Ammonium Bicarbonate Solution Research Articles

Electrochemical exfoliation of graphite using aqueous ammonium hydrogen carbonate solution and the ability of the exfoliated product as a hydrogen production electrocatalyst support

Electrochemical exfoliation of graphite has attracted much attention as a practical mass production of two-dimensional graphene-like materials. There is an increasing desire to find new and improved methods to create unique exfoliated products with excellent functionality. We used aqueous ammonium hydrogen carbonate solution as a new electrolyte for anodic oxidative exfoliation of graphite. The exfoliated product has a porous two-dimensional structure, and it can be dispersed in water for over five years. The oxidized and defected porous surface serves as an ideal support for molecular metal complexes, effectively functioning as heterogeneous electrocatalysts for hydrogen production.

Synergistic Effect of Influence Factors on Ammonia Volatilization in Fertilizer Solution: A Laboratory Experiment

Ammonia volatilization, which is one of the main ways that nitrogen gas is released from farmland, restricts promotion of the utilization of nitrogen fertilizer and contains some potential environmental risks. To investigate the general pattern of ammonia volatilization under actual paddy field conditions, we designed an indoor simulated system to measure the amount of ammonia volatilized within a single time period by controlling the pH and concentration of NH4+ (c(NH4+)) in the solution, the gas–liquid interfacial gas velocity, and the ambient temperature. In this paper, the influence of these factors, the synergistic effect on ammonia volatilization, and their quantitative relationship are discussed. We used solutions of ammonium bicarbonate (SAB) and diammonium phosphate (SDP) for the simulation experiments, and the results showed that there is a significant linear relationship between the amount of ammonia volatilization and c(NH4+). The correlation coefficients were between 0.9214 to 0.9897 and 0.8932 to 0.9904 for SAB and SDP, respectively. The quantitative relationship between temperature and pH and the influence factor (CIF) and the initial ammonia volatilization fluxes (IAVFs) was analyzed by the least-squares method, and the degrees of polynomial were one and two, respectively. The regression equations of the SAB and SDP among the amount of ammonia volatilization with the concentration of ammonium nitrogen, the temperature, and the pH were calculated by using MATLAB. Considering the effects of temperature and pH on the CIF and IAVFs under individual conditions, we used a binary cubic model to fit the relationship between temperature and pH to the CIF and IAVFs. The simulation results showed that the correlation coefficients between the CIF and IAVFs for SAB were 0.9980 and 0.9680, respectively, and the correlation coefficients were 0.9946 and 0.9708 for SDP, respectively. The quantitative equation took into account the coefficient of determination and degrees of polynomial, and the ammonia volatilization fluxes can be calculated by using these equations.

Development of Enteric Diclofenac Sodium Microparticles Through a Spray-Drying Process Facilitated by Different Aqueous Dispersion Systems

The objective of this study was to prepare enteric diclofenac sodium microparticles using an aqueous dispersion system via spray-drying. Two aqueous-based solvent systems, phosphate buffer at pH 7.0 and ammonium hydrogen carbonate solution, were employed as the feed dispersion media in the spray-drying process based on the solubility characteristics of Eudragit® L100. At a drug-to-polymer ratio of 1:1, the optimal solids concentration in the feed dispersion was determined to be 2% w/v, as it enabled an approximately 5-30 µm smooth-surfaced spherical microparticle with a high production yield. Diclofenac sodium was efficiently encapsulated within the microparticles, existing as solid dispersion in a partially amorphous form. Notably, the spray-drying conditions utilized in this study obviated the need for further heating for microparticles prepared using ammonium hydrogen carbonate solution, as the residual ammonium could be completely eliminated during the spray-drying process. The two-stage biorelevant drug release profile of enteric microparticles demonstrated their ability to inhibit drug dissolution under acidic conditions while facilitating drug release under basic conditions. The phosphate buffer-based microparticles exhibited greater protection efficiency under acidic conditions compared to ammonium hydrogen carbonate-based systems, despite residual alkaline salt being present in the microparticles. These results validate the potential of the developed microparticles for use as an enteric drug delivery system.

