农作物秸秆解聚研究

农作物秸秆是重要的生物质资源.本文从我国建立资源节约和环境友好社会目标的角度,论述了农作物秸秆高效利用的重要性和研究农作物秸秆解聚对开发农作物秸秆高效利用的新工艺的重要意义.介绍了农作物秸秆解聚的典型工艺及解聚产物组成分析和利用研究的进展,预测了农作物秸秆解聚研究的发展方向.     

农作物秸秆解聚研究

农作物秸秆是重要的生物质资源.本文从我国建立资源节约和环境友好社会目标的角度,论述了农作物秸秆高效利用的重要性和研究农作物秸秆解聚对开发农作物秸秆高效利用的新工艺的重要意义.介绍了农作物秸秆解聚的典型工艺及解聚产物组成分析和利用研究的进展,预测了农作物秸秆解聚研究的发展方向.     

碱解聚对玉米秸秆的影响

以玉米秸秆为研究对象,氢氧化钠为解聚剂,研究了碱解聚前后玉米秸秆组份、表面形态、化学官能团和纤维结晶度的变化。结果表明:玉米秸秆中木质素的主要组成单体是H-木质素,解聚液中的酚类物质有4-羟基苯甲醛、香草醛、紫丁香醛、对香豆酸和阿魏酸。玉米秸秆经碱解聚,表面形态变得疏松而多孔,红外光谱下木质素的特征吸收峰消失,85%的木质素和52%的半纤维素被脱除,而纤维素的相对含量增加,结晶度增大。说明碱解聚有利于后续酶解和(或)其它生化方法的实施,以实现秸秆纤维的高值转化。     

秸秆材料的改性及其在水处理中的应用研究

当前水体污染问题日趋严重,寻求高效、环保,且成本低廉的水处理剂一直以来是水处理技术研究中的重要方向之一.秸秆是一类农作物废弃物,材料中富含纤维素和木质素等天然高分子,来源十分广泛,且是一类可再生资源.然而目前过剩的秸秆材料大多仍是通过焚烧处理,这不仅给大气环境带来危害.还造成资源的极大浪费.将秸秆材料通过适当的处理和改性,作为水处理剂,应用于污水处理中,无疑具有重要的现实意义和经济价值.本文详细综述了近年来国内外就秸秆材料的改性处理方法及其在水处理中的应用研究情况.     

农作物秸秆红外指纹图谱双指标序列分析

采用傅立叶红外光谱技术研究了不同地区、不同种类农作物秸秆的红外指纹图谱,对其谱带归属进行了判别分析;并利用共有峰率和变异峰率双指标序列法对农作物秸秆样品进行分析鉴别。结果表明:同种农作物秸秆化学成分相似,不同农作物秸秆化学成分差异较大,其中花生秆与其他农作物秸秆化学成分差异最大。     

酸碱解聚玉米秸秆分子结构的实验研究

以玉米秸秆为研究对象,分别采用5%H2SO4和5%NaOH溶液对秸秆进行解聚处理,并对解聚前后秸秆结构、化学组成、热稳定性等进行分析和表征。结果表明,与未处理前相比,经酸或碱解聚处理后,秸秆纤维结晶度由51.8%分别提高到63.5%和67.0%,秸秆中大部分半纤维素和部分木质素组分被脱除,半纤维素由29.10%分别降至7.02%和6.86%,木质素由38.12%分别降至32.21%和16.52%,而纤维素则由31.54%分别升至60.54%和76.15%。经酸碱处理后,秸秆表面形态结构变得疏松,出现小孔和裂缝,降解温度达到350℃,热稳定性能增加。上述结果说明,稀酸或稀碱均对玉米秸秆分子结构有一定程度的解聚作用,但就解聚溶出木质素而言,稀碱的解聚溶出效果要优于稀酸的。     

秸秆资源循环经济利用模式——纸浆与肥料联产的清洁生产技术体系

本文对我国秸秆资源利用和肥料使用现状、清洁制浆技术的进展进行了较为详细的论述,介绍了纸浆与肥料联产的循环经济利用模式的内容和发展前景。该模式采用熔态水解法自制氢氧化钾并联产磷肥以降低原料成本,用氢氧化钾对秸秆进行蒸煮得到纸浆,通过用含钾黑液来制备液体肥料、固体有机肥料和灌溉水,使黑液全部得到资源化利用而实现系统内无污染物排放。秸秆资源来源于农业,所加工的肥料又服务于种植业,同时又生产了造纸工业急需的纸浆,因而采用这种肥料与纸浆联产的技术体系是实现秸秆资源清洁、高效和经济利用的有效途径。     

秸秆资源循环经济利用模式——纸浆与肥料联产的清洁生产技术体系

本文对我国秸秆资源利用和肥料使用现状、清洁制浆技术的进展进行了较为详细的论述,介绍了纸浆与肥料联产的循环经济利用模式的内容和发展前景.该模式采用熔态水解法自制氢氧化钾并联产磷肥以降低原料成本,用氢氧化钾对秸秆进行蒸煮得到纸浆,通过用含钾黑液来制备液体肥料、固体有机肥料和灌溉水,使黑液全部得到资源化利用而实现系统内无污染物排放.秸秆资源来源于农业,所加工的肥料又服务于种植业,同时又生产了造纸工业急需的纸浆,因而采用这种肥料与纸浆联产的技术体系是实现秸秆资源清洁、高效和经济利用的有效途径.     

