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151.
工业腐殖酸提纯前后对泰乐菌素的吸附特性 总被引:1,自引:0,他引:1
本文采用稀碱法对购买的工业腐殖酸进行了提纯,研究了腐殖酸提纯前后对泰乐菌素的吸附特性,并对其吸附机制进行了初步的探讨.研究结果表明:在对腐殖酸提纯之后,其C、H、O、N、S的含量明显增加,灰分含量显著减小.腐殖酸经提纯后对泰乐菌素的吸附明显增强,在24h可以完全达到吸附平衡,其吸附动力学曲线可以用拉格朗日二级动力学方程和颗粒扩散模型较好的拟合;吸附等温线可以用线性吸附模型和Freundlich吸附模型较好的拟合;且提纯后的腐殖酸对泰乐菌素的吸附随着溶液的p H值和离子强度增加而逐渐减小.综上,推测腐殖酸对泰乐菌素的吸附机制可能以疏水性分配、氢键作用和离子交换作用为主. 相似文献
152.
Environmentally friendly green composites were prepared by blending Wheat gluten (WG) as matrix, dialdehyde starch (DAS) as
filler and glycerol as plasticizer followed by compression molding of the mixture at 110 °C. The properties of the WG/DAS
composite are compared with those of the WG/native wheat starch (NWS) composites. While tensile strength and strain at break
decrease with increasing NWS content in the WG/NWS composites, a small content of DAS could improve tensile strength and strain
at break simultaneously in the WG/DAS composites. The WG/DAS composites exhibit reduced moisture absorption in comparison
with the WG/NEW composites. Formation of chemical bonding between DAS and WG is beneficial for the dispersion of DAS in the
WG matrix and WG/DAS composites exhibit improved mechanical properties and reduced moisture absorption over the WG/NWS composites. 相似文献
153.
Total mercury concentrations in organisms typical of those found in the Cilician Basin of the northeastern Mediterranean have been measured from 1977 to the present. These concentrations show seasonal variations. Shrimp shows an approximately constant concentration of mercury which might testify to the regulation capacity of shrimp for mercury. Crab, and particular fish, show a seasonal variation which may be correlated with the local application of mercury fungicide, rainfall, and the physiology of the organisms. The rapidity with which mercury applied to the land causes increased concentrations in fish is noteworthy. 相似文献
154.
155.
Huang Xianfeng Wang Xiran Guan Dong-Xing Zhou Huabin Bei Ke Zheng Xiangyong Jin Zhan Zhang Yejian Wang Qi Zhao Min 《Environmental science and pollution research international》2019,26(9):8516-8524
Environmental Science and Pollution Research - Most prevailing processes are incapable of removing Cr(III)-organic complexes efficiently and facing the problem of in-process formation of highly... 相似文献
156.
Resource use efficiency and economic losses: implications for sustainable rice production in Vietnam
Vo Hong Tu 《Environment, Development and Sustainability》2017,19(1):285-300
The study aimed to estimate resource use efficiency and economic losses by using stochastic frontier analysis. The data set were collected in An Giang Province of Vietnam through personal interviews with 199 rice farmers. The results revealed that returns to scale are decreasing. Rice farmers had high levels of output-oriented and input-oriented technical efficiency with the means of 91.92 and 85.39 %, respectively. The mean environmental efficiency was 82.03 %. The mean efficiency of normal inputs was 61.20 %. Among the bad inputs, pesticide and energy were the least efficient ones with the mean values of 51.39 and 45.53 %, respectively, indicating serious overuses of these inputs. As regards normal inputs, capital had the lowest efficiency score at 21.08 %, followed by seed quantity at 26.4 %. Further, the total economic losses were estimated at 8261 thousand VND (380 USD) per hectare, which is equal to the sales of about 1600 kg of rice per hectare or the efforts to increase by 20 % of output level. This study suggests that rice farmers need to contract inputs, particularly environmentally detrimental inputs to improve profits. To improve the productive efficiency, the use of ecological engineering, collective pump and cultivation of three rice crops per year are possible options. 相似文献
157.