Comparison of Amine-Modified Polymeric Stationary Phases for Polar Metabolomic Analysis Based on Unified-Hydrophilic Interaction/Anion Exchange Liquid Chromatography/High-Resolution Mass Spectrometry (Unified-HILIC/AEX/HRMS).

In metabolomic analysis, one of the most commonly used techniques to support the detection sensitivity and quantitation of mass spectrometry is combining it with liquid chromatography. Recently, we developed a method that enables comprehensive single-run measurement of hydrophilic metabolites using unified-hydrophilic interaction/anion exchange liquid chromatography/high-resolution mass spectrometry (unified-HILIC/AEX/HRMS) with a polymer-based mixed amines column (Gelpack GL-HilicAex). However, the importance of stationary phase functional groups and mobile phase conditions for the separation mechanisms and sensitive detection in unified-HILIC/AEX/HRMS is not yet fully understood. This study aimed to understand the importance of the mobile and stationary phases in unified-HILIC/AEX/HRMS. Two different alkali-resistant polymer-based amines-modified columns (Gelpack GL-HilicAex, primary, secondary, tertiary, and quaternary amine-modified polyglycerol dimethacrylate gel; Asahipak NH2P-50 2D, secondary amine-modified polyvinyl alcohol gel) and two eluents (acetonitrile and ammonium bicarbonate solution, pH 9.8) were used for comparative validation. A comparison of mobile phase conditions using both columns confirmed that the two-step separation from HILIC to AEX characteristic of unified-HILIC/AEX requires a linear gradient condition from acetonitrile to nearly 50% water and AEX with up to 40 mM bicarbonate ions. We found that when alkali-resistant hydrophilic polymer packing materials are modified with amines, unified-HILIC/AEX separation can be reproduced if at least one secondary amine associated with the amine series is present in the stationary phase. Furthermore, the difference in sensitivity in the HILIC and AEX modes owing to the different columns indicates the need for further improvements in the mobile phase composition and stationary phase.

The determination of underivatized chlormequat, fosetyl-aluminium and phosphonic acid residues in maize and soybean by LC-MS/MS.

In this study, a simple, rapid and sensitive method was developed for the simultaneous determination of chlormequat, fosetyl-aluminium and phosphonic acid residues in maize and soybean using liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS). Analytes were extracted with acetic acid solution, purified on an HLB column, and then filtered through a 0.2 μm hydrophilic microporous filter membrane. They were then separated on an IC column using a separation phase consisting of polyvinyl alcohol particles with quaternary ammonium groups. The mobile phase optimised with water was denoted as mobile phase A and that optimised with 200 mmol L-1 ammonium bicarbonate solution containing 0.05% ammonium hydroxide was denoted as mobile phase B. The residues were detected by tandem mass spectrometry with negative electrospray ionization in a multi-reaction monitoring mode. The correlation coefficient (R ≥ 0.997) showed good linear regressions for all analytes in water as well as in maize and soybean matrices with a wide dynamic range of 0.001 to 0.5 mg L-1 for calibration. The mean recoveries (RSDs) of the analytes were in the range 85.0-106.4% (5.5-14.9%), 81.7-109.5% (2.7-11.0%) and 74.7-104.4% (2.9-6.1%) at three concentration levels (0.05, 0.1 and 1 mg kg-1) for the interday test (n = 15). The limit of quantification (LOQ) and detection (LOD) of the method for different matrices were 0.01 and 0.003 mg kg-1, respectively. In conclusion, the established analytical approach has high sensitivity and good accuracy and precision and is suitable for monitoring chlormequat, fosetyl-aluminium and phosphonic acid residues in maize and soybean.

Effects of Amino Acid Additives on Protein Stability during Electrothermal Supercharging in ESI-MS.