秸秆资源循环经济利用模式——纸浆与肥料联产的清洁生产技术体系

本文对我国秸秆资源利用和肥料使用现状、清洁制浆技术的进展进行了较为详细的论述,介绍了纸浆与肥料联产的循环经济利用模式的内容和发展前景.该模式采用熔态水解法自制氢氧化钾并联产磷肥以降低原料成本,用氢氧化钾对秸秆进行蒸煮得到纸浆,通过用含钾黑液来制备液体肥料、固体有机肥料和灌溉水,使黑液全部得到资源化利用而实现系统内无污染物排放.秸秆资源来源于农业,所加工的肥料又服务于种植业,同时又生产了造纸工业急需的纸浆,因而采用这种肥料与纸浆联产的技术体系是实现秸秆资源清洁、高效和经济利用的有效途径.     

提升化学本科生科学思维与逻辑的科研实践

利用学校化学人才培养基地为本科生搭建的科研训练平台,引导和训练大学生在科研项目＂我国东南地区主要秸秆物性分析与评价＂中正确开展科学研究与创新活动,并对获得的结果展开分析与讨论。学生通过独立开展文献查阅、实验方案设计、实验结果分析等工作,研究获得了福建地区不同地理与气候等生态条件对水稻秸秆组分含量的分布特性及差异可能带来的影响,这一结果为水稻秸秆资源的分布、组分特性及今后的高效利用提供了科学依据与评价。     

Selective extraction and conversion of lignin in actual biomass to monophenols: A review

Our over dependency on the fossil resource for industrial chemicals and fuels faces great challenges.Recently, the production of monophenols from lignin in lignocellulosic biomass is regarded as a promising process for sustainable biofuels. This article discusses the conversion of lignin in actual biomass directly to monophenols. The two step way including extraction of lignin from biomass and further degradation of the lignin oligomers to monophenols is especially discussed. The obtained monophenols can also be converted to chemicals with low-oxygen content via hydrodeoxygenation process. For extraction of lignin,co-solvent system is the most adopted for hydrolysis or solvolysis of lignin assisted by acid or alkaline catalysts. The structure of the obtained oligomers derived from lignin is discussed in detail. For lignin depolymerization, hydrogenolysis is an efficient method with the use of gaseous hydrogen or alcohols as hydrogen source. At the meantime, depolymerization mechanism and the route for repolymerization of the reaction intermediates are presented here. In hydrodeoxygenation process, metal catalysts, especially noble metal catalysts are required. The precise effects of the reaction solvents and catalysts on extraction and degradation of lignin need to be further investigated, and this will benefit to design more efficient strategies for lignin utilization.     

The Use of Dual Cyclodextrin Chiral Selector Systems in the Enantioseparation of Pharmaceuticals by Capillary Electrophoresis: An Overview

Cyclodextrin (CD) derivatives are the most efficient and frequently used chiral selectors (CSs) in capillary electrophoresis (CE). There are situations when the use of a single CD as CS is not enough to obtain efficient chiral discrimination of the enantiomers; in these cases, sometimes this problem can be resolved using a dual CD system. The use of dual CD systems can often dramatically enhance enantioseparation selectivity and can be applied for the separation of many analytes of pharmaceutical interest for which enantioseparation by CE with another CS systems can be problematic. Usually in a dual CD system an anionic CD is used together with a neutral one, but there are situations when the use of a cationic CD with a neutral one or the use of two neutral CDs or even two ionized CDs can be an efficient solution. In the current review we present general aspects of the use of dual CD systems in the analysis of pharmaceutical substances. Several examples of applications of the use of dual CD systems in the analysis of pharmaceuticals are selected and discussed. Theoretical aspects regarding the separation of enantiomers through simultaneous interaction with the two CSs are also explained. Finally, advantages, disadvantages, potential and new direction in this chiral analysis field are highlighted.     

Zinc-catalyzed depolymerization of artificial polyethers

Recycling polymers: In the present study, the efficient zinc-catalyzed depolymerization of a variety of artificial polyethers has been investigated. Chloroesters were obtained as the depolymerization products, which are suitable precursors for new polymers. By using straightforward zinc salts, extraordinary catalyst activities and selectivities were feasible (see scheme).     

超声波提取-固相萃取-液相色谱-串联质谱法同时测定沉积物中24种皮质类固醇激素

沉积物中皮质类固醇激素(CSs)的痕量分析对探究其在环境多介质中的赋存状况和环境行为具有重要意义.然而目前相关研究主要集中在水样中糖皮质激素的测定,对基质更为复杂的环境固体样品中CSs的定量分析研究仍十分有限亦缺乏针对性、系统性,且目标物未能覆盖大多数常见常用的糖/盐CSs.本研究系统地优化了样品前处理过程和仪器分析中...     

