pH Neutralization while Succinic Acid Adsorption onto Anion-Exchange Resins

Succinic acid is a useful chemical and its purification from fermentation broth by ion-exchange resins has widely drawn attention. In this study, pH neutralization in the process of adsorption of succinic acid from model solutions and fermentation broth by anion-exchange resin NERCB 04 has been tested. Adsorption capacity of NERCB 04 was about 0.41 g succinic acid/g resin at concentrations of succinic acid in the range of 10–50 g/L in packed column. In the process of succinic acid removal, pH of the system could also be neutralized. The neutralizing ability of the resin as a neutralizing agent has also been studied in the model cycle system and in the real fermentation cycle process. It was found that NERCB 04 showed stable adsorption capacity and pH neutralization ability after each regeneration. A certain amount of anion-exchange resin could neutralize the low pH values (pH 2–5) and maintain the system around pH 7.0. This means the anion-exchange resins have the function of neutralizing reagent in the process of adsorbing succinic acid.     

强酸性阳离子交换树脂催化合成丁二酸二丁酯

用强酸性阳离子交换树脂催化丁二酸和正丁醇的酯化反应,合成了丁二酸二丁酯。研究了影响反应的因素和催化剂的重复使用性能,在丁二酸25mmol,正丁醇200mmol和催化剂1．5g,回流分水120min的反应条件下,酯化率达95．7％。催化剂套用5次,其活性未发生明显变化。     

Assessment of the sorption capacity and regeneration of carbon dioxide sorbents using thermogravimetric methods

Adsorption methods using solid sorbents are an alternative to the absorption technology in the processes of purification gases from carbon dioxide. There is a need to rapidly assess the suitability of sorbents for use it in PSA, TSA, or VPSA installations. Important parameters which determine the quality of the sorbent are the sorption capacity of sorbent, selectivity to CO₂ and the possibility of regeneration. This paper presents the results of sorption/desorption of CO₂ study on the impregnated porous materials using thermogravimetric methods. Thermogravimetry allows for rapid assessment of sorption capacity and regeneration of the sorbents. Specially selected temperature program allowed to determine the sorption capacity of sorbents depending on the concentration of CO₂ in the gas mixture and temperature. Degree of sorbent purification was determined in desorption process.     

New SPE column packing material: Retention assessment method and its application for the radionuclide chromatographic separation

The preparation of the OASIS?-HLB sorbent based solid phase extraction (SPE) resins and their application for the ¹⁷⁷Lu radioisotope separation were investigated. Di-(2-ethylhexyl) orthophosphoric acid (HDEHP) impregnated OASIS-HLB sorbent based SPE resins (OASIS-HDEHP) were successfully developed from this investigation. The wettable porosity structure of the moderately extractant impregnated OASIS-HDEHP resins is favorable for the effective diffusion of polar and ionic solutes giving good separation performance. Its good wetting ability offers ease of packing into conventional chromatographic columns. Their off-gassing-free operation makes OASIS-HDEHP columns good for long term use with highly consistent elution dynamics (several dozens of separations perfectly achievable on the same column). The simple method for the capacity factor (k’) evaluation was developed to facilitate the characterization of the SPE chromatographic resin column. A competent procedure using OASIS-E30RS resin (one member of the OASIS-HDEHP resin group) for the separation of no-carrier added (n.c.a) ¹⁷⁷Lu from the bulk amount of Yb target was developed. This separation procedure has showed very good performance with several prominent advantages such as the much shorter separation time (5–6 hours) and high reproducibility. Its high adsorption capacity for Yb and Lu makes it ideal for the separation of the bulky sample (50 mg Yb target for the 20 g weight resin column) for the production of the several Ci of ¹⁷⁷Lu radioactivity.     

