微细粒浮选精煤絮凝脱水试验研究

为改善浮选精煤压滤过程中微细颗粒煤的损失问题,提出了絮凝压滤脱水工艺,探索了絮凝剂类型及用量、凝聚剂类型及用量对浮选精煤絮凝沉降效果的影响;试验表明,分子量1 000万的阴离子型絮凝剂的效果优于其他絮凝剂,凝聚剂中明矾的凝聚效果优于聚合氯化铝和氯化钙;在浮选精煤煤浆浓度为150 g/L,最佳用量絮凝剂为1.6 mg/L、凝聚剂为400 mg/L条件下,浮选精煤絮凝沉降上清液浊度可降至16.81 NTU,浮选精煤絮凝压滤脱水的精煤回收率比直接压滤脱水提升8.9个百分点,微细粒精煤损失减少61.49%,滤饼水分降低1.67个百分点。     

判断絮凝剂在稀悬浮液中沉降速度的简单方法Je,Chung-Hwan 等 （University of Nevada,USA ） Environmental Geology （ Berlin,Germany ）

提出了用于估算微细悬浮颗粒絮凝沉降速度的一种新的且简单的方法。根据一维垂直连续性方程和经验絮凝方程推导出了简化式。得到的絮凝剂沉降速度(Vs)作为时间、深度和常数的函数表达。同时利用提出的公式推导了按深度平均的沉降速度(Vs)。为了确定絮凝剂对沉降影响的数量级，作出了等沉降速度线。研究了初始浓度和离子强度对絮凝剂沉降速度的影响。     

小纪汗选煤厂煤泥水沉降性能试验研究

为了探讨相关因素对煤泥水絮凝沉降过程的影响规律,研究制定针对小纪汗选煤厂煤泥水处理过程中的加药策略,对该厂煤泥水进行了沉降性能试验;结果表明,煤泥水中微细颗粒较多,絮凝剂浓度对该煤泥水絮凝沉降效果影响较大;随着絮凝剂浓度的增加,初始沉降速度先增大后减小,当絮凝剂浓度为10 g/m~3时,初始沉降速度最大;絮凝剂浓度一定时,初始沉降速度随凝聚剂与絮凝剂质量比的增加而不断增大。     

絮凝剂结构对赤泥沉降速率的影响

考察了絮凝剂不同官能团对赤泥沉降速率的影响差异,采用国外公司最近研发的具有羧基、酰胺基和氧肟酸官能团的3种絮凝剂,并在最佳添加量下,进行了拜尔法氧化铝赤泥絮凝沉降速率的测定,分析了3种官能团不同组合而成的絮凝剂和赤泥的相互作用。从沉降速率、溢流液澄清度和底泥液固比三方面得出含有3种有效官能团的絮凝剂C的絮凝效果最好,比较3种絮凝剂前5min沉降速率,得出C是相对高效的絮凝剂,同时分析了絮凝剂C添加量大是由空间效应导致的,并提出了今后的研究方向。     

水处理絮凝剂的研究现状

絮凝沉降法是一种经济简便的水处理方法。絮凝沉降技术中所使用的絮凝剂性能好坏决定着水处理的效果,所以絮凝剂是絮凝沉降法水处理技术的核心。文章中列举了无机絮凝剂、有机絮凝剂、微生物絮凝剂和复合絮凝剂四种不同类型絮凝剂,并对各自的性能进行了比较。介绍了目前我国最常用的聚丙烯酰胺絮凝剂的主要生产工艺及产品剂型,最后对聚丙烯酰胺水包水乳液的合成及应用情况进行了综述。     

浓缩湿法磷酸中杂质颗粒的沉降特性

随着磷矿品位的日益下降,浓缩湿法磷酸中的杂质含量高达8%,给磷酸的输送、储存和后续加工带来了诸多困难。为了加快磷酸中杂质颗粒的沉降与净化,采用添加絮凝剂的方法来处理浓磷酸中的杂质,对比了添加絮凝剂前后对浓磷酸中杂质颗粒的沉降特性的影响,考察了温度对自然沉降和絮凝沉降的影响以及絮凝剂用量的变化对絮凝沉降速率的影响。结果表明,当沉降温度为60℃时沉降速率最大;絮凝沉降平均速率是自然沉降的2倍;磷酸浓度及杂质含量的不同导致絮凝剂最佳用量不同。     

