Strong Anion Research Articles

Quantifying orthogonality and separability: A method for optimizing resin selection and design.

Recent studies have shown that by combining orthogonal, non-affinity chromatography steps, it is possible to rapidly develop efficient purification processes for molecules of interest. Here, we build upon previous work to develop a flexible framework for identifying resins that remove optimally orthogonal sets of impurities for a wide variety of products. Our approach involves screening a library of proteins with diverse properties (pI ranging from 5.0-11.4 and varying hydrophobicity measured by retention in a HIC gradient) on a library of resins and quantifying each resin's ability to separate every protein pair in the library. Orthogonality is then defined as the degree to which two resins separate mutually exclusive sets of protein pairs. We applied this approach to a library of model proteins and a series of strong, salt tolerant, and multimodal ion exchangers and evaluated which resin combinations performed well and which performed poorly. In particular, we found that strong cation and strong anion exchangers were orthogonal, while strong and salt tolerant anion exchangers were not orthogonal. Interestingly, salt tolerant and multimodal cation exchangers were found to be orthogonal and the best resin combination included a multimodal cation exchange resin and a tentacular anion exchange resin. This approach for quantifying orthogonality is valuable in that it can be used both as a criteria for resin design as well as process design. We envision that, using this framework, it will be possible to design a set of next generation chromatography ligands that are explicitly engineered to optimize separability and orthogonality.

Sulphate Removal from Flotation Process Water Using Ion-Exchange Resin Column System

Water chemistry is one of the most important parameters affecting flotation performance. Various types of ions can dissolve and accumulate in process water depending on ore mineralogy, reagent scheme, grinding medium and chemistry of mine site water. Sulfur-based ions (sulfate, thiosulfate, polythionate) are generally observed in flotation of sulfide ores. High concentrations of these ions may reduce efficiency of the flotation process, causing scale problems. Removal of these ions from process water often requires complex water treatment plants with high capital and operating costs. In this study, partial cleaning of water was investigated as an alternative approach for decreasing high sulphate concentrations of 3000–3800 mg/L down to 1000–1500 mg/L, an acceptable concentration for most sulfide ore flotation plants, by using an ion-exchange resin. For this purpose, detailed adsorption tests were performed using a laboratory-scale column system to determine the most suitable type of resin for adsorption of sulfate and thiosalts, kinetics of adsorption and regeneration of the resins. A strong base anion ion exchange resin (Selion SBA2000) was used in the experiments. The findings from the laboratory scale studies were validated in a Cu-Pb-Zn Flotation Plant in an Iberian mine using a larger scale of column set-up. The results showed that 60–70% of sulphates could be successfully removed from process water. Adsorption capacity of the resin was determined as 80.3 mg SO4/g resin. Concentrations of thiosalts and polythionates were also reduced to nearly zero value from 500 mg/L and 1000 mg/L, respectively. Flowrate of water had a significant effect on adsorption performance. The resin could be regenerated successfully using 2% (w/v) NaOH solution and used multiple times for water treatment.

Comprehensive Vitamer Profiling of Folate Mono- and Polyglutamates in Baker's Yeast (Saccharomyces cerevisiae) as a Function of Different Sample Preparation Procedures.