Effect of binder on the properties of iron oxide sorbent for hot gas desulfurization

The most difficult problem in hot gas desulfurization in Integrated Coal Gasification Combined Cycle (IGCC) is the pulverization of sulfur removal sorbents. Appropriate binders for hot gas sulfur removal sorbents can solve the pulverization problem. In this paper, six sorbents with binders of different argillaceous minerals were prepared by mechanical mixing method. Desulfurization behavior for hot gas desulfurization sorbents was investigated in a fixed-bed reactor. Result showed that sorbent NTKW2 with binder of clay had a better sulfidation performance. NTKW2 had a more stable performance than other sorbents in the continuous sulfidation-regeneration cycles. Sulfur capacity of sorbent remained the same in each cycle. The desulfurization efficiency and mechanical strength of NTKW2 were the best among the tested sorbents. The behavior of NTKW2 at different temperatures showed different performances, and the best reaction temperature was 550 ℃. Higher heat stability, sulfur capacity and desulfurization efficiency were found on NTKW2 in six continuous sulfidation-regeneration cycles.     

Removal of mercury(II) and methylmercury from solution by tannin adsorbents

Adsorption of mercury(II) and methylmercury by two tannin sorbents was investigated using radiotracers. High sorption capacities for mercury are registered for both sorbents at pH 7. ForEucaliptus Saligna Sm sorbent (ETS) the maximum sorption capacity was 1.2±0.2 mmol/g and forLysiloma latisiliqua sorbent (LTS) was 8.5±0.2 mmol/g. Methylmercury adsorption maximum was recorded at pH 4 and in buffered solutions at pH2. This species can be recovered in the presence of mercury(II). Influence of different ions present in water was examined. High recoveries were reported for ETS in tap water samples but a decrease of uptake is observed for seawater.     

Application of different types of resins in the radiometric determination of uranium in waters

The aim of this study is to compare different resins regarding their separation and pre-concentration efficiency for uranium from aqueous solutions and its subsequent radiometric determination by liquid scintillation counting (LSC). The different types of the investigated resins include: (a) a pure cation-exchange resin (Dowex Marathon C), (b) a complex forming resin (Chelex 100) and (c) an impregnated resin (5% diethylene glycol succinate on Chromosorb W-H). The radiometric measurements were performed after mixing of the pre-concentrated aqueous phase with the liquid scintillation cocktail. The effect of experimental conditions such as pH, salinity (e.g. [NaCl]) and the presence of other chemical species (e.g. Ca²⁺ and Fe³⁺ ions or humic acid and silica colloids) on the separation recovery have been investigated at constant uranium/radioactivity concentration. According to the experimental results the maximum chemical recovery differs significantly from one resin to another as a function of either, pH or the other chemical parameters. The optimum pH is found to be 8, 4 and 8 for Marathon C, Chelex-100 and diethylene glycol succinate, respectively. On the other hand, generally Ca²⁺ and Fe³⁺ ions as well as the presence of colloidal species in solution (even at low concentrations) result in a significant decrease of the chemical recovery of uranium, particularly for Marathon C and the diethylene glycol succinate impregnated resins. Generally, among the studied resins Chelex 100 was superior regarding chemical recovery, selectivity, regeneration and reuse.     

Flame AAS determination of lead in water with flow-injection preconcentration and speciation using functionalized cellulose sorbent

The on-line solid phase extraction of trace amount of lead in flow-injection system with flame AAS detection was investigated using cellulose sorbents with phosphonic acid and carboxymethyl groups, C(18) sorbent non-modified and modified with Pyrocatechol Violet or 8-quinolinol, commercial chelating sorbents Chelex 100 and Spheron Oxin 1000, non-polar sorbent Amberlite XAD-2 modified with Pyrocatechol Violet and several cation-exchange resins. The best dynamic characteristics of retention were observed for functionalized cellulose sorbents. For Cellex P assumed as optimum sorbent, elution with a separate fractions of nitric acid and ethanol allows the differentiation between tetraalkyllead and sum of inorganic lead and organolead species of smaller number of alkyl groups. The detection limit for the determination of inorganic Pb(II) was estimated as 0.17 microg/l. at preconcentration from 50 ml sample at a flow rate of 7 ml/min.     

