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91.
Adsorption characteristic of bensulfuron-methyl at variable added Pb^2+ concentrations on paddy soils 总被引:1,自引:0,他引:1
WU Weihong WANG Haizhen XU Jianming XIE Zhengmiao 《环境科学学报(英文版)》2009,21(8):1129-1134
The combined pollution of heavy metal Pb2+ and bensulfuron-methyl (BSM), originating from chemical herbicides, in agroecological environments has become commonplace in southern China. The adsorption of BSM on three paddy soils in the presence of Pb2+ was examined using high-performance liquid chromatograph (HPLC). Results indicated that adsorption of BSM could accurately be described by a Freundlich isotherm equation with correlation constant (R) > 0.98, irrespective of the presence of spiked Pb2+. Of the various factors influencing BSM sorption, soil pH appeared to be the most influential. The constant Kf of Freundlich isotherm equation tended to increase with increasing Pb2+ concentration in soil which indicated that the spiked of Pb2+ in paddy soils would promote the sorption of BSM. ΔGθ of BSM in three paddy soils was less than 40 kJ/mol in all treatments, indicating the adsorption of BSM is mainly physical in nature. The elution of soil dissolved organic matter (DOM) enhanced the adsorption of BSM in paddy soils. The mechanisms involved in the promotion effects of the spiked Pb2+ on BSM adsorption might be the modified surface characteristics of paddy soil solids due to the soil acidification and the increase of soil organic matter concentration because of DOM binding. 相似文献
92.
Guangxue Wu Zhenhu Hu Mark G. Healy Xinmin Zhan 《Frontiers of Environmental Science & Engineering in China》2009,3(3):300-306
Since the solubilization of meat and bone meal (MBM) is a prerequisite in many MBM disposal approaches, enhancement of the
solubilization by means of thermochemical pretreatment was investigated in this study at two temperatures (55°C and 131°C)
and six sodium hydroxide (NaOH) concentrations (0, 1.25, 2.5, 5, 10 and 20 g/L). The MBM volatile solid (VS) reduction ratio
was up to 66% and 70% at 55°C and 131°C, respectively. At the same temperature, the VS reduction ratio increased with the
increase in the dosage of NaOH. The study on the methane (CH4) production potential of pretreated MBM shows that the addition of NaOH at 55°C did not cause the inhibition of the succeeding
CH4 production process. However, CH4 production was inhibited by the addition of NaOH at 131°C. The CH4 production potential was in the range of 389 to 503 mL CH4/g VS MBM and 464 to 555 mL CH4/g VS MBM at 55°C and 131°C, respectively. 相似文献
93.
94.
Natural zeolite was modified by loading cetylpyridinium bromide (CPB) to create more e cient sites for humic acid (HA) adsorption.
The natural and CPB modified zeolites were characterized with X-ray di raction, field emission scanning electron microscopy, Fourier
transform infrared spectroscopy and elemental analysis. The e ects of various experimental parameters such as contact time, initial HA
concentration, solution pH and coexistent Ca2+, upon HA adsorption onto CPB modified zeolites were evaluated. The results showed
that natural zeolite had negligible a nity for HA in aqueous solutions, but CPB modified zeolites exhibited high adsorption e ciency
for HA. A higher CPB loading on natural zeolites exhibited a larger HA adsorption capacity. Acidic pH and coexistent Ca2+ were
proved to be favorable for HA adsorption onto CPB modified zeolite. The kinetic process was well described by pseudo second-order
model. The experimental isotherm data fitted well to Langmuir and Sips models. The maximum monolayer adsorption capacity of CPB
modified zeolite with surfactant bilayer coverage was found to be 92.0 mg/g. 相似文献
95.
通过引入多响应值的归一化评分法进行了污泥水磷和有机物同步混凝去除的多目标优化,并利用响应面(RSM)技术考察了Al/P比、聚丙烯酰胺(PAM)投加量和悬浮固体(SS)浓度对污染物去除的单独效应和联合效应.结果表明,复合投加聚合氯化铝和PAM能同步去除污泥水中磷和有机物,并改善沉降效果.归一化后单目标RSM优化显示,对污泥水中磷和有机物同步去除的贡献为Al/P比SS浓度PAM投加量.在最优条件Al/P比为3、PAM浓度为1.22 mg·L~(-1)、SS浓度为3.58 g·~(L-1)的条件下,正磷和总有机碳去除率分别为93.1%和53.9%.与多响应变量优化相比,引入归一化评分法有效解决了变量间数值量级差异的问题,使结果的分析计算变得简单方便. 相似文献
96.