Folates are a group of B9 vitamins playing an important role in many metabolic processes such as methylation reactions, nucleotide synthesis or oxidation and reduction processes. However, humans are not able to synthesize folates de novo and thus rely on external sources thereof. Baker’s yeast (Saccharomyces cerevisiae) has been shown to produce high amounts of this vitamin but extensive identification of its folate metabolism is still lacking. Therefore, we optimized and compared different sample preparation and purification procedures applying solid phase extraction (SPE). Strong anion exchange (SAX), C18 and hydrophilic–lipophilic-balanced (HLB) materials were tested for their applicability in future metabolomics studies. SAX turned out to be the preferred material for the quantitative purification of folates. Qualification of several folate vitamers was achieved by ultra-high pressure liquid chromatography quadrupole time of flight mass spectrometry (UHPLC-Q-ToF-MS) measurements and quantification was performed by liquid chromatography tandem mass spectrometry (LC-MS/MS) applying stable isotope dilution assays (SIDAs). The oxidation product s-pyrazino-triazine (MeFox) was included into the SIDA method for total folate determination and validation. Applying the best protocol (SAX) in regard to folate recovery, we analyzed 32 different vitamers in different polyglutamate states up to nonaglutamates, of which we could further identify 26 vitamers based on tandem-MS (MS2) spectra. Total folate quantification revealed differences in formyl folate contents depending on the cartridge chemistry used for purification. These are supposedly a result of interconversion reactions occurring during sample preparation due to variation in pH adjustments for the different purification protocols. The occurrence of interconversion and oxidation reactions should be taken into consideration in sample preparation procedures for metabolomics analyses with a focus on folates.

Analysis of glyphosate, AMPA, Glufosinate and MPPA with ION chromatography tandem mass spectrometry using A membrane suppressor in the ammonium form application to surface water of low to moderate salinity

This paper describes a simple and reliable method for the sensitive and selective determination of the pesticides Glyphosate and Glufosinate and their main metabolites aminomethylphosphonic acid (AMPA) and 3-[hydroxy(methyl)phosphinoyl]propionic acid (MPPA) in surface water. The developed method is based on ion chromatography hyphenated to electrospray tandem mass spectrometry and does not require derivatization. A membrane suppressor, regenerated at pH 9, has been used in this work to strongly improve the peak shape of AMPA, which suffered from huge tailing due to the interaction of this compound with acidic membrane suppressors. With this modified suppressor the sensitivity for AMPA improved about 100 times. Moreover, addition of 40% methanol to the hydroxy eluent improved MS sensitivity for all compounds by 1.3–2.8 times. The separation is performed on a strong anion exchange column. Glyphosate and AMPA are detected in the negative ion ESI mode, whereas Glufosinate and MPPA show much better sensitivity in the positive ion ESI mode. Surface water samples were spiked with the labelled parent compounds. Sample preparation comprised a filtering step over coupled solid phase extraction Ba, Ag and Na cartridges to remove chloride and sulphate ions. The performance characteristics of the method were determined with real surface water samples. Samples containing 12.6 g L−1 chloride were also used in the validation process and showed no problem.Nitrate is not removed from the samples and may give ion-suppression for Glyphosate.Linearity of the method was established over at least three orders of magnitude in the measuring range 10–2000 ng L−1 for surface water. The reliability of the results was ensured by the application of the criteria from the Dutch Technical Agreement (NTA 8379) concerning “identification”, “indication”, and “absence” of substances. The limit of quantitation with regard to identification was 10 ng L−1 for all compounds and the limits of detection with regard to indication were 6.5–9.6 ng L−1. The recovery (94–104%) and reproducibility variance (5.5–6.2%) were excellent. The suitability of the developed method was demonstrated by the analysis of 172 surface water samples of low to moderate salinity from different parts of The Netherlands. AMPA was identified in 99% of the samples and always exceeded the maximum allowable concentration of 100 ng L−1. The maximal concentration found in surface water was 9900 ng L−1. Glyphosate was identified in 82% of the samples and in only 6% Glyphosate exceeded the maximum allowable concentration of 100 ng L−1. MPPA was identified in about 75% of the samples whereas Glufosinate was rarely detected and never exceeded the limit of quantitation.

Modification of Lignocellulosic Materials with a Mixture of m-DMDHEU/Choline Chloride to Remove CrO4 2-, NO3 -, and H2AsO4 - in Aqueous Solution.