C. M. Tu 《Journal of environmental science and health. Part. B》2013,48(3):369-378
Abstract Two pyrethroid insecticides were compared with two fungicides for their effects on the rhizobial and seedling components of the N2‐fixing symbiosis in soybeans (Glycine max Merr. variety Olinda). In vitro growth of Rhizobium japonicum RI16, was inhibited in the order of HgCl2 > thiram > cypermethrin > permethrin. The emergence of the seedlings was stimulated by all chemicals tested. Also, none of the pesticides studied had any significant effect on N2 fixation (acetylene reduction), at the dosages used. Consequently, yields of the various organs were also not significantly influenced by the chemicals. 相似文献
158.
Titanium dioxide (TiO2) is a promising sorbent for As removal. There are two main and physico-chemically distinct polymorphs of TiO2 in nature, namely anatase and rutile. Since the difference of arsenic removal by the two polymorphs of TiO2 is now well known, study on the arsenic removal efficiency and the underlying mechanism is of great significance in developing new remediation strategies for As-polluted waters. Here batch experiments were carried out in combination with instrumental analysis of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) to investigate the effects, influential factors and mechanisms of As removal from aqueous solution by two types of nano TiO2 crystals. The adsorption behavior of anatase and rutile for As(V) and As(III) are well described by Freundlich equations. Anatase had higher As removal efficiency and adsorption capacity than rutile. Solution pH had no influence on the As adsorption of anatase TiO2, whereas the As removal by rutile TiO2 was increased by 7?C18% with pH from 4 to 10. Presence of accompanying anions such as phosphate, silicate, nitrate and sulfate, decreased the As(V) and As(III) removal by both crystals, with phosphate being the most effective. However, removal of As by rutile TiO2 was greatly enhanced in the presence of divalent cations i.e. Ca2+ and Mg2+. Shading of light decreased the removal of As(V) and As(III) of anatase by 15.5% and 17.5%, respectively, while a slight increase of As removal was observed in the case of Rutile TiO2. FT-IR characterization of As(V) or As(III)-treated nano TiO2 crystals indicated that both Ti-O and As-O groups participated in As adsorption. Both FT-IR and XPS analysis demonstrated that As(III) was photooxidated into As(V) when adsorbed by anatase under the light condition. Thus, the effect of crystal types and light condition on As removal should be taken into consideration when nano TiO2 is applied for As removal from water. 相似文献
159.
160.
Le Quang Dung Nguyen Viet Linh Nguyen Xuan Thanh Nguyen Duc Cu Vu Van Tu Takaomi Arai 《生态毒理学报》2015,10(3):304-310
Heavy metal concentrations in muscle and their relation to thegrowth of two marine fish species,including tonguefish( Cynoglossus arel) and mullet( Mugil cephalus),were studied. The samples were collected in Bach Dang estuary andconcentrations of heavy metals( As,Cd,Co,Mn,Cu,Zn,Pb,and V) in muscle of the fisheswere determined. The result showed that the accumulated trend of heavy metal is different between fish species. The concentration of As,Zn,Mn,V,Cu,Pb,Co and Cd in tonguefish were 73. 7 ± 30. 6,22. 82 ± 4.87,3. 44 ± 2. 13,1. 61 ± 0. 15,0. 71 ± 0. 13,0. 45 ± 0. 24,0. 03 ± 0. 02 and 0. 02 ± 0. 02 mg·g-1,respectively. Meanwhile the concentration of Zn,As,V,Mn,Cu,Pb,Co and Cd in mullet were 83. 41 ±19. 68,9. 78 ± 1. 92,1. 36 ± 0. 54,1. 29 ± 0. 51,0. 65 ± 0. 12,0. 42 ± 0. 20,0. 06 ± 0. 03 and0. 03 ± 0. 01mg·g-1,respectively. Comparison of metal levels among thesespecies indicated that the concentrations of As and Mn in tonguefish were significantly higher than those in mullet,whereas Zn levels in mullet were found to be higher than that in tonguefish. There is no significant differences of Cd,Co,Cu,Pb and V levels in muscle between two species. Significant inversed relationshipsbetween concentration levels of metals and lengths of tonguefish were found for Mn,Cu and Zn,butnot for As,Cd,Pb,and V. There were no significant relationships between the heavy metal concentrations and the length of mullet. In general,decreasesof the heavy metal concentrations corresponded to the increases of fish body lengths,particularly for As,Co,Cu,Mn and V and the exception for Cd. Terefore reduced risks were associated with consuming biggermullet fish,and increased risks of As and Cd were associated with consuming bigger tonguefish in Bach Dang river mouth. 相似文献