高效脱钙剂在辽河原油中的应用

针对辽河高钙原油研制开发了无磷不含金属的高效脱钙剂,利用原子吸收光谱法对原油脱钙前后的钙含量进行分析,考察了剂钙摩尔比、注水率、反应温度、沉降时间和搅拌时间对脱钙效果的影响。结果表明,剂钙比为0.6、注水率为10%、反应温度为90℃、沉降时间为10h和搅拌时间为5min时,辽河原油的脱钙率达到90%以上。     

Microwave exposure increases bone demineralization rate independent of temperature

There is a long‐standing controversy regarding an effect of microwaves, independent of increasing temperature, on the rate of bone demineralization. In this study, we exposed standardized samples of gerbil femur to constant microwave exposure while maintaining the demineralizing solution (ethylenediamine tetraacetic acid, EDTA) at 20 °C. Random samples were selected at 3 h intervals, embedded in plastic and sectioned for histological evaluation to determine the extent of demineralization. The time to complete demineralization was significantly faster with microwave exposure (33 h) compared to non‐exposure on a tissue rotator (45 h) in a limited amount (5 mL/24 h) of EDTA. The presence of bone marrow was a significant barrier to the rate of demineralization and resulted in an asymmetrical pattern of mineral extraction. Samples without bone marrow were completely demineralized after 21 h of exposure to microwaves and EDTA. Additional comparisons were made between samples exposed to an effectively infinite supply of demineralizing agent (bone marrow intact). There was a significant increase in rate with unlimited demineralizing agent with (24 h) or without (30 h) microwaves when compared to tissue demineralized on the rotator. Our results establish a positive effect of microwaves on the rate of bone demineralization which is independent of temperature.     

Comparative study of accelerated decalcification process among C3S, grey and white cement pastes

This study compared the resistance of Triclinic-C₃S, grey (OPC) and white (WOPC) Portland cement paste to decalcification induced by accelerated leaching in concentrated ammonium nitrate solutions. Paste microstructure was studied with scanning and backscattering electron microscopy (SEM and BSEM) and nitrogen BET surface area techniques. Ca²⁺ leached content was quantified by ICP, XRD and FTIR techniques were used to study phase mineralogy. The conclusions drawn from the findings were that calcium leaching-induced decay in the cementitious materials studied (C₃S, OPC and WOPC), accelerated by immersion in ammonium nitrate, affected the main calcium phases in the samples (CH, C-S-H gel and ettringite), i.e., both the anhydrous and the hydrated phases. The present study showed that the Ca/Si ratio of C-S-H gels declines on a gradient from the sample core outward. Specimen surface area and nanoporosity rose in cementitious materials after Ca leaching-induced decay and subsequently declined as a result of the collapse of the structure of the hydrated cement, and in particular of the C-S-H gel. C₃S paste was impacted more quickly and intensely by leaching than the WOPC and OPC pastes. Further to the findings of this study, the leaching resistance of these three materials, in descending order, is: OPC > WOPC > C₃S.     

Use of weak cation exchange resin Lewatit S 8528 as alternative to strong ion exchange resins for calcium salt removal

Softening of beet sugar juices using the weak cation exchange resin Lewatit® S 8528, both in hydrogen and sodium form has been studied. After analyzing the influence of the main operating parameters on decalcification efficiencies through a Taguchi approach, experimental runs were carried out at 40 BV/h and 80 °C to determine operation time, breakthrough point and resin capacity. The performance of the Lewatit S 8528 resin was compared with that of the industrially used Amberlite SR1L Na, a strong cation exchange resin. The experimental results showed that the use of Lewatit S 8528 in the acidic form is a feasible alternative to the classical strong cation exchange resins, providing calcium removal efficiencies higher than 80%. The mean calcium concentration in the softened thin juice was lower than 18 mg CaO/L. The breakthrough point corresponding to weak resin Lewatit S 8528 in H⁺ form, 700 bed volume, was considerable higher than that obtained for the strong resin Amberlite (300 BV). No considerably increase in the concentration of reducing sugars in the softened juice was observed. The consumption of chemical reagents in the regeneration stage was 3.2 ± 0.5 kg H₂SO₄/m³, considerably lower than the consumption of sodium chloride, 44 ± 1 kg NaCl/m³ when the strong Amberlite resin was used.     

