盐湖资源的开发和综合利用技术

中国是世界上盐湖资源最丰富的国家之一,钾、钠、锉、镁资源储量巨大.随着我国国民经济特别是农业的持续发展,要以钾为龙头,注重资源的综合利用,加快盐湖资源的开发。本文评述了我国盐湖资源的特点、开发现状和现阶段盐湖资源开发和综合利用中有代表性的化工技术:冷结晶法生产氛化钾、从盐湖资源制取硫酸钾、卤水中锉的分离提取、水氯镁石脱水和热解技术以及盆湖资源的深加工和高值化。     

当雄错盐湖卤水提钾盐田日晒工艺扩大试验研究

西藏现代钾锂硼特种盐湖的钾盐开发将对我国钾盐需求形成有利补充。本文首次采用蒸发结晶、分步分离的方法,进行了当雄错盐湖碳酸盐型卤水提钾多级盐田日晒工艺扩大试验研究。通过对卤水蒸发析盐全过程做化学分析和物料衡算,确定了钾、硼等重要无机元素的成盐类型和析盐阶段,以及锂、铷等稀有元素的富集规律,最终获得了较高品位钾混盐和高浓母卤,并取得了大量第一手数据资料,为今后实现当雄错盐湖卤水钾盐资源的产业化开发提供了切实可靠的中试基础和设计参考。     

盐湖资源开发利用进展

本世纪头十年里,国际上再度掀起盐湖资源开发热潮。这很大程度上是由于锂的开发热带动的,同时也是和钾肥的广泛施用、价格一路走高有关。南美安第斯高原地区盐湖蕴藏世界70%以上的锂资源,且卤水锂、钾、硼浓度高。该地区极度干旱,少雨多风,非常适合采用卤水盐田蒸发的节能浓缩工艺技术。老的盐湖开发企业则在钾肥需求的带动下,稳步发展。在我国,新疆罗布泊和青海柴达木盆地盐湖则钾锂镁硼产品多元化,经营多元化取得长足进步。本文对近十年来,国内外盐湖开发的新动向做了概括介绍,特别着重于南美"锂三角"地区这一新的生长点。     

钠型斜发沸石对高钙苦卤中钾离子的吸附研究

我国具有丰富的盐湖苦卤资源[1].其中含有高浓度的钙、镁、铁、钡、钾和溴等有价值的矿产,并已形成了以钾、溴和镁为产品链的苦卤化工行业[2].由于我国陆地钾矿资源相对短缺,从苦卤和海水中选择性地提取钾,一直受到研究者的重视.     

卫浴陶瓷用钾长石中钾含量测定方法的选择

钾长石在我国的资源分布较广，是陶瓷、搪瓷、玻璃、钾肥生产过程中广泛使用的原料。在陶瓷制作中钾长石作为主要的熔剂原料，在高温下熔融后可以溶解部分石英和高岭土的分解产物。由于其等级和市场定价都受钾含量的影响，因此钾含量的准确测定具有重要意义。     

离子色谱法测定盐湖原卤中阳离子

<正>盐湖卤水资源矿化度高,富含多种盐矿资源,柴达木盆地是我国卤水资源最为丰富的地区,其中的察尔汗盐湖自西向东依次为霍布逊、察尔汗、达布逊和别勒滩四大湖区,以液体、固液并存的钾矿资源为主,并伴有钠、镁等资源,还富含铷、铯等稀散元素。盐湖卤水中盐矿资源开发利用的同时,其离子含量的分离测定也是当前热门的分析课题。目前测定锂、钾、钠、钙、镁、铷和铯等无机阳离子的方法有原子吸收光谱法、原子发射光谱法[1-2]、     

非离子型表面活性剂辅助酶水解玉米秸杆蒸爆渣

研究纤维素酶对蒸汽爆破预处理玉米秸杆的水解过程. 实验结果表明,玉米秸杆蒸爆渣中的木质素对纤维素酶存在非生产性吸附,降低了纤维素酶对玉米秸杆蒸爆渣的水解率;通过添加非离子型表面活性剂PEG 6000,减少纤维素酶的非生产性吸附,改善纤维素酶对玉米秸杆蒸爆渣的水解性能;在pH值为4.8,温度为50℃,PEG 6000浓度为3.5g/L的优化条件下,纤维素酶水解玉米秸杆蒸爆渣48h,还原糖水解率和葡萄糖水解率分别为83.61%和64.15%.     

