Application of mixture design to optimize cementation of simu-lated spent radioactive ion exchange resins

The aim of this study was to assess the usefulness of a mixture design for spent resin immobilization in cement as well as to examine the cement-slag-ash system for spent resin solidification. Eighteen distinct combina- tions,consisting of Portland cement,blast furnace slag,fly ash,organic ion exchange resins and water,were selected by a mixture design computer procedure to compose representative experiment points. The measured properties of solidified forms resulting from the combinations included 28-day compressive strength,42-day immersion strength,42-day immersion weight and slump. These data were fit to a mathematic model with the aid of Scheffé quadratic polynomial,and the effects of each ingredient on the measured properties were identified through an analysis of the response trace plots and contour plots. Utilization of an optimality function singled out an optimal combination com- prising water=0.16(wt/wt),slag=0.21,ash=0.10,cement=0.27 and resin=0.26 from which the resulting response was 11MPa for the 28-day strength,110mm for the slump and 5.4% for the 42-day increase in strength.

Stabilization and volume reduction of radioactive spent ion exchange resins

Stabilization and volume reduction Of spent radioactive ion-exchange resins (IERs) were studied. Stabilization technology includes volume reduction with wet Chemical oxidation process and immobilization of the residue into cement. Under suitable conditions, the exhaussted radioactive ion-exchange resins were dissolved successfully in a H2,O2-Fe2+/Cu2+ catalytic oxidation system (Fenton reagent). The analytical results indicated that the radioactive nuclides loaded in the resins were concentrated in decomposed solution and solid residues. The process parameters of wet chemical oxidation and solidification were also obtained. The decomposition ratios were 100% and more than 90% for canon and anion IERs respectively. The waste volume was decreased by 40% compared with that of original spent resins.

Treatment of drilling wastewater using a weakly basic resin

Macroporous weak basic anion exchanger （D301R） was used to remove organic substances from drilling wastewater. The effect of pH, temperature and contact time on adsorption behavior was investigated in batch experiments, which indicated that the COD （Chemical Oxygen Demand） removal ratio of drilling wastewater was approximately 90%, and the COD of treated wastewater was below 70 mg/L under appropriate operating conditions. A mixed liquor of NaOH and NaCI was selected as desorbent because of its better elution performance. The results of column dynamic adsorption and regeneration showed that the COD of wastewater could be efficiently removed by D301R resin, and the resin was easily regenerated by the selected desorbent.

ADSORPTION OF HUMIC SUBSTANCES BY MACRO WEAKLY BASIC IONEXCHANGE RESIN AND THEIR EFFECTS ON REMOVAL OF Cu^(2+) AND Pb^(2+)

Adsorption of humic, tannic and gallic acids by a macro weakly basic ion-exchange resin JN-01 was studied. The adsorption capacity of this resin for gallic and tannic acids is much higher than that for humic acid, which can be explained on the basis of both their molecular size and ionization degree. Furthermore, humic acid is separated into different components with molecular weight in the range from 2000 Da to 100000 Da by ultra-filter, and their adsorption isotherms on resin JN-01 indicate that humic acid＇s molecular weight is an important factor which makes significant influence on adsorption. Finally, changes in the amount of Cu^2＋ and Pb^2＋ adsorbed on resin JN-01 as a function of the concentration of each of these three acids were studied. A large increase in the heavy metal ions uptake is observed in the presence of humic substance, such advantages are due to the interactions between the heavy metal ions and the unbound functional groups of the adsorbed organic acids.

