Spherical Resorcinol‐Formaldehyde Resin Testing for Cesium Removal from Hanford Tank Waste Simulant

Abstract

A new spherical form of resorcinol‐formaldehyde (RF) resin was tested for efficacy of cesium removal from Hanford tank waste. Two spherical RF formulations, prepared by varying curing temperature, were tested. Both resins had a tight particle size distribution and a high degree of sphericity. Small‐scale column testing (on ～20‐mL resin beds) was conducted evaluating the cesium load profile with AZ‐102 simulated tank waste and the cesium elution profile using 0.5 M HNO₃ eluant. The load and elution profiles were compared in side‐by‐side testing with ground‐gel RF resin and SuperLig® 644, the Waste Treatment Plant baseline ion exchanger. Although breakthrough capacity was not as high as the other resins tested, the spherical RF resin met plant cesium loading requirements with the AZ‐102 simulant matrix. Excellent reproducibility of cesium load and elution was demonstrated over three process cycles with no evidence of degraded performance. Residual cesium on the resin beds after elution was nearly a factor of 10 lower than that of the ground‐gel RF and SuperLig^® 644.     

Multiple Ion Exchange Column Tests for Cesium (CS+) Removal from Hanford Site Tank 241‐AW‐101 with SuperLig® 644 Resin

Abstract

Six cycles of loading, elution, and regeneration were performed to remove cesium (Cs⁺) from a Hanford Site tank waste sample using SuperLig^® 644 resin. The sample, which was retrieved from Tank 241‐AW‐101, was diluted to 5.09 M Na⁺ and processed through dual ion exchange columns to remove ¹³⁷Cs. Each column had an inside diameter of 1.45 cm and a height of 30 cm; and contained 15 mL of wet resin in the sodium form. The columns, designated as primary (lead) and polishing (lag), were connected in series during loading, but they were separated during elution and regeneration. The cesium loading on the primary column during the six cycles ranged from 160 to 225 bed volumes (BV) at <50% breakthrough. A gradual decline of the resin loading performances was observed as a function of number of loading cycles. For all cycles, the percent removal of cesium (¹³⁷Cs) was greater than 99.99% and the decontamination factors (DFs) achieved were higher than 1.0 × 10⁴. Elution of the resin with 0.5 M nitric acid at 25 ± 2°C was effective. Approximately 99% of the ¹³⁷Cs bound on the resin was eluted with less than 15 BV of the eluent (0.5 M nitric acid). The cumulative dose absorbed by the resin in the primary column was 1.99 × 10⁷ rad with a 20% loss of ion exchange capacity was at 50% breakthrough after completing six loading cycles.     

Cesium Removal Demonstration Using Selected Actual Waste Samples from the Hanford Reservation Tank Farm

Abstract

Approximately 40 million curies of Cs‐137 are currently contained in High Level Waste stored in 177 underground storage tanks at the Hanford Nuclear Reservation near Richland, Washington. A series of actual waste, small‐scale column tests were performed to evaluate the performance of a selected ion exchange resin for cesium removal from a range of planned feed streams. These tests demonstrated that the selected cationic resin–SuperLig 644^®‐has more than adequate resin capacity to treat each of three potential feed streams. Furthermore, tests indicate an acceptable mass transfer zone for each of the three types of feed material, and that the elution of the resin can be accommodated within the design criteria for the proposed Waste Treatment Plant.     

Modeling Ion-Exchange for Cesium Removal from Alkaline Radioactive Waste Solutions

Abstract

The performance of spherical Resorcinol-Formaldehyde ion-exchange resin for treatment of radioactive waste solutions is investigated through computer modeling. Results show that ion-exchange is an efficient method for cesium removal from highly alkaline radioactive waste solutions. On average, two 1300 liter columns operating in series are able to treat 690,000 liters of waste with an initial cesium concentration of 0.09 mM in 11 days achieving a decontamination factor of over 50,000. The study investigated the sensitivity of ion-exchange column performance to variations in flow, temperature, and column dimensions. Modeling results can be used to optimize the design of the ion exchange system.     

