An ISFET-based anion sensor for the potentiometric detection of organic acids in liquid chromatography

An ion-selective field effect transistor (ISFET) was applied as a potentiometric detector in liquid chromatography (LC) for the determination of organic acids. The ISFET was prepared by coating the gate insulator of the encapsulated transistor with a poly(vinyl chloride) (PVC) matrix membrane containing methyltridodecylammoniumchloride, which enables the detection of organic anions. The ISFET was tested for its applicability as detector for carboxylic acids in ion-exchange and reversed-phase chromatography. Its analytical characteristics were compared to those of a coated-wire electrode (CWE) and of a conventional type of ion-selective electrode (ISE)

Ion Exchange for Nutrient Recovery Coupled with Biosolids-Derived Biochar Pretreatment to Remove Micropollutants

Wastewater, especially anaerobic treatment effluent, contains high ammonia nitrogen (NH4-N) and inorganic orthophosphate (PO4-P), which necessitate additional treatment to meet stringent discharge regulations. Ion exchange regeneration is a process that can be adopted for not only removing but also recovering nutrients. However, recovering nutrients by ion exchange from nutrient-rich effluents that also contain micropollutants (which typically pass through anaerobic treatment as well) may result in subsequent problems, since micropollutants could end up in ion exchange effluent, regenerant, or recovered fertilizer products. Micropollutant removal by a nonselective adsorbent, such as biosolids-derived biochar, before nutrient recovery processes would mitigate potential risks. The objective of this research was to evaluate the capability of biosolids-derived biochar as a pretreatment step for separating micropollutants from nutrient-rich water before ion exchange for nutrient recovery. In the presence of ammonium and phosphate, both pristine and regenerated biosolids-derived biochar could effectively adsorb triclosan (TCS) and estradiol (E2), and to a lesser extent, sulfamethoxazole (SMX) in batch sorption experiments. On the other hand, nutrient ions were not effectively adsorbed by biosolids-derived biochar. A continuous flow-through system consisting of columns in series filled with biochar, LayneRT, and then clinoptilolite was operated to test selective removal of micropollutants and nutrients in a flow-through system. The biochar column achieved more than 80% removal of influent TCS and E2, thereby reducing the chances of micropollutants being adsorbed by ion exchangers. Sulfamethoxazole removal through the biochar column was only 50%, indicating that biosolids-derived biochar would have to be optimized in the future for hydrophilic micropollutant removal. Influent nutrients were not effectively removed by the biochar column, but were captured in their respective selective ion exchanger columns. This research revealed that biosolids-derived biochar could be employed before ion exchange resins for removal of micropollutants from nutrient-rich water

Selective Ion Exchange Resin

ArticleJournal of the Faculty of Textiles and Sericulture, Shinshu University. Ser. C, Chemistry 4: 1-14(1957)departmental bulletin pape

Research in Industrial Use of Ion Exchange and Simulation

We investigated the industrial use of ion exchange technology as well as the modeling of fixed bed, multicomponent ion exchange processes. In this paper we report on both fields of this research. We have developed a complex technology for the selective separation of the long-live radionuclides and the partial recycling of boric acid from radioactive evaporator bottom residue. A wastewater treatment system has been developed by using a cesium-selective inorganic ion exchanger. The selective separation of 137Cs, 134Cs from high salt concentration and strongly alkaline evaporator bottom residue in Paks NPP has a volume reduction factor of about 3500–6500 at the value of the decontamination factor DF > 100, for the samples of four evaporator bottom residue tanks of the NPP. Some important classes of ion exchangers do possess uniform internal pore structures and bring all parts of the solíd structure into much closer contact with the liquid. Such materials are porous organic resins. For these types of exchangers, we have modified Mansour's multicomponent adsorption model and developed a computer program to describe multicomponent breakthrough, cocurrent, and counter-current elution curves for ion exchangers. In addition, we have developed a subroutine for the calculation of multicomponent ion exchange kinetics according to Nernst-Planck equation and successfully tested it. This subroutine will be added to the multicomponent ion exchange breakthrough and elution simulation program to have a real multicomponent ion exchange simulation program. In this paper we report about these research results too

Fate and Impacts of Triclosan, Sulfamethoxazole, and 17β-estradiol during Nutrient Recovery via ion Exchange and Struvite Precipitation

Increasing emphasis on resource recovery from wastewater highlights the importance of capturing valuable products, e.g., nutrients such as nitrogen and phosphorus, while removing contaminants, e.g., organic micropollutants. The objective of this research was to evaluate the fate of the micropollutants triclosan (present as a mixture of neutral and anionic species at neutral pH), 17β-estradiol (neutral at neutral pH), and sulfamethoxazole (anionic at neutral pH) during nutrient recovery using ion exchange-precipitation. Adsorption of the three micropollutants to the phosphate-selective ion exchange resins LayneRT and DOW-HFO-Cu ranged from 54% to 88% in Milli-Q water tests and 50% to 71% in wastewater tests using anaerobic effluent. The micropollutants did not sorb to the ammonium-selective exchanger, clinoptilolite. The presence of the micropollutants reduced the kinetic rates of nutrient exchange onto ion exchangers. However, the micropollutants did not interfere with nutrient capacity on the ion exchangers, likely due to the low concentration of micropollutants and potentially different mechanisms of adsorption (i.e., Coulombic and non-Coulombic attractions for micropollutants) compared to the target ions. Micropollutants that sorbed to the phosphate exchangers were released with phosphate ions during regeneration. Concentrations of NaOH and NaCl in regeneration solutions did not correlate with micropollutant desorption. Among the micropollutants studied, the more hydrophobic triclosan and 17β-estradiol adsorbed to the resins to greater extents. These compounds also demonstrated lower desorption rates than sulfamethoxazole during regeneration in Milli-Q water tests. Batch struvite precipitation tests revealed that the micropollutants were not enmeshed in precipitated struvite crystals nor sorbed during crystallization, indicating that the struvite product was free of triclosan, 17β-estradiol, and sulfamethoxazole

