电感耦合等离子体质谱法测定矿物渣中微量铀和钍

采用改进的微波消解程序处理矿物渣样品,用185Re作为内标同位素,以在线内标加入法补偿样品的基体干扰,提出了测定矿物渣中微量铀和钍的电感耦合等离子体质谱法.铀和钍的方法检出限分别为0.017,0.021 ng·g-1;铀和钍的平均加标回收率(n=6)分别为99.0%,101.3%;相对标准偏差(n=6)分别为4.02%和3.54%.两种标准物质中铀和钍的测定结果与标准值相符合.     

纳米Zr(OH)4及纳米ZrO2对Cu(Ⅱ)的吸附行为

对纳米Zr(OH)4粉体及其在不同温度(350～600℃)下的煅烧产物静态吸附Cu(Ⅱ)的行为进行了研究,并考察了影响静态吸附以及解吸的因素.试验结果表明,煅烧温度越高,样品的吸附效果越差.除了600℃煅烧的样品吸附性能较差外,纳米Zr(OH)4和其它样品在溶液pH》3时对Cu(Ⅱ)有很好的吸附效果,吸附率均大于96%.在实验范围内,吸附量最高可达到26400μg/g.被吸附的Cu(Ⅱ)在低浓度的盐酸(《2.0mol/L)中即可较好的被洗脱,100℃时解吸率可达到96%,同时也有很好的富集效果.     

微色谱柱分离-光度法测定高稀土铁矿石中的微量钍

采用HD-8微色谱柱对高稀土铁矿石样品(白云鄂博矿)中的钍进行分离富集,探讨了影响其分离富集的条件。实验表明,在4 mol/L HCl介质中钍可被树脂完全吸附,用3 mL 40 g/L草酸铵溶液可以从吸附柱上完全解吸钍,并结合偶氮胂Ⅲ分光光度法进行测定。所建立的方法适合于含铁、稀土量高的矿石样品中微量钍的分离与测定。     

电感耦合等离子体质谱法测定包头地区土壤中的钍

采用电感耦合等离子体质谱法(ICP-MS)对土壤中痕量的钍进行了分析。讨论了基体干扰和质谱干扰,采用稀释法降低基体干扰,并进行了内标选择实验,确定了238U作为方法的内标补偿基体效应。通过对土壤标准物质分析,用王水和HF混合酸微波消解样品,加HC lO4蒸干后用王水溶解残渣。观察到仪器对于Th的测定在不同稀释程度下的线性关系良好。标准加入回收率在93%~106%。方法检出限为0.6μg/L(232Th)。     

电感耦合等离子体质谱法测定富铀矿样中的微量钍

建立电感耦合等离子体质谱(ICP–MS)法测定富铀矿样中微量钍的方法。富铀矿样经Na_2O_2分解,用乙二胺四乙酸二钠(EDTA-2Na)–三乙醇胺(TEA)–H_2O_2溶液提取,以Mg(OH)_2作载体共沉淀提取液中的过氧化钍,使钍与大部分金属离子和UO_2~(2+)分离。沉淀用2 mol/L热HNO_3溶液溶解,定容后用ICP–MS法测定。该方法消除了样品中高含量铀组分对仪器进样系统的污染。钍的质量浓度在0~100μg/L范围内具有良好的线性关系,线性相关系数为0.999 7,钍的检出限为0.185μg/L。测定结果的相对标准偏差为2.23%~5.91%(n=6),用该法测定3种国家标准物质,测定值与标准值的相对误差小于4.96%。该法样品分解彻底,铀分离较充分,检测速度快,检出限低,测定结果稳定可靠,适用于富铀矿样中微量钍的测定。     

纳米二氧化钛分离/富集-石墨原子吸收光谱法测定环境样品中痕量镉

以石墨炉原子吸收(GFAAS)为检测手段,研究了纳米二氧化钛(TiO2,锐钛型)对金属Cd(Ⅱ)的吸附性能,考察了吸附和解吸的主要影响因素.结果表明,在较宽的pH范围内,纳米TiO2对Cd(Ⅱ)具有良好的吸附性能,3.0 mol/L HCl能将所吸附的Cd(Ⅱ)完全洗脱.在优化的实验条件下,具有吸附容量大、吸附速度快的特点.本法的检出限(3σ)为10.6 ng/L;相对标准偏差(RSD)为1.5%,(n=7,C=2.0 μg/L),富集50倍.本法测定标准样品的测定值与参考值吻合.用于土壤类样品中Cd(Ⅱ)的测定,结果令人满意.     

