. To avoid polymer swelling by solvents, a particular perfluoropolymer, perfluoro-2,2-dimethyl-1,3-dioxole copolymerized with tetrafluoroethylene, (PDD-TFE), designated CMS-7, was studied. This amorphous glassy extremely hydrophobic copolymer has a very high free volume (FV) fraction. The maximum dimension of FV regions is less than ~ 0.65 nm allowing only single solvent molecule permeation. Further, interactions between polarity, dimensions and shapes of solvent molecules with those of polymer FV elements can lead to extraordinarily selective permeation. RO separation of the following binary systems through a thin 1.67 µm film of this polymer supported on an e-PTFE support was studied over 1000–3500 kPa feed pressure: N-Methyl-2-pyrrolidone (NMP)-toluene; dimethylformamide (DMF)-toluene; dimethylsulfoxide (DMSO)-toluene; NMP-methanol; n-butanol-ethanol. Pure toluene appeared as permeate for three polar aprotic-aromatic systems from highly toluene-rich feeds; the membrane rejected polar molecules having dimensions similar to those of toluene. High osmotic pressure of the feed mixtures employed vis-à-vis feed pressures used reduced toluene permeation flux and the range of separable feed mixtures. Pure methanol permeate was obtained from particular polar aprotic-polar protic NMP-methanol mixtures due to significantly smaller methanol dimensions. Pure ethanol permeate was also similarly obtained from a particular mixture with n-butanol, a case of polar protic1-polar protic2 system where ethanol molecules were smaller. Such novel and clean-cut pressure-driven separations may be due to various combinations of the dimensions of the solvent molecules and the polymer FV regions, high polymer hydrophobicity, polarity of the aprotic/protic solvents and very low swelling of the polymer. Solvent sorption studies of dense polymers provide an insight into swelling of the polymer by the solvent and potential solvent-specific interactions. Sorption studies using 25 µm polymer samples for polar aprotic solvents, NMP, DMF, DMSO, yielded very low levels of sorption, 0.4–0.9 wt%; those for toluene and methanol were already known to be only 1.34 and 1.2 wt% respectively. Permeation behaviors of other solvent mixtures, toluene-n-heptane, NMP-tetrahydrofuran, methanol-water, ethanol-water as well as individual phases of the immiscible mixture of NMP and the nonpolar solvent n-heptane were also studied. To improve understanding, permeation of pure water in reverse osmosis mode was also investigated.

Polyamide–surfactant interaction: Exploration of new avenues for reverse osmosis separation applications

AbstractThin‐film composite (TFC) RO membrane has got widespread acceptability for desalination and water reuse applications. A novel approach toward modification of surface of TFC RO membrane using surfactant (anionic, cationic, and nonionic) has been presented. Anionic surfactant, sodium dodecyl sulfate, increased the water flux of TFC RO membrane up to 142% when TFC RO membrane was exposed to sodium hypochlorite solution of 2,000 mg/L for 2 hr followed by sodium dodecyl sulfate for 1 hr at pH 11. However, surface modification by cationic surfactant, that is, cetrimonium bromide resulted in decreased water flux. Boron rejection decreased to 87.31% when cetrimonium bromide of 500 mg/L was exposed after 2,000 mg/L sodium hypochlorite at pH 11 because of positive charge on the membrane surface. Nonionic surfactant Triton X‐100 exposure lower than critical micelle concentration, that is, 100 mg/L for 1 hr after sodium hypochlorite exposure of 2,000 mg/L for 2 hr, resulted in increased water flux of about 22%, however, on increasing surfactant concentration more than critical micelle concentration, that is, 4% with the same sodium hypochlorite pre‐exposure, resulted in 47.5% decline in water flux. Thus, surfactant can bind the top barrier layer of polyamide membrane to alter its performance.

Methods for recovery and re-use of additive chemicals during CO2 mineralisation

This paper presents options for the recovery and recirculation of ammonium sulphate (AS) and/or ammonium bisulphate (ABS) additive in a process for mineral carbonation referred to as the ÅA route. The process uses magnesium silicate rock (serpentinite) reacting with AS and/or ABS in order to extract magnesium which subsequently will be carbonated. A challenge still is to find ways to recover the chemicals in an efficient way and this paper addresses options for this. The concepts and possible implementation for reverse osmosis separation, precipitation by the addition of alcohol, multiple-step extraction and ion selective membranes/ion exchange resins are presented. It was shown that reverse osmosis membranes will need high pressures in order to achieve sufficient separation. Addition of alcohol (ethanol) will make it possible to precipitate AS, magnesium and iron sulphates. This enables some separation of AS from ABS since ABS remains dissolved in the solution, but subsequent separation and recovery of ethanol from water is in turn required. Multiple-step extraction was tested with a procedure containing both thermal and wet extraction. It was shown, however, that precipitation of some species resulted rather than extraction, which has to be further investigated. The multiple-step extraction procedure included different ratios of rock: AS and/or ABS; it was shown that AS plays an important role in the thermal extraction even if ABS is a more aggressive chemical. The option to apply ion selective membranes for the recovery of ABS is part of ongoing work: first results are promising, as presented here.

