Removal of radioactive cesium from solutions by zinc ferrocyanide

Adsorption of 134Cs from aqueous solution by zinc ferrocyanide, and the effect of experimental conditions on the adsorption were investigated. Preliminary results showed that zinc ferrecyanide was very efficient as an absorbent. Over 98% of 134Cs could be removed by zinc ferrocyanide of 0.33 g.L-1 from 134Cs solution (Co) of one hour and the suitable pH ranged 1～10. No significant differences on 134Cs adsorption were observed at 0～50℃, or in solutions containing Ca2 , Fe3 , Mg2 , HCO3-, CO32-, CI- and SO42-, even though they are 1000 times higher than the anions or cations in groundwater. However, the adsorption rates decreased when solutions contained K or Na . The adsorption process could be described by Freundlich and Langmuir adsorption equations.     

Sorption of uranium(Ⅵ) from aqueous solutions by DEEA organovolcanic: isotherms,kinetic and thermodynamic studies

The sorption of the uranium(VI) ions from aqueous solutions by diethylethanolammonium organovolcanics(Kula-TURKEY) was investigated under different experimental conditions. DEEA was used to modify the surface of basaltic volcanics. The characteristic of basaltic volcanic was analyzed by XRF, SEM–EDS, FTIR, and XRD. The BET surface areas of unmodified volcanics and DEEA-modified volcanics were found as 2.265 and3.689 m~2/g, respectively. The volcanic samples were treated by using different concentrations of DEEA. The adsorption of U(VI) on natural and modified volcanics was examined as a function of the contact time, initial p H of the solution, initial U(VI) concentration, and temperature.Langmuir, Freundlich, and D–R adsorption isotherms were used to describe the adsorption. While examining the adsorption percentage and distribution coefficient, these values for unmodified volcanics were found to be25% ± 0.76 and 10.08 m L/g, while the values for the DEEA-modified volcanics were 88% ± 1.04 and 220 m L/g, respectively. The pseudo-first-order and pseudo-secondorder kinetic models were used to describe the kinetic data.In this study, it can be seen that the adsorption process is suitable for the pseudo-second-order kinetic model. Various thermodynamic parameters(ΔG°, ΔH°, and ΔS°) were calculated with the thermodynamic distribution coefficients obtained at different temperatures. The sorption process was a chemical adsorption process. The results indicated that the processes are spontaneous and endothermic.     

Preparation of a new anion exchanger by pre-irradiation grafting technique and its adsorptive removal of rhenium(Ⅶ) as analogue to ~(99)Tc

A new anion exchanger with pyridine groups was prepared by grafting of 2-vinyl pyridine onto polypropylene(PP) nonwoven fabrics by pre-irradiation grafting technique, followed by quaternization of pyridine rings in grafted chains in reaction with bromoethane. The results showed that the grafting yield increased with the monomer concentration and conversion ratio of quaternization increased with the time. The grafted and quaternized fabrics were characterized by FT-IR, DSC, SEM and ICP. The possibility of adsorption of perrhenate(ReO–4), a nonradioactive analogue to pertechnetate(99TcO–4), from aqueous solution by anion exchanger was investigated. The experiments performed at pH= 0.1–6 showed that p H = 2.2 was the optimal acidity for ReO–4adsorption, and an adsorption equilibrium was achieved in 30 min. The reaction enthalpy was-12.55 k J/mol,indicating that the adsorption process is exothermic. XPS tests indicated that the Re O–4uptake was a typical ion exchange between Cl–on anion exchanger and ReO–4.     

254/185 nm photolysis of p-nitrophenol

<正>Degradation of low-concentration p-nitrophenol(p-NP)aqueous solution was carried out in 254/185 nm photolysis.The effects of Mn~(2+),pH value,O_2 and O_3 on the degradation efficiency have been investigated.It was observed that the singlet oxygen scavenger Mn~(2+)did not affect the degradation of p-NP.In acidic and alkaline solutions,the degradation efficiency was enhanced in comparison to that in neutral solution.The presence of O_2 dramatically promoted the degradation of p-NP,while that of O_3 impeded it.     

