Reverse Osmosis Separation Research Articles

Transport analysis of reverse osmosis of organic aqueous solutions.

Reverse osmosis separations of alcohol aqueous solutions were performed over a wide range of feed concentrations up to 60 wt% using water-selective membranes. The validity of the nonequilibrium thermodynamics model by Spiegler and Kedem was confirmed theoretically and experimentally under the conditions of this study. The parameters of this model were found to have a large dependency on the feed alcohol concentration.

The effect of agitation on reverse osmosis desalination

Chemical and physical phenomena such as precipitation fouling and concentration polarisation are of notorious influence on the performance and lifetime of reverse osmosis (RO) membranes and other similar ones. In analogy to other mass transfer operations we have considered agitation as a means of improving the RO process and have designed a patented self-stirred module, suitable for plate-and-frame operation. The plate acts as a membrane support, and the space accorded by the frame serves as agitation chamber. A flat-blade turbine with appropriate baffles rotates with the liquid flow, its proper construction preventing damage to the membranes. No external access for any axis is required, thus avoiding complication of the set-up. The rotation speed of the turbine is a linear function of inlet flow. RO separation of water from dissolved salts with this self-stirred module has been investigated. Both brackish (1,000 ppm) and seawater (35,000 ppm) have been tested. The improved appearance of the surface, clean and free of fouling, reflected the marked improvement in fluxes, about 90% for brackish water and some 140% for seawater, when compared with unstirred operation. Also, with stirring, some increased salt rejection was noted. Clearly this improvement would apply to other similar membrane processes as well.

無機塩類水溶液の逆浸透分離実験における溶液透過係数および膜内拡散係数の操作条件による変化

無機塩類水溶液の逆浸透分離実験における溶液透過係数および膜内拡散係数の操作条件による変化

Studies on the enhancement of separation characteristics of sulfonated poly(phenylene oxide)/polysulfone thin film composite membranes for reverse osmosis applications. I. Effect of chemical treatment

AbstractThe effect of chemical treatment on the reverse osmosis (RO) separation characteristics of sulfonated poly(phenylene oxide) (SPPO) thin film composite membranes was investigated. The effects of the concentrations of aqueous solutions of formaldehyde, sulfuric acid, hydrochloric acid, phosphoric acid, sodium hydroxide, and treatment time on the RO separation characteristics of the composite membranes with ion exchange capacity (IEC) of 2.14 and 2.50 meq/g in various combinations are reported in detail. The results indicate some enhancement in RO separation characteristics of the SPPO/polysulfone (PS) composite membrane under the best conditions of the chemical treatment.

Studies on the enhancement of separation characteristics of sulfonated poly(phenylene oxide)/polysulfone thin film composite membranes for reverse osmosis applications. II. Effects of nitromethane and the chemical treatment combined with gamma‐ray irradiation

AbstractThe enhancement effect of the addition of nitromethane into the coating solution of sulfonated sodium poly(phenylene oxide) (SPPONa) polymer for the synthesis of sulfonated poly(phenylene oxide)/polysulfone (SPPO/PS) thin film composite membranes on reverse osmosis (RO) separation characteristic was studied. The effect of gamma‐ray irradiation on the SPPO/PS thin film composite membranes was also evaluated when the membrane samples were in the wet and dry conditions. The composite membranes were also subjected to a chemical treatment combined with gamma‐ray irradiation in both wet and dry conditions in the hope of obtaining the maximum possible enhancement under each treatment. However, the experimental data of this combined treatment indicated the possibility of some degradation of the SPPO/PS composite membranes.

Modeling reverse osmosis separations with strong solute‐membrane affinity at different temperatures using the finely porous model

AbstractThe reverse osmosis separation of toluene from water has been studied using an asymmetric cellulose acetate membrane at different temperatures, pressures, and feed concentrations. The finely porous transport model is used to describe the performance of the membrane as a function of the operating conditions. Based on experimental data, the transport parameters for the membrane are estimated. These parameters include the pore size of the membrane, the frictional parameter for the solute in the membrane pore, the relative porosity of the membrane surface, and the partition coefficients on the high and low pressure sides of the membrane. The influence of operating temperature on some of these parameters is presented and discussed. A modified form of the finely porous model which includes the effect of temperature is presented.

