Carboxymethyl cellulose thiol-imprinted polymers:Synthesis,characterization and selective Hg(Ⅱ) adsorption

Sulfur containing ion imprinted polymers(S-IIPs) were applied for the uptake of Hg(Ⅱ) from aqueous solution. Cysteamine which was used as the ligand for Hg(Ⅱ) complexation, was grafted along the epichlorohydrin crosslinked carboxylated carboxymethyl cellulose polymer chain through an amide reaction. The adsorption ability of S-IIPs towards Hg(Ⅱ)was investigated by kinetic and isotherm models, which, corresponding, showed that the adsorption process followed a pseudo-second-order, fitted well with the Langmuir isotherm with a maximum adsorption capacity of 80 mg/g. Moreover, thermodynamic studies indicated an endothermic and spontaneous reaction with the tendency of an enhanced randomness at the surface of the S-IIPs with temperature increases. S-IIPs indicated a high degree of selectivity towards Hg(Ⅱ) in the presence of Cu~(2+), Zn~(2+), Co~(2+), Pb~(2+)and Cd~(2+).Furthermore, the efficiency of S-IIPs was also evaluated against real samples showing86.78%, 91.88%, and 99.10% recovery for Hg(Ⅱ) wastewater, ground water and tap water,respectively. In this study, the adsorbent was successfully regenerated for five cycles, which allows for their reuse without significant loss of initial adsorption capability.     

蚯蚓对菇渣中纤维素和木质素生物转化的研究

为了探索农业废弃香菇菇渣"减量化、无害化、资源化"循环化利用的有效途径.本实验按照不同碳氮比设置菇渣混合基质，接种蚯蚓（Eisenia foetida）对其进行生物转化.实验培养56 d，每14 d取样，分别测定了总氮、总有机碳、木质素和纤维素含量，脲酶、蔗糖酶、纤维素酶和多酚氧化酶活性变化情况，以及菇渣生物转化前后的结构变化情况（扫描电子显微镜SEM）和生物转化产物浸提液的发芽率等指标.结果显示：在蚯蚓生物转化过程中，各处理组总氮、总有机碳和木质纤维素含量与处理前相比均有不同程度的降低，其中，碳氮比为25的处理组纤维素和木质素的降解率最高，分别为50.06%和77.01%；各个处理组中脲酶、蔗糖酶、纤维素酶和多酚氧化酶活性呈不同程度的变化趋势，其中，碳氮比为25的处理组纤维素酶活性增加最多，增加了81.25%；扫描电镜结果显示，蚯蚓生物转化可以将菌渣碎片化；另外，蚯蚓堆肥产物浸提液可以提高黑麦草发芽率.综上，推测碳氮比为25的蚯蚓生物转化体系更有利于菇渣基质处理.     

Evaluation of the Biodegradation of Starch and Cellulose Under Controlled Composting Conditions

In order to verify the response of the controlled composting test method (i.e., the ISO/DIS 14855:1997, the ASTM D 5338-92, or the CEN counterpart) to starch at different concentrations, the maximum amount prescribed by the test method (100 g) and lower amounts (60 and 30 g), as if starch were a coingredient in a blend, were tested. After 44 days of incubation (at a constant temperature of 58°C) the biodegradation curves were in a plateau phase, displaying the following final values (referred to a nominal starch initial amount of 100 g): starch 100 g, 97.5%; starch 60 g, 63.7%; and starch 30 g, 32.5%. The data show a CO₂ evolution roughly equal, in each case, to the theoretical maximum, indicating a complete starch mineralization. We cannot discern whether the deviations found at lower concentrations are caused by a priming effect. In any case, the extent of the deviations is not high and is acceptable in biodegradation studies. The average biodegradation of cellulose, obtained gathering four independent experiments with 11 biodegradation curves, turned out to be 96.8 ± 6.7% (SD) after 47 ± 1 days. The data indicate that the controlled composting is a reliable test method also for starch and cellulose and, consequently, for starch-based and cellulose-based materials.     