Evaluation of influence of cold atmospheric pressure argon plasma operating parameters on degradation of aqueous solution of Reactive Blue 198(RB-198)

The intention of this work is to remove Reactive Blue 198(RB-198) dye components from simulated water solution using cold atmospheric pressure argon plasma jet. Aqueous solutions of RB-198 dye were treated as a function of various operating parameters such as applied potential,reaction time and distance between the plasma jet and surface of the liquid. The efficiency of the degradation of RB-198 molecules was explored by means of UV-Vis spectroscopy. The reactive species involved during the treatment process were examined by optical emission spectra(OES).The present hydroxyl radicals(OH·radical) and hydrogen peroxide(H_2O_2) in the plasma-treated aqueous dye solutions were investigated using various spectroscopic techniques. The other parameters such as total organic carbon(TOC), conductivity and p H were also reviewed. The toxicity of plasma-treated RB-198 solution was finally studied by diffusion bacterial analysis and by tracking seed germination processes. The results show that a higher degradation percentage of99.27% was acquired for the RB-198 treated at higher reaction time and applied potential, and shorter distance between the plasma jet and water surface. This may be due to the formation of various reactive oxygen(OH·radical, atomic oxygen(O) and H_2O_2) and nitrogen species(nitric oxide(NO) radicals and N_2 second positive system(N_2 SPS)) during the processes as confirmed by OES analysis and other spectroscopy analysis. TOC(17.7%-81.8%) and pH(7.5-3.4)values of the plasma-treated RB-198 decreased significantly with respect to various operation parameters, which indicates the decomposition of RB-198 molecules in the aqueous solution.Moreover, the conductivity of plasma-treated RB-198 aqueous solutions was found to have increased linearly during the plasma treatment due to the formation of various ionic species in aqueous solution. The toxicity analysis clearly exhibits the non-toxic behavior of plasma-treated RB-198 aqueous solution towards the bacterial growth and germination of seeds.     

Interaction between uranium and humic acid （Ⅰ）： Adsorption behaviors of U（Ⅵ） in soil humic acids

The adsorption behaviors of uranium on three soil humic acids (HAs), which were extracted from soils of different depths at the same site, were investigated under various experimental conditions. The adsorption results showed that U(Ⅵ) in solutions can be adsorbed by the three soil HAs, with the order of FHA (HA from 5 m depth of soil) >SHA (HA from the surface) >THA (HA from 10 m depth of soil) for adsorption efficiency in each desirable condition, and the adsorption reached equilibrium in about 240 min. Although the maximum adsorption efficiency was achieved at a suitable uranium concentration (10 mg·L-1 U(Ⅵ) for SHA and THA, 20 mg·L-1 U(Ⅵ) for FHA), the adsorption could be described with Langmiur isotherm or Freundlich isotherm equation. The L/S (liquid/solid, mL/g) ratio and pH were important factors influencing the adsorption in our adsorption system besides uranium concentration. The adsorption efficiency decreased with the increase of the L/S ratio and pH at the pH range of 2.0-3.0 for SHA and THA or 2.5-6.0 for FHA. However, no significant difference in adsorption of U(Ⅵ) was observed at the experimental temperature. All the results implied that humic substances have different characteristics in samples even collected at the same site.     

Degradation and mineralization of ciprofloxacin by gas–liquid discharge non-thermal plasma

A typical quinolones antibiotic ciprofloxacin(CIP) in aqueous solution was degraded by a gas–liquid discharge non-thermal plasma system. The discharge plasma power and the emission intensity of the excited reactive species(RS) generated in the gas phase were detected by the oscilloscope and the optical emission spectroscopy. The effects of various parameters on CIP degradation, i.e. input powers, initial concentrations addition of radical scavengers and p H values were investigated. With the increase of discharge power, the degradation efficiency increased but the energy efficiency significantly reduced. The degradation efficiency also reduced under high concentration of initial CIP conditions due to the competitive reactions between the plasma-induced RS with the degradation intermediates of CIP. Different radical scavengers(isopropanol and CCl_4) on ·OH and H· were added into the reaction system and the oxidation effects of ·OH radicals have been proved with high degradation capacity on CIP.Moreover, the long-term degradation effect on CIP in the plasma-treated aqueous solution proved that the long-lived RS(H_2O_2 and O_3, etc) might play key roles on the stay effect through multiple aqueous reactions leading to production of ·OH. The degradation intermediates were determined by the method of electrospray ionization(+)-mass spectroscopy, and the possible degradation mechanism were presented.     