Styrene-grafted cellulose acetate reverse osmosis membrane for ethanol separation

Reverse osmosis separation of ethanol from the system ethanol-water by cellulose acetate and styrene-grafted cellulose acetate membranes at various operating conditions is discussed. Styrene was grafted onto the cellulose acetate chain by γ,-irradiation of a styrene-containing casting solution in the dose level range 0.25-3.0 Mrad and at styrene concentrations in the range 10-50% (on a cellulose acetate basis). Grafted membranes were found to be superior to ordinary cellulose acetate membranes in terms of chemical resistance and separation properties. Polystyrene content in the casting solution and γ-irradiation dose level both affected membrane properties. Operating pH affected both separation efficiency and flux whereas temperature did not significantly affect separation.

Surface Force-Pore Flow Model in Predicting Separation and Concentration of Polyhydric Alcohols in Aqueous Solutions Using Cellulose Acetate Membranes

Abstract The reverse osmosis separation and concentration of polyhydric alcohols were experimentally tested by using cellulose acetate membranes of different average pore sizes. An attempt was made to predict membrane performance data, such as the solute separation and the product permeation rate, on the basis of the surface force-pore flow model, and the results were tested by experimental values. The processing capacities of the membranes were also calculated.

Effects of polarity and steric hindrance on reverse osmosis separation of amino acids using an anion exchange membrane.

Effects of polarity and steric hindrance on reverse osmosis separation of amino acids using an anion exchange membrane.

Reverse Osmosis Separation of Solutions by Fine-Porous Membranes

Reverse Osmosis Separation of Solutions by Fine-Porous Membranes

Reverse osmosis separations of some organic and inorganic solutes in ethanol solutions with cellulose acetate membranes

Reverse osmosis separations of some organic and inorganic solutes in ethanol solutions with cellulose acetate membranes

Reverse Osmosis Separations of Aqueous NaCl–Organic Solute Systems

Abstract Some of alcohols, amides, aromatic hydrocarbons and surfactants were used as organic solute. Addition of NaCl increased the rejections of aromatic hydrocarbons and decreased the rejections of amides. It was also found that the permeability of NaCl was influenced by organic solutes.

Rejection of phenolic derivatives in aqueous solution by an interpolymer anionic composite reverse osmosis membrane

AbstractReverse osmosis separation for 23 phenollic derivatives was examined by an anionic charged composite membrane. The solute permeation was carried out in single‐solute aqueous solution (200 mg/L) under applied pressure of 3.92–7.85 MPa at 25°C. The correlation between the solute rejection and polar parameters for phenolic derivatives has been investigated. For p‐alkylphenols, the solute rejection increased with molecular weight and/or molecular branching. In undissociated state, the rejection of phenolic derivatives was closely related with the Taft's number and the Hammett's number of substituents. Also rejections of phenolic derivatives depended upon the pH value of feed soultion and the polar effect of substituted groups. For example, rejections of aminophenols showed the minimum value at a certain pH value and on either side of the minimum point, the rejection of aminophenol increased. From these facts, the main factors in reverse osmosis serparation by an anionic composite membrane were discussed.

Reverse Osmosis Separations of Some Inorganic Solutes in Ethanol Solutions Using Cellulose Acetate Membranes

Abstract Reverse osmosis separations of 20 inorganic solutes from ethanol solutions were studied by using porous cellulose acetate membranes. The experimental results were analyzed by basic transport equations developed by Kimura and Sourirajan. On the basis of the above analysis the free energy parameters of ions were calculated and compared with the values obtained from water and methanol solvent systems. The study confirms that the difference in the free energy parameters among univalent cations and univalent anions is widened in the solvent of a lower dielectric constant; such an enhanced difference is further reflected in the increase of the difference among inorganic solute separations from the solvent of a lower dielectric constant. Consequently, fractionation of inorganic solutes can be performed more easily in ethanol solvent than in water and in methanol solvent.