A new denaturation agent is the mixture of 4,5-dihydroxy-1,3-bis(methoxymethyl)imidazolidin-2-one (m-DMDHEU)/choline chloride (CC) introduced to modify three kinds of lignocellulosic materials containing different lignin contents in the following order: cotton used in medicine < sawdust from acacia auriculiformis wood < powder from the coconut shell. The modification process is carried out through two main steps: 0.2 N NaOH solution with 70% v/v ethanol and 30% v/v water was applied to remove lignin and activate the initial raw materials, and then delignified materials were modified with m-DMDHEU/CC by using a parched heat supply method after chemical impregnation. Structural characterictics and physicochemical properties of modified materials were tested and dissected by scanning electron microscopy, Fourier transform infrared spectroscopy, solid-state 13C nuclear magnetic resonance spectroscopy (solid-state 13C CP-MAS NMR), specific surface area, and pH at the point of zero charge (pHPZC). The ability to adsorb and exchange anions of modified materials was referred and examined by using aqueous solutions containing CrO42–, NO3–, and H2AsO4– anions in different conditions. The results revealed that anionite lignocellulosic materials could separate these anions with very good efficiency and better than strong anion exchange resin (GA-13) in the same conditions; outlet water could meet the permissible drinking and living water standards; and the m-DMDHEU cross-link bridge also was a good bridge to connect CC to cellulose chain beside other common urea cross-link bridges.

Surface analysis of ancient parchments via the EVA film: The Aleppo Codex.

The margins of several pages of the Aleppo codex have been found to be corroded and contaminated by diffuse maculae. In order to understand the origin of this decay these margins have been analysed by applying EVA (ethylene vinyl acetate plastic embedded with strong cation and anion exchangers and mixed with C8 and C18 hydrophobic resins) diskettes for harvesting surface material. The captured compounds have been eluted, digested with trypsin and analysed by nano-HPLC-MS. Three major strains of Aspergillus have been identified, namely Aspergillus fumigatus, Aspergillus pseudoglaucus, Aspergillus amstelodami, together with a lactobacillus strain and human keratins. The novelty of this investigation is that for the first time the EVA technology has been applied to ancient parchments in the absence of mechanical deformation or distortion that could be induced if there had been water exchange between the EVA diskettes and the parchment. These findings should help curators to find suitable restoration protocols for these precious documents belonging to the world Cultural Heritage.

Experimental study on the application of Eluex process in acid ISL

An applicable Eluex process was developed for acid in situ leaching (ISL) uranium mine in Bayanwula. In this process, uranium was adsorbed with strong base anion resin from the pregnant solution, then the loaded resin was eluted by sulfuric acid, after Di-(2-ethylhexyl) phosphoric acid (D2EHPA) extraction, the concentrated eluate was enriched and the loaded organic phase was stripped by sodium carbonate, and the yellow cake was obtained by sodium hydroxide precipitation at last. The uranium concentration in loaded strip solution was 52.8 g L−1. Parameters of the process were determined, and the impact of Eluex process in underground leaching was also investigated. In industrial design, 95% of raffinate went back to elution and 5% back to ISL. No significant effect on uranium leaching or resin adsorption has been found.

Synthesis and characterization of a novel soluble hesperetin monoglucoside-copper(Ⅱ) complex using ion exchange column

The coordination of flavonoids with metal ions often improve the biological activity of flavonoids. In this study, an integrated method using ion exchange column for the synthesis of the hesperetin monoglucoside-copper(Ⅱ) complex (the HMG-Cu(Ⅱ) complex) was investigated. The integration including the separation and the coordination reaction of HMG was studied firstly. The stoichiometric ratio of the complex was studied by the method of equimolar solutions and the molar ratios. The compound structures were characterized by theoretical quantum chemical calculation, elemental analysis, ultraviolet–visible (UV–Vis) spectra analysis, Fourier transform infrared (FT-IR) spectra analysis, X-ray diffraction (XRD) patterns analysis, scanning electron microscope (SEM) and thermal methods (TG/DSC) analysis. Results showed that both the carboxyl group and its ortho hydroxyl group in hesperetin monoglucoside (HMG) participated in the coordination reaction. The D296 strong basic anion exchange resins could effectively adsorb HMG. The static adsorption equilibrium time was 20 h and equilibrium data fitted better to the Langmuir model than Freundlich model. The adsorption process was a monolayer adsorption process on homogenous surface of D296 resins and the fitting of the pseudo-second-order model was better. The metal-to-ligand ratio was 1:2. In addition, the complex was greatly affected by pH, the stablest at pH 8.0. So, this research offered a feasible pathway of getting a high value-added complex of HMG-Cu(Ⅱ).