随着我国天然气发电比例的不断增加,天然气发电的安全问题逐渐引起人们的关注。为定量分析天然气发电的风险预警等级,针对风险评估过程中的小样本问题,引入信息扩散理论确定风险事故发生的概率,并结合故障类型及影响、危险度分析方法,建立了天然气发电风险预警的定量计算数学模型。以某天然气电厂燃气轮机系统为研究对象,将该厂燃气轮机2007—2014年所发生事故的统计数据作为观测样本,利用构建的风险预警数学模型并结合Matlab软件,计算得到该天然气电厂燃气轮机事故的发生概率以及不同事故模式下事故后果的严重度,最终确定该电厂燃气轮机系统的风险预警等级为Ⅲ级。与传统的安全预警方法相比,该风险预警技术更加客观有效。 相似文献
97.
Yanhui Zhan Jianwei Lin Yanling Qiu Naiyun Gao Zhiliang Zhu 《Frontiers of Environmental Science & Engineering in China》2011,5(1):65-75
Surfactant-modified natural zeolites (SMNZ) with different coverage types were prepared by loading hexadecyltrimethyl ammonium
bromide (HTAB) onto the surface of a natural zeolite. The adsorption behavior of humic acid (HA) on SMNZ was investigated.
Results indicate that the adsorbent SMNZ exhibited a higher affinity toward HA than the natural zeolite. HA removal efficiency
by SMNZ increased with HTAB loading. Coexisting Ca2+ in solution favored HA adsorption onto SMNZ. Adsorption capacity decreased with an increasing solution pH. For typical SMNZ
with bilayer HTAB coverage, HA adsorption process is well described by a pseudo-second-order kinetic model. The experimental
isotherm data fitted well with the Langmuir model. Calculated maximum HA adsorption capacities for SMNZ with bilayer HTAB
coverage at pH 5.5 and 7.5 were 63 and 41 mg·g−1, respectively. E2/E3 (absorbance at 250 nm to that at 365 nm) and E4/E6 (absorbance at 465 nm to that at 665 nm) ratios of
the residual HA in solution were lower than that of the original HA solution. This indicates that the HA fractions with high
polar functional groups, low molecular weight (MW), and aromaticity had a stronger tendency for adsorption onto SMNZ with
bilayer HTAB coverage. Results show that HTAB-modified natural zeolite is a promising adsorbent for removal of HA from aqueous
solution. 相似文献
98.
99.
Yang Li Yixin Zhang Guangshen Xia Juhong Zhan Gang Yu Yujue Wang 《Frontiers of Environmental Science & Engineering》2021,15(1):1
100.
双酚A是一种日常生活中无处不在的环境雌激素,具有生殖和神经毒性,但低剂量长期暴露对发育期青少年的危害性常常被低估或忽视。本研究以4周龄雄性清洁级小鼠为实验对象,以茶油作为溶媒对照,分别以双酚A浓度为0μg·m L-1、0.1μg·m L-1、10μg·m L-1和1 000μg·m L-1的茶油灌胃小鼠8周,然后利用彗星电泳法检测各组小鼠脑细胞的DNA损伤。结果显示,不同浓度双酚A暴露8周后,彗星电泳图像显示小鼠脑细胞DNA出现不同程度的损伤,随着暴露剂量的增加,带有彗尾的脑细胞比率从对照组小鼠的9.5%分别升高到暴露组小鼠的34.5%、36.0%和50.5%,细胞总体的尾部DNA含量、尾长和尾矩也都逐渐增加,而且各双酚A暴露组小鼠与溶媒对照组小鼠脑细胞都具有显著性差异(P0.01),这说明中长期双酚A暴露(包括低浓度环境暴露)会导致雄性幼龄小鼠脑细胞的DNA损伤。 相似文献