废树脂辐解气体对普通硅酸盐水泥矿物成分影响的热力学分析

水泥的矿物相成分及含量是影响水泥固化体性能的关键因素,本文基于热力学吉布斯自由能最小化方法,采用GEMS软件研究了废树脂辐解产生的H_(2)、CH_(4)、CO_(2)3种气体对普通硅酸盐水泥矿物相组成和矿物相总体积的影响。结果表明:仅有少量H_(2)和CH_(4)与水泥水化产物反应,造成高Ca/Si的矿物相溶解,矿物相的总体积基本稳定;辐解产生的CO_(2)会先与水泥水化产物中的羟钙石反应,羟钙石完全溶解后,硅酸盐矿物开始溶解,最后形成由大量碳酸盐和少量黏土矿物组成的体系,矿物相的总体积减小。本研究结果揭示了废树脂辐解产生气体引起水泥固化体降解的演变规律及机制,可为废树脂水泥固化体处置安全评价提供数据支撑。

放射性废树脂处理技术研究进展

本文介绍了各种放射性废树脂处理技术的工艺原理、优缺点和研究进展。放射性废树脂的处理技术可分为水泥、沥青、聚合物等固化法,热态压实和桶内微波干燥等脱水减容法以及焚烧、湿法氧化或蒸汽重整等氧化分解减容方法。通过分析不同处理技术的特点,发现放射性废树脂处理具有前景的研究方向为设计和开发操作条件温和、效率更高的氧化分解减容工艺。

Environmentally benign chemical fixation of CO_(2) catalyzed by the functionalized ion-exchange resins

Basic ion-exchange resins,one kind of polystyryl-supported tertiary amine,were demonstrated to be highly efficient and recyclable catalysts for the fixation of carbon dioxide with aziridines under mild conditions,leading to the formation of 5-aryl-2-oxazolidinone with excellent regio-selectivities.Notably,neither solvents nor any additives were required,and the catalyst could be recovered by simple filtration and directly reused at least five times without significant loss of catalytic activity and selectivity.The present protocol has been applied to reactions of epoxides/propargyl amines with CO_(2)/CS2.This solvent-free process thus represents environmentally friendly catalytic conversion of CO_(2) into value-added chemicals and may have potential in various continuous flow reactors in industry.

Adsorption of three pharmaceuticals on two magnetic ion-exchange resins

The presence of pharmaceuticals in aquatic environments poses potential risks to the ecology and human health. This study investigated the removal of three widely detected and abundant pharmaceuticals, namely, ibuprofen（IBU）, diclofenac（DC）, and sulfadiazine（SDZ）, by two magnetic ion-exchange resins. The adsorption kinetics of the three adsorbates onto both resins was relatively fast and followed pseudo-second-order kinetics. Despite the different pore structures of the two resins, similar adsorption patterns of DC and SDZ were observed, implying the existence of an ion-exchange mechanism. IBU demonstrated a combination of interactions during the adsorption process. These interactions were dependent on the specific surface area and functional groups of the resin. The adsorption isotherm fittings verified the differences in the behavior of the three pharmaceuticals on the two magnetic ion-exchange resins. The presence of Cl-and SO2-4suppressed the adsorption amount, but with different inhibition levels for different adsorbates. This work facilitates the understanding of the adsorption behavior and mechanism of pharmaceuticals on magnetic ion-exchange resins.The results will expand the application of magnetic ion-exchange resins to the removal of pharmaceuticals in waters.

Ultra-low concentration of total organic carbon in ultrapure water using ion-exchange resin embedding silanized magnetic nanoparticles

Regeneration of pure water is an important issue not only for the healthy life but also for the fine control of precise processes in various industries.One important issue in ultrahigh purified water is to reduce the amount of total organic carbon(TOC).Herein,we introduce a new approach to reduce the TOC using the surface silanized nanoparticles,in which the magnetic nanoparticles(mNPs)are silanized and then complexed with ion exchange resin(IER)beads.The Fe3O4 mNPs are surface modified by using high concentrated vinyltrimethoxysilane(VTMS)and then adhered on the surface of IER beads.The surface modified mNPs have a thick-shell of polysiloxane layer varying from 5 to 22 nm depending on the amount of VTMS used,which leads the significant increase of specific surface area.The IER beads embedding VTMS-silanized mNPs achieves about 7μg/L of the TOC level in ultrapure water system,which is two orders less than 228μg/L of the feeding water and one order less than 96μg/L from the system using pristine IER beads.This result is mainly attributed to the polysiloxane layer forming broccoli-like surface structure and some part by the vinyl group of VTMS exposed to the amines in the water.