Sorption behavior of uranium from Sulfate media using purolite A400 as a strong base anion Exchange resin

ABSTRACT The sorption characteristics of uranium onto a strongly basic anion exchanger, Purolite A400, were investigated. The characteristics of Purolite A400, before and after sorption of uranium, were determined using scanning electron microscopy (SEM) and energetic-dispersive X-ray (EDX). The influence of the different parameters, which may affect the process of uranium sorption process, had been tracked. Specifically, impacts of initial uranium concentration, pH, contact time and temperature, on uranium removal, were studied. In addition, the sorption kinetics and equilibrium parameters were assessed. At the optimum conditions, the adsorption capacity of uranium was found to be nearly 117.6 mg/g. The kinetics and isotherm studies could show that the uranium sorption onto Purolite A400 is following the models of pseudo-second-order and Langmuir isotherm respectively. The thermodynamic parameters had indicated that the adsorption of uranium is an exothermic and spontaneous process. The detected results of uranium sorption could reveal that Purolite A400 is a suitable material for pre-concentration of uranium (VI) species from sulfate leach liquor.

Extraction and Quantification of Soluble, Radiolabeled Inositol Polyphosphates from Different Plant Species using SAX-HPLC.

The phosphate esters of myo-inositol, also termed inositol phosphates (InsPs), are a class of cellular regulators playing important roles in plant physiology. Due to their negative charge, low abundance and susceptibility to hydrolytic activities, the detection and quantification of these molecules is challenging. This is particularly the case for highly phosphorylated forms containing 'high-energy' diphospho bonds, also termed inositol pyrophosphates (PP-InsPs). Due to its high sensitivity, strong anion exchange high-performance liquid chromatography (SAX-HPLC) of plants labeled with [3H]-myo-inositol is currently the method of choice to analyze these molecules. By using [3H]-myo-inositol to radiolabel plant seedlings, various InsP species including several non-enantiomeric isomers can be detected and discriminated with high sensitivity. Here, the setup of a suitable SAX-HPLC system is described, as well as the complete workflow from plant cultivation, radiolabeling and InsP extraction to the SAX-HPLC run and subsequent data analysis. The protocol presented here allows the discrimination and quantification of various InsP species, including several non-enantiomeric isomers and of the PP-InsPs, InsP7 and InsP8, and can be easily adapted to other plant species. As examples, SAX-HPLC analyses of Arabidopsis thaliana and Lotus japonicus seedlings are performed and complete InsP profiles are presented and discussed. The method described here represents a promising tool to better understand the biological roles of InsPs in plants.

Extraction and Quantification of Soluble, Radiolabeled Inositol Polyphosphates from Different Plant Species using SAX-HPLC

The phosphate esters of myo-inositol, also termed inositol phosphates (InsPs), are a class of cellular regulators playing important roles in plant physiology. Due to their negative charge, low abundance and susceptibility to hydrolytic activities, the detection and quantification of these molecules is challenging. This is particularly the case for highly phosphorylated forms containing ‘high-energy’ diphospho bonds, also termed inositol pyrophosphates (PP-InsPs). Due to its high sensitivity, strong anion exchange high-performance liquid chromatography (SAX-HPLC) of plants labeled with [3H]-myo-inositol is currently the method of choice to analyze these molecules. By using [3H]-myo-inositol to radiolabel plant seedlings, various InsP species including several non-enantiomeric isomers can be detected and discriminated with high sensitivity. Here, the setup of a suitable SAX-HPLC system is described, as well as the complete workflow from plant cultivation, radiolabeling and InsP extraction to the SAX-HPLC run and subsequent data analysis. The protocol presented here allows the discrimination and quantification of various InsP species, including several non-enantiomeric isomers and of the PP-InsPs, InsP7 and InsP8, and can be easily adapted to other plant species. As examples, SAX-HPLC analyses of Arabidopsis thaliana and Lotus japonicus seedlings are performed and complete InsP profiles are presented and discussed. The method described here represents a promising tool to better understand the biological roles of InsPs in plants.

