Evaluation of Metal Antimonate Compounds for the Removal of Radiostrontium from Radioactive Liquid Waste: Characterization and Sorption Behavior

⁹⁰Sr having moderate half life (t1/2 = 30 yr) is of major concern for radioactive waste management. Metal antimonate compounds have been employed for the removal of ⁹⁰Sr from low level liquid waste stream (LLW). Antimonate compounds of tin, manganese, and zirconium were synthesized and their composite materials were prepared by coating with polymethyl metha acrylate beads (PMMA). The composite materials were evaluated for the removal of radiostrontium. The K_d value of about 1800–2000 was observed for all the three metal antimonate composite materials. Effect of pH, salt concentration, temperature, and strontium ion concentration on K_d value was studied. The sorption behavior was examined with various sorption isotherms like Langmuir, Freundlich, and Dubinin-Radushkevich. The thermodynamic parameters for the three composite materials were evaluated. The sorption was observed to be spontaneous and endothermic in nature. From the practical utilization point of view, the rate of uptake of radiostrontium by the composite material was investigated. Weber Morris diffusion model of the uptake studies suggested an intraparticle diffusion mechanism. The kinetics was found to follow pseudo first order pattern with intraparticle diffusion. However, intraparticle diffusion is not the rate controlling step.     

乳液法聚甲基丙烯酸甲酯／蒙脱土纳米复合材料的合成与表征

利用Na2SiO3的改性机理来纯化Na基蒙脱土,通过调节体系的pH值及其聚合阴离子的作用,使蒙脱土边面带负电荷,有效调节蒙脱土在水中的分散状态,使其与有机阳离子的交换反应充分进行,得到有机蒙脱土的阳离子交换量达115mmol/110g,并且能均匀分散在甲基丙烯酸甲酯9MMA）单体中,借助普通的乳液聚合方法,制备出PMMA／有机蒙脱土纳米复合材料,复合材料经甲苯抽提,FTIR,XRD,TEM,DSC,TGA等一系列分析方法表征,表明有机蒙脱土在PMMA基体中已达到纳米级分散,多数已发生剥离,而且复合材料的热性能较纯PMMA有很大提高,其Tg和Td最大分别提高31．45℃和42．13℃。     

Effects of monomer compositions on physicochemical properties of composite resins

The aim of this study was to evaluate the cohesive strength (CS), surface roughness (Ra), and weight loss (WL) of different composite resins. Three composite resins (Filtek Z100; Filtek Z350; Filtek P90, 3M ESPE) were tested. To evaluate CS, an hourglass silicone mold (11 × 2 × 1 mm) was used (n = 10). The Ra and WL tests were performed using a circular mold (5 × 2 mm, n = 10). The composite resins were light-cured with an LED light curing device (FreeLight 2, 3M ESPE) for 40 s and 1000 mW/cm². The CS test was performed using a universal testing machine (Instron 4411, Instron) at a crosshead speed of 0.5 mm/min and cell load of 500 N. The initial mass weight was registered (analytical digital balance) and the initial Ra reading evaluated using a profilometer (Surftest 211, Mitutoyo). The specimens were submitted to 30,000 brushing cycles. The WL and the final Ra were evaluated. All data were subjected to one-way ANOVA, followed by Tukey’s test (p < 0.05). Filtek Z100 showed the highest values of Ra and Filtek Z350 the lowest values of Ra. When considering CS, Filtek Z350 and Z100 had the highest mean values. Filtek P90 had the highest mean value of WL. The organic matrix and the type, shape, and size of fillers may influence the physicochemical properties of composite resins.     

PMMA微流控芯片最佳注射成型工艺的实验研究

以聚甲基丙烯酸甲酯(PMMA)为原料,通过注塑加工的方式制备微流控芯片,经过多次注塑实验得出影响PMMA微流控芯片成型质量的主要因素是:模具温度、保压压力、熔体温度和注射速度.在其他参数不变的情况下,通过正交实验和极差分析确定了PMMA微流控芯片注射成型的最佳工艺:熔体温度260℃,模具温度50℃,保压压力60 MPa...     

Dielectric and Mechanical Behavior of Treated Paper Sheet

Abstract

The dielectric properties of different polymers, polymethyl methacrylate. polystyrene, mixture of them (1:1) and polyvinyl alcohol films were studied. Also, the dielectric and mechanical properties were measured to study the intermolecular interactions of paper sheet impregnated in the different polymers under investigation. The retained polymer on dipped paper sheet is lowest in case of mixed polymer solutions than that of each polymer solution alone. The retained polymer on paper sheet from aqueous polymer solution is lower than that dipped in organic solvent polymer solutions. The mixture of 1:1 PS and PMMA has a higher permittivity than that of each of both polymer alone. The treatment of paper sheet with polymer solutions improved their dielectric and mechanical properties, whereas the mixture of PS and PMMA is the best one for improving treated paper sheet.     