碳羟基磷灰石除废水中铬(Ⅵ)吸附动力学和热力学研究

利用废弃蛋壳合成碳羟基磷灰石(CHAP)对含铬(Ⅵ)离子废水进行吸附实验研究,考查了溶液的pH值、吸附时间和温度对吸附平衡的影响,并探讨了吸附动力学和热力学行为.结果表明:常温下,吸附时间为30min、pH=3.0、5g/L CHAP对50mg/L的铬(Ⅵ)离子的吸附率达到98.3%以上,CHAP对铬(Ⅵ)离子的吸附机理符合Langmuir和Freundlich方程;准二级动力学模型比准一级动力学模型能更好地描述CHAP对含铬(Ⅵ)离子吸附动力学行为;不同温度下的吸附热力学的吉布斯自由能以及熵变和焓变显示该吸附过程为自发吸热反应.     

石英晶体微天平实时监测低密度脂蛋白在胆固醇修饰葡聚糖上的吸附及其动力学研究

利用石英晶体微天平实时监测低密度脂蛋白(LDL)在胆固醇修饰葡聚糖(CMD)上的吸附,并对其吸附动力学进行研究.结果表明,CMD与LDL之间的相互作用符合Langmuir吸附方程,当LDL浓度(ng/μL)为9.9,12.38和14.14时,其吸附平衡常数[K/(mol·L-1·s-1)]分别为0.0477,0.0536和0.0628,表面吸附量(ng/cm2)分别为107.6,139.6和167.9.最大吸附量达到284.8ng/cm2,吸附率为72.91%.     

碳纳米管对Rh-Ce-Mn/SiO2催化剂催化CO加氢合成含氧化合物性能的影响

 制备了碳纳米管(CNTs)促进的Rh-Ce-Mn/SiO2催化剂,采用X射线光电子能谱、程序升温还原、 N2物理吸附、 X射线衍射以及吸附H2或CO的程序升温脱附对催化剂进行了表征,并考察了催化剂对CO加氢合成含氧化合物的催化性能. 结果表明, CNTs的添加促进了铑的分散,铑及助剂在载体表面发生富集; 活性组分铑与助剂及载体间的相互作用和催化剂样品的还原性能发生了改变; 在铑基催化剂中加入CNTs后,强吸附的H2和CO的量明显增大. CNTs促进的铑基催化剂的CO加氢活性明显提高,当CNTs添加量为10%时,一定条件下催化剂上含氧化合物的时空收率可达336.2 g/(kg·h).     

纳米零价铁与土壤组分的相互作用及其环境效应

纳米零价铁(nZVI)具有良好的还原活性和吸附性能,已应用于土壤和地下水污染修复,且前景广阔。但性能优越的nZVI会与土壤组分相互作用,不仅可能影响土壤理化性质及其生态功能,也会影响nZVI的存在形态和修复功能。本文阐述了nZVI与土壤空气、孔隙水、黏土矿物、有机质、微生物等土壤组分的相互作用,分析了其对相应土壤组分及土壤整体理化性质的影响,探讨了各土壤组分作用下nZVI的形态转化,并提出了几个需要进一步研究的科学问题。本文将有助于nZVI环境修复应用领域的科学研究与技术进步。     

Radiation Induced Grafting of Glycidylmethacrelate onto Polypropylene Films for Removal of Mercury from Aqueous Solutions

This work illustrates the modification of polypropylene (PP) films through its grafting with glycidylmethacrelate monomer (GMA). Further chemical treatment of PP-g-GMA to convert epoxy groups into amine groups is discussed. Different factors affecting the grafting percent such as solvents, monomer concentrations, irradiation dose have been studied. Fourier transform infrared (FTIR) and thermogravimetric (TGA) analysis confirm the grafting of PP. Morphological changes of PP, PP-g-GMA and treated PP-g-GMA are confirmed by scanning electron microscopy (SEM). The X-ray diffraction (XRD) pattern shows changes in the crystallinity on grafting. Adsorption and kinetic studies of mercury onto the prepared PP grafted and chemically treated films in sorption of Hg^{+ 2} metal ions from aqueous solutions have been studied. The experimental data fit favorably to the Langmuir isotherm with a high correlation coefficient. Moreover, the pseudo first and second order kinetics is also indicated. The results suggest that the pseudo-second-order kinetic model better represent the adsorption kinetics, suggesting that the adsorption process may be chemisorptions. It is more likely to predict that the adsorption behavior may involve valence forces through the sharing of electrons between Hg^{2 +} and adsorbent. On the basis of these investigations, the applicability of the prepared membranes is discussed. Also the confirmation of metal ions adsorbed was confirmed using EDS spectrometric techniques.     

