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251.
Chi Kim Lim Hui Han Bay Chin Hong Neoh Azmi Aris Zaiton Abdul Majid Zaharah Ibrahim 《Environmental science and pollution research international》2013,20(10):7243-7255
In this study, the adsorption behavior of azo dye Acid Orange 7 (AO7) from aqueous solution onto macrocomposite (MC) was investigated under various experimental conditions. The adsorbent, MC, which consists of a mixture of zeolite and activated carbon, was found to be effective in removing AO7. The MC were characterized by scanning electron microscopy (SEM), energy dispersive X-ray, point of zero charge, and Brunauer–Emmett–Teller surface area analysis. A series of experiments were performed via batch adsorption technique to examine the effect of the process variables, namely, contact time, initial dye concentration, and solution pH. The dye equilibrium adsorption was investigated, and the equilibrium data were fitted to Langmuir, Freundlich, and Tempkin isotherm models. The Langmuir isotherm model fits the equilibrium data better than the Freundlich isotherm model. For the kinetic study, pseudo-first-order, pseudo-second-order, and intraparticle diffusion model were used to fit the experimental data. The adsorption kinetic was found to be well described by the pseudo-second-order model. Thermodynamic analysis indicated that the adsorption process is a spontaneous and endothermic process. The SEM, Fourier transform infrared spectroscopy, ultraviolet–visible spectral and high performance liquid chromatography analysis were carried out before and after the adsorption process. For the phytotoxicity test, treated AO7 was found to be less toxic. Thus, the study indicated that MC has good potential use as an adsorbent for the removal of azo dye from aqueous solution. 相似文献
252.
Fang Jinzhong Zhang Huibo Ren Peng He Bao-Jie Tang Mingfang Feng Chi 《Environmental science and pollution research international》2022,29(10):14158-14175
Environmental Science and Pollution Research - In recent years, moisture buffering materials for interior finishing have received much attention for their ability to regulate indoor humidity... 相似文献
253.
以学生为中心的外语教学模式不再是以老师为中心开展教学活动.学习者的地位有所改变,然而与此同时,教师也被赋予了一个新的角色.本文引用语言学的理论对教师在这一全新的外语教学模式中的新角色作了阐述,探讨要适应这一角色所应具备的素质. 相似文献
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环保企业往往涉及许多化学品的处理与处置,对企业员工来说,是带有一定危险性的行业.因此,安全生产至关重要,而企业职工的安全心理教育也是刻不容缓的.本文以大连东泰产业废弃物处理有限公司为例,分析了此类环保企业员工可能存在的一些不良安全心理,指出了安全教育的重要性和紧迫性,并结合其他企业安全生产的经验,提出了制定必要的奖惩制度、优化企业管理水平、解决工作紧张给职工带来的心理问题、加强职工心理素质的培养和训练,提高其沟通减压的能力等提升企业员工安全心理健康发展、提高员工安全意识的方法和措施. 相似文献
256.
Removal of nitrogen in wastewater before discharge into receiving water courses is an important consideration in treatment systems. However, nitrogen removal efficiency is usually limited due to the low carbon/nitrogen (C/N) ratio. A common solution is to add external carbon sources, but amount of liquid is difficult to determine. Therefore, a combined wood-chip-framework substrate (with wood, slag and gravel) as a slow-release carbon source was constructed in baffled subsurface-flow constructed wetlands to overcome the problem. Results show that the removal rate of ammonia nitrogen (NH4+-N), total nitrogen (TN) and chemical oxygen demand (COD) could reach 37.5%–85%, 57.4%–86%, 32.4%–78%, respectively, indicating the combined substrate could diffuse sufficient oxygen for the nitrification process (slag and gravel zone) and provide carbon source for denitrification process (wood-chip zone). The nitrification and denitrification were determined according to the location of slag/gravel and wood-chip, respectively. Nitrogen removal was efficient at the steady phase before a shock loading using slag-wood-gravel combined substrate because of nitrification–denitrification process, while nitrogen removal was efficient under a shock loading with wood-slag-gravel combined substrate because of ANAMMOX process. This study provides a new idea for wetland treatment of high-strength nitrogen wastewater. 相似文献
257.
湖南攸县稻米镉(Cd)富集特征及原因解析 总被引:2,自引:0,他引:2
攸县大米富镉(Cd)问题受到社会的广泛关注.通过实地调查和采样分析,应用路径分析模型(PA),多元回归分析和K-means聚类方法分析Cd在土壤-稻米系统中的富集特征,潜在风险和主要影响因子.结果显示攸县稻米Cd平均含量为0.47 mg·kg~(-1),约为国家粮食安全质量标准的2.5倍.稻米Cd富集因子(PUF)服从自然对数分布,变化范围较大.回归分析和PA分析显示土壤pH、土壤Mn和土壤Zn含量为影响PUF变化的主要环境因子,其中土壤Mn对PUF的影响主要体现在对稻米Cd的直接作用,土壤pH和土壤Zn对PUF的影响主要是通过影响土壤Cd含量而间接影响稻米Cd含量.K-means聚类分析显示土壤pH=5.6和土壤Mn含量=333 mg·kg-1可作为研究区对生产严重超标Cd米的土壤进行治理的初步调控阈值. 相似文献
258.
Gang Xiao Baosheng Jin Mingjiang Ni Kefa Cen Yong Chi Zhongxin Tan 《Frontiers of Environmental Science & Engineering》2011,5(2):193-204
Considering high-moisture municipal solid waste (MSW) of China, a steam dried MSW gasification and melting process was proposed, the feasibility was tested, and the mass and energy balance was analyzed. Preliminary experiments were conducted using a fixed-bed drying apparatus, a 200 kg per day fluidized-bed gasifier, and a swirl melting furnace. Moisture percentage was reduced from 50% to 20% roughly when MSW was dried by slightly superheated steam of 150°C?C350°C within 40 min. When the temperature was less than 250°C, no incondensable gas was produced during the drying process. The gasifier ran at 550°C?C700°Cwith an air equivalence ratio (ER) of 0.2?C0.4. The temperature of the swirl melting furnace reached about 1240°C when the gasification ER was 0.3 and the total ER was 1.1. At these conditions, the fly ash concentration in the flue gas was 1.7 g·(Nm3)?1, which meant over 95% fly ash was trapped in the furnace and discharged as slag. 85% of Ni and Cr were bound in the slag, as well as 60% of Cu. The mass and energy balance analysis indicates that the boiler heat efficiency of an industrial MSW incineration plant reaches 86.97% when MSW is dried by steam of 200°C. The boiler heat efficiency is sensitive to three important parameters, including the temperature of preheated MSW, the moisture percentage of dried MS Wand the fly ash percentage in the total ash. 相似文献
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