Use of Nickel Sulphide–PMMA Composite Beads for Removal of 106Ru from Alkaline Radioactive Liquid Waste

Abstract

Use of NiS coprecipitation was found to be very effective at a concentration level of 2500 ppm of Ni⁺² and 1300 ppm of S^?2 for the effective removal of ¹⁰⁶Ru from the effluent stream. However, the NiS precipitate increases the sludge volume. Efforts were made to form the composite material of NiS in combination with Poly methyl metha acrylate (PMMA) polymer beads. The NiS–PMMA composite beads were loaded in a column and its ruthenium uptake behavior was studied. The NiS–PMMA beads were found to be functioning satisfactorily in alkaline conditions. It has shown a K_d value of about 8000–9000. The NiS–PMMA composite material has also shown the potential for the uptake of ¹²⁵Sb. The effect of salt concentration on the K_d value is negligible. The equilibrium conditions are achieved in around 25–30 min in batch mode of operation. The composite material can be suitably used in the column mode of operation.     

Preparation of Porous Polymethyl Methacrylate/Organo-Montmorillonite Composite Membranes for Phenolic Compound Adsorption

The preparation of porous poly(methyl methacrylate)/organo-montmorillonite composite membranes for adsorption application was carried out via entrapment methods. The sponge-like membrane structure was characterized by a scanning electron microscope, whereas the X-ray diffraction, Fourier transform infrared, and thermogravimetric analyses confirmed the incorporation of organo-clays inside the composite membranes. To investigate the applicability of the composite membranes on phenolic compound adsorption, batch-mode adsorption of p-nitrophenol at 0.025 mg/mL was conducted. The optimum feed organo-clay/polymer ratio was 0.3 for the membrane prepared by the emulsion polymerization method, and in this case 75% of p-nitrophenol was adsorbed after 34 h. 80% methanol was selected as the desorbent for its high ability to desorb p-nitrophenol from the composite membrane. The membrane performance in the flow process was similar to the batch result, and the adsorption/desorption cycle was successfully repeated three times.     

聚氨酯丙烯酸酯改性聚甲基丙烯酸甲酯防水涂料的研究

以聚氨酯丙烯酸酯树脂(PUMA)为柔性链段与活性单体甲基丙烯酸甲酯进行自由基共聚反应,生成改性的聚甲基丙烯酸甲酯(PMMA)防水涂料。研究了PUMA的用量对PMMA防水涂膜性能的影响,包括固化情况、硬度、附着力、力学性能、不透水性及低温柔性等。当PUMA的用量为60%时制得的PMMA涂膜拉伸强度为16.5 MPa,断裂伸长率达130%,与混凝土粘结强度为3.5 MPa,1.8 MPa、24 h不透水,是一种性能优异的防水材料。     

碳纤维含量对PMMA-PMA基复合材料显微结构及力学性能的影响(英文)

以甲基丙烯酸甲酯(polymethyl methacrylate,PMMA)和丙烯酸甲酯(polymethyl acrylate,PMA)为原料、短切碳纤维(Cf)为增强相,采用悬浮聚合法制备碳纤维增强聚甲基丙烯酸甲酯-聚丙烯酸甲酯基复合材料(carbon fiber-reinforced polymethyl methacrylate-polymethyl acrylate matrix composites,Cf/PMMA-PMA)。研究碳纤维含量(质量分数,下同)对Cf/PMMA-PMA显微结构及力学性能(抗折强度、抗压强度和拉伸强度)的影响。结果表明:随碳纤维含量增加,Cf/PMMA-PMA的挠度呈线性增长,而抗折强度、抗压强度和拉伸强度呈先增大后减小趋势。当碳纤维含量为15%时,Cf/PMMA-PMA的抗折强度、抗压强度和拉伸强度分别达到最大值115.5、244.6MPa和158.6MPa。     

利用综合热分析仪研究橱柜用亚克力板材的耐热性

采用ZRY-2P型高温综合热分析仪,选用动态模式,对两个厂家的九种橱柜用亚克力板材在50～600℃下进行了热分解测试.结果表明添加剂的增加会改善亚克力板材耐热性,各个厂家的板材中的添加剂种类有所不同,同一厂家的不同饭材,添加剂也会有所不同,九种板材中耐热性最差在159.2℃开始分解,对于普通厨房可以使用,但应避免与高温...