NO_x storage and reduction assisted by non-thermal plasma over Co/Pt/Ba/γ-Al_2O_3 catalyst using CH_4 as reductant

N_Ox storage and reduction(NSR) technology has been regarded as one of the most promising strategies for the removal of nitric oxides(NO_x) from lean-burn engines, and the potential of the plasma catalysis method for NO_x reduction has been confirmed in the past few decades. This work reports the NSR of nitric oxide(NO) by combining non-thermal plasma(NTP) and Co/Pt/Ba/γ-Al_2O_3(Co/PBA) catalyst using methane as a reductant. The experimental results reveal that the NO_x conversion of NSR assisted by NTP is notably enhanced compared to the catalytic efficiency obtained from NSR in the range of 150 °C–350 °C, and NO_x conversion of the 8% Co/PBA catalyst reaches 96.8% at 350°C. Oxygen(O_2) has a significant effect on the removal of NO_x, and the NO_x conversion increases firstly and then decreases when the O_2 concentration ranges from 2% to 10%. Water vapor reduces the NO_x storage capacity of Co/PBA catalysts on account of the competition for adsorption sites on the surface of Co/PBA catalysts. There is a negative correlation between sulfur dioxide(SO_2) and NO_x conversion in the NTP system, and the 8% Co/PBA catalyst exhibits higher NO_x conversion compared to other catalysts, which shows that Co has a certain SO_2 resistance.     

Removal of cesium from radioactive wastewater using magnetic chitosan beads cross-linked with glutaraldehyde

A novel magnetic chitosan bead cross-linked with glutaraldehyde was prepared, characterized and applied for Cs(I) removal from aqueous solution. Characteristics and mechanism of Cs(I) removal were investigated. The equilibrium data of Cs(I) adsorption by magnetic chitosan beads were fitted using the Langmuir,Freundlich, Tempkin, Redlich–Peterson(R–P), Slips and Dubini–Radushkevich(D–R) models. The maximum adsorption capacity was estimated at 3.86 mg/g from the Langmuir isotherm. FTIR study revealed that N atom was mainly involved in Cs(I) sorption by magnetic chitosan.The magnetic chitosan is a promising adsorbing material for treating Cs(I)-containing radioactive wastewater.     

Preparation of amidoxime-based PE/PP fibers for extraction of uranium from aqueous solution

A novel amidoxime-based fibrous adsorbent,denoted as PE/PP-g-(PAAc-co-PAO), was prepared by preirradiation grafting of acrylic acid and acrylonitrile onto polyethylene-coated polypropylene skin-core(PE/PP)fibers using 60 Co γ-ray irradiation, followed by amidoximation. The original and modified PE/PP fibers were characterized by a series of characterization methods to demonstrate the attachment of amidoxime groups onto the PE/PP fibers. Breaking strength tests confirmed that the fibrous adsorbent could maintain good mechanical properties. The adsorption capacity of the PE/PP-g-(PAAc-coPAO) fibers was investigated in simulated seawater with an initial uranium concentration of 330 μg/L. The uranium adsorption capacity was 2.27 mg/g-adsorbent after 24 h in simulated seawater, and the equilibrium data were well described by the Freundlich isotherm model. The PE/PP-g-(PAAc-co-PAO) adsorbent exhibited good regeneration and recyclability during five adsorption-desorption cycles.The adsorption test was also performed in simulated radioactive effluents with uranium concentrations of 10 and100 μg/L. The effect of the pH value on the adsorption capacity was also studied. At a very low initial concentration 10 μg/L solution, the PE/PP-g-(PAAc-co-PAO)fiber could remove as much as 93.0% of the uranium, and up to 71.2% of the uranium in the simulated radioactive effluent. These results indicated that the PE/PP-g-(PAAcco-PAO) adsorbent could be used in radioactive effluents over a wide range of pH values. Therefore, the PE/PP-g-(PAAc-co-PAO) fibers, with their high uranium selectivity,good regeneration and recyclability,good mechanical properties, and low cost, are promising adsorbents for extracting uranium from aqueous solutions.     

