Separation Of Sodium Chloride Research Articles

Beyond dumping: New strategies in the separation of preservative salt from tannery waste mixed salt and its reuse for tannery industrial application

The tannery effluent treatment plants produce tonnes of waste in the form of mixed salts containing sodium chloride, sulfate, calcium, and magnesium salts. Disposal of these mixed salts may create an environmental problem. The proposed method broadly consists of the separation of sodium chloride from reverse osmosis (RO) reject and raw-hide waste salt (preservative salt) of the tannery. This study used the physicochemical method to treat waste salt from tannery industrial waste. The addition of sodium hydroxide and sodium carbonate improved calcium and magnesium removal efficiency in the RO reject and preservative waste salts. The optimization of the sodium salt of hydroxide and carbonate is very important to remove an unwanted substance from waste salt. The sodium chloride was recovered, and the purity was about >98% which was successfully reused as preservative salt as well as in the pickling process in the tannery industry.

Isolation of Chloride Sodium from Concentrated Wastewater in Chemical Productions

The process of separation of sodium chloride from its aqueous solutions with concentrations of more than 14.65 wt % by adding acetone to the system was studied. The solubility equation of NaCl in the water–ac-etone–NaCl system was derived at acetone concentrations of more than 84.5 wt %. It was shown that the optimal mass ratio of acetone and the initial salt solution is (8–9): 1. In this case, more than 94% NaCl precipitates. A block diagram of the wastewater treatment process for chemical plants with a high NaCl content is presented.

Defect-free highly selective polyamide thin-film composite membranes for desalination and boron removal

Removal of boron from saline water sources has presented a major challenge for commercially available reverse osmosis desalination membranes. In this work, we report the boron and sodium chloride separation properties of truly defect-free, highly selective, interfacially polymerized aromatic polyamide thin-film composite membranes. The fabricated membranes show potential for separating sodium chloride with a maximum rejection of 99.6% obtained for the optimized film-forming protocol under lab-scale brackish water desalination conditions. This translated into promising boron rejection performance with rejections of up to 99% at pH 10, higher than a number of commercially available reverse osmosis membranes tested in-house. Comprehensive characterization including X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, ellipsometry, and surface charge measurements revealed intimate insights on interfacially polymerized polyamide membrane structure-property relationships. Increased membrane crosslinking was shown to be the primary determining factor for membrane permselectivity performance. Furthermore, relationships were established between microstructural properties such as crosslinking and morphological characteristics like surface roughness, highlighting an intricate and complex structure formation mechanism.

Studies on process development for the separation of sodium chloride from residue after evaporation of reverse osmosis reject solution

Abstract The membrane reject streams generated in industrial waste stream are evaporated in solar evaporation pan/multiple effect evaporator. The residue after evaporation (RAE) from reverse osmosis reject streams lacks reusable characteristics, due to a high contamination of inorganic and organic salts. In this investigation, a process was developed to separate sodium chloride from the RAE by selective ion precipitation using hydrogen chloride gas. The possible ways of hydrogen chloride gas was evaluated and used for the precipitation of sodium chloride. The optimized process parameters for the separation of sodium chloride were as follows: hydrogen chloride gas purging time, 3 min; pH, 8.0; temperature, 30 °C; concentration of RAE, 60% (w/v) and H/D ratio, 2.23 for the 100 mL working volume. The RAE and the recovered sodium chloride were characterised, for SEM, XRD and Cyclic voltametry to identify the structural and composition of the material. The results confirmed that the recovered salt is NaCl. The cost toward the disposal of this RAE was also analyzed against present process.

Separation of calcium and magnesium using dual precipitation/chelation scheme from saline solutions

A process scheme has been developed for the selective separation of calcium (Ca) and magnesium (Mg) from the Red Sea water and reverse osmosis (RO) brine using combined dual precipitation/chelation units. Two precipitation stages have been adopted for sequential Ca and Mg removal using sodium carbonate and sodium hydroxide, respectively. Calcium removal using sodium carbonate approached 96.6 and 93.2% for Red Sea (pH 9) and RO brine (pH 9.2), respectively. Maximum Mg removal efficiencies achieved using sodium hydroxide at pH 12 for both Red Sea and RO brine were 99.6 and 74%, respectively. The decalcified filtrate of the second precipitation stage was further processed for Mg removal using ethylene glycol bis(2-aminoethyl ether)-N,N,N′,N′-tetra acetic acid (EGTA), diethylenetriaminepentaacetic acid (DTPA), and N-(2-Hydroxyethyl) ethylene diamine-N,N,N′-triacetic acid (HEDTA) as selected chelating agents. Almost complete removal of Mg was achieved using the three tested chelating agents with maximum Mg adsorption capacity of 490 mg/g. The final rich monovalent effluents could be directed to thermal or membrane desalination plants or selective monovalent ion separation/salt recovery units. The purified streams after Ca and Mg removal could be utilized immediately for lithium, potassium, and sodium chloride separation.