Spherical Resorcinol‐Formaldehyde Performance Testing with Hanford Tank Waste

The efficacy of a new spherically engineered form of resorcinol‐formaldehyde (RF) resin was tested for cesium removal on two actual Hanford tank wastes. Small‐scale processing was conducted according to the River Protection Project‐Waste Treatment and Immobilization Plant flowsheet in a lead‐lag column format. The RF resin processed 95 bed volumes (BVs) of high potassium‐bearing waste (AP‐101) and >200 BVs of a high complexant‐bearing waste (AN‐102) before reaching 50% cesium breakthrough. Elution with 0.5 M nitric acid was effective and complete after processing 16 BVs. Cesium and other analyte fractionations to the process stream effluent and eluate were evaluated. The RF resin resulted in very little metal and radionuclide fractionation, other than cesium, to the eluate. The spent resins were measured for most analytes relevant to land‐disposal requirements. The actinide concentrations on the spent resins were <3% of the transuranic waste limit; the residual cesium concentrations were <4 mCi/kg; chromium was the only metal, regulated by the Resource Conservation Recovery Act, that was measured in quantities significant to land‐disposal regulations.     

High Aspect Ratio Ion Exchange Resin Bed – Hydraulic Results for Spherical Resin Beads

Abstract

A principal role of the DOE Savannah River Site is to safely dispose of a large volume of liquid nuclear waste held in many storage tanks. An in-tank ion exchange unit is being considered for cesium removal to accelerate waste processing. This unit is planned to have a relatively high bed height to diameter ratio (10:1). Complicating the design is the need to cool the ion exchange media; therefore, the ion exchange column will have a central cooling core making the flow path annular. To separate cesium from waste the media being considered is made of resorcinol formaldehyde resin deposited on spherical plastic beads and is a substitute for a previously tested resin made of crystalline silicotitanate. This spherical media not only has an advantage of being mechanically robust, but, unlike its predecessor, it is also reusable, that is, loaded cesium can be removed through elution and regeneration. Resin regeneration leads to more efficient operation and less spent resin waste, but its hydraulic performance in the planned ion exchange column was unknown. Moreover, the recycling process of this spherical resorcinol formaldehyde causes its volume to significantly shrink and swell. To determine the spherical media's hydraulic demand a linearly scaled column was designed and tested. The waste simulant used was prototypic of the wastes' viscosity and density. This paper discusses the hydraulic performance of the media that will be used to assist in the design of a full-scale unit.     

A ROBUST ALKALINE-SIDE CSEX SOLVENT SUITABLE FOR REMOVING CESIUM FROM SAVANNAH RIVER HIGH LEVEL WASTE#

ABSTRACT

A robust solvent suitable for extracting cesium from alkaline nitrate media like that of the high-level liquid waste stored at the U.S. Department of Energy Savannah River Site has been developed. The solvent is composed of the cesium extractant calix[4]arene-bis-(tert-octylbenzo-crown-6) (“BOBCalixC6”) at 0.01 M, the modifier l-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol (“Cs-7SBT”) at 0.50 M, trioctylamine (“TOA”) at 0.001 M, and the aliphatic diluent Isopar® L. The solvent holds up exceptionally well under various stresses, such as sustained contact with waste simulant and dilute nitric acid; repeated extraction, scrubbing, and stripping cycles; and excessive loading. The behavior of the solvent in batch-equilibrium flowsheet tests conducted at 15, 25, and 45 °C is presented. Flowsheet calculations show that the Savannah River Site requirements for a decontamination factor of 40,000 and a cesium concentration factor of 12 could be met in a 22-stage bank of 25-cm centrifugal contactors at 25 °C with conservative assumptions regarding hydrodynamics and stage efficiency. Exploiting the temperature dependence of extraction and stripping could reduce the number of stages to 18.     

