湿法磷酸过滤设备和管道结垢原因分析及控制研究

分析湿法磷酸过滤设备与管道结垢的主要原因是氟硅酸钾、钠盐因磷酸液相温度下降而沉积下来。提出采用添加剂,抑制或提前析出氟硅酸钾、钠盐,同时进行了5种添加剂的实验室研究:均有较好的阻垢效果,但最终选择添加剂E(氟硅酸),阻垢率可达70%以上,添加量以0.5g/100g磷矿为宜。     

碱土金属在萃取剂与树脂间反应平衡常数的测定

研究了碱土金属离子在Ｄ００１树脂与８－羟基喹啉三氯甲烷溶液间的平衡常数Ｏ－ｔＫ的测定。其值依Ｍｇ、Ｃａ、Ｓｒ、Ｂａ次序减小。并得出萃取剂浓度［ＨＡ］。与金属离子在两相分配的关系。     

汽轮发电机组负荷波动的原因分析及解决措施

详细分析了汽轮发电机组在运行过程中出现电负荷波动和瞬间突降的原因，重点介绍了如何调节、维持汽轮发电机组的经济运行以及解决电负荷波动的措施，从而保证汽轮发电机组的稳定运行。     

超临界流体技术应用研究

超临界流体技术具有许多传统技术所没有的快速，高效，低能耗，污染少等优点，在材料制备，医药工业，生物工程，食物，环境，化工等许多方面展现了广阔的应用前景。综述了其在萃取，材料制备和作为反应介质等方面的应用。     

固相萃取技术在农药残留分析中的应用

固相萃取是一种新型的样品预处理技术，操作简便，节省有机溶剂，易于实现自动化操作，已广泛应用于环境保护、药物检测、食品检验检疫等领域。在农药残留分析中，固相萃取技术的应用还使得提取不同类别农药的选择性增强，样品回收率提高，尤其是结合HPLC—MS、GC-MS、CE-MS等仪器的联合鉴定，可实现自动化分析，能简单、快速、灵敏地提取定量许多物质，从而大大提高了分析效率和精密度，具有广阔的发展前景。     

Effect of granule size and the placement geometry on the efficiency of urea supergranules for wetland rice grown on a permeable soil

In a laboratory experiment 5 cm depth of water was allowed to percolate daily down through a 15 cm thick soil (Typic Ustipsamment) layer. It was observed that leaching losses of urea supergranules (USG)-N could be decreased by about 20% by the placement of four 0.25 g granules at four points instead of one 1 g granule at one point. In field microplots, the placement of approximately 30 granules of 0.30 g size instead of 9 granules of 1.00 g size resulted in reduced leaching of USG-N and, in turn, increased rice yield. In a follow-up field study, the advantage of more frequently placed USG was confirmed. As compared with 1 g USG placed in the usual manner in the center of four rice hills, increasing the density of placement in soil produced 15% more rice grain. Further increase in rice yield could be obtained by increasing the number of USG placed in the soil and decreasing the size of the granule from 1.00 g to 0.70 or 0.35 g. With USG of 0.35 and 0.70 g yields were equal or sometimes even slightly higher than with split application of prilled urea on a heavily percolating, low-CEC, light-textured soil.     

In vitro effects of urease inhibitors on rate of urea hydrolysis in soils

We studied the effect of urease inhibitors on the urea hydrolysis in some Sundanese soils belonging to the orders of Vertisol and Entisol. The hydrolysis showed a lag period of about 3 days and its rate (Y) per unit time (t) could be described by a two constants exponential equation of the general form Y = K₁t^K ₂. Statistical analysis showed that the intercept K₁ (rate of urea hydrolysis) was significantly affected by soil type rather than treatment. It seems that K₁ is associated with the soils' initial urease activity as it closely correlates with the Michaelis constant (km).The gradient, K₂, being significantly affected by soil type as well as treatment is probably associated with the induced urease activity with time and it, therefore, varied with variations in soils and treatments. Of the so-called urease inhibitors used in this study Ca(OH)₂, p-benzoquinone (PBQ) and orthophosphoric acid (OP) only PBQ reduced urea hydrolysis while the other chemicals have effects possibly related to modifying the soil pH. Inhibitor treated soils had substantial amounts of unacounted for N which was believed to be present, presumably, in the form of carbamate.Contribution from the Department of Biochemistry and Soil Science, Faculty of Agriculture, Shambat, Sudan.     

Outlook on fertilizer use efficiency in the tropics

In this paper efficiency of applied fertilizers under tropical conditions is examined. Understanding of the fertilizer efficiency is particularly important for the developing countries mainly because there is need for enhancement of crop yields at a reduced cost. Many of the soil, plant and climatic factors of the tropical regions that contribute to the efficiency of the applied fertilizers have been discussed. Many of the tropical soils are acidic in nature and in these soils efficiency of applied fertilizer is relatively poor, mainly because plant roots are unable to grow and function to their fullest extent in utilizing the soils available nutrients. To enhance yield potentials there is need for understanding of interaction between crop species and soil and climatic variables. Incorporation and adoptation of a suitable application time can greatly enhance efficiency of urea form of nitrogen. Research findings in tropical soils have shown that an initial broadcast application of P and subsequent band treatment is more effective than either method of application alone. Current crop yields in tropical countries are far below the known yield potentials. Such low production potentials are attributed to the lack of suitable crop germplasms and understanding of improved agronomic practices. Intensification of research activities in fertilizer use efficiency in tropical countries is suggested.Senior author formerly was a Research Advisor to EMBRAPA/IICA/World Bank Program in Brazil.     

De-oiling contaminated bleaching clay by high-pressure extraction

The disposal and re-use of spent bleaching clay from the vegetable oil processing industry is a problem of growing importance. Although today the only practical way of removal of the spent material is disposal, extraction with organic solvents is a well-known method of de-oiling contaminated bleaching clay. In our investigations we compare the extractibility of two different types of bleaching clays with CO₂ as a solvent. All experiments were carried out with a high-pressure extraction plant. The extraction and separation conditions, temperature and pressure, as well as the CO₂ mass flow, were varied during experiments. The aim of our investigations was a complete separation of the oil from the adsorbent. The latter should then be re-used as bleaching clay. The oil and the bleaching clay were analyzed and tested, respectively. The results show that oil of good quality can be recovered and the bleaching clay still has an activity approximately 50% of fresh clay.