碳酸盐及腐植酸盐对拜尔法赤泥絮凝与澄清的影响研究

研究了溶解离子对拜尔法氧化铝赤泥浆液絮凝的影响。实验表明，碳酸根离子、腐植酸盐和有机杂质优先附着在赤泥浆液中矿物颗粒的表面，影响合成高分子絮凝剂的凝聚沉降。添加少量的熟石灰可即刻消除碳酸根和腐植酸盐等有机杂质的影响。应用合成高分子絮凝剂替代淀粉，可以使赤泥浆液中矿物颗粒空出更大面积，吸附生产流程中积集的腐植酸盐和有机杂质，从而得到高质量的溢流。     

海洋地衣芽孢杆菌的絮凝活性研究及机理探讨

以海洋地衣芽孢杆菌DHS-40为絮凝剂产生菌,通过定性测试鉴定所产微生物絮凝剂的絮凝活性有效成分,采用程控混凝实验六联搅拌仪和重力沉降法评价其絮凝稳定性,通过扫描电子显微镜和原子力显微镜表征微生物絮凝剂和絮凝颗粒的微观形貌,并初步探讨了微生物絮凝剂的絮凝机理。结果表明,海洋地衣芽孢杆菌DHS-40所产微生物絮凝剂的絮凝活性有效成分为多糖和蛋白质的混合物;当微生物絮凝剂投加量为0.05g·L~(-1)、环境pH值为4.0~8.0、环境温度为0~50℃时,絮凝活性达80%以上;絮凝活性基本不受环境pH值的影响,但在碱性较强(pH8.0)时絮凝活性迅速下降,在pH值为10.0时完全丧失;微生物絮凝剂呈链状结构,且有深浅不等的沟回;絮凝颗粒呈层叠结构。微生物絮凝剂依靠电荷吸附和桥联作用带动水中的浑浊物共同沉降,从而达到净化水体的目的。     

5种絮凝剂复配及在电镀含铬废水中的应用

通过研究5种无机、有机絮凝剂对电镀废水的处理效果，确定了能有效除去铬的复合絮凝剂的复配比和复配关系。复合絮凝法具有沉淀污泥少、絮凝颗粒大、沉降速度快等特点，当以最佳量投加时，滤液无色。铬的除去率达到99．99％。     

微生物絮凝剂的研究与应用

絮凝沉降法是目前国内外用来提高水质处理效率的一种既经济又简便的水处理方法,絮凝剂是絮凝沉降法的核心;而微生物絮凝剂则是利用生物技术,通过微生物发酵抽提精制得到的一类沉降效率高、生物降解性好、使用范围广的新型絮凝剂。本文概述了微生物絮凝剂的研究现状,介绍了微生物絮凝剂的种类,分析了微生物絮凝剂的絮凝作用机理及其在水处理中的应用,展望了微生物絮凝剂的发展趋势。     

生物基1,6-己二醇的研究进展

传统的以石油化工产品为原料的石化基1,6-己二醇(1,6-HDO)的生产存在能耗高、反应产物分离困难、污染环境等缺点,以5-羟甲基糠醛(5-HMF)为原料制备生物基1,6-HDO可以克服这些缺点。本文介绍了国内外制备生物基1,6-HDO的研究进展,总结并讨论了由5-HMF制备1,6-HDO的不同反应路径,并从反应物吸附、金属粒径、活性组分协同作用、载体等角度对比了不同催化剂体系及其催化机理,探讨了各种催化剂促进C=O加氢、呋喃环C=C加氢、呋喃环C—O氢解开环反应,抑制呋喃环、呋喃环侧链C—C氢解断裂反应的性能。与多步法相比,一步法制备1,6-HDO的反应步骤简单,但1,6-HDO的产率相对较低,因此开发高效的催化剂体系和反应工艺将是今后研究的重点。     

Aggregation pheromone system of adult gregarious desert locust schistocerca gregaria (forskal)

Six electrophysiologically active aromatic compounds, viz., anisole, benzaldehyde, veratrole, guaiacol, phenylacetonitrile, and phenol, were identified in the volatiles of older-adult male desert locust. Young adults and females of all age groups produced none or only trace quantities of these compounds. Comparison of the aggregation responses of young and older adults to the crude, older-adult, volatile extract and different synthetic blends of the six compounds showed that the aggregation pheromone system of the adult gregarious locust consists of phenylacetonitrile, guaiacol, phenol, and benzaldehyde. Like the crude volatile extract of older males, neither the synthetic blend of the six compounds nor the adult pheromone blend evoked any significant aggregation responses from nymphs. These results confirm our previous report of sexual differentiation in the production of adult aggregation pheromone in the desert locust and of the evidence of two distinct aggregation pheromone systems in the two stages of the insect.     

