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71.
白腐菌降解纤维素和木质素的研究进展 总被引:20,自引:0,他引:20
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。 相似文献
72.
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). 相似文献
73.
Adsorption of heavy metal ions from aqueous solution by carboxylated cellulose nanocrystals 总被引:2,自引:0,他引:2
Xiaolin Yu Shengrui Tong Maofa Ge Lingyan Wu Junchao Zuo Changyan Cao Weiguo Song 《环境科学学报(英文版)》2013,25(5):933-943
A novel nanoadsorbent for the removal of heavy metal ions is reported.Cotton was first hydrolyzed to obtain cellulose nanocrystals(CNCs).CNCs were then chemically modified with succinic anhydride to obtain SCNCs.The sodic nanoadsorbent(NaSCNCs) was further prepared by treatment of SCNCs with saturated NaHCO 3 aqueous solution.Batch experiments were carried out with SCNCs and NaSCNCs for the removal of Pb 2+ and Cd 2+.The effects of contact time,pH,initial adsorption concentration,coexisting ions and the regeneration performance were investigated.Kinetic studies showed that the adsorption equilibrium time of Pb 2+ and Cd 2+ was reached within 150 min on SCNCs and 5 min on NaSCNCs.The adsorption capacities of Pb 2+ and Cd 2+ on SCNCs and NaSCNCs increased with increasing pH.The adsorption isotherm was well fitted by the Langmuir model.The maximum adsorption capacities of SCNCs and NaSCNCs for Pb 2+ and Cd 2+ were 367.6 mg/g,259.7 mg/g and 465.1 mg/g,344.8 mg/g,respectively.SCNCs and NaSCNCs showed high selectivity and interference resistance from coexisting ions for the adsorption of Pb 2+.NaSCNCs could be efficiently regenerated with a mild saturated NaCl solution with no loss of capacity after two recycles.The adsorption mechanisms of SCNCs and NaSCNCs were discussed. 相似文献
74.
文章以标准纤维素为对照吸附剂,以菲为对照吸附质,采用批量平衡振荡法进行吸附实验,研究不同pH条件下,小麦根吸附极性污染物(2,4-二氯苯酚和硝基苯)的行为差异。结果表明:污染物吸附以疏水性分配为主,吸附系数(K_d)值随化合物疏水性的增强而增强;非解离型极性污染物(硝基苯)的吸附与疏水性污染物(菲)类似,吸附等温线呈线性,相关系数(R2)均大于0.98,同时pH对吸附的影响无显著性差异(P>0.05);解离型极性污染物(2,4-二氯苯酚)的吸附随pH增加而降低,仅在pH 5.0时呈现吸附线性,在pH 7.0和8.0时均呈非线性,等温线逐渐向浓度轴弯曲,这源于疏水作用以及解离的2,4-二氯苯酚与吸附剂之间静电作用的共同影响。根的吸附能力大于纤维素,这与根中含有类脂物质有关。 相似文献
75.
76.
Preliminary Studies on Converting Agricultural Waste into Biodegradable Plastics – Part III: Sawdust
Christopher?H.?SchillingEmail author Piotr?Tomasik David?S.?Karpovich Bruce?Hart Jagdeep?Garcha Paul?T.?Boettcher 《Journal of Polymers and the Environment》2005,13(2):177-183
Summary Hardwood sawdust was derivatized either by carboxymethylation, glutaration, maleiation, phthallation, or succination in order to produce anionic materials suitable for complexation with soy protein isolate. Blending each derivative with soy protein isolate resulted in instant precipitation of gels. Infrared spectroscopy and differential scanning calorimetry suggested that each derivative formed a complex with protein. Reaction products could be dried into pellets exhibiting tensile strengths between 0.9–2.4 MPa, suggested that these materials could be promising candidates for biodegradable structural materials. 相似文献
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79.
D. F. Gilmore R. C. Fuller B. Schneider R. W. Lenz N. Lotti M. Scandola 《Journal of Polymers and the Environment》1994,2(1):49-57
Blends of the bacterially produced polyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with cellulose acetate esters (CAE) further substituted with propionyl or butyryl groups (degree of substitution: 2.60 propionyl and 0.36 acetyl or 2.59 butyryl and 0.36 acetyl, respectively) were exposed for 4 months to activated sludge to determine their biodegradability. Samples of such blends made by solution-mixing and solvent-casting had complex morphologies in which both individual components as well as a miscible blend phase were present. Additionally, the two opposite surfaces of solvent-cast films showed both physical and chemical differences. After 2 months, samples of pure PHBV had degraded by more than 98% (15 mg/cm2 of surface area), whereas a pure CAE sample had degraded less than 1% (<0.2 mg/cm2). Samples containing 25% CAE lost less than 40% of their initial weights (6 mg/cm2) over the total 4-month period. Samples with 50% CAE lost up to 16% weight (2 mg/cm2), whereas those containing 75% CAE lost only slightly more weight than corresponding sterile control samples (1 mg/cm2). NMR results confirm that weight loss from samples containing 25% CAE resulted only from degradation of PHBV and that the surface of samples became enriched in CAE. Solvent-cast film samples containing equal amounts of PHBV and CAE degraded preferentially on the surface which formed at the polymer-air interface. Scanning electron microscopy and attenuated total reflectance infrared spectroscopy revealed this surface to have a rougher texture and a greater PHBV content. 相似文献
80.
生态浮床是一种无占地、环境友好、集水体美化和污染物去除为一体的生态修复工程。首先分析了组合式生态浮床的原理、特点和弊端,以及生态浮床技术的研究现状,引出了湿地槽式生态浮床的概念;其次阐述了纤维素物质在生态浮床领域的应用现状和发展;最后探讨了纤维素物质在生态浮床领域应用急需解决的难题。为生态浮床技术的发展和革新提供参考。 相似文献