Identification of the sources of organic compounds that decalcify cement concrete and generate alcohols and ammonia gases

This study identifies the emission sources of various types of airborne organic compounds, which deteriorate cement concrete by penetrating into the concrete together with moisture. The study used high-performance liquid chromatography and gas chromatograph mass spectrometry. The results show that the types of organic compounds contained in decalcified cement concrete were very similar to those found in the total suspended compounds in the air, and that the source of the emissions was particles of exhaust from diesel vehicles and radial tires used in summer. Such organic compounds include substances suspected of having endocrine disrupting properties. Hydrolysis occurs when these substances penetrate into highly alkaline cement concrete, and leads to deterioration of the cement concrete and the release of alcohols and ammonia gases which pollute indoor air and may be a cause of the sick building syndrome.     

超声波在辽河原油脱钙中的应用

针对辽河高钙原油研制开发了无磷不含金属的高效脱钙剂,利用原子吸收光谱法对原油在超声波作用下实验前后的钙、镍、铁及镁4种金属含量进行分析,考察了反应时间、超声波的频率及强度对原油脱金属率的影响.结果表明,注水率为10%、反应时间为15 min,超声波的频率28 kHz及强度8W/cm时,原油的脱钙率达到90%以上,其它3种金属的脱除率达到70%以上.     

甲壳素制备工艺及其对壳聚糖质量的影响

研究了甲壳素制备中稀酸脱钙质及稀碱脱蛋白质的工艺条件,认为在室温条件下一次酸处理时间不必超过1h;在较短时间内(10min)提高酸处理温度(80℃)可制得中等粘度壳聚糖产品;增加碱的浓度或增加碱处理的次数能够明显提高蛋白质分离准备效果;甲壳素及壳聚糖对蛋白质等的吸附作用是影响产品质量的重要原因。     

The effect of decalcification on the microstructure of articular cartilage assessed by 2H double quantum filtered spectroscopic MRI

²H quadrupolar splitting of deuterated water molecules is a sensitive measure of the order and density of the collagen fibers in articular cartilage. In the calcified zone, near the bone, two pairs of quadrupolar split satellites were previously observed. To examine whether the large splitting observed originates from the presence of calcium ions and hydroxyapatite, one-dimensional ²H single and double quantum filtered spectroscopic imaging were performed on articular cartilage-bone plugs before and after decalcification. After decalcification, the magnitude splitting of the two pairs of satellites did not change and orientation dependency was kept. However, the intensity of the large splitting was greatly enhanced. According to these results the two pairs of satellites do not stem from the presence of calcium ions and hydroxyapatite but originate from the presence of two groups of collagen fibers with different degrees of hydration. The enhanced intensity of the large splitting is attributed to an increased amount of water molecules that fill the void, resulting from the removal of hydroxyapatite, which resides near the fibers responsible for the large splitting. The quadrupolar splitting observed in the trabecular bone was not orientation-dependent, indicating a random orientation of the collagen fibers in that tissue.     

Complete Decalcification of Saline Effluent by Associating a Carboxylic Resin with a Chelating Resin

Abstract

Saline effluent from the glucose industry can be reused as resin regenerants after treatment by a bipolar membrane electrodialysis process preceded by chromatographic decalcification. Ca²⁺/Na⁺ isotherms measured on two weak acidic resins showed that the chelating resin has a higher selectivity for calcium. The decalcification process was optimized by combining rough decalcification on a carboxylic resin, followed by a finishing step on a chelating one. This chromatographic system led to the expensive chelating resin being spared and to the treatment of 60% more volume of effluent than with the carboxylic resin alone.     

Predicting the durability of Portland cement systems in aggressive environments—Laboratory validation

Portland cement systems are often exposed to severe environments, and their long-term performance is of concern. The main results of a comprehensive investigation of deterioration processes that may affect the behavior of Portland cement systems exposed to chemically aggressive environments is presented. As part of this investigation, well-cured cement paste discs were fully characterized and exposed to deionized water and sodium sulfate solutions. Degradation experiments were conducted under saturated and unsaturated conditions. At the end of the exposure period, microstructural alterations were investigated by microprobe analyses, scanning electron microscope observations and energy-dispersive X-ray analyses. Test results provide information on the basic aspects of various degradation phenomena, such as decalcification and external sulfate attack. Experimental results were also compared with results obtained by a numerical model. The analysis reveals that the intricate microstructural features of the degraded samples could be accurately reproduced by the model.