The surprising formation of highly charged protein ions from aqueous ammonium bicarbonate solution is a fascinating phenomenon referred to as electrothermal supercharging (ETS). Although the precise mechanism involved is not clearly understood, previous studies predominantly suggest that ETS is due to native protein destabilization in the presence of bicarbonate anion inside the electrospray ionization droplets under high temperatures and spray voltages. To evaluate existing hypotheses surrounding the underlying mechanism of ETS, the effects of several additives on protein charging under ETS conditions were investigated. The changes in the protein charge state distributions were compared by measuring the ratios between the intensities of highest intensity charge states of native and unfolded protein envelopes and shifts in the lowest and highest observed charge states. This study demonstrated that source temperature plays a more important role in ETS compared to spray voltage, especially when using a nebulized microelectrospray ionization source. Moreover, the effect of amino acids on ETS were generally in good agreement with the extensive literature available on the stabilization or destabilization of proteins by these additives in bulk solution. Among the natural amino acids, protein supercharging was significantly reduced by proline and glycine; however, imidazole provided the highest degree of noncovalent complex stabilization against ETS, outperforming the amino acids. Overall, our study shows that the simple addition of stabilizing reagents such as proline and imidazole can reduce the extent of apparent protein unfolding and supercharging in ammonium bicarbonate solution and provide evidence against the roles of charge depletion and thermal unfolding during ETS.

Degree of Dissolution of Nickel(II) Hydroxide in Mixtures of Aqueous Solutions of Ammonia and Ammonium Bicarbonate

The degree of dissolution of nickel(II) hydroxide in mixtures of aqueous solutions of ammonia and ammonium bicarbonate has been studied. The equilibrium between the solid and liquid phases was reached in 11–12 h after the start of experiment. Nickel(II) hydroxide showed higher solubility in the ammonia–carbonate mixture compared with aqueous solutions of ammonia and ammonium bicarbonate. The ratio of ammonium bicarbonate and ammonia concentrations in solution at which the highest degree of dissolution of Ni(OH)2 was achieved was determined. An analytical description of the ion-molecular equilibrium in the ammonia– carbonate mixture was given, and the equilibrium concentrations of molecules and ions in the system were calculated. A stoichiometric equation describing the dissolution of nickel(II) hydroxide in an ammonia–carbonate solution was given.

Degree of Dissolution of Nickel(II) Hydroxide in Mixtures of Aqueous Solutions of Ammonia and Ammonium Bicarbonate

Degree of Dissolution of Nickel(II) Hydroxide in Mixtures of Aqueous Solutions of Ammonia and Ammonium Bicarbonate

Desorption of Ammonia Adsorbed on Prussian Blue Analogs by Washing with Saturated Ammonium Hydrogen Carbonate Solution

Prussian blue analogs (PBAs) have been reported as promising ammonia (NH3) adsorbents with a high capacity compared to activated carbon, zeolite, and ion exchange resins. The adsorbed NH3 was desorbed by heating and washing with water or acid. Recently, we demonstrated that desorption was also possible by washing with a saturated ammonium hydrogen carbonate solution (sat. NH4HCO3aq) and recovered NH3 as an NH4HCO3 solid by introducing CO2 into the washing liquid after desorption. However, this has only been proven for copper ferrocyanide and the relationship between the adsorption/desorption behavior and metal ions in PBAs has not been identified. In this study, we investigated the adsorption/desorption behavior of PBAs that are complexes of first row transition metals with hexacyanometalate anions. Six types of PBAs were tested in this study and copper ferricyanide exhibited the highest desorption/adsorption ratio. X-ray diffraction results revealed high structural stability for cobalt hexacyanocobaltate (CoHCC) and nickel ferricyanide (NiHCF). The Fourier transform infrared spectroscopy results showed that the NH3 adsorbed on the vacancy sites tended to desorb compared to the NH3 adsorbed on the interstitial sites as ammonium ions. Interestingly, the desorption/adsorption ratio exhibited the Irving-Williams order.

Unified-Hydrophilic-Interaction/Anion-Exchange Liquid Chromatography Mass Spectrometry (Unified-HILIC/AEX/MS): A Single-Run Method for Comprehensive and Simultaneous Analysis of Polar Metabolome.

