热纤维梭菌不同菌株的纤维素降解和酒精生产能力

以高温厌氧细菌热纤维梭菌(Clostridium thermocellum LQRI和VPI菌株)和嗜热厌氧乙醇菌(Thermoanaerobacterethanolicus X514和39E菌株)为对象,以不同浓度纤维素为底物,分析了热纤维梭菌不同菌株的纤维素降解和酒精生产能力.结果表明,在热纤维梭菌纯培养体系中,LQRI对纤维素的降解能力明显高于VPI,前者约为后者的1.2倍,但两者的酒精生产能力没有显著差异,LQRI在1%纤维素条件下酒精终浓度约为12 mmol/L,VPI约为10 mmol/L.随着底物纤维素浓度的增加(1%、2%、5%),两者对纤维素降解和酒精生产能力均呈明显下降趋势.在热纤维梭菌和嗜热厌氧乙醇菌混合培养体系中,LQRI对纤维素的降解能力明显高于VPI,前者约为后者的1.28～1.58倍.随着底物浓度的增加,两者的纤维素降解率均逐渐下降,但热纤维梭菌对纤维素降解的绝对数值还受到其它混合培养菌种的影响.此外,LQRI+Thermoanaerobacter混合培养体系的酒精生产能力明显高于VPI+Thermoanaerobacter,前者约为后者的1.27～1.77倍.随着底物浓度的增加,混合培养体系酒精生产能力没有明显下降趋势.     

胞外多聚物对酶催化污泥厌氧水解的影响研究

研究了胞外多聚物对酶催化污泥溶解效果和催化过程中污泥化学组分变化的影响.向原污泥及去除胞外多聚物的剩余污泥外加酶,并与未加酶组水解效果进行对比.结果表明,酶浓度〈20 mg/g时仅水解污泥胞外物质,加大酶量能显著引起污泥破解.溶菌酶用于原污泥水解效果较好,SCOD/TCOD最高可达28.14%,投加量60 mg/g,反...     

碱处理对玉米秸秆纤维素结构的影响

介绍了在高固含率条件下氢氧化钠(NaOH)和氢氧化钙(Ca(OH))2堆沤处理对玉米秸纤维素结构的影响。分别用2.5%、5%和7.5%(ρ)的NaOH和Ca(OH)2将玉米秸在常温下堆沤处理3 d后,提取其纤维素,采用傅立叶变换红外光谱(FTIR)和X射线衍射光谱(XRD)对比研究了处理前后纤维素的结构和结晶度的变化。结果表明碱堆沤处理使玉米秸秆中纤维素的形态结构发生了变化,部分分子间氢键断裂,部分酯键消失,随着碱用量的增加,纤维素结构被破坏的程度越大;纤维素的晶体类型与002面微晶位置虽然没有改变,但是纤维素的结晶度与002面微晶尺寸增大。这些变化表明碱处理能提高玉米秸秆纤维素的可及度和反应性,从而改善厌氧消化性能。其中NaOH较Ca(OH)2表现出更好的纤维素润胀能力和反应性,在处理秸秆提高其厌氧消化产甲烷性能上具有更大的潜力。     

白腐菌降解纤维素和木质素的研究进展

纤维素和木质素是潜在的可再生资源，近年来，利用微生物对它们进行降解已成为研究的热点。虽然纤维素较木质素易降解，但其被木质素包裹，故降解的关键问题就是木质素的降解。本文从木质纤维素的生物可降解性出发，重点讨论白腐菌降解木质素酶系及其作用机理。     

Adsorption of phosphate ions from water using a novel cellulose-based adsorbent

A novel cellulose-based adsorbent, iron(III)-coordinated amino-functionalised poly(glycidylmethacrylate)-grafted cellulose [Fe(III)–AM-PGMACell] was developed for the removal of phosphate from water and wastewater. The scanning electron micrograph showed that AM-PGMACell has a rougher surface than cellulose and the adsorption of Fe(III) on AM-PGMACell made the surface even rougher. Infrared spectroscopy revealed that amino groups on the surface of AM-PGMACell complexed with Fe(III) played an important role in the removal of phosphate from solutions. X-Ray diffraction patterns showed a decrease in crystallinity after graft copolymerisation onto cellulose. The effects of contact time, initial sorbate concentration, pH, agitation speed, dose of adsorbent and temperature on the removal process were investigated. Maximum removal of 99.1% was observed for an initial concentration of 25 mg·L ^?1 at pH 6.0 and an adsorbent dose of 2.0 g·L ^?1. A two-step pseudo-first-order kinetic model and Sips isotherm model represented the measured data very well. Complete removal of 11.6 mg·L ^?1 phosphate from fertiliser industry wastewater was achieved by 1.6 g·L ^?1 Fe(III)–AM-PGMACell. The adsorbent exhibited very high reusability for several cycles. Overall, the study demonstrated that Fe(III)–AM-PGMACell can be used as an efficient adsorbent for the removal and recovery of phosphate from water and wastewater.     

