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231.
Xu J Zhang JS Liu X Gao Z 《Journal of the Air & Waste Management Association (1995)》2012,62(6):671-679
The partition and effective diffusion coefficients of formaldehyde were measured for three materials (conventional gypsum wallboard, "green" gypsum wallboard, and "green" carpet) under three relative humidity (RH) conditions (20%, 50%, and 70% RH). The "green" materials contained recycled materials and were friendly to environment. A dynamic dual-chamber test method was used. Results showed that a higher relative humidity led to a larger effective diffusion coefficient for two kinds of wallboards and carpet. The carpet was also found to be very permeable resulting in an effective diffusion coefficient at the same order of magnitude with the formaldehyde diffusion coefficient in air. The partition coefficient (K(ma)) of formaldehyde in conventional wallboard was 1.52 times larger at 50% RH than at 20% RH, whereas it decreased slightly from 50% to 70% RH, presumably due to the combined effects of water solubility of formaldehyde and micro-pore blocking by condensed moisture at the high RH level. The partition coefficient of formaldehyde increased slightly with the increase of relative humidity in "green" wallboard and "green" carpet. At the same relative humidity level, the "green" wallboard had larger partition coefficient and effective diffusion coefficient than the conventional wallboard, presumably due to the micro-pore structure differences between the two materials. The data generated could be used to assess the sorption effects of formaldehyde on building materials and to evaluate its impact on the formaldehyde concentration in buildings. 相似文献
232.
233.
菱镁矿尾矿经预处理后,在一定条件下制备高活性MgO。使用热重-差热分析仪,分析菱镁矿尾矿的分解温度,应用X射线衍射、SEM分析不同煅烧温度、保温时间对MgO晶体结构的影响,并根据Scherrer公式计算MgO晶粒的尺寸。通过电导率仪测定MgO水化电导率,分析不同条件下的MgO活性,探讨煅烧温度、保温时间、颗粒细度与MgO活性之间的关系。结果发现:煅烧温度在1 050℃,保温时间60 min时,菱镁尾矿完全分解,MgO活性最佳;煅烧温度越高,保温时间越长,MgO的活性越差;MgO颗粒细度越小,活性越高。 相似文献
234.
林可霉素菌(Streptomyces lincolnensis)利用吡唑酮废水的研究 总被引:1,自引:1,他引:0
采用被吡唑酮废液驯化、分离、筛选后的林可霉素菌,并对其在摇瓶上利用吡唑酮废液中的硫酸铵发酵(7 d)生产林可霉素进行了研究。实验结果表明,废液加入培养基体积比都为1∶10,实验1中菌丝代谢和对照比正常,其中还原糖利用最快,在发酵后期为0.24 mg/L,林可霉素起步效价最低为2 100 IU/mL,与对照相比最后发酵效价降低了70 IU/mL;实验2发酵过程pH值偏低,全程为5.86~6.50,氨基氮代谢缓慢为40 mg/100 mL,最后林可霉素效价最低为4 480 IU/mL;实验3中废液在发酵进入48 h中后期的时候补入能促进菌丝体分泌,最后林可霉素为5 180 IU/mL,比对照发酵水平高出8.82%。可见实验3的实验设计有利于林可霉素菌利用吡唑酮废液生产林可霉素,为废物循环利用、变废为宝的可行性作了有意义尝试。 相似文献
235.
采用竹炭-微生物联合法,考察了竹炭用量、菌液用量、进水氨氮浓度、pH、DO、HRT等因素对氨氮废水处理效果的影响;同时采用对比实验,初步探讨了竹炭-微生物联合法处理沼液的作用机理。结果表明,竹炭-微生物法去除沼液氨氮的最优条件推荐为:竹炭用量30 g/L,微生物活性液用量3%,pH 7.0~8.0,DO为2 mg/L,HRT为48 h。竹炭-微生物法对沼液氨氮的去除过程可用一级反应动力学模型C=272.56e-0.0148描述,其去除效果来源于竹炭吸附和生物降解的协同作用,协同程度为48.45%。 相似文献
236.
旋流分离器油水分离效率的模拟研究 总被引:1,自引:0,他引:1
采用计算流体力学的方法,探讨了操作条件和物料特性对旋流分离器分离油水效率的影响。旋流器为单锥双入口,其主直径为50 mm,锥角为5.5°。模拟过程中,采用商业用软件‘Fluent 6.3’中的雷诺应力模型和欧拉多相流模型来模拟不同条件下油水旋流分离器的分离性能。模拟结果表明,对于本研究的油水旋流分离器,最佳的分流比是10%,最佳的油滴浓度是0.5%(V/V)。在最佳的分流比和油滴浓度下,当进口流速为10.46 m/s时,油水旋流分离器可将15μm的油滴去除80%以上,油滴的分离界限粒径d50(50%的分离效率)为9.2μm。在模拟的基础上,用统计软件STATISTICA6.0对分离效率与操作条件和物料特性之间的关系进行拟合。通过拟合式预测的分离效率与实测值相吻合,误差小于15%。 相似文献
237.
238.
The soil fumigants 1,3-dichloropropene (1,3-D) and chloropicrin (CP) are often used for controlling soil-borne plant pathogens and parasitic nematodes before reestablishing new vineyards and orchards. To evaluate crop safety and environmental risks with the replant fumigation, four field experiments were performed over 2 yr to examine 1,3-D and CP lateral movement away from the treated fields. Shank injection with or without a virtually impermeable film (V1F) was used in two vineyard fumigation experiments, and spot drip application without tarp cover was used in two orchard experiments. Results showed that 1,3-D and CP gases moved laterally to 6 m from the treated fields when the fumigants were applied by shank injection. The maximum 1,3-D or CP soil gas concentration at 6 m was approximately 10 ng cm(-3) when the fumigated plot was not cover with a tarp. With VIF, the measured maximum concentration increased to approximately 100 ng cm(-3). In the spot drip application, maximum 1,3-D and CP gas concentrations reached approximately 100 ng cm(-3) but at 1.5 m radial distance from the point of fumigant injection. 相似文献
239.
Mobility of radium and trace metals in sediments of the Winterbeek: Application of sequential extraction and DGT techniques 总被引:1,自引:0,他引:1
For several decades, phosphate ores containing 226Ra as well as several trace metals have been processed in Belgium to produce calcium phosphate for use in cattle food. The waste water is discharged in two small rivers, the Laak and the Winterbeek.In this study, the levels of 226Ra and trace metals in surface water and sediments of the Winterbeek were investigated and the mobility of these compounds was assessed using DGT (Diffusive Gradient in Thin Films) and sequential extraction techniques.The concentrations of 226Ra and trace metals in water and sediment indicate a decreasing trend in inputs to the Winterbeek.The mobility of 226Ra, assessed by DGT, is related to the reductive mobilization of Fe. The sequential extraction technique shows that at some stations an important fraction of 226Ra is found to labile sediment phases.Diffusive 226Ra sediment fluxes, are however, relatively small and have only a minor contribution to the water column concentration of 226Ra. 相似文献
240.
Guan-yong Su Zi-shen Gao Yijun Yu Jia-chun Ge Si Wei Jian-fang Feng Feng-yan Liu John P. Giesy Hong-xia Yu 《Environmental science and pollution research international》2010,17(3):634-642