Use of Adsorbents for Recovery of Acetic Acid from Aqueous Solutions Part III—Solvent Regeneration

Solvent leaching was investigated as a method of regeneration for activated carbons and polymer sorbents loaded with acetic acid by contact with aqueous solutions. Both batch-equilibration and fixed-bed experiments were employed. Methanol, methyl acetate, and acetone are suitable regeneration solvents for most activated carbons. Amoco GX-031 is an exception, giving incomplete regeneration. Methanol provides still more efficient regeneration for macroreticular styrene-divinylbenzenes adsorbents. Among basic sorbents, amine resins give incomplete regeneration by solvent leaching, as does a poly N oxide. Polybenzimidazole, a weaker base, gives higher recoveries of acetic acid when leached by solvents. Poly(4-vinylpyridine) is regenerated completely and efficiently by methanol, methyl acetate, and acetone in a fixed-bed geometry. It thus appears that an intermediate degree of basicity is desirable in a synthetic sorbent for acetic acid – strong enough to give the uptake benefits of acid-base interactions, but weak enough to be regenerable.     

离子交换法分离乳酸转化液中的丙酮酸

从13种树脂中筛选出SD-4型弱碱性离子交换树脂,用于分离乳酸转化液中的丙酮酸.考察了不同操作条件对固定床离子交换效果的影响.结果表明,上样pH为1.85,流速1.5BV/h时,可得到较高的工作交换容量(2.08mmol/g湿树脂),并且可以用流出液pH 2.5作为判断终止进样的依据;考察了固定床洗脱工艺条件,结果表明,去离子水淋洗即可除去乳酸,然后用盐酸洗脱丙酮酸.当盐酸浓度为2.0mol/L,逆流洗脱速度为1.0BV/h时,洗脱效果较好.采用较佳工艺进行固定床单柱操作,丙酮酸的收率达到85%.     

Performance evaluation of two chelating ion-exchange sorbents for the fractionation of labile and inert metal species from aquatic media

The performance of two iminodiacetate chelating resins, applied in an element fractionation scheme, was investigated for the characterization of marine and stream water samples collected in potentially contaminated harbor and industrial zones. The comparison involved an evaluation of the sorption/desorption behavior of Cd, Cu, Pb and Zn on Chelex-100, a sorbent extensively employed for metal speciation studies, and on Lewatit TP-207, a material with similar chelating characteristics for which no applications for fractionation studies are reported. A characterization of the latter resin in terms of the influence of sample pH on the uptake of metals from aqueous solutions and their subsequent acid elution was carried out. Fractionation studies were performed on natural water samples and model solutions resembling their composition, spiked with micromolar concentrations of the metals. The operationally defined fractionation scheme is based on dynamic adsorption of the resin-labile fractions of metals on microcolumns made of the sorbents. This stage is followed by a batch procedure in which the eluent from the column is contacted with fresh resin to discriminate between the relatively stable species unable to react with the resin during the column interaction time, and the strongly complexed metals that do not interact with the sorbent even for periods of several hours. Results were obtained from coarsely filtered sub-samples and from specimens passed through membrane filters of pore size 0.45 and 0.22 µm. The method was also assessed with model solutions of the metals containing variable concentrations (in the 10^-3–10^-7 molar range) of complex forming agents such as nitrilotriacetic acid and trans-1,2-diaminocyclohexane-N,N,N,N-tetraacetic acid. An additional batch method, in which a fixed amount of resin was contacted with sample solution for increasing periods of time and the amount of metal remaining in solution measured as a function of the elapsed time, was used to obtain information on the kinetics of dissociation of species formed in the presence of added complexants. The behavior of both resins was similar, demonstrating that the discrimination of species derived from experiments with Chelex-100 may be properly validated by independent fractionation tests carried out with Lewatit TP-207. The behavior of the sorbents is also discussed in terms of the possible influence of particulate or colloidal materials and of kinetic effects related to the presence of complexing agents.     