Ag_(3)PO_(4)/P-C_(3)N_(4)材料的制备及其对铀的吸附性能北大核心CSCD

为设计一种对U(Ⅵ)具有较高吸附容量和较高选择性的吸附材料,采用石墨相氮化碳(g-C_(3)N_(4))与磷酸二氢铵作为原料,通过热共聚法制备P-C_(3)N_(4),再利用磷酸氢二钠与硝酸银通过原位共沉淀法制备Ag_(3)PO_(4)/P-C_(3)N_(4)复合吸附材料。吸附实验结果表明,Ag_(3)PO_(4)/P-C_(3)N_(4)复合吸附材料在室温下对U(Ⅵ)的吸附容量达到524.6 mg/g;在溶液中同时存在Na^(+)、K^(+)、Mg^(2+)、Ca^(2+)、Sr^(2+)、Zn^(2+)、Ni^(2+)和Co^(2+)等竞争离子时,对U(Ⅵ)的吸附分配系数达到6.13×10^(3)mL/g。XPS分析结果表明,Ag_(3)PO_(4)/P-C_(3)N_(4)复合吸附材料中的含N和含P官能团可能参与U(Ⅵ)吸附过程。因此,Ag_(3)PO_(4)/P-C_(3)N_(4)复合吸附材料是一种对U(Ⅵ)具有较高吸附容量和较高选择性的吸附材料。     

碳纳米管-环糊精复合材料对Eu(Ⅲ)的吸附

在等离子体条件下用有机大分子材料环糊精对碳纳米管进行功能化处理,制备出一种新的放射性核素吸附材料,即碳纳米管-环糊精复合材料。实验研究了pH、时间、离子强度对该材料吸附Eu(Ⅲ)的影响。该材料对废水中Eu(Ⅲ)的吸附速率快,吸附率在95%以上,通过吸附方程推算得到对Eu(Ⅲ)的最大吸附量可达约80mg/g,废水中其它离子及浓度对Eu(Ⅲ)的吸附无明显影响。     

The characteristics and mechanism of Co(II) removal from aqueous solution by a novel xanthate-modified magnetic chitosan

A novel xanthate-modified magnetic chitosan (XMCS) was prepared, characterized and applied for Co(II) removal from aqueous solution, and compared with magnetic chitosan (MCS). The characteristics and mechanism of Co(II) sorption was investigated. The experimental results showed that the introduction of thiol group on magnetic chitosan greatly increased the adsorption capacity for Co(II). The kinetics of Co(II) sorption could be described by pseudo second-order equation, and the adsorption isotherm followed the Langmuir model for both MCS and XMCS. The maximum adsorption capacity was found to be 18.5 mg/g and 2.98 mg/g, respectively from the Langmuir isotherm for XMCS and MCS. The mechanism of Co(II) adsorption onto XMCS was tentatively proposed through FTIR and XPS analysis.     

水合二氧化锰对Co2+的吸附行为研究

以KMnO₄为原料合成了水合二氧化锰（HMO）,采用XRD、BET、TG-DTA和FT-IR对HMO进行了表征。在此基础上,研究了各实验条件对HMO吸附Co²⁺的影响,并将其用于含⁶⁰Co废水的实际处理研究。结果表明：HMO对溶液中的Co²⁺具有良好吸附能力,在pH=7、T=298 K条件下,其最大吸附量达132.98 mg/g;溶液pH值能显著影响Co²⁺在HMO上的吸附,在实验pH值范围内,吸附量随pH值增大而增加;在钴初始浓度相同的条件下,吸附量随温度升高而增加;Na⁺、K⁺、Mg²⁺、Ca²⁺、Zn²⁺、Fe³⁺等离子的存在对HMO吸附Co²⁺具有一定影响。HMO对Co²⁺的吸附过程符合准二级动力学模型（R²＞0.99）,推测吸附过程中可能存在一定的化学吸附;吸附热力学行为可用Langmuir等温吸附方程进行描述（R²＞0.99）,表明Co²⁺在HMO上为单分子层吸附;由吸附热力学数据ΔH=46.96 kJ/mol、ΔG=-26.09 kJ/mol可知,此吸附行为是自发进行的吸热反应。另外,在实际处理含⁶⁰Co废水的动态柱实验中,HMO对初始放射性浓度为2.78×10⁵ Bq/L的⁶⁰Co废液的去除率可达56.90%。     

