Graft polymerization of vinyl acetate onto granular starch: Comparison on the potassium persulfate and ceric ammonium nitrate initiated system

This work was undertaken to discuss in depth the vital differences in the morphological development during synthesis, and properties of starch‐g‐poly‐(vinyl acetate) copolymers using two different initiators, potassium persulfate (KPS) and ceric ammonium nitrate (CAN). KPS‐initiated system gave relatively low values of grafting ratio and grafting efficiency, indicating a great tendency for the formation of poly(vinyl acetate) homopolymer (PVAc). Yet, higher values were seen for the CAN‐initiated system. Transmission electron microscope observations indicated a relatively broad distribution of latex particles for the KPS‐initiated system. The surface potential of latex particles was about ?3.5 mV, which turned out to be insufficient to maintain stability of latex particles. On the other hand, a uniform particle size distribution was found for the CAN‐initiated system, as the surface potential of latex particles was 21.5 mV. Moreover, radicals on starch molecules were generated directly through a redox reaction with positively charged ceric ion. The hydrophobic PVAc chains were thus grafted on starch, resulting in an amphiphilic graft copolymer, which provides a sufficient stabilization degree as a role of surfactant to render a relatively uniform distribution of latex particles. The synthesized starch‐g‐poly(vinyl acetate) copolymers were further converted to starch‐g‐poly(vinyl alcohol) through saponification, which were subjected to evaluations regarding the biodegradation and cell culture capability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3017–3027, 2006     

磷化工作液中亚硝酸盐的检测

介绍了几种检测磷化工作液中亚硝酸盐浓度的原理、试剂和计算方法。     

聚醚二醇钾盐引发D．L－丙交酯的开环聚合研究

以聚乙二醇－４０００钾盐为引发剂．合成了食不同长度聚醚链段的聚Ｄ．Ｌ－乳酸－聚乙二醇－聚Ｄ．Ｌ－乳酸（ＰＬＡ－ＰＥＧ－ＰＬＡ）三嵌段共聚物。考察了溶剂用量、引发剂用量、反应温度和时间、ＰＥＧ分子量、不同溶剂对聚合反应的影响。以１Ｈ－ＮＭＲ、ＩＲ、ＤＳＣ、ＧＰＣ对共聚物进行了表征。     

The effect of ionic strength on soil P reactions is negligible

The electrolyte concentration of the soil solution affects the availability of some nutrients in the soil, especially of P, but it is not know at what salt concentration the reactions start to be significantly affected and their magnitude. This study was carried out to evaluate the effect of rates of potassium chloride (KCl) on some soil parameters that determine supplying of P, K, Ca, Mg, and Al in an unlimed acid soil. Increasing rates of KCl (from zero up to 2000 mg K kg^–1) were applied to soil samples fertilized with 360 mg P kg^–1. Solution (C_li) and exchangeable (C_si) forms of P, Ca, Mg, K, and Al were determined in the treated soil samples after 30-days of incubation; cation activity in solution and their selectivity coefficients were then calculated. Addition of KCl at rates equal to or above 500 mg K kg^–1 caused a large relative increase on P in the soil solution (P_li) but a small and insignificant increase on the absolute value of P_li. All forms of soil K increased with increases on K applied, and buffer power for K varied according to the range of soil K. At all KCl rates, K displaced Ca, Mg, and Al from the solid phase to the soil solution, but had no effect on the extractable values. The relative preference of cations for the adsorption sites increased with increase on cation valency, and only those selectivity coefficients involving K were affected by K applied.     

硫酸钾生产工艺改造

介绍了曼海姆炉的结构特点、生产硫酸钾的反应原理，以及新砌筑曼海姆炉的烘炉程序、生产运行所需条件和生产中曼海姆炉常出现的问题及解决问题的办法，推荐了几种曼海姆炉的工艺改造方案。经过改进后反应炉运行良好，可以延长反应炉的修炉周期，从而延长了反应炉的使用寿命，提高了硫酸钾的产量，节约了大量的修炉费用。     

污水COD超标的影响因素及解决措施

通过对总排污口污水中主要还原性物质逐项进行掩蔽,分析掩蔽前后污水COD值的变化,找出了影响COD的主要因素并提出了改进措施,使排污总口COD值大幅降低。     

十六烷基三甲基溴化铵活化催化合成香豆素

以无水碳酸钾为催化剂、十六烷基三甲基溴化铵(HTMAB)为活化剂，用水杨醛和醋酸酐为原料通过Perkin反应合成香豆素，研究了物料比、催化剂用量和HTMAB用量和反应近结束时保温时间对产率的影响。结果表明：用HTMAB为活化剂，可有效活化碱催化剂无水碳酸钾，提高了其碱性，与无HTMAB时相比，香豆素产率有较大提高，其最佳反应条件是n(水杨醛)：n(乙酸酐)：n(碳酸钾)：n（HTMAB)为1．00：3．00：0．25：0．03，反应温度185℃，反应近结束时保温3h，香豆素产率可达85．3％。     

厌氧污泥处理含铬废物的研究

利用城市污水处理厂的厌氧污泥对含铬废物进行解毒研究,结果表明,在厌氧条件下,厌氧污泥对重铬酸钾溶液和铬渣进行解毒后,滤液中的Cr6+质量浓度极低,大大低于《污水综合排放标准》的0.5 mg/L。厌氧污泥的解毒效果与含铬物料的量、解毒时间等因素有关。     

The roles of nitrogen,phosphorus and Potassium in the production of sugarcane in South Africa

The amounts of N and K fertilizers used in the South African sugar industry have increased dramatically in the past four decades, due partly to an increase in the area under sugarcane but also to large increases in the amounts of N and K fertilizers applied per hectare. There has also been an increase in the amount of P fertilizer used but this has been more gradual. The main fertilizer carriers for cane and their relative efficiency are discussed. During this period there has been considerable research into the nutrient requirements of sugarcane. Correlations established between soil and leaf analysis and crop responses to N, P and K fertilizers, and their effects on cane quality, are reviewed. While fertilizer recommendations based on soil and leaf analysis have provided a useful guide for determining the nutrient requirements of cane, they are continually being modified in the light of current research.     

无隔膜电解槽制备铁氰化钾的研究

在无隔膜电解槽中采用钛阳极、铜阴极电解制备铁氰化钾。本文探索了影响此过程电流效率及能耗的各种因素，分析确立了实际应用的电解条件