流动注射离子选择电极法自动测定阳离子交换树脂交换容量的研究

基于流动注射离子选择电极法(FIA-ISE)测定痕量Na 原理,建立了一种能自动测定阳离子交换树脂各种交换性能的方法,对影响阳阳离子交换树脂交换容量的各种因素进行考察,筛选出凝胶型强阳离子交换树脂(SACR)交换性能测定的最佳条件:微型交换柱内径3.0mm、长80mm;树脂填充量0.1951g;再生剂HCl浓度为3.0%,其流速为0.90mL/min(7.64m/h),再生剂耗量350mL/g(干树脂);样品为20mg/LNa 溶液,其流速为1.50mL/min;实现了一次测定同时获得SACR的工作交换容量、平衡交换容量、全交换容量、交换速率和树脂利用率。与ASTM法进行对照实验,其结果相关性良好(r=0.9922)。     

Effects of alumina phases on CO2 sorption and regeneration properties of potassium-based alumina sorbents

A range of potassium-based alumina sorbents were fabricated by impregnation of alumina with K₂CO₃ to examine the effects of the structural and textural properties of alumina on the CO₂ sorption and regeneration properties. Alumina materials, which were used as supports, were prepared by calcining alumina at various temperatures (300, 600, 950, and 1,200 °C). The CO₂ sorption and regeneration properties of these sorbents were examined during multiple tests in a fixed-bed reactor in the presence of 1 vol% CO₂ and 9 vol% H₂O. The regeneration capacities of the potassium-based alumina sorbents increased with increasing calcination temperature of alumina. The formation of KHCO₃ increased with increasing calcination temperature during CO₂ sorption, whereas the formation of KAl(CO₃)(OH)₂, which is an inactive material, decreased. These results is due to the fact that the structure of alumina by the calcination temperature is related directly to the formation of the by-product [KAl(CO₃)(OH)₂]. The structure of alumina plays an important role in enhancing the regeneration capacity of the potassium-based alumina sorbent. Based on these results, a new potassium-based sorbent using δ-Al₂O₃ as a support was developed for post-combustion CO₂ capture. This sorbent maintained a high CO₂ capture capacity of 88 mg CO₂/g sorbent after two cycles. In particular, it showed a faster sorption rate than the other potassium-based alumina sorbents examined.     

Production of succinic acid by anaerobiospirillum succiniciproducens

The effect of an external supply of carbon dioxide and pH on the production of succinic acid byAnaerobiospirillum succiniciproducens was studied. In a rich medium containing yeast extract and peptone, when the external carbon dioxide supply was provided by a 1.5M Na₂CO₃ solution that also was used to maintain the pH at 6.0, no additional carbon dioxide supply was needed. In fact, sparging CO₂ gas into the fermenter at 0.025 L/L-min or higher rates resulted in significant decreases in both production rate and yield of succinate. Under the same conditions, the production of the main by-product acetate was not affected by sparging CO₂ gas into the fermenter. The optimum pH (pH 6.0) for the production of succinic acid was found to be in agreement with results previously reported in the literature. Succinic acid production also was studied in an industrial-type inexpensive medium in which light steep water was the only source of organic nutrients. At pH 6.0 and with a CO₂ gas sparge rate of 0.08 L/L-min, succinate concentration reached a maximum of 32 g/L in 27 h with a yield of 0.99 g succinate/g glucose consumed.     

Effect of Calcium Oxide Additive on Sorbent for High-Temperature the Performance of Iron Oxide Coal Gas Desulfurization

The effect of calcium oxide additive in iron oxide sorbent for hot gas desulfurization was investigated by XRD and TPR techniques. XRD characterization showed that CaO was highly dispersed after the calcination of sorbents. Calcium sulfate formed in the desulfurization was decomposed and regenerated to CaO by reacting with CO before the next sulfidation process. Calcium participated in every sulfidation/regeneration cycle and contributed to the enhancement of sulfur capacity. The TPR results showed that the reduction temperature of the sorbent increased with the increase of the content of calcium. Calcium played a role of retarding reduction. Therefore, the addition of calcium oxide additive will benefit the utilization of iron oxide sorbent in strongly reducing atmospheres.     

Effect of Calcium Oxide Additive on the Performance of Iron Oxide Sorbent for High-Temperature Coal Gas Desulfurization

The effect of calcium oxide additive in iron oxide sorbent for hot gas desulfurization was investigated by XRD and TPR techniques.XRD characterization showed that CaO was highly dispersed after the calcination of sorbents.Calcium sulfate formed in the desulfurization was decomposed and regenerated to CaO by reacting with CO before the next sulfidation process.Calcium participated in every sulfidation/regeneration cycle and contributed to the enhancement of sulfur capacity.The TPR results showed that the reduction temperature of the sorbent increased with the increase of the content of calcium.Calcium played a role of retarding reduction.Therefore,the addition of calcium oxide additive will benefit the utilization of iron oxide sorbent in strongly reducing atmospheres.     