Highly improved reverse osmosis performance of novel PVA/DGEBA cross-linked membranes by incorporation of Pluronic F-127 and MWCNTs for water desalination

A novel Poly (vinyl alcohol) (PVA) reverse osmosis (RO) membrane with unique performance and characteristics was synthesized for water desalination. PVA thin film nanocomposite (TFN) membranes were fabricated by the infusion of Pluronic F-127 and multi-wall carbon nano-tubes (MWCNTs) in a single layer crosslinked by bisphenol A diglycidyl ether (DGEBA). The overall RO performance of the membranes including hydrophilicity, surface roughness, water permeability, salt rejection, chlorine resistance and biofouling resistance was evaluated using a dead end RO filtration unit. The incorporation of Pluronic F-127 and MWCNTs improved the overall RO performance of the membranes. It was found that the modified membranes surface became smoother and highly hydrophilic compared to the pristine PVA membranes surfaces. This study indicated that the membranes that contain 0.08 and 0.1wt% MWCNTs provided excellent permeation, salt rejection, Chlorine and biofouling resistance and mechanical strength. The most striking result to emerge from this study is that the overall RO performance enhancement has transpired while utilizing PVA as an active RO separation layer without a polymeric or ceramic substrate. This study shows that proper crosslinking of PVA coupled with mechanical strength enhancement overcomes the common PVA drawbacks, mainly swelling and rupture under very high pressure.

A Study on Kinetic Characteristics of Reverse Osmosis Separation of Wastewater Containing Heavy Metals Ions

A Study on Kinetic Characteristics of Reverse Osmosis Separation of Wastewater Containing Heavy Metals Ions

Nuclide separation modeling through reverse osmosis membranes in radioactive liquid waste

The aim of this work is to investigate the transport mechanism of radioactive nuclides through the reverse osmosis (RO) membrane and to estimate its effectiveness for nuclide separation from radioactive liquid waste. An analytical model is developed to simulate the RO separation, and a series of experiments are set up to confirm its estimated separation behavior. The model is based on the extended NernstePlank equation, which handles the convective flux, diffusive flux, and electromigration flux under electroneutrality and zero electric current conditions. The distribution coefficient which arises due to ion interactions with the membrane material and the electric potential jump at the membrane interface are included as boundary conditions in solving the equation. A high Peclet approximation is adopted to simplify the calculation, but the effect of concentration polarization is included for a more accurate prediction of separation. Cobalt and cesium are specifically selected for the experiments in order to check the separation mechanism from liquid waste composed of various radioactive nuclides and nonradioactive substances, and the results are compared with the estimated cobalt and cesium rejections of the RO membrane using the model. Experimental and calculated results are shown to be in excellent agreement. The proposed model will be very useful for the prediction of separation behavior of various radioactive nuclides by the RO membrane.

РАЗРАБОТКА ВИРТУАЛЬНОГО ТРЕНАЖЕРА ЭКСПЕРИМЕНТАЛЬНОГО ИССЛЕДОВАНИЯ ОБРАТНООСМОТИЧЕСКОГО РАЗДЕЛЕНИЯ ПРОМЫШЛЕННЫХ СТОЧНЫХ ВОД

РАЗРАБОТКА ВИРТУАЛЬНОГО ТРЕНАЖЕРА ЭКСПЕРИМЕНТАЛЬНОГО ИССЛЕДОВАНИЯ ОБРАТНООСМОТИЧЕСКОГО РАЗДЕЛЕНИЯ ПРОМЫШЛЕННЫХ СТОЧНЫХ ВОД

Feasibility of Combining Reverse Osmosis–Ferrite Process for Reclamation of Metal Plating Wastewater and Recovery of Heavy Metals

The feasibility of reverse osmosis (RO) separation combined with ferrite reaction was investigated for the reclamation and recovery of heavy metals from metal plating wastewater. Disc tube-type RO modules were used for simultaneous purification and concentration of wastewaters containing zinc and chromium ions. A subsequent ferrite reaction was performed to recover zinc ions from RO concentrates. The operating conditions of the RO and ferrite reaction were determined in several lab-scale experiments with several types of model wastewater. Pilot-scale RO test results revealed that the zinc plating wastewater treated by one-pass RO and the chrome plating wastewater treated by two-pass RO were acceptable for preplating rinsewater. After ferrite reaction, 99.7% of zinc ions were recovered from the second-stage RO concentrate in the form of zinc ferrite, while significant amounts of chromium ions were retained in the concentrate. As a result of economic analysis, we suggested a retrofitting option, including a...