One of the technical challenges in the field of metabolomics is the development of a single-run method to detect the full complement of polar metabolites in biological samples. However, an ideal method to meet this demand has not yet been developed. Herein, we proposed a simple methodology that enables the comprehensive and simultaneous analysis of polar metabolites using unified-hydrophilic-interaction/anion-exchange liquid chromatography mass spectrometry (unified-HILIC/AEX/MS) with a polymer-based mixed amines column composed of methacrylate-based polymer particles with primary, secondary, tertiary, and quaternary amines as functional groups. The optimized unified-HILIC/AEX/MS method is composed of two consecutive chromatographic separations, HILIC-dominant separation for cationic, uncharged, and zwitterionic polar metabolites [retention times (RTs) = 0-12.8 min] and AEX-dominant separation for polar anionic metabolites (RTs = 12.8-26.5 min), by varying the ratio of acetonitrile to 40 mM ammonium bicarbonate solution (pH 9.8). A total of 400 polar metabolites were analyzed simultaneously through a combination of highly efficient separation using unified-HILIC/AEX and remarkably sensitive detection using multiple reaction monitoring-based triple quadrupole mass spectrometry (unified-HILIC/AEX/MS/MS). A nontargeted metabolomic approach using unified-HILIC/AEX high-resolution mass spectrometry (unified-HILIC/AEX/HRMS) also provided more comprehensive information on polar metabolites (3242 metabolic features) in HeLa cell extracts than the conventional HILIC/HRMS method (2068 metabolic features). Our established unified-HILIC/AEX/MS/MS and unified-HILIC/AEX/HRMS methods have several advantages over conventional techniques, including polar metabolome coverage, throughput, and accurate quantitative performance, and represent potentially useful tools for in-depth studies on metabolism and biomarker discovery.

Determination of the species origin and thrombin-like enzyme content of Bothrops atrox venom by ultra-high performance liquid chromatography-tandem mass spectrometry based on marker peptide

蛇毒血凝酶类药物是以蝮蛇蛇毒为原料制备的止血药,主要活性成分为蛇毒类凝血酶(svTLEs)。不同蛇种来源的svTLEs结构不同,止血机制不同,药理作用也存在差异,因此准确鉴别蛇毒种属来源和svTLEs含量对于保障该类产品的质量至关重要。研究基于蛋白质组学技术,筛选出了具有种属特异性的矛头蝮蛇svTLE特征肽,并建立了基于特征肽的超高效液相色谱-串联质谱(UHPLC-MS/MS)检测矛头蝮蛇蛇毒种属来源及类凝血酶含量的方法。采用胰蛋白酶对纯化的矛头蝮蛇svTLE进行酶解,利用纳升液相色谱-四极杆/静电场轨道阱高分辨质谱(Nano LC-Q-Exactive-MS)和Proteome Discoverer 2.2软件分别进行多肽的检测和鉴定,通过BLAST搜索与Uniprot数据库对比分析,筛选出具有种属特异性的矛头蝮蛇svTLEs特征肽“EAYNGLPAK”。针对该特征肽对酶解温度、酶解时间和酶用量等样品前处理方法进行了优化,利用超高效液相色谱-串联质谱,以m/z 481.9>315.2和481.9>485.2作为检测离子对,采用ESI+模式进行了多反应监测(MRM)定性定量分析。结果显示,特征肽在2.5~30 ng/mL范围内线性关系良好,相关系数(r)大于0.9996,多水平加标回收率范围为95.5%~101.9%,各水平平行测定结果的相对标准偏差(RSD)为1.1%~3.2%,完全能够满足实际样品检测需求。方法简便快捷,灵敏度高,专属性强,可用于矛头蝮蛇蛇毒种属鉴别及svTLE含量测定,从源头保证血凝酶类产品的质量,并可为其他蛇毒类产品的质量控制提供参考。

Water and nutrient recovery from stored urine by forward osmosis with an ammonium bicarbonate draw solution

Forward osmosis with an ammonium bicarbonate draw solution was investigated as a low energy non-sewered sanitation solution, to recover nutrients and water from source separated urine. Stored urine collected from Urine Diversion Dry Toilets in the eThekwini Municipality (Durban), South Africa was used as the feed solution. Water recoveries of up to 45.9% with water fluxes up to 6.0 L m−2 h−1 were achieved using undiluted stored urine over an 8-h operating period with a 2.5 M draw solution. Rejections of up to 95% for phosphates, 85% for nitrogen and chlorides, and 75% for potassium and sodium were achieved. Low fouling of the membrane was observed after multiple runs and cleaning the membrane by circulation of deionized water or by osmotic backwash was sufficient to recover >95% of the original water flux. Little irreversible fouling was detected, assumed to be caused by carbonate calcium scaling from SEM-EDX analysis. This study suggests that forward osmosis with an ammonium bicarbonate solution could be integrated as a closed loop nutrient recycling technology for source separated urine with the prospect of clean water and draw solution recovery that could use waste heat from, for example, fecal sludge combustion.