Photochemical reactions of musk ketone

The photolysis of musk ketone in cyclohexane and methanol afforded several cyclization products while the product spectrum in cyclohexene and squalene was characterized by an amino derivative and a ring expansion product, respectively. On cellulose stearate layers the photochemical reactions of musk ketone proceeded readily both under sun simulator and in natural sunlight and several photoproducts identified in solvent experiments were detected. Photoproducts were isolated by preparative HPLC and TLC and analyzed by means of HPLC, GC/MS, MS, LC/MS, ¹H‐ and ¹³C‐NMR.     

改性枸杞枝作为反硝化脱氮碳源的研究

为提高枸杞枝作为反硝化碳源的效能,采用甲醇（体积占比分别为0、20%、50%、100%）-水-NaOH （0.01 g·mL^-1）体系（分别简称为0组、20%组、50%组、100%组）对枸杞枝进行改性处理,研究原枸杞枝的静态释碳、改性前后枸杞枝的静态反硝化特性、表面形态和脱氮动力学.结果表明,原枸杞枝释碳过程同时符合二级动力学方程和Ritger-Peppas方程;第I阶段（1~3 d）为碳源快速释放期,第II阶段（4~21 d）为碳源稳定释放期;改性后枸杞枝纤维素和半纤维素含量占比增加了8.7%~35.2%;不同甲醇-水-NaOH体系改性枸杞枝平均反硝化速率依次为20%组>50%组>0组>100%组>对照组,20%甲醇-水-NaOH组反硝化速率最高（0.76 mg·g^-1·d^-1）,表明20%甲醇-水-NaOH （0.01 g·mL^-1）是枸杞枝改性的最佳条件;改性后的枸杞枝表面结构粗糙、不规则且有大量的孔洞产生,适合脱氮微生物附着生长,其反硝化脱氮过程符合Monod动力学方程（R²=0.96）.     

PBS共聚物对蚯蚓的蛋白质含量和纤维素酶活性的影响

以赤子爱胜蚓Eisennia foetida为研究对象,在滤纸接触法的基础上,采用自然土壤法进行急性毒性试验,研究了不同相对分子质量的PBS-co-PCL共聚物对蚯蚓蛋白质含量和纤维素酶活性的毒性效应。研究结果表明：随着暴露时间的增长,蚯蚓蛋白质含量呈现先增加后减小的趋势;第7天时,数均相对分子质量（Mn）为8.0×103的聚合物对蛋白质的影响较明显;第14天时,相对分子质量（Mn）为1.6×104和2.8×104的聚合物对蛋白质的影响较明显。聚合物相对分子质量（Mn）为8.0×103处理组中,纤维素酶活性受到的抑制作用较明显,聚合物含量为2.5%时,抑制作用达到最大。但是随着暴露时间的增长,这种抑制作用逐渐减小,即影响是暂时性的,纤维素酶活性变化比蛋白质含量变化更敏感。以上结果表明蚯蚓在实验过程中没有出现致病或致死现象,即聚合物对蚯蚓的影响较小。     

Functional Properties of Extruded Acetylated Starch-Cellulose Foams

Acetylated starches, with degrees of substitution (DS) of 2, 2.5 and 3, were blended with 3%, 7.5% and 12% -cellulose and 14%, 17% or 20% (d.b.) ethanol and twin-screw extruded at 165°C barrel temperature and 225 rpm screw speed. A response surface methodology experimental design was applied to the sub-plot and a completely randomized design to the whole plot design to test the differences among the acetylated starches and the effects of cellulose and ethanol. DS, cellulose and ethanol contents significantly affected the functional properties and specific mechanical energy requirement. DS had positive effects on radial expansion ratio (RER), compressibility and specific mechanical energy requirement and a negative effect on bulk density. Highest (RER) was obtained from 20% ethanol content. Extrudates containing 12% cellulose had the highest bulk density and the highest compressibility. Higher cellulose contents required more specific mechanical energy.     

纤维素热裂解的二次反应研究

在热重红外联用分析仪上开展了纤维素的热裂解失重研究,通过对纤维素热裂解的TG和DTG曲线以及热解产物的红外析出图谱的分析研究,探讨了纤维素热裂解的二次反应过程及机理,并在经典Broido—Shafizdeh模型的基础上．提出了改进的纤维素热裂解模型。