Depth profiling of the free-volume holes in cellulose triacetate hollow-fiber membranes for reverse osmosis by means of variable-energy positron annihilation lifetime spectroscopy

Two types of commercial cellulose triacetate hollow-fiber membranes with different water fluxes, apposite for a reverse osmosis separation process, were investigated by means of positron annihilation lifetime spectroscopy with a 22Na-radioisotope-based energy-tunable positron beam, in order to elucidate a depth profile of the free-volume hole size in a subnanoscopic viewpoint. The lifetimes of ortho-positronium (o-Ps), the triplet positron-electron pair, for the two membranes were measured as a function of positron incident energy E. The E dependence of the hole size, quantified from the o-Ps lifetime, indicated that the separation-active dense layers with the smallest hole sizes are located at the near-surface region for both the membranes. The ratio of the dense-layer thicknesses for the two membranes was estimated to be more than 50% of the ratio of the respective effective thicknesses calculated from the water flux based on Darcy's law. The result signified that the dense layer with the smallest hole size at the near-surface region considerably contributes to the difference in the water flux.

유·무기계 역삼투 복합막의 제조와 해양심층수의 기능화 특성분석

In this study, a microfilter medium was prepared using a melt-blown system and used as a pre-filter in a reverse osmosis (RO) separation system. Asymmetric RO composite membranes, which are inorganic/organic-reverse osmosis (IPO-RO) membranes composed of polysulfone and polyamide with tourmaline nanoparticles, have been designed to develop a new desalination membrane showing high selectivity and permeability. The practical separation performance of IPO-RO composite membranes was investigated for the desalination of seawater, especially for deep ocean water. The separation characteristics of IPO-RO composite membranes were discussed by changing some parameters such as applied pressure and temperature. The permeation flux of the IPO-RO composite membranes was investigated using a module composed of RO plate-frame and spiral wound units. The solute rejection and flux for the IPO-RO composite membrane were 99.0-99.4% and 7.4-23.3 <TEX>$L/m^2{\cdot}h$</TEX> in deep ocean water at <TEX>$20^{\circ}C$</TEX>, respectively. Further, the separation performance of the IPO-RO composite membrane for deep ocean water was very steady-state for a long time. Remarkably, the solution permeated through the IPO-RO composite membrane matched drinking water standards.

Effects of acyl chloride monomer functionality on the properties of polyamide reverse osmosis (RO) membrane

In this work, three novel polyacyl chloride monomers: 2,4,4′,6-biphenyl tetraacyl chloride (BTAC), 2,3′,4,5′,6-biphenyl pentaacyl chloride (BPAC) and 2,2′,4,4′,6,6′-biphenyl hexaacyl chloride (BHAC) have been successfully synthesized. For the purpose of investigating the effects of the polyacyl chloride functionality on the reverse osmosis (RO) membrane properties, the thin film composite (TFC) RO membranes were prepared through interfacial polymerization of trimesoyl chloride (TMC), BTAC, BPAC, and BHAC with m-phenylenediamine (MPDA) respectively. The membrane properties including physicochemical properties and separation performances were evaluated by a combination of attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle (CA), streaming potential measurements as well as cross-flow reverse osmosis tests. The results reveal that the functionality of the acid chloride monomer strongly influences the properties of the RO membrane. As the functionality of the acid chloride monomer increased, the resulting membrane skin layer became more negatively charged, thinner and smoother. However, the change of hydrophilicity did not seem to follow any rule or trend, which could be ascribed to the cooperative effects of surface roughness and the carboxylic acid group content. In addition, all the four membranes exhibited close salt rejection rates according to the RO separation performance tests. However, with the increase of acid chloride functionality the permeate flux of the resulting RO membrane became lower, due to a combination of the increase in the carboxylic acid groups on the membrane surface, lower surface roughness, and lower mobility of the crosslinked polyamide chains.