Sustainable separation of oil from oily wastes using ionic liquids regulated by CO2

Oily wastes are easily generated in many processes of exploitation, solvent extraction is the common method for treating the oily waste. However, traditional solvent extractions are difficult to recycle the solvent, and oil is difficult to separated. As a low-volatility solvent, ionic liquid is simple in synthesis, low in cost, so it has good application prospect. In this work, the sustainable separation of oil from oily waste was implemented by using CO2-switchable ionic liquids. On the basis of solvent extraction, ionic liquids can reduced losses and costs. The CO2-switchable ionic liquids were prepared by poly (propylene glycol) bis(2-aminopropyl ether) D-230 and fatty acids with low volatility at the mole ratio of 1:2. Upon the alternate bubbling CO2 and N2, ionic liquids could be transformed alternately from water-miscible state to water-immiscible state. The water-immiscible state was bi-phasic system containing hydrophobic fatty acids and ammonium bicarbonate solution by bubbling CO2. Based on the bi-phasic system, the oil (kerosene, paraffin oil and crude oil) could be mixed with fatty acids, and were separated from fatty acids in the hydrophilic state upon N2, where the recovery rate of oil was more than 97% and fatty acids was not residual in recovered oil. Treating oily waste, the oil could be extracted from oily waste by the bi-phasic system. The ionic liquids were reused and the oil was separated by bubbling N2 without extra additives, where the recovery rate of oil from oily waste was more than 85.57%. Due to the simplified process and negligible solvent loss, the economic benefit of recovering per barrel crude oil reached 76.7% of the price of crude oil. Compared with the existing technology, this sustainable separation is simpler, more economical and more environmentally friendly. Hence, it is expected that this sustainable separation based on CO2-switchable ionic liquids will meet the development of green separation with low-energy consumption.

Biogenic preparation of biphasic calcium phosphate powder from natural source of snail shells: bioactivity study

In this present work, carbonated apatite powder (CAP) and β-tricalcium phosphate (β-TCP) were prepared from waste snail shells via thermal decomposition followed by chemical precipitation method with phosphoric acid in a one step process. The CAP produced was thereafter reacted with a pore forming agent solution of ammonium bicarbonate to formed carbonated apatite powder- ammonium bicarbonate scaffold composites (CAP-AMB) and was deployed in a bioactivity experiment with simulated body fluid (SBF) media. The phase purity, crystallinity, particle size, thermal behaviour, elemental composition, morphology as well as the functional groups of snail shells, synthesized CAP and CAP-AMB scaffold were assessed by XRD, FE-SEM, TGA, EDX, TEM and FT-IR. XRD and selected area electron diffraction (SAED) results confirmed the synthesized apatite as pure amorphous powder which upon heat treatment, transformed to polycrystalline powder. Analysis of FT-IR results revealed that the apatite produced from snail shells (SS) contains phosphates and hydroxyl functional groups. Furthermore, the formation of carbonated apatite was also confirmed from the FT-IR result with peaks which appeared at 882 and 1484 cm−1 respectively, thus depicting a B-type apatite. Microscopy analyses by FE-SEM and TEM indicated that the prepared apatite is composed of different morphologies in the range of 5 to 200 nm long. The presence of trace elements such as K, C, Na, Mg and Mg which could play crucial functions in biological applications were detected by EDX measurement alongside Ca and P. The mixture of CAP with AMB produced interconnected pores structure with porosity in the range of 35–67%. The bioactivity study of the SBF treated CAP-AMB composite confirmed apatite formation on the scaffold surface which totally covered the pores after seven days of incubation. Thus, waste biomaterial of snail shells origin can be use for the production of pure apatite that could be useful in medical application.Graphical abstract