Interfacial parameters governing reverse osmosis for different polymer material—solution systems through gas and liquid chromatography data

In this paper interfacial properties governing reverse osmosis separations were studied by using gas and liquid chromatography data with respect to four cellulosic and two aromatic polyamide membrane materials. The data on interfacial water layer thickness obtained from gas chromatography were used together with equilibrium distribution constants obtained from liquid chromatography and reverse osmosis separation data to calculate the force constants associated with the electrostatic repulsion working on ionic solutes. The force constants were further used to calculate the average pore sizes (diameters) required for achieving 99.9% separation of sodium chloride by membranes made of the different materials studied. The theories and calculation procedures involved are illustrated.

Effect of Polymer Membrane Material on Reverse Osmosis Separations of Free Radicals in Aqueous Solutions

Abstract The reverse osmosis separations of four different piperidinooxy free radicals, one undissociated piperidine solute, and one dissociated hydrochloride solute of similar molecular structure were studied by using cellulose acetate (CA-398) and aromatic polyamidohydrazide (PPPH 8273) membranes of different surface porosities under different operating pressures. Liquid chromatography experiments were conducted parallel to the reverse osmosis experiments, and the order of the preferential sorption among solute compounds and solvent water was found to be, ionic solutes < D2O < radical solutes < nonionized solute in the case of cellulose acetate material, and ionic solutes < radical solutes < D2O < nonionized solute in the case of aromatic polyamidohydrazide, with the one exception of the piperidinooxy free radical containing an amino group which was slightly more strongly adsorbed to the latter polymeric material than D2O. The above order of preferential adsorption is reflected in the reverse osmosis se...

Reverse osmosis separations of some organic and inorganic solutes in methanol solutions using cellulose acetate membranes

Les resultats experimentaux de chromatographie liquide permettent d'avoir des donnees pour la retention de volume. Ces donnees ajoutees a celles de la separation par osmose inverse permettent de determiner les constantes de forces d'interaction interfaciale (forces steriques, de van der Waals, et electrostatiques). Ces constantes permettent de predire la performance de la membrane de meme que le diametre des pores a la surface de la membrane. Comparaison de la meme osmose inverse mais en presence de methanol ou d'eau. La performance de la membrane est etroitement liee aux caracteristiques de sorption des solutes dans differents environnements de solvant

Effect of membrane materials and average pore sizes on reverse osmosis separation of dyes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of membrane materials and average pore sizes on reverse osmosis separation of dyesLiu Tinghui, Takeshi Matsuura, and S. SourirajanCite this: Ind. Eng. Chem. Prod. Res. Dev. 1983, 22, 1, 77–85Publication Date (Print):March 1, 1983Publication History Published online1 May 2002Published inissue 1 March 1983https://doi.org/10.1021/i300009a018RIGHTS & PERMISSIONSArticle Views152Altmetric-Citations21LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-Alerts

Reverse Osmosis Separations of Free Radicals in Aqueous Solutions

Abstract The reverse osmosis separations of two piperidinooxy radicals from aqueous solutions were studied at operating pressures of 1724 to 6895 kPag. Both radicals are stable during the reverse osmosis experiment and positively separated by using cellulose acetate membranes. The liquid chromatography data indicates that piperidinooxy radicals are weakly adsorbed to cellulose acetate polymer, while their electrolyte analogues are rejected, and undissociated piperidine solute (also a structural analogue of the radicals) is strongly adsorbed.

Short cut design methods for reverse osmosis separation with tubular modules

The basis for obtaining explicit flux expressions in reverse osmosis separations with concentration polarization has been illustrated for tubular modules with turbulent flow. Various analytical equations developed thereby to predict the required number of tubes and the permeate solute concentrations are described and compared with one another as well as with the currently used numerical methods. The utility of such simple design procedures are pointed out. The possibilities and difficulties of adopting these procedures for designing spiral-wound modules have been discussed. The analytical equations can be adopted to “tapered-flow” reverse osmosis without much difficulty.