Parametric Effects of the Performance of Nanofiltration Membrane

The effects of pressure, concentration and feed temperature using a high pressure membrane filtration test rig capable of handling nanofiltration and reverse osmosis separation was investigated. The experimental results indicated that the applied pressure across the membrane has a significant positive influence on the flux produced and increasing the pressure will rupture the membrane if excessive force or pressure is applied. The high concentrations of solutes/molecules inhibit the flow of fluid through the membrane consequently lower fluxes and improved separation is and subsequently all variables, including their interactions, examined was found to be significant.

The Comprehensive Test for Geothermal Tail-Water Disposal

Geothermal reservoirs and groundwater resources in layered porous media in large sedimentary basins have enormous exploitation potential because of their extensive distribution, great quantity, and feasible temperatures and drilling depths. The discharge of geothermal wastewater (i.e. tail-water) on the surface is a serious environmental issue because of its high salinity content, so the Bureau of Geology Exploration and Mineral Resources Exploitation in Shandong Province, China called for the study of the disposal technique of the geothermal tail-water. The disposal test process is as follows: take the waste of geothermal water to make physics-chemistry preparative disposal; filtration with manganese-sand set and/or double-medium equipment; filtration with ion exchange resins; nanofiltration membrane separation; and reverse osmosis separation. After separation, the cheap, clean water can be used as a material for chemical plants. However, in the case of deeply embedded geothermal groundwater resources, connate water(buried water), or bad recharge conditions, must be dried up for a long time exploitation, causing ground depression. Therefore, it is concluded that systems utilizing reinjection, i.e. closed-circuit cycle mode injection, in sandstone reservoirs are ideal for the realization of sustainable exploitation of the geothermal groundwater resources with favorable environmental conditions on the surface.

Miscibility and interfacial property studies of the blends of ethyl cellulose with copolyamide6/66/1010

Interfacial properties governing reverse osmosis separations were studied by using liquid chromatography data with respect to ethyl cellulose/copolyamide6/66/1010 (EC/PA-130) blends. The miscibility of ethyl cellulose/copolyamide6/66/1010 (EC/PA-130) blends was investigated by using differential scanning calorimetry (DSC) and Fourier transform infrared, while the interfacial properties of the blends, including the interfacial adsorption, hydrophobicity, polar and non-polar parameters and β-parameters, were studied by using liquid chromatography. The results show that EC and PA-130 are miscible at compositions of (80/20), (70/30) and (50/50). The hydrophobicity of EC/PA-130 increases with the of PA-130 content. The EC/PA-130(70/30) is superior to the other blends for separating non-dissociable polar organic solute and is more suitable for use as desalting membrane material. It seems that liquid chromatography is an effective tool for studying the interfacial properties of polymer blend materials and selecting high performance of membrane materials.

A solar-powered reverse osmosis system for high recovery of freshwater from saline groundwater

Desalination of groundwater is essential in arid regions that are remote from both seawater and freshwater resources. Desirable features of a groundwater desalination system include a high recovery ratio, operation from a sustainable energy source such as solar, and high water output per unit of energy and land. Here we propose a new system that uses a solar-Rankine cycle to drive reverse osmosis (RO). The working fluid such as steam is expanded against a power piston that actuates a pump piston which in turn pressurises the saline water thus passing it through RO membranes. A reciprocating crank mechanism is used to equalise the forces between the two pistons. The choice of batch mode in preference to continuous flow permits maximum energy recovery and minimal concentration polarisation in the vicinity of the RO membrane. This study analyses the sizing and efficiency of the crank mechanism, quantifies energy losses in the RO separation and predicts the overall performance. For example, a system using a field of linear Fresnel collectors occupying 1000m2 of land and raising steam at 200°C and 15.5bar could desalinate 350m3/day from saline water containing 5000ppm of sodium chloride with a recovery ratio of 0.7.

Removal of fluorions from trifluoroacetic acid by reverse osmosis

The separation characteristics of fluorions and trifluoroacetic acid (TFA) by reverse osmosis (RO) were investigated in detail. Separation results revealed that the fluorion rejection depended strongly on pH of the feed solution. The fluorion rejection could be very low by adjusting pH of the feed solution to acidic condition. Under operating pressure of 2.5 MPa, the fluorion rejection decreased sharply from 96% to 17.71% with the feed pH decreased from 6.7 to 2.75. Experimental results illustrated that RO separation can effectively remove fluorions from TFA solutions. Multi-stage RO separation can decrease the fluorion concentration to desirable level. Therefore, RO separation is an efficient and alternative method to remove fluorions from waste effluents or other fluorine compounds.