Determination of donkey skin ingredients in Asini Corii Colla by ultra-high performance liquid chromatography-tandem mass spectrometry

近年来由于驴皮资源短缺,阿胶价格大幅度上涨,市场上出现了大量以马、骡、猪、牛皮等熬制而成的假胶,导致阿胶质量的参差不齐,严重扰乱了市场,急需高效准确的检测方法提升阿胶品质。该研究采用超高效液相色谱-串联质谱技术,建立了阿胶中驴皮源成分的检测方法。样品加水溶解后,于37 ℃下经胰蛋白酶酶解,产生驴源性特征肽段,以0.1%甲酸乙腈溶液和0.1%甲酸水溶液作为流动相进行梯度洗脱,单次分析时间10 min,在电喷雾正离子(ESI+)模式下进行多反应监测(MRM),同位素内标法定量。驴源多肽A1、A2在50~1250 μg/L范围内线性关系良好,相关系数(r)均大于0.996,方法定量限(S/N=10)为20 mg/kg,在300、600、900 mg/kg 3个添加水平上驴源多肽A1、A2的回收率范围为103.2%~108.3%,各加标水平平行测定结果的相对标准偏差(RSD)为1.0%~3.0%,完全能够满足实际样品检测需求。对29批不同生产企业的阿胶进行测定,结果表明,不同企业生产的阿胶中驴源多肽A1、A2的含量之和存在差异,含量为0.096%~0.180%,平均值为0.151%,提示驴源多肽A1、A2含量较低的阿胶生产厂家应注重皮源质量,改进生产工艺,以提升产品质量。该方法操作简便,结果可靠,重现性好,可用于阿胶中驴皮源成分的测定。

Synthesis and Consolidation of Ag/ZnO Composite Powders via SPS Method

The present research was conducted to synthesize and densify Ag/8wt.% ZnO composites via co-precipitation and spark plasma sintering (SPS) methods. The initial precipitates were precipitated by adding ammonium hydrogen carbonate solution to a solution mixture of silver and zinc nitrate. The precipitates were characterized by using the particle size analyzer and X-ray diffraction techniques. The precipitates were calcined at 500°C and consolidated with SPS method for 5 and 10 min at 540°C under 35 MPa in vacuum. The results showed that rearrangement and bulk deformation had a significant effect on densification of the composite powders. The scanning electron microscopy investigations revealed that the SPSed composites had nearly dense microstructures with homogenous and fine dispersion of ZnO particles within the silver matrix. Moreover, it was confirmed that prolonging the sintering time from 5 to 10 min had no significant effect on the microstructure, relative density and hardness of the samples. Composites with relative densities above 99% and 62 HV hardness were synthesized through the applied procedure.

Ammonium salt production in NH3-CO2-H2O system using a highly selective adsorbent, copper hexacyanoferrate

Ammonia is a beneficial material that is widely used in agriculture, but its emission into the atmosphere causes air pollution. Recently, Prussian blue (PB) and its analogs (PBA) were found to be ammonia adsorbents with high selectivity and capacity. In this study, we utilized a highly potent PBA adsorbent, copper hexacyanoferrate (CuHCF), to desorb ammonia and turn it into a reusable form. Because the reported NH3-CO2-H2O system phase diagram suggests the possibility of the recovery of solid NH4HCO3, we examined whether adsorbed ammonia desorbs into the saturated ammonium hydrogencarbonate solution (sat. NH4HCO3aq). We demonstrated that 40% of adsorbed ammonia desorbed into sat. NH4HCO3aq. After the desorption, CO2 was blown into the washing liquid, and NH4HCO3 precipitated, which was confirmed by Fourier transform infrared spectroscopy. The molar amount of solid NH4HCO3 was almost equal to that of desorbed ammonia. Our findings pave the way for recovery of ammonia as a valuable product from waste gas.