Comparison studies adsorption of thorium and uranium on pure clay minerals and local Malaysian soil sediments

Adsorption studies of thorium and uranium radionuclides on 9 different pure clay minerals and 4 local Malaysian soil sediments were conducted. Solution containing dissolved thorium and uranium at pH 4.90 was prepared from concentrate sludges from a long term storage facility at a local mineral processing plant. The sludges are considered as low level radioactive wastes. The results indicated that the 9 clay minerals adsorbed more uranium than thorium at pH ranges from 3.74 to 5.74. Two local Malaysian soils were observed to adsorb relatively high concentration of both radionuclides at pH 3.79 to 3.91. The adsorption value 23.27 to 27.04 ppm for uranium and 33.1 to 50.18 ppm for thorium indicated that both soil sediments can be considered as potential enhanced barrier material for sites disposing conditioned wastes containing uranium and thorium.     

Organic/Inorganic bioactive materials Part III: in vitro bioactivity of gelatin/silicocarnotite hybrids

In this work we present our experimental results on synthesis, structure evolution and in vitro bioactivity assessment of new gelatin/silicocarnotite hybrid materials. The hybrids were obtained by diluting gelatin (G) and silicocarnotite (S) ceramic powder with G:S ratios of 75:25 and 25:75 wt.% in hot (40°C) water. The hybrids were characterized using XRD, FTIR, SEM/EDS and XPS. FTIR depicts that the “red shift” of amide I and COO⁻ could be attributed to the fact that the gelatin prefers to chelate Ca²⁺ from S. The growth of calcium phosphates on the surface of the hybrids synthesized and then immersed in 1.5 SBF for 3 days was studied by using of FTIR, XRD and SEM/EDS. According to FTIR results, after an immersion of 3 days, A and B-type CO₃HA can be observed on the surface. XRD results indicate the presence of hydroxyapatite with well defined crystallinity. SEM/EDS of the precipitated layers show the presence of CO₃HA and amorphous calcium phosphate on the surface of samples with different G/S content when immersed in 1.5 SBF. XPS of the G/S hybrid with 25:75 wt.% proved the presence of Ca-deficient hydroxyapatite after an in vitro test for 3 days.     

Nanocomposite hydrogel from grafting of acrylamide onto HPMC using sodium montmorillonite nanoclay and removal of crystal violet dye

Hydrogel nanocomposites were synthesized from grafting of acrylamide onto hydroxypropyl methylcellulose using methylenebisacrylamide crosslinker and sodium montmorillonite (Na-MMt) nanoclay. The effect of nanoclay content on the swelling of nanocomposites was investigated and an optimum swelling capacity was obtained at 12.7 wt% of Na-MMt. The effect of salt solutions on the swelling of nanocomposites revealed that the degree of swelling of samples depends only slightly on the salinity. The structure of nanocomposites was characterized by XRD, SEM, FTIR, and TEM techniques. The XRD and TEM results confirmed the exfoliation of Na-MMt nanoclay in nanocomposite matrix. The morphology of the nanocomposites was characterized by SEM technique and according to the results a loose surface was observed. The nanocomposite hydrogels were evaluated to remove cationic crystal violet dye from water. The investigation of the dye adsorption capacity and rate of nanocomposite hydrogels as a function of Na-MMt content revealed that the both adsorption capacity and rate is enhanced as the nanoclay content is increased in nanocomposite composition. The experimental equilibrated adsorption capacity of nanocomposites was analyzed using Freundlich and Langmuir isotherm models. The best fit to the experimental data was obtained with the Langmuir model.     

Highly efficient elimination of thorium(IV) from aqueous solution using poly(cyclotriphosphazene-co-melamine) microspheres

Highly crosslinked organic–inorganic hybrid polymer poly(cyclotriphosphazene-co-melamine) microspheres (PZM) were synthesized by a simple method. The microspheres was characterized by FTIR, SEM and EDX. It was applied to eliminate thorium(IV) from aqueous solution under various conditions, i.e., pH, initial concentration, dosage and contact time. The experimental data were well-imitated via the pseudo-second-order kinetic model and its adsorption processes comply with the Langmuir isotherm model. Adsorption thermodynamic studies demonstrated that the adsorption process, in essence, was spontaneous and endothermic. Furthermore, the maximum experimental adsorption capacity was 98.6 mg g^?1 for initial thorium(IV) concentration 50 mg L^?1. When pH?=?0.0, the thorium(IV) removal efficiency reached at 76.9%, which indicates that the adsorbent can also was used in a peracid environment. Adsorption behavior of thorium(IV) onto the microspheres were weakly affected via temperature, implying that adsorption would be done at room temperature.