Turn the World Green Project

In the video the Chairman of The KIN Consortium discusses and economic indicator called HOME STARTS. Said indicator has been highlighted by the media and certain analysts as an indicator of economic growth. The Chairman clearly states in his video that new homes that are built out of trees are the source of Warming. For the pundits in the media to be consistent in their pursuit of saving the planet they should be focussed on NEW HOMES BUILT FROM CEMENT as the indicator of economic growth.The Chairman of the Board of the KIN Consulting & Research Services, has decided to publish some of his solutions for the Issues. His solution is simply to turn the world green. We must follow up an initiative started up by The Kingdom of Saudi Arabia, that involves turning salt water into drinking water. The Chairman is promoting these ideas in an effort to enhance competition in the production of the latest technology called, Osmosis.Lets end famine in the Third World by saving the planet with food, water, and clean air. The plan is to use the Global Warming enthusiasts as a lead in. For example, when they whine about the weather or the polar ice caps. Mention that Chairman Natto believes that his Turn the World Project will have fantastic repercussion's in terms of its Economic impact, Environmental Impact, & Humanitarian Impact:I. Investment Perspective (An investor can potentially profit from at least three angles):A. Invest in more desalination companies and techniques (Reverse Osmosis Technique).B. Invest in the desert lands of Mexico, Tijuana, North Africa, Mid East, Australia, New Mexico,Nevada, Arizona, China, etc.C. Agricultural sales for Import and Export.II. Potential Investors:A. Everybody who owns land at the beach.B. Everybody who thinks its too hot!C. Everybody who lives in a desert region and wants to turn it green.D. World Bank and other financial institutions.III. Investment in Equipt:A. Desalination equipt.B. Sea water sourceC. LandD. FertilizerE. Electricity sourcei. Fuel Generatorsii. Electricity CompaniesIV. What seeds to plant?A. Fruits and vegetables that can be sold to friendly markets.V. How do the investors recoup there investment?A. The land will be used for agricultural purposesB. They sell the fruits and vegetables to pay back the loan.VI. Fore casted Economic impact of the Turn the World Green Project:An increase in Fruits and Vegetables coming to market, should bring about a deflationary impact on the economy. Thus reversing any inflationary costs that arose due to fuel costs.VII. The Environmental Impact:The Environmental Impact would naturally be a cooling effect. As the deserts turn green, the carbon-dioxide will turn into Oxygen.VIII. Humanitarian Impact:End famine in the Third World by saving the planet with food, water, and clean air.Here is the Process for the State of the Art Solution called Reverse Osmosis:Reverse Osmosis (RO)separation technology is used to remove dissolved impurities from water through the use of a semi-permeable membrane. RO involves the reversal of flow through a membrane from a high salinity, or concentrated, solution to the high purity, or permeate, stream on the opposite side of the membrane. Pressure is used as the driving force for the separation. The applied pressure (P) must be in excess of the osmotic pressure of the dissolved contaminants to allow flow across the membrane.Meeting desalination needs in water-scarce regions:Customers in water-scarce regions find that the Seawater Reverse Osmosis (SWRO) Technology solves their need for desalination while optimizing operating costs. The SWRO Series covers a range of customer applications, including:* Boiler feed water make-up* Irrigation water* Plant process make-up water* Small community potable water demandI strongly encourage you to search Google under the following search parameters for the VIDEO and Website:Global warming solutions The KIN ConsortiumIf you need the configuration for the hardware or software please contact Chairman Natto for further information.

Treatment of Chemical Mechanical Polishing Wastewater for Water Reuse by Ultrafiltration and Reverse Osmosis Separation

This paper describes the treatment of chemical mechanical polishing (CMP) wastewater from a semiconductor plant through membrane-based ultrafiltration (UF) and reverse osmosis (RO) processes to improve the removal efficiency under different water recovery and to determine the possible mechanisms of membrane blocking and rejection. UF pretreatment led to 42.1–46.9% conductivity, 98.1–99.4% turbidity, and 4.5–24.5% total organic carbon (TOC) removal. These contaminants were almost completely rejected after performing subsequent RO processing: the values of the conductivity, turbidity, and TOC were reduced to 6 μS/cm, 0.01 NTU, and 1.6 mg/L, respectively. The water quality of the permeates after UF or RO membrane filtration could meet the water reuse standards for tap water, cooling water, boiler water, and the feed for a water purification machine. The variation with time of the permeate flux for the UF process was fitted to the Hermia model to examine the possible blocking mechanisms during the filtration ...