磁性MOFs材料Fe3O4@SiO2@UiO-66-SO3H对Co(Ⅱ)的吸附性能

通过水热法制备了磁性MOFs材料Fe₃O₄@SiO₂@UiO-66-SO₃H,并利用红外光谱仪（FT-IR）、X射线衍射仪（XRD）、比表面积测试（BET）、振动样品磁强计（VSM）、X射线光电子能谱仪（XPS）等对材料结构、形貌和性能进行表征。考察了溶液pH值、时间、温度、Co(Ⅱ)初始浓度对Fe₃O₄@SiO₂@UiO-66-SO₃H吸附性能的影响。结果表明,在pH=8.3、温度为298 K下,Fe₃O₄@SiO₂@UiO-66-SO₃H对Co(Ⅱ)的理论最大吸附量为106 mg/g;吸附过程符合准二级动力学模型和Langmuir等温模型,吸附是一个自发的吸热过程。Fe₃O₄@SiO₂@UiO-66-SO₃H在外加磁场下易从水溶液中分离,5次循环后仍具有较强的吸附性能。     

Synthesis of a Magnetic Composite Resin and Its Cobalt Removal Characteristics in Aqueous Solution

A series of stepwise procedures to prepare a new organic-inorganic composite magnetic resin with phenolsulphonic-formaldehyde and freshly formed iron ferrite was established, based upon wet-and-neutralization method for synthesizing iron ferrite and pearl-polymerization method for synthesizing rigid bead-type composite resin. The ion exchange and sorption characteristics of the composite resin prepared by the above method at various conditions were experimentally disclosed. The composite resin prepared shows stably high removal efficiency to Co(II) species in aqueous solution in a wide range of solution pH. The overall isotherm is qualitatively explained by the generalized adsorption isotherm concept proposed by McKinley. The standard enthalpy change derived from van't Hoff equation conforms to the typical range for chemisorption or ion exchange. The selectivity of the PSF-F (phenolsulphonic formaldehyde-iron ferrite) composite resin to Co(II) species and other competing chemicals (i.e. Na₂EDTA, Ca(II) and Na) was compared. It is anticipated that the composite resin can also be used for column-operation with process-control by applying external magnetic field, since the rigid bead-type composite resin shows magnetic-susceptibility due to its paramagnetic inorganic constituent (i.e. iron ferrite).     

北山新场BS34钻孔岩样在不同温度下的水岩作用北大核心CSCD

高放废物深地质处置过程中,放射性核素衰变可能产生大量的热量,释放到处置硐室周围环境中将影响深部地质环境局部的水岩作用。为探究温度对新场场址深部地下水化学环境的影响,使用新场场址原状地下水与BS34钻孔深部花岗岩岩样,开展了不同温度下室内水岩作用研究。结果表明:BS34钻孔岩样与原状地下水反应后,水相的pH为6.4~8.5,总溶解固体(TDS)为1653.9~1759.6 mg/L。随着温度的升高,水溶液Na^(+)、K^(+)浓度增大,其中Na^(+)可能来源于钠长石溶解、阳离子交换作用,K^(+)可能来源于钾长石溶解;Ca^(2+)、Mg^(2+)、HCO_(3)^(-)浓度减少,主要以方解石和白云石的形式沉淀析出,反应温度越高,沉淀析出越多。     

用碳纳米管从硝酸溶液中回收镅

研究了用碳纳米管从放射性废硝酸溶液中进行镅的回收。在浓硝酸溶液中,碳纳米管对镅的吸附率小于1％;随着硝酸浓度的降低,镅的吸附率迅速升高,当溶液的pH值大于5时,碳纳米管对镅的吸附率达到99.95％以上。用1．5mol／L硝酸进行解吸,一次解吸能够从碳纳米管回收99％以上的镅。     

β-环糊精交联磁性壳聚糖对U(Ⅵ)的吸附性能及机制研究

利用接枝共聚的方法制备了β-环糊精交联磁性壳聚糖,并将其用于吸附水溶液中的U(Ⅵ),考察了溶液初始pH、吸附时间、温度等因素对U(Ⅵ)去除率的影响。吸附实验结果表明：β-环糊精交联磁性壳聚糖对U(Ⅵ)的吸附平衡时间为60 min;温度越低,吸附剂投加量越大;溶液初始pH在3.0～6.0的弱酸性范围内有利于β-环糊精交联磁性壳聚糖对U(Ⅵ)的吸附。解吸实验结果表明,β-环糊精交联磁性壳聚糖经5次解吸后对U(Ⅵ)的吸附去除率仅下降7.41%。SEM表明,β-环糊精交联磁性壳聚糖表面粗糙。IR分析显示,β-环糊精交联磁性壳聚糖表面的-OH、-NH₂是U(Ⅵ)结合的主要位点,吸附U(Ⅵ)后并未明显改变原有结构。