Separation Of Monovalent Ions Research Articles

Physical and chemical synergistic strategy: A facile approach to fabricate monovalent ion permselective membranes

Separation of monovalent ions is essential for chemical engineering industries, such as metallurgy, bio-refining, and waste recovery. As a critical consideration of separation, constructing functional layer on the membrane surface to fabricate “special grade” ion exchange membrane (monovalent permselective membrane, MVS) is an effective strategy for monovalent ions sieving via electrostatic repulsion mechanism. Here in this study, we proposed an electrical deposition (physical-assembly) and in-situ chemical reaction (nucleophilic substitution) synergized approach to fabricate MVS. By using commercial AMX membrane as the substrate, polydopamine assisted co-deposition of chitosan was pre-performed on pristine membrane, and then the reactive blue 4 was selected and electrically deposited. The synergistic approach strengthened the ion sieving through counter-charged layer, while the chemical reaction provide long-term stability. The resultant membrane displayed Cl− permselectivity up to 11.85 without significant sacrificing of ion-flux. And this membrane can keep appropriate stability after operating the electrodialysis process for ten cycles.

Electrically Driven Molecule Transport within a Series of Ionomers and Improvement of Electrodialysis Process

Electrodialysis (ED) is a separation technique for ionic solutions through an electrochemical membrane that has been used in industry for several decades. ED process can significantly change the features of conventional processes and have great advantage in the recovery of resources, the control of pollutants, and the chemical processing because of the simple process, high efficiency, and low disposal of wastes. It can be used in the separation and concentration of salts, acids and bases from aqueous solutions, the separation of monovalent ions from multivalent ions and the separation of ionic compounds from uncharged molecules. It can be used for either electrolyte reduction in feed streams or recovery of ions from dilute streams. Industrial applications encompass several industries and include the desalination, amino acids from protein hydrolysates, salts, acids, and alkali from industrial rinse waters, fruit juice deacidification, sugar and molasses desalting and blood plasma protein recovery. In our study, we analyze the process of ion flow through the anion exchange membrane, AEM (PC-SA) and cation exchange membrane, CEM (PC-SK) (provided by PCCell Corp.) and poly[t-butyl styrene-b-hydrogenated isoprene-b-sulfonated styrene-b-hydrogenated isoprene- b-t-butyl styrene) (tBS-HI-S-HI-tBS), Penta Block Copolymer, (PBC)(provided by Kraton Polymers LLC, Houston, TX and used to replace PC-SA). Comparing the power consumption of commercial polymers and PBC, it is significantly accepted that PBC is a kind of novel, low energy consuming, and less time requiring ionomer in the process of ED with great chemical and physical properties.

Electrically Driven Molecule Transport within Penta Block Copolymer and Improvement of Electrodialysis Process

Electrodialysis (ED) is a separation technique for ionic solutions through an electrochemical membrane that has been used in industry for several decades. ED process can significantly change the features of conventional processes and have great advantage in the recovery of resources, the control of pollutants, and the chemical processing because of the simple process, high efficiency, and low disposal of wastes. It can be used in the separation and concentration of salts, acids and bases from aqueous solutions, the separation of monovalent ions from multivalent ions and the separation of ionic compounds from uncharged molecules. It can be used for either electrolyte reduction in feed streams or recovery of ions from dilute streams. Industrial applications encompass several industries and include the desalination, amino acids from protein hydrolysates, salts, acids, and alkali from industrial rinse waters, fruit juice deacidification, sugar and molasses desalting and blood plasma protein recovery. In our study, we analyze the process of ion flow through the anion exchange membrane, AEM (PC-SA) and cation exchange membrane, CEM (PC-SK) (provided by PCCell Corp.) and poly[t-butyl styrene-b-hydrogenated isoprene-b-sulfonated styrene-b-hydrogenated isoprene- b-t-butyl styrene) (tBS-HI-S-HI-tBS), Penta Block Copolymer, (PBC) as shown in Fig. 1 (provided by Kraton Polymers LLC, Houston, TX and used to replace PC-SA). Comparing the power consumption of commercial polymers and PBC, it is significantly accepted that PBC is a kind of novel, low energy consuming, and less time requiring ionomer in the process of ED with great chemical and physical properties.

Wastewater treatment and water reuse of food processing industries. Part II: Techno-economic study of a membrane separation technique

To reuse pretreated water effluent of the El-Nile Company for the food industry in Egypt, NF and RO membrane separation techniques were investigated. Two sets of experiments were carried out by using laboratory separation unit with maximum pressure of 7 bars and pilot plant membrane separation unit with maximum pressure of 14 bars. Based on the analyses of collected samples, a hydration model was used to determine the combined salts in the wastewater. The combined salts were used in the preparation of a synthetic solution simulated to the wastewater of El Nile Company. The experiments were divided into two parts: the first part was concerned with the application of membrane separation experiments to synthetic solutions and the second part was concerned with the pretreatment and membrane separation experiments of the industrial wastewater. The first part was carried out by using NF followed by RO membrane separation technology. Best performance for NF process is observed in separation of divalent ions and the less in separation of monovalent ions, NF membrane succeeded in ~30% removal of divalent and trivalent ions, while RO membrane proved separation of 99% of sulphate ions, 96% of iron, 93% of bicarbonate, ~90% of sodium, magnesium and sulphide ions, 86% of potassium, 73% of phosphate and 25% of calcium ions. The second part was concerned with industrial wastewater, where oil and grease were completely removed by floatation, 11% of TSS and 12% of COD were removed by clarification, while coagulation by using 2 mg/l of anionic polymer removed 93% and 30% of TSS and COD respectively. The pretreated wastewater was allowed to pass through NF membrane at 14 bars followed by RO membrane at pressure of 14 bars. The separation efficiencies of monovalent, divalent and trivalent ions were nearly 2-3% less than that in case of synthetic solutions, while COD and BOD were completely removed. The water resulted from NF may be used in industrial processes and low pressure boilers while the water resulted from RO membrane may be used for high pressure boilers. Based on the previous results, preliminary techno-economic evaluation for 1200 m 3/day treatment plant was performed. The designed plant consists of: holding tank, oil separator, flash mixer, coagulation unit, clarification and settling unit, MAF unit, MIF unit, UF unit, NF unit and RO unit. The fixed capital cost was 1.46 million Egyptian pounds. The cost of treatment of 1 m 3 wastewater was 1.3 LE.

Isocratic elution of sodium, ammonium, potassium, magnesium and calcium ions by ion-exchange chromatography

Isocratic elution conditions for five cationic species were investigated using conductivity and UV absorption detectors. Using several kinds of eluents and silica and styrene—divinylbenzene separating columsn, the detection sensitivity, separation efficiency, separation time, system peak interference, etc., were examined. As a result, two types of eluents were concluded to be useful: a solution of benzylamine, citric acid and N-hydroxyethylenediamine-N,Nt́,Nt́-triacetic acid (EDTA · OH) and a solution of 1,1′-di- n-heptyl-4,5′-bipyridinium (DHBP) ion and citric acid. When the former eluent is used, monovalent cations are separated clearly and divalent cations can be eluted without being caputred in the column. With a slightly lower precision, divalent cations at the parts per million level can also be determined. The latter eluent is suitable mainly for determining Mg 2+ and Ca 2+ ions with no interference from heavy metal ions. The separation of monovalent ions was poor with a commercially available separation column, but the detection sensitivity with a UV absorption detector was higher than that with the benzylamine eluent. Several examples of application are shown