Influence of potassium titanate whisker on the mechanical properties and microstructure of calcium aluminate cement for in situ combustion

This study investigated potassium titanate whisker-reinforced calcium aluminate cement (CAC)-based composites, and evaluated the influence of the quantity (0–5% of the weight of the binder) of potassium titanate whiskers on the mechanical properties of hardened cement mortar. X-ray diffraction analysis and Scanning electron microscopy (SEM) were employed to determine the phase compositions and micro-morphology of the cement composites, respectively. Experimental results indicated that the addition of potassium titanate whisker exhibits significant potential to improve the tensile strength and toughness of cement mortars. The compressive and tensile strengths of samples cured at 50 °C were increased by 46.90 and 74.10%, and the tensile strength samples under high-temperature treatment increased by 113.67%, with the addition of 4% potassium titanate whisker. Typical cement slurry properties, such as basic rheology, free water, and fluid loss could maintain stability when added with 0–5% dosages of potassium titanate whiskers. SEM analysis indicated that the whisker could increase the toughness of oil cement, which contributed to whisker pullout and whisker-cement coalition pullout in the cement matrix.     

铬酸钡比色法测定垢样中硫酸盐含量的探讨

对垢样中硫酸盐含量测定方法进行改进,建立铬酸钡比色测定法.通过精密度实验和回收率实验,验证该测定方法准确可靠,缩短分析时间,降低分析成本.     

用磷石膏、氯化钾制取无氯钾肥—硫酸钾铵的研究

通过实验研究得出以磷石膏、氯化钾和碳酸氢铵为原料制取硫酸钾铵的方法和工艺条件。流程中包括硫酸铵溶液的制备、硫酸钾铵的合成及副产品氯化钾铵的回收等三个部分。结果表明,此法简单可行,实验的重现性良好,为磷石膏制取无氯钾肥的工业化提供了依据。     

Effect of ultrasonic assisted KOH pretreatment on physiochemical characteristic and anaerobic digestion performance of wheat straw

In this study, ultrasonic field was applied during potassium hydroxide (KOH) pretreatment of wheat straw (WS). Three concentrations of KOH (2%, 4%, and 6%) were tested during pretreatment. The results showed that there was a significant influence of the ultrasonic assisted KOH pretreatment (KOH_Upt) on physiochemical characteristics of WS during pretreatment as well as on digester performance. The pretreatment time was optimized to 36 h for all KOH concentrations. The highest total volatile fatty acid (TVFA) productions (3189 mg·L⁻¹) from 6%KOH_Upt samples were observed. Similarly, the SEM analysis and FTIR observation revealed that KOH_Upt effectively disrupted the physical morphology of WS and successful breaking of lignin and hemicellulose linkage between carboxyl groups. Moreover, the highest biogasification (555 ml·(g VS_loaded)⁻¹) and biomethane productions (282 ml·(g VS_loaded)⁻¹) from 4%KOH_Upt digesters, with 69% of biodegradability, indicated significant availability of organic matter from KOH_Upt. The R² values (0.993–0.998) in Modified Gompertz Model indicated that the model was feasible to predict methane yield for this study. Similarly, the B_o values for 4%KOH_Upt (283.30 ± 2.74 ml·(gVS_loaded)⁻¹) were also in agreement to the experimental methane yield. These results suggested that ultrasonic addition during KOH pretreatment of WS can effectively increase the organic yield during pretreatment. Moreover, the increase in methane production from 4% KOH_Upt suggested that digester performance can be improved with lower KOH concentrations using this pretreatment.     

Removal of manganese from water supplies intended for human consumption: a case study

In the Volcano Etna area (Sicily) a substantial part of groundwater, used for potable purpose, has concentrations of metals (vanadium, iron and manganese) higher than the maximum contaminant levels (MCLs) set by European and National regulations (European Directive 98/83 and D.Lgs. 31/2001). Specifically, high levels of manganese, up to 1810 μg/l, significantly exceeding the maximum contaminant level (MCL = 50 μg/l), were detected in groundwaters currently used as drinking water supply upwelled from the Etna Volcano aquifer. The paper presents the results of the manganese removal process by potassium permanganate oxidation followed by flocculation, settling and filtration. Batch tests were carried out varying pH, oxidant doses and polyelectrolytes. Two different filters (35 μm and 0.45 μm mesh) were tested as a final step of the treatment. Significant removal (up to 95%) was achieved by addition of polyelectrolytes at pH 8.5, with a 0.5 stoichiometric dose of oxidant and final filtration through 35 μm mesh filter.     