The Ion Exchange and Sorption Properties of Microcrystals of Inorganic Oxides

Detailed studies have been made on the ion exchange and sorptive properties of aqueous dispersions of single crystals of beta-iron oxide hydroxide and monoclinic zirconia. These microcrystals were prepared in the laboratory and characterised by transmission electron micrographs and electron diffraction patterns. The crystals are typically 1000-2000A in size and have amphoteric ion exchange properties. In this work, a multiion selective electrode titration system working with a highly developed computational and graphic system was developed to determine the ion exchange and sorption properties of these crystals. Ion sieving characteristics of betaFeOOH have been proven and extended to include a separation of chloride from solutions containing iodide and bromide and, in alkali, exclusion of sodium ion. Fluoride uptake is determined by ion selective electrode response and alkaline earth uptake is determined by flame emission spectroscopy. Single ion exchange uptake of anions in acid and cations in base is explained by a Donnan model. This predicts anion (cation) capacity to be a single-valued function of the negative logarithm of the corresponding acid (base) activity in the equilibrium solution. Adsorptive properties of fluoride ion on monoclinic zirconia is explained by ligand exchange or incorporation of this adsorbate into the framework of the oxide. Exchange is shown to be reversible for most simple univalent ions and variations in exchange capacity controlled by solution pH and salt concentrations

NEW TECHNOLOGY SCHEME FOR HANDLING AND BURIAL FOR THE RADIOACTIVE EVAPORATOR BOTTOM OF THE PWR PAKS

At the Department of Chemical Technology we developed a complex technology for handling the radioactive evaporator bottom in Paks before burial. The basic concept of the technology is the primary selective separation of the long-lived radioisotopes and then the partial recovery of the boric acid content of the inactive solution. The selective separation is accomplished by using iom exchange and adsorption materials and reagents and the partial recovery of the boric acid content of the inactive solution. The selective separation is accomplished by using ion exchange and adsorption materials and reagents and the partial recovery of the boric acid is carried out by neutralisation with carbon dioxide combined with a purification step involving ammonium-ion exchange. The overall volume reduction factor is about 96

Stability of the Ion Pair Between Ca2+ and 2-(Hydroxymethyl)-3-Deoxy-D- erythro -Pentonate (α-Isosaccharinate)

Ion-pair formation between Ca2+ and α-isosaccharinate, Ca2+ + ISA-CaISA⇄+, was studied by two independent methods: an ion-exchange and a potentiometric method (Ca-selective electrode). The two methods gave similar values for the complexation constant, log KCaISA+o at I = 0, (22 ± 1)°C. The ion-exchange method gave a value of log KoCaISA+ = (1.8 ± 0.1) and the potentiometric method resulted in logKCaISA+o = (1.78 ± 0.04). These values are in good agreement with the estimated value, log KCaISA+o = 1.7, based on the formation of a Ca-gluconate ion pai

Synthesis, Characterization and Ion Exchange Properties of a New Ion Exchange Material: Bismuth (III) Iodophosphate

Eight samples of the three component cation  exchanger  [Bismuth(III)iodophosphate]  has  been  synthesized by mixing different  ratio of 0.1M bismuth nitrate, 0.1M potassium iodate, 0.1M orthophosphoric acid at pH between 0-1. The material shows ion exchange capacity for Na+ ion of 0.5meq/g.  It  has  been  characterized using  I.R., X-ray, TGA studies. A number of ion exchange studies like pH titration, chemical stability, thermal stability and distribution behaviour were studies. Ion exchange capacity has also been determined for various metal ions such as K+, Mg2+ etc. pH titration method was also used for the determination of ion exchange capacity. On account of the Kd values and elution pattern, the cation exchanger is found to be selective for Pb2+

Using small molecules to facilitate exchange of bicarbonate and chloride anions across liposomal membranes

Bicarbonate is involved in a wide range of biological processes, which include respiration, regulation of intracellular pH and fertilization. In this study we use a combination of NMR spectroscopy and ion-selective electrode techniques to show that the natural product prodigiosin, a tripyrrolic molecule produced by microorganisms such as Streptomyces and Serratia, facilitates chloride/bicarbonate exchange (antiport) across liposomal membranes. Higher concentrations of simple synthetic molecules based on a 4,6-dihydroxyisophthalamide core are also shown to facilitate this antiport process. Although it is well known that proteins regulate Cl-/HCO3- exchange in cells, these results suggest that small molecules may also be able to regulate the concentration of these anions in biological systems