Synthesis and Characterization of Ink (Carbon)-Perovskite/Polyaniline Ternary Composite Electrode for Sodium Chloride Separation

We reported the synthesis of ink-perovskite/Polyaniline composite electrode material for the separation of sodium chloride solution. These electrode materials are prepared by in situ polymerization process of aniline in the presence of perovskite ceramic material with carbon catalyst surface. This material is having the highest conductivity as a cathode material, environmentally benign and low cost material. The structure and morphological properties of prepared ternary composites are characterized by Fourier transform infrared, X-ray diffraction, SEM and TGA. The electrochemical properties are also investigated using four probe method and cyclic-voltametry method. Electrochemical measurement shows that the conductivity of ternary composites is 128 Scm-1. Resulting composites are promising cathode material for low power consuming electrolysis process of sodium chloride solution.

Separation of sodium chloride from the evaporated residue of the reverse osmosis reject generated in the leather industry – optimization by response surface methodology

Reverse osmosis (RO) concentrate is being evaporated by solar/thermal evaporators to meet zero liquid discharge standards. The resulted evaporated residue (ER) is contaminated with both organic and inorganic mixture of salts. The generation of ER is exceedingly huge in the leather industry, which is being collected and stored under the shelter to avoid groundwater contamination by the leachate. In the present investigation, a novel process for the separation of sodium chloride from ER was developed, to reduce the environmental impact on RO concentrate discharge. The sodium chloride was selectively separated by the reactive precipitation method using hydrogen chloride gas. The selected process variables were optimized for maximum yield of NaCl from the ER (optimum conditions were pH, 8.0; temperature, 35°C; concentration of ER, 600 g/L and HCl purging time, 3 min). The recovered NaCl purity was verified using a cyclic voltagramm.

Electrochemical treatment of evaporated residue of reverse osmosis concentrate generated from the leather industry

Proposed scheme for the separation of sodium chloride, calcium sulphate and removal of organic pollutants from ER.

Comparison of cellulose acetate (CA) membrane and novel CA membranes containing surface modifying macromolecules to remove pharmaceutical and personal care product micropollutants from drinking water

Abstract Pharmaceutical and personal care products (PPCPs) enter the environment mainly through municipal wastewater effluents, agricultural run-off, pharmaceutical and related chemical industry discharges. The present study was conducted to remove PPCPs through nano-filtration (NF) membranes prepared with two different tailor-made polymeric additives. The first is a novel charged surface modifying macromolecule (CSMM) additive synthesized by reactive diisocyanate and dihydroxy naphthalene disulfonate. The second additive was a tailor made hydrophi l ic SMM (LSMM), which was manufactured incorporating poly(ethylene glycol) as end groups. Cellulose acetate (CA) membranes with and without 3 wt% CSMM or LSMM were prepared by the phase inversion technique. The membranes were characterized by static contact angle, X-ray photoelectron spectroscopy, scanning electron microscopy with energy dispersive spectrometer, and atomic force microscopy. The NF filtration studies were conducted at two different operating pressures (150 and 400 psig). They consisted of pure water flux tests, sodium chloride separation tests, and individual PPCP (ppm level carbamazepine, ibuprofen, and sulfamethazine) separation tests. The long term NF performance for the removal of ibuprofen was also conducted. Significant effect of CSMM blending on the separation performance of ibuprofen for long hours operation was observed.

Effect of salt type on mass transfer in reverse osmosis thin film composite membranes

Reverse osmosis separation of inorganic salts in aqueous solutions has been studied using polyamide thin film composite membrane, in spiral wound configuration. Various inorganic salts involving monovalent and divalent ions have been studied. The solute transport through the membrane and the mass transfer coefficient at the high pressure feed side of the spiral wound module were determined for each type of salt. The mass transfer coefficient of each inorganic salt was predicted from the experimental data for the reverse osmosis separation of sodium chloride as reference and the mass transfer empirical correlations. The values obtained were compared with the experimental ones. The free energy parameters for monovalent cations, monovalent anions and divalent cations have been calculated. These parameters were used to predict the reverse osmosis performance of inorganic salts in spiral wound reverse osmosis module. It was observed that the free energy values of the cations are negative while those of the anions are positive, suggesting that the surface of the membrane used is positively charged.