Field validation of multifunctional ion exchange process for reverse osmosis pretreatment and phosphate recovery during impaired water reuse

Conventional reverse osmosis (RO) pretreatment hardly achieves multifunctionality for simultaneous membrane scaling prevention and nutrient recovery during impaired water reuse. To address the challenge, we probed a multifunctional ion exchange pretreatment process achieving pH adjustment, calcium and organic compound removal, and phosphate recovery using real impaired surface water. Three types of ion exchangers were integrated in train including a polystyrene strong base anion exchanger (psSBA), a shallow-shell weak acid cation exchanger (SSWAC), and a hybrid anion exchanger (HAIX). The novelty is that SSWAC, which decreased aqueous pH from neutral to ∼ 5 and removed > 70 % calcium, was regenerated by recovered waste CO2 (> 80 % regeneration efficiency) to avoid strong acid regenerants and achieve CO2 utilization and sequestration. The front-positioned psSBA selectively pre-removed hydrophobic ionizable organic compound (HIOC) such as diclofenac at > 80 % removal to reduce HIOC interference on the latter-positioned HAIX. HAIX doped with ferric oxide nanoparticles (FeOnp) enabled selective phosphate removal from complex real impaired water. Over 70 % removal of phosphate and calcium by HAIX and SSWAC reduced calcium phosphate scaling risk and facilitated phosphate recovery as hydroxyapatite from spent regenerants that enriched with calcium and phosphate. We envision this study to facilitate resource recovery in water-nutrient-carbon nexus via engineered multifunctional ion exchange processes.

"1984": What Orwell could not predict. Proteomic analysis of his scripts.

George Orwell, fighter for the Republican Army during the Spanish Civil War, was shot through the throat by a sniper on 20th May 1937 and nearly killed. After receiving only a summary external treatment, on the 29th, he was cured in a Barcelona hospital where he was infected by the Koch bacillus. After fleeing from Spain on 23rd June 1937, he repaired to his cottage in Wallington, Hertfordshire, wherefrom he wrote a letter to Sergey Dynamov, Editor of Soviet journal "Foreign Literature." This typewritten letter was analyzed by application of five EVA strips (ethylene vinyl acetate studded with strong cation and anion and with C8 and C18 resins; four on the corners and one over his signature), searching for biological traces. Upon elution of the captured biologicals, trypsin digestion and Orbitrap Fusion trihybrid mass spectrometer analyses, three of the five strips yielded clear traces of six unique proteins (via proteotypic peptides) of the tuberculosis bacterium. Additionally, MALDI TOF analysis of saliva of a tuberculosis patient and the EVA strip eluates gave a spectrum of 14 peptide bands (Mr 2700 to 6700Da range) coincident between the two samples, thus, fully confirming Orwell's pathology. These results are attributed to saliva traces on Orwell's fingertips and to the fact that the letter was written on 2nd July 1937, when Orwell's pathology was at its peak.

Etiology, therapy and prophylaxis of bovine parturient paresis (hypocalcaemia)