Hydraulic Testing of Ion Exchange Resins for Cesium Removal from Hanford Tank Waste

Abstract

The granular ion exchange resin SuperLig^® 644 is the ion exchange resin of choice for ¹³⁷Cs separation from Hanford tank wastes. Current testing activities are evaluating both ground gel and spherical resorcinol‐formaldehyde (RF) resins as alternatives to the sole‐source supplied SL‐644 while achieving comparable loading and elution performance. The purpose of this testing was then to compare the bed forces, resin particle breakage, and differential pressure across the resin bed during multiple load‐elute cycles. These tests were conducted in a small‐scale column with high flow rates to simulate the hydraulic conditions that would be experienced in a full‐scale column.     

离子交换法分离提取发酵液中L-亮氨酸

研究了发酵液中L-亮氨酸的分离提取方法。将发酵液经过预处理,除去大部分杂氨基酸,得到L-亮氨酸粗品结晶,溶于水,脱色,用树脂吸附,考察了pH对吸附容量的影响,确定出树脂最大吸附量的吸附速度;分别用氨水和氯化铵作为洗脱剂,用不同的流速洗脱,寻找最佳洗脱剂和最佳洗脱流速：结果以氯化铵作洗脱剂进行梯度洗脱,成功的将L-亮氨酸与L-缬氨酸分离。     

Modeling Ion-Exchange Processing with Spherical Resins for Cesium Removal

The spherical Resorcinol-Formaldehyde and hypothetical spherical SuperLig® 644 ion-exchange resins are evaluated for cesium removal from radioactive waste solutions. Modeling results show that spherical SuperLig® 644 reduces column cycling by 50% for high-potassium solutions. Spherical Resorcinol Formaldehyde performs equally well for the lowest-potassium wastes. Less cycling reduces nitric acid usage during resin elution and sodium addition during resin regeneration, thereby significantly decreasing life-cycle operational costs. A model assessment of the mechanism behind “cesium bleed” is also conducted. When a resin bed is eluted, a relatively small amount of cesium remains within resin particles. Cesium can bleed into an otherwise decontaminated product in the next loading cycle. The bleed mechanism is shown to be fully isotherm-controlled vs. mass transfer controlled. Knowledge of residual post-elution cesium level and resin isotherm can be utilized to predict rate of cesium bleed in a mostly non-loaded column. Overall, this work demonstrates the versatility of the ion-exchange modeling to study the effects of resin characteristics on processing cycles, rates, and cold chemical consumption. This evaluation justifies further development of a spherical form of the SuperLig® 644 resin.     

Application of Single-Ion Activity Coefficients to Determine the Solvent Extraction Mechanism for Components of High-Level Nuclear Waste

Abstract

The TRUEX solvent extraction process is being developed to remove and concentrate transuranic (TRU) elements from high-level and TRU radioactive wastes that are currently stored at U.S. Department of Energy sites. Phosphoric acid is one of the chemical species of concern in the application of solvent extraction processes for removal of actinides, for instance at the Hanford site, where bismuth phosphate was used to recover plutonium.

The mechanism of phosphoric acid extraction with TRUEX-NPH solvent at 25°C was determined from phosphoric acid distribution ratios, which were measured by using a phosphoric acid radiotracer and a variety of aqueous phases containing different concentrations of nitric acid and nitrate. A model was developed for predicting phosphoric acid distribution ratios as a function of the thermodynamic activities of nitrate ion, and hydrogen ion. The Generic TRUEX Model (GTM) was used to calculate these activities based on the Bromley method. The derived model supports extraction by CMIO and TBP in TRUEX-NPH solvent of a phosphoric acid-nitric acid complex and a CMPO-phosphoric acid complex.     