Study of the structure and transport of asymmetric polyamide membranes for reverse osmosis using the electron spin resonance (ESR) method

The electron spin resonance technique (ESR) was used to study the structure and transport of asymmetric aromatic polyamide membranes. TEMPO (2,2,6,6-tetramethyl-1-piperridinyloxy free radical) was used as a spin probe that was brought into the membrane either by (a) immersion ofthe membranes in aqueous TEMPO solutions, (b) reverse osmosis (RO) experiments with feed solutions involving TEMPO or (c) blending TEMPO in casting solutions. The membranes were further tested for the separation of sodium chloride and TEMPO from water by RO. It was concluded that aromatic polyamide membranes contain water channels in the polymer matrix like cellulose acetate membranes. The presence of such water channels allows aromatic polyamide membranes to be used as RO membranes. The diffusion of organic solutes through the water channels seems much slower in aromatic polyamide membranes than in cellular acetate membranes, which probably causes a higher separation of organic solutes by aromatic polyamide membranes than cellulose acetate membranes. A comparison was made with other RO membranes (cellulose acetate, CA) and ultrafiltration membranes (polyethersulphone, PES). It was observed that the ESR technique can be used to study the structure of OF and RO membranes. The presence of water channels in the polymer matrix seems indispensable for the RO membrane.

The deduction of fine structural details of reverse osmosis hollow fiber membranes using surface force–pore flow model

In order to elucidate the relationship between the dope extrusion shear rate and membrane performance, sodium chloride transfer through the asymmetric cellulose acetate reverse osmosis hollow fiber membranes is modeled, allowing fine details of the fiber structure to be deduced from the NaCl-H2O rejection characteristics. The structural information such as the pore size radius and skin thickness of the active layer deduced from the sodium chloride separation experimental data and surface force-pore flow model (SF-PF) is then used to interpret the relationship between the rheological conditions during spinning and membrane performance. The modeling results revealed that increased extrusion shear rate would decrease both pore size and thickness of the active layer, thus increasing the separation performance of the RO hollow fiber membranes.

Dual-purpose chemical desalination process

The separation of sodium chloride from sabkha water was carried out using a chemical conversion approach. A sdium cation and chloride anion were converted into sodium bicarbonate, which is precipitated under experimental conditions, and ammonium chloride, which can be separated by crystallization, respectively. Concentrated brine solutions of 25% salt content were the feedstock used. In addition to partially desalted water, chemical products of economic potential values were produced, namely soda ash and ammonium chloride. Utilization of the brine exit from MSF desalination plants as feed stock is another alternative.

Treatment of saline wastewater for zero discharge at the Debiensko coal mines in Poland

The drainage water from mines in Poland has a daily contribution of, in the order of magnitude, 6,500 tons of chlorides and 0.5 ton of sulphates to the rivers Vistula (Wisla) and Oder (Odra). The largest amounts of these salts, about 78%, derive from 18 mines located mainly in the Katowice mine district. The high salt content in the water from the Vistula prevents at present its use in agriculture and causes tremendous economic losses due to corrosion attacks on pipes, machines, etc., within the industry. At present only about 4% of the river water can be classified as drinking water. To combat this problem a desalination project in Katowice has now almost been completed, including advanced treatment of wastewater for zero discharge from the two adjacent coal mines, Debiensko and Budryk. It implies elimination of 310 tons/d of salt discharge to the Odra River. The complete treatment processes are divided into three main sections: (1) pretreatment before reverse osmosis (RO) of about 12,400 m 3/d drainage water from the two mines with a salinity of around 16,000 mg/l TDS on the average; (2) RO plant including post-treatment of the RO permeate; (3) a thermal plant for concentration of brine (about 4,600 m 3/d) and separation of sodium chloride (NaCl) by crystallization, centrifuging and drying. The RO pretreatment includes algicide dosing in a storage tank, disinfection, flocculation/sedimentation and dual media filtration as well as granular activated carbon filtration. After a two-stage microfilter system (50 μ and 5 μ, respectively), the pretreated water is desalinated at 6–7 MPa in a RO system with spiral wound RO membranes. The RO permeate is decarbonated in a part-flow followed by addition of chemicals for disinfection and increase of the temporary hardness before distribution in the drinking water net. The flow into the thermal plant consists of the RO reject (about 2,700 m 3/d) with a salinity of around 80 g/l TDS and the brine flow (about 1,870 m 3/d) from the Budryk mine with about the same salinity. The first section of the thermal plant is composed of two brine concentrators, designed by Resources Conservation Company (RCC), USA. By using the seed crystal recycling technique it is possible to concentrate the feed to near the precipitation point for NaCl. The second section of the thermal plant includes one crystallizer for production of NaCl, two pusher centrifuges for salt removal from supersaturated brine and one fluidized bed dryer. The crystallizer is a forced circulation submerged-tube evaporator equipped with a mechanical vapor compressor. An additional section is also planned to be constructed for treatment of the purge from the crystallizer in order to recover other valuable chemical products and distillate. The process is fully automatic and controlled by programmable logic controllers. The plant has finally been designed by Energotechnika, Poland, after preparation of technical and economical planning of the project in coordination with Nordcap Ltd., RCC and VBB Viak-SWECO, Stockholm. In the summer 1994 the thermal plant was started up, and the RO plant is expected to be in operation during the spring 1995. The paper covers the project design with illustrations of the main parts of the plant and summarizes the results of the initial operation.