特种水泥固化放射性废离子交换树脂的初步研究

本文采用一种新型的 ASC特种水泥 ,研究了放射性废离子交换树脂的水泥固化技术。实验得到的最佳配方为 10 0 0 g水泥 + 5 0 0 g树脂 + 35 0～ 4 0 0 m L水 ,据此配方获得的固化体包容量为 4 2 %～4 8% ,其 2 8d抗压强度为 2 0± 2 MPa。第 4 2 d13 7Cs、90 Sr和60 Co的浸出率分别为 :7.92× 10 -5、5 .7× 10 -6和 1.19× 10 -8cm/ d。结果表明 ,该种水泥固化体的抗压强度。

模拟放射性废树脂热等离子体处理系统设计及试验分析

为了解决低放射性废树脂的处理难题,提高最终废物体的减容效果和稳定性,采用等离子体高温焚烧熔融方法,将树脂中的有机成分和无机成分分别高温分解和熔融。针对废离子交换树脂,研制了等离子体高温焚烧冷实验台架,开展了模拟废物等离子体高温焚烧特性及工艺的初步研究。研究结果表明:等离子体高温焚烧技术能够彻底分解废树脂,系统减容比达到53.5,玻璃体抗压强度>74 MPa,尾气中氮氧化物质量浓度为20～300mg/m3,二氧化硫质量浓度为0～95mg/m3,达到《危险废物焚烧污染控制标准》的要求。等离子体技术可以实现低放射性废树脂减容的稳定化处理,放射性核素被包容在玻璃体中,固化体性能稳定。

模拟放射性废树脂的沸石和特种水泥混合物固化

利用特种水泥（ASC）和沸石的混合物研究固化放射性废树脂的行为。实验比较了不同的沸石添加量对固化体抗压强度和Cs浸出率的影响，并从微观角度分析了沸石添加量对固化体结构的影响。结果表明：沸石的添加使针状结晶向片状结晶发展；10％～20％的沸石添加量可大幅降低Cs的浸出率，而固化体抗压强度降低却很少。

废树脂湿法氧化减容处理技术路线及问题探讨

从废树脂湿法氧化处理技术的优势出发,分析比较了国内外湿法氧化处理技术的发展和研究现状,设计了废树脂湿法氧化减容及水泥固化处理技术路线,探讨了该处理技术的关键技术问题。

放射性废离子交换树脂特种水泥固化体的微观结构分析

研究了特种水泥 (ASC)树脂固化体的微观结构。用压汞实验比较了ASC特种水泥的树脂固化体和普通硅酸盐水泥 (OPC)固化体多孔性能 ,通过电镜扫描 (SEM )观察比较了ASC和OPC的微观晶体结构。分析结果发现ASC水泥固化体具有较好的孔形结构 ,这是ASC固化体浸出率低的原因 ;ASC水泥固化体晶体呈针状结构 ,OPC水泥固化体晶体呈片状结构 ,针状结构的力学性能和结构强度要比OPC的片状结构好 ,该结构是ASC固化放射性废树脂包容量大、强度高的根本原因。

模拟放射性树脂特种水泥固化提高包容量的研究

研究了用ASC特种水泥固化放射性废树脂过程中增加树脂包容量对固化体强度、核素浸出率和水化热温升的影响。研究结果表明:增加树脂包容量将使固化体强度有所降低,但当树脂包容量不大于60%的时候仍然可以满足废物处理和处置的要求;增加树脂包容量对核素浸出率影响很小,并且可使固化过程中的水化热温升有所降低。