Due to the sudden increase of calcium demand at the onset of lactation many high yielding dairy cows experience a certain level of hypocalcaemia following parturition. The incidence of hypocalcaemia (parturient paresis) increases with age but also depends on many other factors such as the acid-base status and the availability of calcium as well as other minerals and trace elements. Hypocalcaemia can easily be treated by supplementation of calcium parenterally or orally, nonetheless, prophylaxis of the condition should be the main focus in modern dairy farming, in order to avoid its negative effects. Oral administration of calcium around parturition is the simplest way of prophylaxis, but results in a high work load and requires exact knowledge of the date of parturition. The latter also applies for the parenteral administration of vitamin D3, which should be injected 1 week before parturition. Additionally, repeated treatment with vitamin D increases the risk for calcinosis. Reducing the calcium concentration of the ration fed during the late dry period also decreases the risk for hypocalcaemia by activating the mechanisms for calcium homeostasis within the body. The induction of a mild (compensated) metabolic acidosis to increase the sensitivity of parathormone receptors and enhance intestinal calcium uptake may also be employed to prevent milk fever. For this purpose, a DCAD (dietary cation anion difference) diet is fed during the late dry period, in which the concentrations of strong cations (potassium and sodium) as well as strong anions (sulfate and chloride) are altered. This may either be achieved by reducing the potassium concentration (partial-DCAD) or by adding anionic salts (full-DCAD). This method, especially the full-DCAD variant, requires a substantial level of surveillance and monitoring. Suitable prophylactic measures for the prevention of hypocalcaemia must be chosen individually for each farm, depending on the incidence of hypocalcaemia as well as personnel and structural resources.

EVA Technology and Proteomics: A Two-Pronged Attack on Cultural Heritage.

A novel way for exploring the world's cultural heritage in the absence of damage or contamination (such as removing pigments in paintings or chipping away pieces of bones) of the items under investigation is here reported, called the EVA technique. It is based on films of ethylene vinyl acetate (EVA) impregnated with strong anion and cation exchangers, admixed with hydrophobic resins, C8 and C18. When in contact with any surface these films can harvest nanomoles of macromolecules (proteins and DNA) as well as metabolites, which can then be identified by standard instrumentation. Some important applications are reported, such as the findings of the renal pathology and assumption of morphine in the original manuscript of Master I Margarita by Bulgakov, the presence of TBC bacterium in Chekhov's shirt and in a letter by Orwell, the Y.pestis and anthrax bacteria in the death registries of Milan's lazaretto in the 1630 plague bout, as well as ample traces of five metals in Kepler's manuscripts, suggesting his potential practice of alchemy. Also, in the pages of the Memoirs of Casanova, although the gonorrhea bacterium could not be found, spots of HgS could be measured, suggesting its use for curing the disease. A family of EVA films is described, enlarging its use to dedicated applications, such as the capture of drugs of abuse in the pages of famous writers and even in the paintings of fauvists. It is hoped that the present methodology could open the doors of museums, state archives, and private collections for detecting biological traces left by artists, literates, and men of culture in their masterpieces.

Engineering Anion Resin based Amorphous Molybdenum Sulphide Composite for Treatment of Authentic Acid Mine Drainage

Abstract Acid mine drainage (AMD) is an acidic effluent containing many toxic heavy metal ions (e.g. Cu2+, Cd2+, Hg2+) in mining industry, leading to serious environmental issues such as natural soil and aquatic pollution that threats the whole ecosystem and biosafety. Conventional neutralization and precipitation process cannot effectively remove heavy metal ions due to the risk of secondary contamination. Herein, we report an engineered amorphous molybdenum sulphide composite for selective removal of heavy metal ions from other co-existing ions in AMD solution. This composite was prepared by a facile ion exchange reaction, in which tetrathiomolybdate (MoS42-) anions are firmly bonded to strong anion exchange resins by replacing chloride ions. The obtained composite was used to remove heavy metal ions from both synthetic and authentic AMD solution. The results of batch and fixed-bed column tests suggest high selectivity towards heavy metals, fast adsorption kinetics, good reusability and excellent adsorption capacities in the order of Hg(II)>>Pb(II)>Cu(II)>Cd(II). The adsorption data are fitted well by Langmuir model, indicating the single-layer adsorption mechanism. The theoretical adsorption capacities calculated by Langmuir model are 259.0 mg/g for Cu(II), 204.1 mg/g for Cd(II), 495.0 mg/g for Pb(II) and 1538.4 mg/g for Hg(II). The interaction between metal ions (Cu, Cd, Pb, Hg) and MoS42- anions are demonstrated by the formation of Mo-S-metal (Cu, Cd, Pb, Hg) bonding (the red shift of S2p peak in XPS spectra). Our results support the potential practical application of this new material for scavenging heavy metal ions in AMD wastewater.