Preparation of rod-like γ-alumina/volcanic rock porous material and the adsorption property of Congo red

The porous materials of rod-like γ-alumina interlaced in pores of volcanic rock were prepared by in-situ growth using volcanic rock as matrix material, aluminum nitrate and ammonium bicarbonate as raw materials. The structure and properties of the materials were characterized by XRD, SEM, N2 adsorption-desorption and TG-DSC technology. The adsorption performance of Congo red was also studied. It was found that the aluminum nitrate solution filled the pores of volcanic matrix materials by diffusion and adsorption, and amorphous alumina was formed after calcination. During hydrothermal treatment and calcination, the formed alumina was transformed into ammonium aluminum carbonate hydroxide and γ-alumina. The optimal reaction conditions for the preparation of rod-like γ-alumina/volcanic rock porous materials were as following: the concentration of ammonium bicarbonate solution was 0.8 mol/L, the reaction temperature was 140°C, and the reaction time was 4 h. The rod-like γ-alumina stacked in the channels of volcanic rock with a diameter of 50–150 nm and length of 3–10 μm. The specific surface area and pore volume of the porous material was 0.1 mL/g and 47 m2/g, respectively. When the concentration of Congo red solution was 500 mg/L and the dosage of porous material was 2 g/L, the removal rate was 96% with the adsorption amount of 243 mg/g.

The Influence of Concentration and Temperature on the Membrane Resistance of Ion Exchange Membranes and the Levelised Cost of Hydrogen from Reverse Electrodialysis with Ammonium Bicarbonate.

The ohmic resistances of the anion and cation ion-exchange membranes (IEMs) that constitute a reverse electrodialysis system (RED) are of crucial importance for its performance. In this work, we study the influence of concentration (0.1 M, 0.5 M, 1 M and 2 M) of ammonium bicarbonate solutions on the ohmic resistances of ten commercial IEMs. We also studied the ohmic resistance at elevated temperature 313 K. Measurements have been performed with a direct two-electrode electrochemical impedance spectroscopy (EIS) method. As the ohmic resistance of the IEMs depends linearly on the membrane thickness, we measured the impedance for three different layered thicknesses, and the results were normalised. To gauge the role of the membrane resistances in the use of RED for production of hydrogen by use of waste heat, we used a thermodynamic and an economic model to study the impact of the ohmic resistance of the IEMs on hydrogen production rate, waste heat required, thermochemical conversion efficiency and the levelised cost of hydrogen. The highest performance was achieved with a stack made of FAS30 and CSO Type IEMs, producing hydrogen at 8.48× 10 kg ms with a waste heat requirement of 344 kWh kg hydrogen. This yielded an operating efficiency of 9.7% and a levelised cost of 7.80 € kg.

A Novel Methodology for Online Analysis of Amine Solution Degradation Caused by Fly Ash

Two research goals were set for this study. (1) The first goal was to develop a reliable and cost-effective online analytical technique to measure amine solvent concentration, loading, and to quantify the amine degradation process based on Gas Chromatography (GC). (2) The second goal was the investigation of amine degradation in the presence of fly ash, which includes: the identification of proper chemistry of degradation; and, the identification and quantification of the degradation products of the amines. For this study, aqueous monoethanolamine (MEA) and aqueous methyldiethanolamine (MDEA) have been selected. To accomplish the first goal, an online analytical technique to quantify the amine solvent chemistry based on Gas Chromatography (GC) was developed and set up in the lab. An automatic liquid sample injection system was attached to the GC to study the impact of the concentration of fly ash on the degradation process of two well-known amines (MEA and MDEA) by measuring the concentrations of amine, water and carbon dioxide (CO2). The flow system was equipped with filters to avoid the introduction of large particles into the GC column. A solvent back-flush system was used to allow for automated cleaning of the particulate filters. GC was then calibrated for the amine and water using various concentrations of aqueous amines (MEA and MDEA), and various CO2 loaded aqueous MDEA solutions and aqueous solutions of ammonium bicarbonate (NH4HCO3) were used to calibrate the GC for quantification of CO2 using a Total Organic Carbon / Total Inorganic Carbon (TOC/TIC) analyzer. To accomplish the second goal, two kinds of fly ash samples were collected from a coal burning power plant. Fly ash samples collected from the power plant were analyzed by SGS Canada Inc. ASTM methods were used to estimate the ash percentage, moisture content and elemental composition of the fly ash (silica and other metal oxides). A lab scale experimental setup was designed and developed to observe the influence of fly ash on amine-based solvents (MEA or MDEA) degradation.