核电站废树脂清洁解控问题探讨

对轻微污染的废树脂采取解控处理是核电站废物最小化工作的重要内容。在介绍近几年开展的核电站废树脂解控监测工作的基础上,对核电站目前的废树脂废物管理中存在的问题进行了总结,提出了有利于实施废树脂废物最小化的技术途径。解控后的废树脂可能采取的处置出路包括危险固体废物填埋处置和水泥窑协同处置,暂时尚不具备进行高温焚烧处置的条件。为了提高核电站这类废物最小化的实施效率,建议对不同类型放射性核素在废树脂中含量的相关性问题,对放射性核素在离子交换柱树脂中的空间分布问题,对废树脂分拣的在线监测技术以及其它类型固体废物的分拣监测问题等进行深入研究,以期在保证取样代表性的同时,减少取样量和测量工作量,提高工作效率,降低废物最小化的经济成本。

基于流体体积模型的放射性废树脂蒸汽重整流态化数值模拟分析

放射性废树脂蒸汽重整反应器通常采用流化床结构。树脂在流化床中达到较好的流态化是保证反应持续、提高处理效率、实现树脂减容和核素包容的关键因素。为对流化床中树脂的流态化情况进行分析优化,建立了鼓泡流化床树脂蒸汽重整的计算模型,针对废树脂蒸汽重整中试流化床采用流体体积(volume of fluid,VOF)模型模拟流化床内树脂蒸汽多相流动状态。重点分析了不同流化操作气速下的床层压降、床高空隙率分布,获得了不同操作气速下的树脂流化状态。数值计算分析及后续测试结果表明,采用VOF模型可较好用于废树脂鼓泡流化床的计算模拟;操作气速增加,树脂的流化状态产生明显变化;当操作气速控制在0.7 m/s左右时,该中试流化床可达到最佳的流化状态。在此操作气速下开展了多组树脂蒸汽重整试验,最终获得的树脂重整平均减容倍数达到了6以上,在流化床内构件未发现树脂聚团,结焦现象,树脂在流化床形成了较好的流化状态。

芬顿氧化法预处理放射性废离子交换树脂

为了对放射性废树脂进行预处理，使用芬顿试剂对其进行了氧化降解预处理实验研究。通过正交试验获得了实验操作的合理条件：当过氧化氢的初始浓度为4．0mol／L、亚铁离子的初始浓度为20mmol／L、反应时间为4h、反应温度为95℃、溶液的初始pH值为2．5时，该法对3种不同的含铀废湿树脂（50g）均有理想的降解效果。反应进行2h后废树脂被完全分解，残液中化学需氧量（COD）的去除率达97％以上，由8．0～10．0g／L降至0．2～0．3g／L，且吸收液中铀含量无明显增加。实验结果表明，芬顿试剂对放射性废离子交换树脂有较好的氧化降解效果。

废树脂微波处理工艺研究

废树脂微波处理工艺主要利用微波的穿透能力强和体加热的特点,首先将废树脂中的水分除去,然后将废树脂中的有机组分去除,从而达到有机废物无机化的目的。与原始废树脂相比,微波干燥、灰化处理后,得到的灰分减容和减重比均极大。利用该技术处理得到的产物,可以方便的进行后续处理。通过研究,确定了废树脂微波桶内干燥及废树脂微波灰化工艺参数。

Ru/TiO_2催化湿式氧化废离子交换树脂技术研究

该研究采用浸渍法制备了多种贵金属催化剂,从中筛选出对废离子交换树脂的氧化催化活性最好、且稳定性较好的Ru/TiO_2催化剂。考察了不同反应条件对废离子交换树脂处理效果的影响。实验结果表明,反应温度、初始反应压力、反应时间、树脂形态、搅拌强度等因素均对树脂处理效果有一定的影响,其中反应温度及初始反应压力是催化湿式氧化过程中的主要影响因素,对处理效果起决定性作用。