Cellulose acetate biodegradability upon exposure to simulated aerobic composting and anaerobic bioreactor environments

Cellulose acetate (CA) films with degree of substitution (d.s.) values of 1.7 and 2.5 were exposed to biologically active in-laboratory composting test vessels maintained at approximately 53 °C. The CA 1.7- and 2.5-d.s. films (thickness values of 0.5–1.0 and 2.0 mil, respectively) had completely disappeared by the end of 7- and 18-day exposure time periods in the biologically active bioreactors, respectively. The relatively small CA film weight loss observed in the poisoned control test vessels allows the conclusion that CA film erosion during the composting exposures resulted, at least in part, from biologically mediated processes. Under strictly anaerobic conditions, an active methanogenic inoculum was developed by acclimation of a sewage sludge to a synthetic municipal solid waste (SMSW) mixture at 42°C. The CA 1.7-d.s. film samples (0.5- to 1.0-mil thickness) were exposed in anaerobic serum bottles containing a 25% solids loading of SMSW in which methanogenic activity was rapidly established after introducing of the developed inoculum. For exposures of 30 days only small visually distinguishable fragments of the CA 1.7-d.s. films were recovered. In contrast, exposure of the CA 1.7-d.s. film to a poisoned control test vessel resulted in negligible weight loss. Therefore, degradation of the CA 1.7-d.s. films upon exposure to the anaerobic bioreactors was due, at least in part, to biologically mediated processes.Guest Editor: Dr. Graham Swift, Rohm & Haas.     

Determination of the aerobic biodegradability of polymeric material in a laboratory controlled composting test

A laboratory method is presented for investigating the biodegradation of an organic test material in an aerobic composting system based on the evolution of carbon dioxide. In addition to carbon conversion, biodegradation can also be monitored through weight loss and physical disintegration. The test method is different from other biodegradation tests, especially aquatic tests, because of the elevated temperature representative for real composting conditions and also because of enhanced fungal degradation activities. A ring test was run using paper and poly-β-hydroxybutyrate/valerate as test materials and cellulose powder as a reference material. The test results and the experience gained by the participants showed that the method is suitable and practicable. Experience with real technical-scale composting facilities confirms that the method provides test results of high predictive value. The test is designed to become a European Standard in connection with determining the compostability of packagings and packaging materials.     

处理秸秆纤维素乙醇废水的东北土著白腐真菌筛选及特性研究

为了提高秸秆纤维素乙醇废水的处理效果,选择6种东北土著白腐真菌,对2%的秸秆纤维素乙醇废水中木质素进行降解处理.采用正交试验法对筛选出的高效降解菌进行产漆酶培养基的优化.结果表明:6种白腐真菌最高酶活大小顺序为青顶拟多孔菌>血红密孔菌>糙皮侧耳菌>彩绒革盖菌>烟色烟管菌>灵芝;血红密孔菌、糙皮侧耳菌、彩绒革盖菌、青顶拟多孔菌、灵芝、烟色烟管菌在第0天起始质量浓度为640.9~716.6 mg/L,在第14天木质素的质量浓度分别为434.0、411.2、441.8、441.7、533.3、503.5 mg/L,对木质素的去除率分别为37.1%、37.0%、31.8%、31.7%、25.6%、21.4%,并分别在第12、12、4、4、2、6天木质素降解趋于平稳,表明降解效果最好的菌种为血红密孔菌.血红密孔菌产漆酶培养基最优组合方案:最佳碳源为锯末,质量浓度为35 g/L;最佳氮源为蛋白胨,质量浓度为4 g/L;最佳pH为5.极差分析表明,各因素对血红密孔菌产漆酶的影响顺序为碳源>氮源> pH >氮源质量浓度>碳源质量浓度.在最佳培养基条件下,废水中木质素降解率达41.1%.研究显示,血红密孔菌可以作为生物法处理秸秆纤维素乙醇废水的菌种资源,也可为今后的进一步应用研究提供科学依据.      