Graphene oxide based molecularly imprinted polymers modified with β‐cyclodextrin for selective extraction of di(2‐ethylhexyl) phthalate in environmental waters

Graphene oxide based molecularly imprinted polymers modified with β‐cyclodextrin were prepared as solid‐phase extraction column sorbents for specific recognition and sensitive detection of di(2‐ethylhexyl) phthalate in water samples. The morphology and composition of synthesized sorbents were characterized by scanning electron microscopy, thermo‐gravimetric analysis, Raman spectroscopy, and Fourier‐transform infrared spectroscopy. The conditions affecting the performance of extraction procedures such as desorption solvent types and volume, sample pH and volume were investigated. The loading capacity (8.2 μg/mg) of the prepared sorbents increased eight times after modification with β‐cyclodextrin. The developed extraction procedures coupled to high‐performance liquid chromatography exhibited good linearity (0.2–500 μg/L), low limit of detection (0.052 μg/L), and good precision (relative standard deviation?5.7%) under optimized conditions. The developed solid‐phase extraction technique with prepared sorbents has been successfully applied in extracting trace di(2‐ethylhexyl) phthalate from real natural waters with high efficiency, good selectivity, and desirable recoveries.     

Sorption of carbon dioxide by the composite sorbent “potassium carbonate in porous matrix”

Sorption of CO₂ in the presence of water vapor by the K₂CO₃—-Al₂O₃ composite sorbent was studied by IR spectroscopy in situ, X-ray diffraction analysis, and the differentiating dissolution method and reasons for a decrease in its dynamic capacity are given. The samples containing K₂CO₃·1.5H₂O in pores are characterized by the maximal dynamic capacity. A mechanism for CO₂ sorption was proposed, which qualitatively explains the obtained dependence of the capacity on the water content in the composite sorbent. A high dynamic capacity can be maintained by regeneration of the sorbents by water vapor at 170 °N. The capacity of the sorbents decreases during the first 10 sorption—regeneration cycles due to the formation of an inactive phase of potassium aluminum carbonate.     

Continuous production of succinic acid by a fumarate-reducing bacterium immobilized in a hollow-fiber bioreactor

Enterococcus faecalis RKY1, a fumarate-reducing bacterium, was immobilized in an asymmetric hollow-fiber bioreactor (HFBR) for the continuous production of succinic acid. The cells were inoculated into the shell side of the HFBR, which was operated in transverse mode. Since the pH values in the HFBR declined during continuous operation to about 5.7, it was necessary to change the feed pH from 7.0 to 8.0 after 24 h of operation in order to enhance production of succinic acid. During continuous operation with a medium containing fumarate and glycerol, the productivity of succinate was 3.0–10.9 g/(L·h) with an initial concentration of 30 g/L of fumarate, 4.9–14.9 g/(L·h) with 50 g/L of fumarate, and 7.2–17.1 g/(L·h) with 80 g/L of fumarate for dilution rates between 0.1 and 0.4 h⁻¹. The maximum productivity of succinate obtained by the HFBR (17.1 g of succinate /[L·h]) was 1.7 times higher than that of the batch bioconversions (9.9 g of succinate /[L·h]) with 80 g/L of fumarate. Furthermore, the long-term stability of the HFBR was demonstrated with a continuously efficient production of succinate for more than 15 d (360 h).     

侧链液晶聚醚螯合树脂研究进展

相对于传统聚醚螯合树脂,侧链液晶聚醚型螯合树脂由于刚性介晶基元的引入,赋于了聚醚分子更好的使用性能,具有热稳定性好、吸附容量大、离子选择性高、易于设计与合成等优势,成为近年来树脂领域研究的热点之一。本文介绍了近年来国内外侧链液晶聚醚螯合树脂的合成、性能与应用现状。最后依据对侧链液晶聚醚螯合树脂机械性能、吸附选择性、再生性能以及环保性能的使用要求,对其分子设计与合成方法及新应用领域进行了展望。