Rapid Quantification of Urinary Organic Acids by HPLC Mass Spectrometry to Assess Nutritional Individuality in Chinese Children.

A urinary organic acids profile can be utilized as an effective screening tool for analyzing abnormality of nutrient metabolism. By using these metabolic markers in conjunction with one another, it helps in understanding how individual nutrient metabolism is executed and to determine where there may be imbalances in the metabolic cycle. In this study, we developed a rapid quantification method of 20 urinary organic acids by HPLC-mass spectrometry. A pre-analytical process of organic acid extraction from a urine sample is crucial in this methodology. The process was accomplished by liquid-liquid extraction followed by strong anion exchange. Compared with previous methods, this method greatly reduces the analysis time and allows for the simultaneous quantification of 20 organic acids within 10 min for the first time. This methodology enabled us to analyze urine samples collected from 34 Chinese children. The abnormalities of some urinary organic acids were found in this group, which revealed evidence of functional inadequacy of specific nutrients. The preliminary data in this study confirmed the suitability of the method for rapid and accurate quantification of the target organic acids in urine samples.

Electrochemical Destruction of per- and Polyfluoroalkyl Substances (PFAS) in Complex Solution Matrices

Per- and Polyfluoroalkyl substances (PFAS) are a group of manmade chemicals which are persistent in the environment and have shown to be toxic to human health. They have accumulated in drinking water, groundwater, and wastewater around the globe for over six decades. Although the production of some chain lengths has ceased, remediation is critical. Current remediation techniques include adsorbents such as granular activated carbon (GAC) and Ion exchange (IX) columns. GAC is merely used to adsorb the PFAS, but struggles with capturing shorter chains and requires regeneration with incineration.1 IX has shown improvement in its ability to capture all PFAS chain lengths, and can be regenerated with a solution comprised of a salt or base and an alcohol.1 This regenerate solution desorbs all of the PFAS from the resin into a smaller concentrated solution of roughly a few hundred gallons. This solution is typically comprised of PFAS in the parts per million (ppm) range.2 These concentrated PFAS solutions can lead to further contamination of the environment through discharge of landfill leachate to wastewater treatment plants from landfill disposal. Due to the high salinity, low volume, and high concentration of PFAS in IX regenerate solutions, electrochemical oxidation is a promising treatment technology to destroy the PFAS and remove the chance of future human exposure.This study employs a boron-doped diamond (BDD) on niobium (Nb) electrode stack to investigate the role that current density has in the electrochemical destruction of PFAS in a complex solution matrix. The electrode stack was comprised of two anode plates sandwiched in between three cathode plates. This entire stack was then placed into a constantly stirred reactor comprised of 750 ml of solution. A constant current density of 50 mA/cm2 was investigated initially for a total of 12 hours. In order to save on energy consumption, further studies used a combined current density approach. This involved applying 50 mA/cm2 for only the first hour of the test before lowering the current density to 5 mA/cm2 for the remaining 11 hours. Multiple literature IX regenerate solutions were simulated and spiked with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS).3–6 Multiple samples were taken over the course of the oxidation experiments and sent for PFAS analysis using the Environmental Protection Agency’s (EPA) modified 537 method. Additional process parameters were monitored over time including the pH, voltage, temperature, and the reduction in chemical oxygen demand (COD) and ammonia depending on the simulated regenerate solution used. Further analysis showed a significant reduction in energy with a minimal additional amount of PFAS remaining in the initial combined current density study compared to the traditional constant current density approach. 1. Woodard, S., Berry, J. & Newman, B. Ion exchange resin for PFAS removal and pilot test comparison to GAC. Remediation 27, 19–27 (2017).2. Liang, S., Pierce, R. “David”, Lin, H., Chiang, S. Y. D. & Huang, Q. “Jack”. Electrochemical oxidation of PFOA and PFOS in concentrated waste streams. Remediation 28, 127–134 (2018).3. Conte, L., Falletti, L., Zaggia, A. & Milan, M. Polyfluorinated Organic Micropollutants Removal from Water by Ion Exchange and Adsorption. in CHEMICAL ENGINEERING TRANSACTIONS 43, (2015).4. Zaggia, A., Conte, L., Falletti, L., Fant, M. & Chiorboli, A. Use of strong anion exchange resins for the removal of perfluoroalkylated substances from contaminated drinking water in batch and continuous pilot plants. Water Res. 91, 137–146 (2016).5. Chularueangaksorn, P., Tanaka, S., Fujii, S. & Kunacheva, C. Regeneration and reusability of anion exchange resin used in perfluorooctane sulfonate removal by batch experiments. J. Appl. Polym. Sci. 130, 884–890 (2013).6. Deng, S., Yu, Q., Huang, J. & Yu, G. Removal of perfluorooctane sulfonate from wastewater by anion exchange resins: Effects of resin properties and solution chemistry. Water Res. 44, 5188–5195 (2010).