Zinc‐Catalyzed Depolymerization of End‐of‐Life Polysiloxanes

Polymers occupy an important role in our current society. Besides their great success, an issue is the accumulation of huge amounts of end‐of‐life polymers. Currently, the waste management is based primarily on landfills, thermal recycling, and downcycling. Notably, only a small portion of end‐of‐life materials is recycled by depolymerization, which refers to the creation of synthetic precursors that can be polymerized to new polymers to close the cycle. Widely used polymers in modern times are silicones (polysiloxanes), the intrinsic properties of which make their depolymerization demanding; only a few high‐temperature or less environmentally friendly processes have been reported. In this regard, we have established an efficient low‐temperature protocol for the depolymerization of silicones with benzoyl fluoride in the presence of cheap zinc salts as precatalysts to yield defined products. Notably, the products can be useful synthetic precursors for the preparation of new polymers, so that an overall recycling process is feasible.     

An efficient method to depolymerize polyamide plastics: a new use of ionic liquids

Treatment of polyamides in an ionic liquid at 300 degrees C resulted in the efficient depolymerization of polyamides to give corresponding monomeric lactam in good yields. The recovered monomer was collected by direct distillation of the reaction mixture. PP13 TFSI furnished the best results for the depolymerization. The ionic liquid could be recycled five times in the present reaction.     

煤的化学降解研究——Ⅰ.煤的氯化降解

用水介质中氯化的方法对煤进行降解研究,考察了降解后煤的化学组成和在有机溶剂中抽提性质的变化。降解后,煤中碳、氢含量下降,氯、氧含量增加,腐植酸及活性官能团增多,使煤具有一系列新的性质。如在极性溶剂中抽出量显著增加,其中丙酮抽出率高达86.4%。     

Enantiomer discrimination by mass spectrometry: noncovalent interactions of an N-derivatized dipeptide with various cinchona alkaloid derivatives and comparison with enantioselective liquid-phase separations

The enantiomer discrimination properties of cinchona alkaloid derived chiral selectors (CSs) towards a dipeptide analyte are examined by electrospray ionization mass spectrometry. The complexes formed between the CSs and the analyte enantiomers owing to various noncovalent interactions are analyzed and the magnitudes of enantiomer discrimination are determined from the complexes mass spectrometric intensities. The influence of different structural features of the CSs on enantioselectivity is discussed. The enantiomer discrimination results obtained by mass spectrometry are compared with those from related liquid chromatography enantiomer separations. A certain coherence between the chromatographic and mass spectrometric enantioselectivities could be established and the enantiomer discrimination patterns, i.e., the relative binding strengths, were identical for the two techniques. Thus, the use of mass spectrometry as a screening tool in the development of new CSs for chromatographic applications seems feasible.     

Preparation of Monodispersed Carbon Spheres via Hydrothermal Carbonization of Ascorbic Acid and Their Application in Lithium Ion Batteries

Hydrothermal carbonization is one of the most appealing strategies to prepare carbon spheres(CSs). Nevertheless, the precursors of hydrothermal carbonization are limited to several saccharides currently and the obtained CSs are easily interconnected among each other, giving rise to difficulties in further treatment and applications. In this work, ascorbic acid was used as precursor in the hydrothermal procedure and monodispersed CSs could be fabricated without any catalysts. In addition, the composites of CSs and chemical reduced graphene oxide(CRG) possessing three dimensional network structures were fabricated, which exhibited excellent electrochemical performance used as anode in lithium ion battery(LIB). Meanwhile, the effects of size distributions of CSs on the electrochemical performances were evaluated.     

Chromatographic methods for product-profile analysis and isolation of oligosaccharides produced by heparinase-catalyzed depolymerization of heparin.

A two-dimensional chromatography method for monitoring the formation of oligosaccharides produced by heparinase-catalyzed depolymerization of heparin is reported. In the first step of the two-dimensional method, the depolymerized heparin is size-fractionated by high-performance gel permeation chromatography (HPGPC). The size-uniform fractions are then separated on the basis of charge by strong anion-exchange (SAX) HPLC on a high resolution CarboPac PA1 column. To demonstrate application of the two-dimensional product-profile analysis method, data are presented for the heparinase I-catalyzed depolymerization of heparin in the absence and presence of histamine, a ligand that binds site-specifically to heparin. Results from the two-dimensional analysis indicate that histamine alters the extent of depolymerization and the product-profiles for the tetrasaccharide and hexasaccharide fractions. The use of CarboPac PA1 columns for the semi-preparative scale separation of oligosaccharides in size-uniform fractions isolated from depolymerized heparin by low-pressure (gravity flow) GPC is also reported. The semi-preparative scale CarboPac PA1 column gives high resolution and excellent reproducibility after repeated use over an extended period of time, making it possible to reliably combine fractions from multiple separations. The oligosaccharides are eluted from the CarboPac PA1 column with a NaCl gradient at relatively low pH (3 or 7) where they are stable. An efficient two-step procedure is described for desalting oligosaccharides separated