科学开发我国的盐湖资源

随着我国经济的持续发展和国家西部大开发战略的有力实施,我国盐湖资源正处于大规模开发的新阶段。本文阐述了国内外盐湖开发的相关技术与钾肥、锂盐和镁工业的发展状况,并按照资源综合利用的开发要求和可持续发展的原则,对科学开发我国盐湖资源开发的有关问题提出了建议。     

稀土元素的第一位发现人加多林

我国的稀土资源极为丰富,为世界任何国家所不及。我国不仅已经发现、研究和开发了一批稀土矿床,而且新的稀土资源还在不断地被发现。因此,我们从化学史角度谈谈稀土元素的第一位发现人,对于学化学的人,可能不是没有兴趣的。英国化学家威廉·克鲁克斯(William Crookes)     

伯胺N-1923从硫酸铝溶液中萃取除铁的初步研究

我国铝的资源非常丰富,每年从明矾石、煤矸石等矿石中提炼大量的铝。由于铝及其化合物广泛的应用,在工业、农业、国防、医学等国民经济各个领域具有重要意义。全国科学大会提出的“八年科学发展规划纲要”中指出,要加强铝资源开发的研究,使铝的提炼技术接     

Adsorption performance and stability of the modified straws and their extracts of cellulose,lignin, and hemicellulose for Pb2+: pH effect

Adsorption performance and stability of the carboxyl groups modified straws and their extracts of cellulose, lignin, and hemicellulose for Pb²⁺ were investigated, and the optimum pH range for Pb²⁺ adsorption was determined by considering both the stability and capacity of the modified biosorbents for the first time. Results showed that adsorption capacity and stability of the straws and extracts were both improved significantly after modification. Adsorption capacities of the modified straws and extracts followed the order: modified hemicellulose > modified lignin, modified straw > modified cellulose, while stability of them followed the reverse order. In the optimum pH range from 4.0 to 5.0, modified rape and cotton straw showed better stability than the modified maize straw, and total organic carbon (TOC) values determined from the two modified straws and extracts were lower than 5.0 mg L⁻¹ even after adsorption for 30 days, which reached the drinking water standard in China.     

硝酸乙醇法测定纤维素含量

根据秸秆乙醇的工艺特点,对硝酸乙醇法测定玉米秸秆、小麦秸秆、稻草及其预处理后物料的纤维素含量进行了研究.优化了粉碎时长、硝酸-乙醇混合液处理遍数、试样粒度及抽滤漏斗孔径四个参数.确定了优化后的测定方法:秸秆试样粉碎时长15 s,硝酸-乙醇混合液处理4遍,粒度40～60目,使用G2玻璃砂芯漏斗.秸秆预处理后物料试样粉碎时...     

Experimental thermal characterization of timber frame exterior wall using reed straws as heat insulation materials

Journal of Thermal Analysis and Calorimetry - The research presented in this paper proposes structures of timber frame exterior walls using reed straws as insulation materials. Having thicknesses...     

Textile grade long natural cellulose fibers from bark of cotton stalks using steam explosion as a pretreatment

Textile grade long natural cellulose fibers with fineness of 27 dtex have been extracted from bark of cotton stalks by a combination of steam explosion, potassium hydroxide and peroxide treatments (explosion–KOH–H₂O₂). It was reported that natural cellulose fibers from bark of cotton stalks had significantly better mechanical properties than those from other lignocellulosic agricultural byproducts such as rice and wheat straws. Fibers from bark of cotton stalks were used to reinforce thermoplastic composites but could not be spun into yarns for textile applications due to their high fineness value (around 50 dtex) and/or low aspect ratio (around 660). In this research, barks of cotton stalks were treated using three methods, including steam explosion, a combination of steam explosion and potassium hydroxide treatments (explosion–KOH) and explosion–KOH–H₂O₂. The morphology, composition, carding yield, crystalline structures and tensile properties of three different cotton stalk fibers were analyzed. Results showed that cotton stalk fibers extracted by explosion–KOH–H₂O₂ had the lowest fineness value of 27 dtex and moderate aspect ratio of 1,150 in three kinds of fibers. The fibers also had most clean and smooth surfaces, highest carding yield of 68.6 %, and highest cellulose content of 82.1 wt% due to effective removal of non-cellulose impurities. Moreover, the fibers had tensile properties close to cotton fibers. Overall, the cotton stalk fibers presented a better potential to be used as textile fibers than those reported by previous researches. explosion–KOH–H₂O₂ could be an efficient method for exploring textile applications of bark of cotton stalks.     