添加物对LaCrO3材料烧结的影响

以钙质铬酸镧微粉为主原料,研究了分别添加ZrO2、CaO、MgO、SiO2或Al2O3五种微粉对铬酸镧材料烧结的影响。通过测定试样的体积密度、显气孔率,并借助电镜观察分析,对铬酸镧材料的烧结性进行了探讨。结果表明:在铬酸镧材料中分别添加ZrO2、CaO、MgO、SiO2或Al2O3,均能促进材料的烧结,使材料达到致密,并能使烧结温度降到1650℃。从显微结构看,添加ZrO2、MgO或CaO的铬酸镧烧结体,晶粒以固-固结合为主,而添加SiO2或Al2O3的铬酸镧烧结体晶粒间则以液相结合为主,且结构中有较多的封闭气孔。当温度再升高时,由于铬离子的挥发以及具有较低体积密度的相的生成,反而会使铬酸镧材料的密度下降。     

Improved process to prepare high-purity anhydrous potassium fluoride from wet process phosphoric acid

The production of potassium fluoride (KF) through recovering fluorine from wet process phosphoric acid (WPA) is very attractive as it not only makes a profitable use of the fluorine resource but also purifies WPA to some extent. The current route to prepare KF from WPA was assessed and significantly improved. Both the purity and yield of the KF product are increased with the upgraded process. Key improvements include (1) the recovery of the KF wrapped in the silicon dioxide filter cake with controlled amount of water and (2) the removal of unreacted KOH and meta aluminate impurities in the KF mother liquor with controlled amount of fluosilicic acid solution. The suitable dosage of the wash water and fluosilicic acid solution were recommended, which can be practically controlled by measuring the density and pH of KF mother liquor, respectively. Repeated experiments have verified that the improved process, compared to the current one, successfully increases the purity of KF product from 96 to 99% and the yield from 78 to 93%.     

快干型改性淀粉粘合剂的研制

本试验过程中，改变氧化剂、糊化剂、络合剂的用量，同时加入催干剂、分散剂等助剂，不但使胶液的粘接力提高还缩短了纸板的干燥时间。快干型改性淀粉胶原料配比：木薯淀粉（＞1009目）100g水400ml高锰酸钾（3％）20rnl尿素0．3g盐酸（IO％）ZOml六偏磷酸钠og氢氧化钠（1％）23ml陶土309硼砂（2％）27ml磷酸三丁酯适量（消泡剂）甲醛（防腐剂）适量根据产品相对粘度指标在60～80秒为宜。结果表明，3％KMnO4的用量4．oml为宜。氧化剂的用量必需严格控制。ID％Na0H用量为23ml。（注：淀粉用量为1009）硼砂的用量应控制在0．4～O．sg。用1…     

萃取法制取硝酸钾并联产氮钾复合肥的工艺研究

介绍了以硝酸、氯化钾和氨为原料，利用有机萃取剂使硝酸和氯化钾进行反应，制取农用或工业级硝酸钾并联产氮钾复合肥的新工艺；同时对该工艺的成本与其它工艺作了简单的比较，从而说明了进行工业化生产的可能性。     

Nickel ion removal by porous potassium magnesium titanate made from plate-like crystals

Plate-like potassium magnesium titanate (KMTO) powder prepared by molten salt growth method and the KMTO porous ceramic synthesised by polymeric sponge replication method were used as sorbents to remove nickel ions from wastewater. Both powder and porous ceramic were characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The maximum adsorption capacities of powder and porous ceramic were 96 and 24?mg?g^??1 respectively at a pH value of 6 (25°C). However, the removal efficiencies of both could reach up to 99%. Moreover, the adsorption kinetics for the KMTO powder and the porous ceramics followed the pseudo-second-order kinetic model, and the equilibrium data for the KMTO powder fitted the Langmuir isothermal model well, while the porous ceramics fitted with the Freundlich model. The mechanism of the adsorption by the KMTO powder and the porous ceramic was ion exchange. It was also shown that the nickel saturated KMTO powder and the porous ceramics were stable in leaching tests.