甜菜糖蜜发酵废液中提取甜菜碱新工艺研究

研究了采用三段离子交换法从甜菜糖蜜发酵废液中提取甜菜碱的工艺条件和影响因素。三段交换分别使用D31 4、D0 0 1及 0 0 1× 7等苯乙烯型离子交换树脂。第一段交换使脱色、脱盐和除杂同时进行 ,免除了活性炭脱色过程。确定了第二段脱盐交换以pH =3为终点 ,使甜菜碱与金属离子彻底分离。第三段为吸附纯化甜菜碱 ,使用 c(HCl) =1 4mol/L为洗脱剂 ,直接制取了盐酸甜菜碱 ,并使洗脱与树脂再生同时进行 ,简化了工艺操作。所得产品纯度达 98%以上 ,收率(对甜菜 )达 90 %以上。     

Salt Splitting Using Ceramic Membranes

Abstract

Inorganic ceramic membranes for salt splitting of radioactively contaminated sodium salt solutions are being developed for treating U.S. Department of Energy tank wastes. The process consists of electrochemical separation of sodium ions from the salt solution using sodium (Na) Super Ion Conductors (NASICON) membranes. In contrast to conventional organic-based bipolar or ion exchange membranes used in salt splitting, NaSICON membranes are resistant to gamma/beta radiation and are highly selective for sodium ions. Potential applications include 1) caustic recycle for sludge leaching, regeneration of ion exchange resins, inhibition of corrosion in carbon steel tanks, or retrieval of tank wastes; 2) pH adjustmet and reduction of competing cations to enhance cesium ion exchange processes; 3) sodium reduction in high-level waste sludges; and 4) sodium removal from acidic wastes to facilitate calcining. Initial experiments with dysprosium-based NaSICON membranes have demonstrated the feasibility of the process.     

Comparison of Uranium Recovery by Ion Exchange from Sulfuric Acid Liquor in Iodide and Chloride Media

Uranium is normally leached from its ores with sulfuric acid, separated from impurities using solvent extraction or ion exchange, and precipitated to yield a commercial product known as “yellow cake.” This research has investigated the use of sodium chloride and potassium iodide with the sulfuric acid leach to recover the uranium, mercury and cesium from the cemented waste. Sulfuric leaching using KI improves the solubilization of Hg by a combination of acidification, complexation, and oxidation and form a mercury tetraiodide complex. Mercury and cesium were recovered selectively using thiourea resin and solid potassium cobalt hexacyanoferrate respectively with removal efficiencies reaching 99%. The U recovery from sulfuric liquor using the chelating resin Lewatit TP260 is very efficient. The loading curve for U recovery in iodide media shows a better uptake than in chloride media and the resulting breakthrough is delayed. High purity yellow cake was obtained by precipitation as sodium diuranate.     

离子交换树脂纯化发酵液中的核糖醇

为从发酵液中获得核糖醇产品,采用离子交换树脂对发酵液中的核糖醇进行分离纯化,探讨了进样浓度、柱的高径比、温度以及洗脱速度对分离效果的影响。结果表明,PCR-642钙型离子交换树脂具有良好的选择性,在发酵液脱色、减压浓缩至原液的20%,进料量为25 g、层析柱的高径比为25,洗脱流速为3.0 mL/min的条件下对核糖醇发酵液进行分离,得到核糖醇组分的收率为91.60%,核糖醇产品纯度达99%以上,结构经红外光谱确证。     

Characterization of SuperLig® 639 Rhenium and Technetium Resin with Batch Contact and Column Tests

Two new (2013) lots of SuperLig^® 639 ion exchange resin (IBC Advanced Technologies, American Forks, UT) were tested for the first time above typical sodium concentrations (7.8 M sodium, along with typical 5 M concentration) in highly alkaline solutions. Batch contact and ion exchange column tests characterized rhenium (perrhenate) adsorption as a surrogate for pertechnetate. The work supports technetium removal options for Supplemental Low Activity Waste processing at the Hanford River Protection Project Waste Treatment Plant (WTP). The current work found that the resin performs well in the 7.8 M sodium simulant despite complete floating of the beads. A notable difference in performance between the two new resin lots was found. Resin loading overall versus temperature, potassium concentration, and rhenium/nitrate ratios is consistent with previous data and expectations despite the high sodium concentration and floating of the resin beads.     