Ensiling Agricultural Residues for Bioethanol Production

The potential of using ensiling, with and without supplemental enzymes, as a cost-effective pretreatment for bioethanol production from agricultural residues was investigated. Ensiling did not significantly affect the lignin content of barley straw, cotton stalk, and triticale hay ensiled without enzyme, but slightly increased the lignin content in triticale straw, wheat straw, and triticale hay ensiled with enzyme. The holocellulose (cellulose plus hemicellulose) losses in the feedstocks, as a result of ensiling, ranged from 1.31 to 9.93%. The percent holocellulose loss in hays during ensiling was lower than in straws and stalks. Ensiling of barley, triticale, wheat straws, and cotton stalk significantly increased the conversion of holocellulose to sugars during subsequent hydrolysis with two enzyme combinations. Enzymatic hydrolysis of ensiled and untreated feedstocks by Celluclast 1.5 L-Novozyme 188 enzyme combination resulted in equal or higher saccharification than with Spezyme CP-xylanase combination. Enzyme loadings of 40 and 60 FPU/g reducing sugars gave similar sugar yields. The percent saccharification with Celluclast 1.5 L-Novozyme 188 at 40 FPU/g reducing sugars was 17.1 to 43.6%, 22.4 to 46.9%, and 23.2 to 32.2% for untreated feedstocks, feedstocks ensiled with, and without enzymes, respectively. Fermentation of the hydrolysates from ensiled feedstocks resulted in ethanol yields ranging from 0.21 to 0.28 g/g reducing sugars.     

固相配位化学反应——ⅩⅩⅩ.室温下铁氰化钾的固相反应

本文首次报道了铁氰化钾在室温下与碘化钾、硫化钾的固相氧化还原反应,实验发现在固相下铁氰化钾与碘化钾混合后,生成单质碘和亚铁氰化钾,而在溶液中该反应是反方向进行的.实验还发现,在固相下铁氰化钾与还原剂硼氢化钠不反应,而在溶液中,该反应却能进行.对反应机制进行了初步探讨.     

固相配位化学反应——ⅩⅩⅩ.室温下铁氰化钾的固相反应

本文首次报道了铁氰化钾在室温下与碘化钾、硫化钾的固相氧化还原反应,实验发现在固相下铁氰化钾与碘化钾混合后,生成单质碘和亚铁氰化钾,而在溶液中该反应是反方向进行的.实验还发现,在固相下铁氰化钾与还原剂硼氢化钠不反应,而在溶液中,该反应却能进行.对反应机制进行了初步探讨.     

秸秆发酵燃料乙醇关键问题及其进展

利用木质纤维素原料生产燃料乙醇是国际公认的难题。本文从秸秆原料组分不均一性出发,分析了秸秆难以高值化原因;进一步分析了秸秆酶解发酵燃料乙醇的关键问题,介绍了有关秸秆原料预处理、纤维素酶生产、秸秆酶解发酵乙醇和产业化示范工程等的进展。秸秆酶解发酵燃料乙醇产业化示范工程具有自主知识产权,为实现我国秸秆转化燃料乙醇的规模化、产业化、低成本生产奠定了基础。     

四苯硼钾从水到二甲基亚砜混合溶剂⒇中的标准迁移自由能和介质效应

二甲基亚砜（ＤＭＳＯ）是一种特殊的有机溶剂，它不但是良好的萃取剂、增塑剂和有机化学反应的中间体，而且由于它含有ＳＯ基团，可以作为良好的质子接受体，与Ｌｅｗｉｓ酸形成氢键缔合物，致使一些含ＤＭＳＯ的混合溶剂表现出很多的反常特性。因此，ＤＭＳＯ在溶液化学...     

Ion mobilities in DMF-water mixtures at 25°C

Densities and viscosities of mixtures of N,N-dimethylformamide (DMF) with water at 25°C have been determined. Limiting equivalent conductances of cesium chloride, potassium chloride, potassium bromide and potassium thiocyanate in these solvent mixtures at 25°C are presented together with corresponding values of ion association constants and distance of closest approach parameters. The transference number of the potassium ion has been determined in solvent mixtures ranging from 0 to 0.75 mol fraction in DMF in water at 25°C. The conductimetric Hittorf method has been used for both potassium bromide and potassium chloride in solutions of up to 0.496 mole fraction of DMF. For solutions of potassium thiocyanate in 0.5 and 0.75 mole fraction in DMF the cationic transference number has been determined using the moving boundary method. Stokes radii have been evaluated. Transport properties are examined in relation to-solvent properties such as composition, dielectric constant, excess volume of mixing and free volume.To whom correspondence should be addressed.