Strong anion–anion hydrogen bond in the ionic liquid 1-ethyl-3-methylimidazolium hydrogen sulfate

This work discusses the remarkable differences in the mid- and far-infrared regions of the spectrum of the ionic liquid 1-ethyl-3-methylimidazolium hydrogen sulfate, [C2C1im][HSO4], in comparison to ionic liquids based on other anions. The infrared spectrum unveils the occurrence of anion–anion hydrogen bond in [C2C1im][HSO4]. The band related to the anion OH stretching mode, ν(OH), covers a large frequency range (2000–3400 cm−1) and exhibits the spectral pattern of strongly hydrogen bonded systems. The far-infrared (FIR) spectrum of [C2C1im][HSO4] also exhibits the signature of the anion–anion interaction, that is, the stretching mode of the hydrogen bond, ν(O…O), at ~170 cm−1. Hydrogen bond between [HSO4]− anions also occurs in ionic liquids containing imidazolium cation with longer alkyl chain ([C4C1im]+) or tetraalkylammonium cation. The vibrational frequencies of ν(OH) and ν(O…O) modes satisfy empirical correlations that characterize the anion–anion interaction in [C2C1Im][HSO4] as a strong hydrogen bond.

SAP fractions from light, medium and heavy oils: Correlation between chemical profile and stationary phases

The chemical composition of oil samples is fundamentally important for planning the recovery, transportation and refining processes of the oil industry. In this work, we examined how stationary phase affects the recovery of non-retained substances and the separation of saturated, aromatic and polar fractions from different density oils by column chromatography. We evaluated four stationary phases: silica gel, alumina, strong anion exchange (SAX) and C-18 silica gel, the latter being the only nonpolar one. The experiment was carried out in quintuplicate and the fractions obtained were analyzed by gas chromatography coupled with mass spectrometry and positive-ion mode electrospray ionization FT-ICR mass spectrometry (ESI(+)-FT-ICR MS). The influence of the stationary phase on the separation of the various classes of substances found in petroleum was observed by chemometrics. For saturated compounds, light and medium oils presented n-paraffins, iso-paraffins, naphthenes, terpanes and steranes, while heavy oil presented intense biodegradation, with a higher concentration of terpanes and steranes. When heavy oil was fractionated with C-18 silica gel, the presence of n-paraffins could also be observed. Alumina generated a saturated fraction, that was less contaminated with aromatics, and it showed a separation capacity similar to that of silica gel and SAX. For aromatics, all stationary phases generated fractions contaminated with saturated compounds, and polar fractions showed a greater presence of basic heteroaromatics compounds containing predominantly one nitrogen. A more reliable SAP separation of crude oil fractions depends on their density.