微污染水体水平潜流湿地强化脱氮研究

以纤维素碳源(玉米芯)作为反硝化碳源和微生物载体,在烧杯静态浸泡20 d,河水的可生化性由最初的0.17提高至0.26。采用水平潜流湿地对微污染水体进行处理,考察了导气管复氧和纤维素碳源投加对水平潜流湿地去污效果的影响。试验结果表明:在湿地基质床内合理的布设导气管和合适位置适量投加纤维素碳源,在提高湿地系统脱氮的同时,未使湿地出水COD浓度升高,碳源湿地对COD、TN、氨氮、硝态氮的平均去除率分别达38.52%、70.55%、65.06%和71.92%,并且出水亚硝态氮维持在较低水平。     

微波加热PEI改性纤维素纤维的制备及其对水中Cu~(2+)的吸附性能研究

采用微波辅助加热的方法快速制备了聚乙烯亚胺(PEI)改性的纤维素纤维材料,并与常规加热法制备的改性纤维进行对比。利用元素分析(EA)、热重分析(TGA)对改性纤维进行了表征。同时,还讨论了溶液p H、吸附时间、温度、溶液浓度对改性纤维吸附性能的影响。结果表明:与常规加热制备相比,采用微波加热改性的纤维素纤维接枝率更高且反应时间更短。在p H为6时,改性纤维对Cu2+的吸附性能达到最大,最大吸附量为134.4 mg/g,吸附过程符合Langmuir等温模型和准二级动力学方程。100 W微波加热条件下,经5次吸附/解吸后,吸附量无显著变化。     

Effect of Sequential Mixing and Compounding Conditions on Cellulose Acetate/Layered Silicate Nanocomposites

Injection molded nanocomposites have been successfully fabricated from cellulose acetate (CA), eco-friendly triethyl citrate (TEC) plasticizer, and organically modified clay with and without maleic anhydride grafted cellulose acetate butyrate (CAB-g-MA) as a compatibilizer. The effects of processing conditions such as mixing methods, pre-plasticizing times, extruder retention times (RT) and addition of compatibilizer on the performance of these nanocomposites have been evaluated. The cellulosic plastic with CA/TEC (80/20 wt%) was used as the polymer matrix for nanocomposite fabrication. The morphologies of these nanocomposites were evaluated through X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies. The mechanical properties of the nanocomposites were measured and have been correlated with the XRD and TEM observations. From all of the sequential mixing methods used, powder–powder mixing leads to the most transparent nanocomposites. Cellulosic plastic-based nanocomposites obtained using increased pre-plasticizing times and RT showed better exfoliated structures. In the system containing compatibilizer, the minimum retention time required for obtaining almost completely exfoliated hybrid nanocomposites was shorter than in the system without compatibilizer.     

Characterization of the effective cellulose degrading strain CTL-6

An efficient cellulose degrading bacteria exists in the thermophilic wheat straw-degrading community, WDC2. However, this strain cannot be isolated and cultured using conventional separation techniques under strict anaerobic conditions. We successfully isolated a strain of effective cellulose degrading bacteria CTL-6 using a wash, heat shock, and solid-liquid alternating process. Analysis of its properties revealed that, although the community containing the strain CTL-6 grew under aerobic conditions, the purified strain CTL-6 only grew under anaerobic culture conditions. The strain CTL-6 had a striking capability of degrading cellulose (80.9% weight loss after 9 days of culture). The highest efficiency value of the endocellulase (CMCase activity) was 0.404 μtmol/(min-mL), cellulose degradation efficiency by CTL-6 was remarkably high at 50-65°C with the highest degradation efficiency observed at 60°C. The 16S rRNA gene sequence analysis indicated that the closest relative to strain CTL-6 belonged to the genus Clostridium thermocellum. Strain CTL-6 was capable of utilizing cellulose, celiobiose, and glucose. Strain CTL-6 also grew with Sorbitol as the sole carbon source, whereas C.therrnocellum is unable to do so.