干湿交替过程对黄土高原几种主要土壤钾有效性的影响

室内模拟试验研究不同温度条件下干湿交替对黄土高原区四种土壤有效钾的影响,结果表明:(1)土壤钾有效性受干湿交替过程影响较大,干湿交替次数与有效钾含量间具有y=a blogx函数关系;(2)温度升高,增强了干湿交替的剧烈程度,提高土壤钾的固定量,显著降低了土壤钾的有效性;(3)建立了反映干湿交替次数、土壤物理性粘粒和粘粒含量比值、以及钾固定量三者之间的关系方程。     

油类对COD测定结果影响的探讨

本文通过对重油、15号机油、正已烷3种有机物质的加入实验,查明了以上物质在标准重铬酸钾法中的氧化情况,并得出在钢铁企业含油废水中,用重铬酸钾法所测得的COD值不能全部包括废水中油类(机油、重油)的有机物质的结论。     

Synergic influence of potassium loading and plasma-treatment on anti-coke property of K-Promoted bimetallic NiCoNiAl2O4 nanocatalyst applied in O2-Enhanced dry reforming of CH4

K-promoted bimetallic NiCoNiAl₂O₄ nanocatalysts with various loadings of potassium (0, 0.25, 0.75 and 1.25) were fabricated by utilization of hybrid sol-gel plasma method. Nanocatalysts were assessed by XRD, FESEM, AFM, EDX, BET-BJH and TPR analyses. Also, used nanocatalysts were tested by TG-DTG, XRD, and EDX analyses. Nanocatalysts were appraised in O₂-enhanced dry reforming of CH₄. XRD patterns indicated that by increasing of K loadings, amorphous behaviour was amplified. However, intensity of all peaks was decreased but reduction amount in the case of prone planes for coke formation slightly was greater than others. Great surface area and uniform dispersion was gained for the non-promoted nanocatalyst (NCK0A (SGP)), but surface covering by K addition led to the unsuitable properties. Owing to the EDX and FESEM, for K rich samples, surface area was decreased, average particle size got larger and dispersion of particles got worse. Noted attributes led to the lower yields of syngas for K rich samples. Despite the adverse impact of K such as lower activity, covering of defected site, enhanced reducibility and improving the rate of carbon gasification, led to the improved stability and less amount of coke deposition for K rich ones. Efficiency of NCK0A (SGP) and 0.25 wt% K promoted one (NCK0.25A (SGP)) were close to each other, but lower amount of deposited coke and more stable performance was gained for NCK0.25A (SGP). However, H₂ yields of NCK0A (SGP) and NCK0.25A (SGP) at first tests of TOF was close to each other but due to the 48 h test, they reached to 73 and 75%, respectively. Yields drop of NCK0A (SGP) was 8.5% while for NCK0.25A (SGP) was just 2.8%. Based on opposite tendency of TOF and yields and also, excellent properties of NCK0.25A (SGP) such as high enough activity, stable performance and high coke resistance, it seems that NCK0.25A (SGP) is a promising nanocatalyst for O₂-enhanced dry reforming of CH₄. H₂ yield of NCK0.25A (SGP) at 850 °C was 87%. Small average particle size, tunable morphology, larger surface area and optimum amount of appended K, were the reasons which led to the superior performance of NCK0.25A (SGP).     

用乳状液膜分离富集钾（1）与测定微量钾

用二苯并－１８－冠－６为流动载体的乳状液膜体系，研究了钾（１）的迁移行为。实验结果表明，只有Ｋ＋能与其它金属离子得到满意的分离。如大量的Ｎａ＋，ＮＨ４＋，Ｎｉ２＋，Ｌｉ＋，Ｃａ２＋，Ｍｇ２＋，Ｆｅ３＋，Ｍｏ６＋，Ａｌ３＋，Ｃｕ２＋，Ｃｏ２＋，Ｃｄ２＋，Ｚｎ２＋等，均不被迁移透过这乳状液膜。确定了最佳液膜体系的组成：二苯并－１８－冠－６，表面活性剂ＬＭＳ－１，四氯乙烯，苯甲酸甲酯和内相（ｐＨ４～６水溶液）；分离富集钾（１）的最适宜实验条件。Ｒｏｉ＝１∶１（油内比），Ｒｅｗ＝２０∶６０（乳水比）。此法已用于富集和测定食盐、卤水和工业废水中的微量钾（１），其回收率为９９．３％以上，相对标准偏差为３．６％以下，结果十分满意。     

Surface quality of {111} side-walls in KOH-etched cavities

A number of potential causes for the observed roughness of the side-walls in anisotropically etched cavities for silicon pressure sensors are investigated. Wafer stress is found to be the primary cause, possibly enhanced by the presence of precipitates from which etching irregularities may be initiated.     

Soot oxidation catalyzed by a Cu/K/Mo/Cl catalyst: evaluation of the chemistry and performance of the catalyst

Several non-supported oxidic compounds potentially present in a Cu/K/Mo/Cl catalyst (copper molybdates, potassium molybdates, and a mixed copper-potassium molybdate (K₂Cu₂(MoO₄)₃)) have been tested individually on their activity in the oxidation of a model soot (Printex-U, which non-catalytically oxidizes at 875 K). These oxidic compounds are active between 665 and 720 K, but only after establishment of ‘tight contact’ between the catalyst and soot in a ball mill. Without the ball mill procedure (‘loose contact’) these oxides are less active (the soot oxidation temperature is shifted to about 790 K), while a ZrO₂ supported Cu/K/Mo/Cl catalyst still shows a high activity around 670 K. Hence, the ‘loose contact’ activity of the supported Cu/K/Mo/Cl catalyst is not explained by the presence of an active oxidic compound. DRIFT and XRD analyses have shown that addition of KCl to CuMoO₄ (two compounds present within the Cu/K/Mo/Cl catalysts) followed by calcination at 950 K in air, eventually results in the formation of a mixed potassium-copper molybdate. Simultaneously several volatile copper, potassium and chlorine containing compounds (e.g. K₂CuCl₄) are formed. These copper and chlorine containing compounds possess a high ‘loose contact’ soot oxidation activity between 600 and 690 K. A catalytic cycle, involving Cu₂OCl₂, is proposed to explain the high ‘loose contact’ activity of copper chlorides and supported Cu/K/Mo/Cl catalysts. The activity of the latter catalyst will be maintained as long as Cu₂OCl₂ can be reformed by reaction of copper molybdates with KCl, which serves as a chlorine supplier.     

萃取盐酸法制备硝酸钾

本文讨论了以氯化钾和硝酸为原料,利用戊醇萃取盐酸法制备硝酸钾的方法,氯化钾的转化反应快速而且完全,制得的硝酸钾纯度可达99.5％。     

GROWTH RATES OF POTASSIUM SULPHATE CRYSTALS OF DIFFERENT SURFACE QUALITIES IN THE SIZE RANGE FROM 10-100 μm

Growth rate data of surface-integration controlled growing potassium sulphate crystals in the size range. 10-100μm are presented. The experiments were carried out in an agitated vessel crystallizer. The crystal growth rates were calculated from the shift of the population distributions with time as measured by a Coulter-Counter. In particular the effect of different surface qualities on the growth rates was investigated and clearly demonstrated. The existence of a growth rate dispersion (GRD) was shown for crystals in an agitated crystallizer. This is a new observation since previously this effect was only investigated for stagnant solutions in the case of the above mentioned range of crystal sizes.