Emerging role of nanobiocatalysts in hydrolysis of lignocellulosic biomass leading to sustainable bioethanol production

Catalytic conversion (hydrolysis) of carbohydrate polymers present in the lignocellulosic biomass into fermentable sugars is a key step in the production of bioethanol. Although, acid and enzymatic catalysts are conventionally used for the catalysis of various lignocellulosic biomass, recently application of immobilized enzymes (biocatalysts) have been considered as the most promising approach. Immobilization of different biocatalysts such as cellulase, β-glucosidase, cellobiose, xylanase, laccase, etc. on support materials including nanomaterials to form nanobiocatalyst increases catalytic efficacy and stability of enzymes. Moreover, immobilization of biocatalysts on magnetic nanoparticles (magnetic nanobiocatalysts) facilitates easy recovery and reuse of biocatalysts. Therefore, utilization of nanobiocatalysts for catalysis of lignocellulosic biomass is helpful for the development of cost-effective and ecofriendly approach. In this review, we have discussed various conventional methods of hydrolysis and their limitations. Special emphasis has been made on nanobiocatalysts used for hydrolysis of lignocellulosic biomass. Moreover, the other most important aspects, like nanofiltration of biomass, conversion of lignocellulose to nanocellulose, and toxicological issues associated with application of nanomaterials are also discussed.     

Soil nutrient depletion by agricultural production in Southern Mali

The degree of soil mining by agricultural production in Southern Mali is assessed by calculating nutrient balances: differences between the amount of plant nutrients exported from the cultivated fields, and those added to the fields. Export processes include extraction by crops, losses due to leaching, to erosion, and to volatilization and denitrification. Inputs include applications of fertilizer and manure, restitution of crop residues, nitrogen fixation, atmospheric deposition of nutrients in rain and dust, and enrichment by weathering of soil minerals. Nutrient balances are calculated for N, P, K, Ca, and Mg. Both pessimistic and optimistic estimates are given.The resulting figures indicate, even when the most optimistic estimates are used, large deficits for nitrogen, potassium and magnesium. For the region as a whole, the calculated deficits are -25 kg N/ha,-20 kg K/ha, and -5 kg Mg/ha. Further, acidification is to be expected, in particular in areas where cotton is grown. The deficits are caused by traditional cereal crops, but also by cotton and especially by groundnut. The latter two crops are fertilized, but insufficiently. It is important to note, that the negative figures are not automatic recommendations for application of a specific amount of additional fertilizer. For phosphorus and calcium the balance of the region as a whole appears to be about in equilibrium, but locally large variations may occur.Erosion and denitrification are important causes of nutrient loss, accounting respectively for 17 and 22% of total nitrogen exports. Atmospheric deposition and weathering of minerals in the soil are still important nutrient inputs that contribute as much as nutrients as organic and mineral fertilizer combined. Nutrient depletion is very large in comparison to the amount of fertilizer applied. Drastic options, such as doubling the application of fertilizer or manure, or halving erosion losses, even if feasible, would still not be enough to make up for the calculated deficits.The annual value of withdrawn nutrients, if related to prices of fertilizers, varies between 10,000 and 15,000 FCFA/ha (40-60 US $/ha). Since the estimated average gross margin from farming in this area is 34,000 FCFA/ha (123 US $/ha), soil mining appears to provide an amount equal to 40% of farmers' total income from agricultural activities.     

Observation and measurement of the appearance of metallic materials. Part II. Micro appearance

Part I of this article dealt with the appearance of metallic materials observed at a distance of a few meters. This part deals with the appearance at reading distance. Metallic materials exhibit various appearance attributes, including glitter, glints, depth, coherence glitter, binocular luster, binocular glitter, and binocular mottle. Color disparity is proposed as a measure of binocular luster. Metallic materials resemble grainy photographs, so the method used in photography to quantify graininess by measuring blending distance is introduced. Objective measures of granularity are proposed as correlates of graininess. The term “subsurface” is applied to the apparent “surface” lying beneath the glossy surface. Methods of optical image analysis, such as point spread function, edge spread function, Wiener spectrum, modulation transfer function, and image correlation are proposed to characterize the appearance of metallic surfaces. Polarization and cylindrical presentation may aid measurements. Binocular attributes of appearance introduced here require analysis of the disparity between two points of view. New kinds of pigments may require new methods of measurement. © 1998 John Wiley & Sons, Inc. Col Res Appl, 23: 362–373, 1998     