石煤水浸液中钒的富集研究

采用离子交换法对石煤水浸液中钒的富集进行了研究。通过静态树脂筛选实验,从四种离子交换树脂中筛选出D301树脂。在pH为6.55～7.12、室温25℃、树脂用量为20g、流速为12s/滴条件下,进行动态离子交换实验,树脂吸附量为142.5238mg/g湿,以4%NaCl+6%NaOH为解吸剂,解吸率达95%以上,解吸液最高峰为112g/L,平均解吸液浓度达70g/L左右,富集倍数为12～25倍,富集效果优良。水浸及中性环境避免了酸性腐蚀,减少了废酸、废水的排放量,大大减小了环境污染,符合清洁生产的宗旨。     

KINETICS OF URANIUM EXTRACTION BY MACROPOROUS BIFUNCTIONAL PHOSPHINIC ACID RESIN

ABSTRACT

The rate of extraction of uranium by macroporous bifunctional phosphinic acid (MPBPA) resin from nitric acid medium has been studied under particle diffusion controlled conditions. The internal diffusion coefficient was found to increase with increase in temperature and decrease with increase in particle size. The activation energies and entropies suggest that the extraction of uranium essentially follows ion exchange mechanism at low concentration of nitric acid while it is through linkage of >P=0 group of the resin at high concentrations.     

离子交换法处理含Cr(Ⅵ)废水的研究

采用201×7强碱性阴离子交换树脂处理模拟含Cr(Ⅵ)废水,探讨了废水酸度、交换时间、浓度对Cr(Ⅵ)去除率的影响以及树脂再生所需的合适温度和再生剂浓度。结果表明,201×7强碱性阴离子交换树脂处理模拟含Cr(Ⅵ)废水,具有交换容量大、交换效果好、树脂再生条件较简单等优点。并对实际含铬废水进行了处理,废水中Cr(Ⅵ)的初始浓度为1 540 mg/L,处理量达52 BV(床体积)时,出水中Cr(Ⅵ)的浓度仍小于0.5 mg/L,达到国家排放标准。树脂交换容量约80 mg/g。用8%NaOH溶液,在50℃条件下进行再生效果较好,再生率大于95%,可实现树脂的重复使用。     

CESIUM REMOVAL FROM HIGH-pH,HIGH-SALT WASTEWATER USING CRYSTALLINE SILICOTITANATE SORBENT

ABSTRACT

Treatment and disposal options for Department of Energy (DOE) underground storage tank waste at Hanford, Savannah River, Idaho National Engineering and Environmental Laboratory (INEEL), and Oak Ridge National Laboratory (ORNL) are limited by high gamma radiation fields that are produced by high concentrations of cesium in the waste. Treatment methods are needed to remove the cesium from the liquid waste and thus concentrate the cesium into high-activity, remote-handled waste forms. The treated liquids could then be processed and disposed of by more cost-effective means with less radiation exposure to workers.

A full-scale demonstration of one cesium removal technology has been conducted at ORNL. This demonstration utilizes a modular, mobile ion-exchange system and existing facilities for the off-gas system, secondary containment, and utilities. The ion-exchange material, crystalline silicotitanate (CST), was chosen on the basis of its effectiveness in laboratory tests. The CST, which was developed through a Cooperative Research and Development Agreement between DOE and private industry, has several advantages over current organic ion-exchange technologies. These advantages include (1) the ability to remove cesium in the presence of high concentrations of potassium, (2) a high affinity for cesium in both alkaline and acidic conditions, (3) physical stability over wide alkaline and acidic ranges, and (4) the elimination of large volumes of secondary waste required for regeneration of organic ion exchangers. Approximately 116,000 L of supernate was processed during the demonstration with ～1,142 Ci of¹³⁷CS removed from the supernate and loaded onto 265L (70 gal) of sorbent. The supernate processed had a high salt content, about 4 M NaNO₃, and a pH of 12 to 13. This paper discusses the results of the full-scale demonstration and compares these results with data from the laboratory tests.