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381.
W. S. Chow S. G. Tan Z. Ahmad K. H. Chia N. S. Lau K. Sudesh 《Journal of Polymers and the Environment》2014,22(1):140-147
In this study, bio-thermoset from epoxidized soybean oil (ESO) was prepared in the presence of methylhexahydrophthalic anhydride curing agent and 2-ethyl-4-methylimidazole catalyst. The crosslink densities of the synthesized ESO are ranged from 0.109 × 10?3 to 0.308 × 10?3 mol/cm3. The ESO bio-thermosets were exposed to the soil-burial test for 8 months. Weight change and morphology of the degraded ESO specimens were assessed. It was found that the weight loss of ESO was governed by the materials compositions, crosslink density and the soil-burial exposure time. The 3 mm thickness ESO bio-thermosets with crosslink density of 0.109 × 10?3 mol/cm3 had fully biodegraded after soil-burial for 6 months. In addition, 16S rDNA sequencing was carried out to identify the soil microorganisms. It was suggested that Comamonas sp., Bacillus sp., Streptomyces sp. and Acinetobacter sp. are the possible soil microbes that degrade the ESO bio-thermosets in the compost soil environment. 相似文献
382.
利用响应面优化实验设计方法对CCl4增强超声降解左旋氧氟沙星模拟废水的影响因素进行探讨和分析,考察了溶液初始pH值、超声功率、左旋氧氟沙星初始浓度的影响。应用Box-Behnken中心组合设计得到一个二次多项式数学模型,确定了US/CCl4降解左旋氧氟沙星的优化条件:初始pH值6.8,超声功率189 W,左旋氧氟沙星初始浓度为5 mg/L时,左旋氧氟沙星的去除率达到最大(82.99%)。经实验验证, 实际值与模型预测值吻合性良好,偏差仅为0.036%。 相似文献
383.
384.
Z. Osman 《Journal of Polymers and the Environment》2013,21(4):1100-1108
Autocondensation and copolymerization reactions of the Acacia nilotica subspecies tomentosa (Ant) and the subspecies adansonii (Ana) tannins extracts solutions have been studied at several pH values by thermomechanical analyzer. Results of chemical analysis of these tannins revealed that the studied tannins, Ant and Ana contained high percentages of extractable tannins (54 and 57 %) for and polyphenolic materials (78 and 80 %) respectively. Different hardeners such as paraformaldehyde, Urea and pMDI were added at different ratios and their polycondensation reactions was studied and compared with their autocondensation ones. The aim was to evaluate the tannins suitability for the production of commercially and technically viable tannin adhesives with reduced Formaldehyde emission for wood products and to study the interference between the autocondensation and the copolymerization reaction. The obtained results of autocondensation reaction for both of the tannins studied showed that the best Young’s modulus values for Ant (3,500 and 2,750 MPa) and Ana (2,650 and 2,620 MPa) were obtained at pH 5 and 7. The Young’s modulus values obtained by the tannins Ant were higher than those achieved by Ana. This indicates that the Ant is more reactive than Ana. These results were also in line with results achieved by the gel time for both of the tannins. Gel time results indicate that the reactivity of both tannins increased towards alkalinity with Ana being more reactive at alkaline pH. Addition of 8 % of paraformaldehyde was adversely affecting the autocondensation reactions, as the best Young’s modulus values were achieved at pH 4 for Ant tannins. As for Ana the higher Young’s modulus values (2,000 and 2,310 MPa) were achieved at pH 5 and 7. This indicates that autocondensation reaction was contributed to the final network of the copolymerization reaction. When smaller ratio of paraformaldehyde and Urea (5 %) was added to Ant tannins it favors the autocondensation reaction and the best Young’s modulus values were obtained at pH 5 and 7. Addition of pMDI (10–30 %) was found to decrease the temperature of copolymerization and the obtained Young’s modulus values by Ant were lower than those obtained by autocodensation reaction. Best Young’ modulus values were obtained by Ant at pH 5 and 7. Ana gave the best Young’s modulus values at pH 4 and 5 indicating that the autocondensation appears to depress the copolymerization reactions. The obtained results by both reactions were very important from technical and economical point of view as they concluded that it is very possible to produce adhesives system with zero emission depending on the tannins autocondensation reaction and pH values. Reduction of formaldehyde emission was also possible upon addition of smaller amount of paraformaldehyde and Urea. 相似文献
385.