丙烷氧化脱氢制丙烯研究进展

开发新型丙烯制备工艺对于满足人们日益增长的丙烯需求具有重要意义。由于商业化无氧脱氢技术存在热力学平衡限制、反应温度高、催化剂易积炭等不足,近年来,人们将研究重心转向了丙烷氧化脱氢技术。本文简述了丙烷氧化脱氢制丙烯的发展现状,综述了近年来文献报道的丙烷氧化脱氢催化剂体系（V基、Cr基、Co基、Ni基、Mo基、Pt基、Ce基和非金属基催化剂）、机理研究和不同氧化剂选择,并对各自的优势和不足进行了简单分析。分析发现,虽然目前丙烷氧化脱氢催化剂的种类非常广泛,但产物丙烯的收率仍有待提高,机理研究也需要更加系统和深入。最后指出,系统研究丙烷氧化脱氢机理,并在此基础上开发先进催化剂,进一步提高丙烯的选择性和收率是未来丙烷氧化脱氢研究的重要方向。     

从废旧高温合金的硫酸浸出渣中浸出分离钨钼铼

对废旧高温合金硫酸浸出残渣选择HCl-FeCl3-H2O2体系氧化浸出、浸出后加入NaOH调节溶液pH值,使钨、钼、铼与铌、钽等分离,研究了反应时间、反应温度、HCl用量、FeCl3用量、H2O2用量对钨、钼、铼浸出率的影响. 结果表明,该体系能充分浸出渣中钨、钼、铼3种金属,添加FeCl3可提高钼在盐酸溶液中的浸出率. 在浸出温度70℃、浸出时间5 h、FeCl3用量100 g/L、H2O2用量10 mL/g及HCl初始用量10 mL/g的条件下,钨、钼、铼浸出率分别大于97%, 86%, 91%.     

镍基催化剂的研究进展

镍基催化剂是一种由多孔结构的镍铝合金的细小晶粒组成的固态异相催化剂。镍基催化剂因具有机械强度高、催化活性好、制备简单、价格低廉等优点,被广泛地应用到石油、化工、制药、油脂、香料、双氧水、合成纤维等方面的加氢、脱氢、脱卤、脱硫等转化反应过程中。随着催化工业的逐步发展,对催化剂性能的要求也越来越高,原始的镍基催化剂利用率低、抗酸性差等缺点限制了该催化材料的进一步应用。因此,近年来,许多研究者一直在尝试对镍基催化剂进行改性,以改善其使用寿命、催化活性、抗酸性等性能。着重介绍了镍基催化剂的强化措施以及镍基催化剂的应用,并对镍基催化剂在各类催化反应中的应用情况进行了详细概述,在此基础上展望了镍基催化剂的未来发展。     

氨基纤维素合成与应用的研究进展

氨基纤维素是末端带有氨基的纤维素衍生物,化学结构与壳聚糖相似。氨基基团的引入使纤维素大分子具有很好的溶解性、成膜性和吸附重金属离子特性,并在酶的固定、药物缓释等生物领域有很好的应用前景。氨基纤维素的合成过程相对复杂,主要体现在中间产物的制备以及氨基纤维素的合成2个阶段,其合成过程的选择性和经济性较差,导致氨基纤维素的生产和应用受限。笔者主要对氨基纤维素的合成途径进行了综述,并对氨基纤维素的膜保护、固定酶和吸附等应用进行了总结。     

活化过硫酸盐氧化法降解酚类污染物的研究进展

活化过硫酸盐氧化法因具有经济、高效、环保、安全稳定等优势,近年来在酚类污染物的降解中备受关注。目前活化过硫酸盐降解酚类污染物的方法主要包含外加能量活化和外加催化剂活化两大类。其中单一的热活化、光活化、超声活化、电化学活化、等离子体活化等外加能量活化过程能量消耗较大,且对酚类污染物不易达到满意的降解效果。过渡金属活化和碳质材料活化等外加催化剂活化方式,由于环境污染小、操作成本低、降解率高等优点,越来越受到科研工作者的重视。为了提高对酚类污染物的降解率,不同的过硫酸盐活化方式不断融合,逐渐形成多种耦合活化方式,例如,碳质材料与过渡金属的耦合活化、电化学与过渡金属催化剂的耦合活化以及光与外加催化剂的耦合活化等。本文论述了活化过硫酸盐氧化法降解酚类污染物的研究进展,概述了活化过硫酸盐的影响因素,分析了活化过硫酸盐降解酚类污染物存在的问题,展望了活化过硫酸盐降解酚类污染物的发展方向。