Preparation and testing of polyvinyl alcohol composite membranes for reverse osmosis

AbstractThin film composite membranes were prepared by coating porous polysulfone membranes with a polyvinyl alcohol layer and further cross‐linking its surface. The thin layer of cross‐linked polyvinyl alcohol served as a selective membrane. The membranes were prepared under various conditions and tested for sodium chloride separation. A high sodium chloride separation was achieved but the permeation rate was low compared with commercially available thin film composite membranes. Resistance against the flow of solvent water and sodium chloride solute were determined for individual component barrier layers.

Reverse Osmotic Separation of Sodium Chloride and Cobalt (II) Chloride through Membranes Prepared from Schiff Bases of Polyallylamine

Abstract Crosslinked membranes from Schiff base derivatives of polyallylamine were prepared with 2-pyridinecarboxaldehyde (P) and with P followed by salicyl-aldehyde, and used for the reverse osmotic separation between sodium chloride (NaC1) and cobalt (II) chloride (CoCl2). The membranes whose rejection (R) was high against CoCl2 and low against NaCl at each single feed supply showed a reduced difference in R in the case of a mixed solute feed due to Donnan exclusion by fixed charges in the CoCl2-complexed membrane. An approximate calculation of the complexed CoCl2 revealed that a very small portion of Schiff base groups took part in the complexation. Composite membranes on a cellulosic sheet solved the problem of an extreme reduction of the membrane strength after complexation, enabling continuous and repeated use. Some transport parameters were determined. Since they indicated a semipermeable character for CoCl2, multistage runs of a single membrane or low pressure runs of a more porous composite membr...

Kinetic Analysis off Ion-Exclusion Chromatography by the Moment Method

Abstract The separation of sodium chloride and alcohols by ion exclusion was studied by an pulse response technique. Kinetic parameters were evaluated by the moment method. The HETP was calculated and the contributions of each mass transfer process to the HETP were elucidated. Both axial dispersion and intraparticle diffusion were dominant for alcohols. Agreement between experimental and calculated elution curves is excellent.

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.

The performance of cyclic and steady-state electrodialysis separation processes in the presence of iron(II) fouling

The performance of a bench-scale cyclic electrodialysis process was compared to that of a conventional process under fouling conditions. The feed solution contained 2000 ppm sodium chloride and 0, 1, and 5 ppm ferrous chloride. Each run lasted for 20 hours and the amount of deposit and its effects on cell performance, including sodium chloride separation factor and pressure drop, were measured under a variety of operating conditions. Higher separation factors were obtained with the unsteady-state process and, unlike the conventional operation, the pressure drop did not increase during a run. However, inspection of the membrane surfaces exposed to the process fluid showed that deposition was not completely prevented by the periodic reversal of the current and flow direction. A small amount of deposit was also observed in the non-flow region between each membrane-pair, which could prove fatal to the cyclic process in the long run.

Calcium alkoxyalanates : II. Advances in the synthesis

Simple syntheses of calcium alkoxyalanates starting from NaAlH 4, CaCl 2 and alcohols involving evolution of hydrogen and separation of sodium chloride are reported. More complex methods, which allow the preparation of calcium alkoxyllalanates without loss of hydride hydrogen from NaAlH 4, CaCl 2, NaOR and AlX 3 (X = OR, Cl) have also been developed.