Nilesh S. Gangurde Riyaz Z. Sayyed Shashi Kiran Arvind Gulati 《Environmental science and pollution research international》2013,20(1):488-497
During screening for poly-β-hydroxybutyrate (PHB) producing bacteria from distillery effluent sample, six out of 30 isolates comprising of three strains of Alcaligenes sp., two strains of Bacillus sp., and one strain of Pseudomonas sp. were found to accumulate varying levels of intracellular PHB. Amongst the various isolates, Alcaligenes sp. RZS4 was found as the potent PHB-producing organism, accumulating higher amounts of PHB. PHB productivity was further enhanced in the presence of oxygen, nitrogen-limiting conditions, and cloning of PHB synthesizing genes of Alcaligenes sp. RZS 4 into Escherichia coli. A twofold increase in PHB yield was obtained from recombinant E. coli vis-à-vis Alcaligenes sp.; the recombinant E. coli accumulated more PHB in NDMM, produced good amount of PHB in a single-stage cultivation process under both nutrient-rich and nutrient-deficient conditions. Extraction of PHB with acetone–alcohol (1:1) was found as suitable method for optimum extraction of PHB as this mixture selectively extracted PHB without affecting the non-PHB cell mass. PHB extract from recombinant E. coli showed the presence of C–H, =O stretching, =C–H deformation, =C–H, =CH, and =C–O functional groups characteristic of PHB. 相似文献
386.
Cadmium tolerance in six poplar species 总被引:5,自引:1,他引:4
Jiali He Chaofeng Ma Yonglu Ma Hong Li Jingquan Kang Tongxian Liu Andrea Polle Changhui Peng Zhi-Bin Luo 《Environmental science and pollution research international》2013,20(1):163-174
Selection of poplar species with greater Cd tolerance and exploiting the physiological mechanisms involved in Cd tolerance are crucial for application of these species to phyto-remediation. The aim of this study is to investigate variation in Cd tolerance among the six poplar species and its underlying physiological mechanisms. Cuttings of six Populus species were cultivated for 10 weeks before exposure to either 0 or 200 μM CdSO4 for 20 days. Gas exchange in mature leaves was determined by a portable photosynthesis system. Cd concentrations in tissues were analyzed by a flame atomic absorbance spectrometry. Subsequently, Cd amount per plant, bio-concentration factor (BCF) and translocation factor (T f) were calculated. Nonenzymatic compounds and activities of antioxidative enzymes in tissues were analyzed spectrophotometrically. Cd exposure caused decline in photosynthesis in four poplar species including Populus cathayana (zhonghua 1). Among the six species, P. cathayana (zhonghua 1) displayed the highest Cd concentrations in tissues, the largest Cd amount in aerial parts, the highest BCF in aerial parts and T f under Cd exposure. Under Cd stress, increases in total soluble sugars in roots but decreases in starch in roots, wood, and leaves of P. cathayana (zhonghua 1) were found. Induced O 2 ?? and H2O2 production in roots and leaves, and increases in free proline, soluble phenolics, and activities of antioxidative enzymes were observed in P. cathayana (zhonghua 1). Based on results of this pot experiment, it is concluded that P. cathayana (zhonghua 1) is superior to other five species for Cd phyto-remediation, and its well-coordinated physiological changes under Cd exposure confer the great Cd tolerance of this species. 相似文献
387.
X. Q. Liang Z. Y. Nie M. M. He R. Guo C. Y. Zhu Y. X. Chen Küppers Stephan 《Environmental science and pollution research international》2013,20(10):6972-6979
One strategy to combat nitrate (NO3-N) contamination in rivers is to understand its sources. NO3-N sources in the East Tiaoxi River of the Yangtze Delta Region were investigated by applying a 15N–18O dual isotope approach. Water samples were collected from the main channel and from the tributaries. Results show that high total N and NO3-N are present in both the main channel and the major tributaries, and NO3-N was one of the most important N forms in water. Analysis of isotopic compositions (δ 18O, δD) of water suggests that the river water mainly originated from three tributaries during the sampling period. There was a wide range of δ 15N-NO3 (?1.4 to 12.4 ‰) and a narrow range of δ 18O-NO3 (3.7 to 9.0 ‰) in the main channel waters. The δ 15N and δ 18O-NO3 values in the upper, middle, and lower channels along the river were shifted as 8.2, 3.5, and 9.5 ‰, and 9.0, 4.2, and 6.0 ‰, respectively. In the tributary South Tiao, the δ 15N and δ 18O-NO3 values were as high as 9.5 and 7.0 ‰, while in the tributaries Mid Tiao and North Tiao, NO3-N in most of the samples had relatively low δ 15N and δ 18O-NO3 values from 2.3 to 7.5 ‰ and 4.7 to 7.0 ‰, separately. Our results also suggest that the dual isotope approach can help us develop the best management practice for relieving NO3-N pollution in the rivers at the tributary scale. 相似文献
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