     

ZIF-8/改性聚丙烯腈电纺纳米纤维的制备及其高效去除水中孔雀石绿

通过原位生长方法，将最常见的金属有机骨架（MOFs）——沸石咪唑酯骨架材料（ZIF‐8）固定到羧甲基化聚丙烯腈静电纺丝纳米纤维（PAN‐COOH NFs）表面，得到ZIF‐8/PAN‐COOH NFs。通过扫描电子显微镜（SEM）、能量色散光谱（EDS）、X射线粉末衍射（XRD）和傅里叶变换红外光谱（FTIR）对合成的ZIF‐8/PAN‐COOH NFs形貌和结构进行表征，并深入研究ZIF‐8/PAN‐COOHNFs从废水中去除孔雀石绿（MG）的性能。研究发现： ZIF‐8/PAN‐COOH NFs对MG的吸附符合拟二级动力学方程，吸附过程可采用Langmuir等温线模型拟合，其对MG的最大吸附容量可达3 604 mg·g^-1。此外，ZIF‐8/PAN‐COOH NFs在染料吸附实验中表现出良好的分离功能和重复利用性。     

Effects of soil pH and organic matter on distribution of thorium fractions in soil contaminated by rare-earth industries

The labilities of thorium fractions including mobility and bioavailability vary significantly with soil properties. The effects of soil pH and soil organic matter on the distribution and transfer of thorium fractions defined by a sequential extraction procedure were investigated. Decrease of soil pH could enhance the phytoavailability and the potential availability of thorium in soil. Increase of organic matter reduced the phytoavailability of thorium, but enhanced the potential availability of it. The reasons why soil pH and soil organic matter affect thorium fractions were discussed, and the behavior of the effects of soil properties on thorium fractions was elucidated. Fourier-transform infrared (FTIR) spectra were employed to reveal the positive relationship between the amounts adsorbed in humic material and/or amorphous oxides and the content of soil organic matter.     

ZIF-8/改性聚丙烯腈电纺纳米纤维的制备及其高效去除水中孔雀石绿

通过原位生长方法,将最常见的金属有机骨架(MOFs)——沸石咪唑酯骨架材料(ZIF-8)固定到羧甲基化聚丙烯腈静电纺丝纳米纤维(PAN-COOH NFs)表面,得到ZIF-8/PAN-COOH NFs。通过扫描电子显微镜(SEM)、能量色散光谱(EDS)、X射线粉末衍射(XRD)和傅里叶变换红外光谱(FTIR)对合成的ZIF-8/PAN-COOH NFs形貌和结构进行表征,并深入研究ZIF-8/PAN-COOHNFs从废水中去除孔雀石绿(MG)的性能。研究发现： ZIF-8/PAN-COOH NFs对MG的吸附符合拟二级动力学方程,吸附过程可采用Langmuir等温线模型拟合,其对MG的最大吸附容量可达3 604 mg·g^-1。此外,ZIF-8/PAN-COOH NFs在染料吸附实验中表现出良好的分离功能和重复利用性。     

Studies on the adsorption behaviors of Pb(II) onto an acyl-thiourea resin

In this paper, an acyl-thiourea resin (PIDTR) was synthesized and its adsorption performances to Pb(II) were investigated by adsorption tests, scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses. A pH of 6.0 was found to be the optimum pH to obtain the maximum adsorption capacity in 12 hours of equilibration time. The Langmuir model was well fitted to the adsorption data with adsorption capacity of 0.756?mmol?·?g^?1. The adsorption kinetics showed that the adsorption process experienced liquid film diffusion and chemical reaction. The thermodynamic studies indicated that the adsorption for Pb(II) was spontaneous and endothermic. The results of SEM suggested that Pb(II) adsorbed on the surface of PIDTR. The FTIR and XPS analyses further confirmed Pb(II) might chemisorb onto PIDTR surfaces and N–Pb, O–Pb, and S–Pb were formed with the breakage of C?O, C?S, and N-H bonds in the PIDTR molecule.     

钙蒙脱土吸附镧的影响因素及其应用

以钙基蒙脱土(Ca-MMT)为载体,研究其对镧(La)的吸附。 采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和元素mapping分析、傅里叶红外光谱(FT-IR)、BET、X射线荧光光谱分析(XRF)对其晶型结构、表面形态、比表面积、化学结构进行表征,考察了La的初始浓度、pH值、温度对Ca-MMT吸附镧性能的影响,考察了载镧钙基蒙脱土(Ca-MMT@La)的除磷效果。 结果表明:Ca-MMT投入量为10 g/L时,Ca-MMT的平衡吸附量随镧的初始浓度增加而增大,最大吸附量为49.62 mg/g;随着pH值增大,吸附能力增强,pH=6时为最佳pH吸附镧条件,吸附量为38.36 mg/g;随温度的升高,其吸附量先下降再上升,20 ℃吸附能力最大,吸附量为41.23 mg/g。 Langmuir等温吸附方程推断其吸附属于单分子层吸附。 Ca-MMT不具有吸附磷效果,而Ca-MMT@La对磷酸根有很强的吸附能力,吸附量为7.24 mg/g,除磷率为72.41%,其除磷率随含镧量增大而增大。