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131.
Yi-Hsuan Chuang Gui-Bing Hong 《Journal of the Air & Waste Management Association (1995)》2014,64(6):738-742
In this study, polyvinyl alcohol (PVA) and titania (TiO2) Degussa P-25 were mixed to generate TiO2 nonwoven filters using electrospinning. The wires of titanium dioxide and the nonwoven binding titania nanofibers were formed using 14 kV voltage and a distance of 15 cm. A single-factor experimental method was used to investigate the effects of parameters such as initial concentration, retention time, and light source on acetone removal by nonwoven binding titania nanofibers. Furthermore, the effects of parameters such as gas pressure, particle size, initial concentration, and retention time on the removal of particulates were also assessed. The results showed that the degradation efficiency increased with decreasing initial concentrations and increasing retention time. The best operational conditions during this study for the removal of acetone using the TiO2 nonwoven filters were a retention time of 100 sec, initial acetone concentration of 250 ppm, and ultraviolet (UV) light source of 254 nm. Under those conditions, 99% acetone removal efficiency was obtained. In addition, 90% particulate matter removal efficiency was reached when the particulate size was greater than 200 nm and the reaction time was longer than 5 minutes. The prepared TiO2/nanofiber has good performance for volatile organic compounds (VOCs) and particulate removal at the same time.
Implications: In this study, polyvinyl alcohol (PVA) and titania (TiO2) Degussa P-25 were mixed to generate TiO2 nonwoven filters using electrospinning. The results showed that the optimum operating conditions for the removal of acetone using the TiO2 nonwoven filters were a retention time of 100 sec, initial acetone concentration of 250 ppm, and UV light source of 254 nm. Under those conditions, 99% acetone removal efficiency was obtained. 相似文献
132.
Competitive adsorption of dye metanil yellow and RB15 in acid solutions on chemically cross-linked chitosan beads 总被引:1,自引:0,他引:1
One kind of adsorbent with a high adsorption capacity for anionic dyes was prepared using ionically and chemically cross-linked chitosan beads. A batch system was applied to study the adsorption behavior of one acid dye (MY, metanil yellow) and one reactive dye (RB15, reactive blue 15) in aqueous solutions by the cross-linked chitosan beads. The adsorption capacities was 3.56 mmol g(-1) (1334 mg g(-1)) for dye MY and 0.56 mmol g(-1) (722 mg g(-1)) for dye RB15 at pH4, 30 degrees C. The Langmuir model agreed very well with the experimental data (R(2)>0.996). The kinetics of adsorption for a single dye and the kinetics of removal of ADMI color value in mixture solutions at different initial dye concentrations were evaluated by the nonlinear first-order and second-order models. The first-order kinetic model fits well with the dynamical adsorption behavior of a single dye for lower initial dye concentrations, while the second-order kinetic model fits well for higher initial dye concentrations. The competitive adsorption favored the dye RB15 in the mixture solution (initial conc. (mM): MY=1.34; RB15=1.36); while it favored the dye MY in the mixture solution (initial conc. (mM): MY=3.00; RB15=1.34) and the adsorption kinetics for dye RB15 has the tendency to shift to a slower first order model. 相似文献
133.
134.
Habitat evaluation using suitability index and habitat type diversity: a case study involving a shallow forest stream in central Taiwan 总被引:3,自引:0,他引:3
In recent years, the Taiwanese government has strongly promoted the concept of ecological engineering in the hope that doing so will encourage the maintenance of the ecosystem and its integrity. As a result, the riprap spur dike is one of the most commonly used measures for protecting stream banks. Traditionally, a spur dike is used at concave banks to prevent their scouring and/or to increase their stabilization. An additional benefit of deflector structures, like spur dikes, may be to increase the weighted usable area (WUA) for aquatic life survival during periods of increased flow (examples include typhoon, flood, etc.). A two-dimensional river habitat simulation program (River2D) coupled with a developed shallow water habitat type diversity module was used for the case study at a headwater stream in central Taiwan. The habitat suitability index for this study was established using substrate, depth, and velocity from field surveys for the fish family Cyprinidae by prepositioned area electrofisher. The ungauged flood conditions were calculated using digital elevation models within a watershed delineation and hydrological modeling system in accordance with local regulations. Simulated results indicate that the spur dikes currently in use on the stream in this study need be improved from a WUA point of view more effectively handle a flood event. 相似文献
135.
官厅水库主要入库河流(洋河)表层沉积物重金属污染特征及风险水平 总被引:4,自引:1,他引:3
洋河是官厅水库重要的入库河流,而水体沉积物污染将直接影响水库水质安全.因此,采集了洋河水系表层沉积物,研究了6种重金属的污染特征及风险水平.结果表明,洋河水系表层沉积物中Cd、Cr、Cu、Ni、Pb和Zn的含量均值分别为0.34、59.91、30.64、30.85、39.51和129.27mg·kg~(-1).源解析表明,Cd、Pb和Zn主要来源于人为活动(富集系数EF1.5),Cr、Cu和Ni主要来源于自然过程.洋河水系表层沉积物单元素潜在生态风险顺序为CdPbCuNiCrZn,其中,Cd表现为强生态风险,特别是在支流清水河段呈现极强生态风险,其他5种重金属在流域尺度上表现为生态风险较小;6种重金属综合潜在生态危害指数均值为143.70,处于轻微风险等级.洋河水系表层沉积物中重金属无生物毒性或生物毒性发生率较低,但清水河段和干流中游段生物毒性发生率相对较高. 相似文献
136.
137.
重化工园区产能增加将加大园区挥发性有机物(VOCs)排放总量,进而影响本地及周边城市O3浓度.珠三角实施的“VOCs倍量替代”政策可在城市层面有效抵消重化工园区VOCs排放量上升的不利影响,还可进一步降低城市VOCs排放总量,实现区域O3浓度下降.以惠州市某大型重化工园区为例,编制2018—2020年重化工园区产能增加以及实施“VOCs倍量替代”政策的污染物排放清单,基于WRF-CMAQ模拟体系,定量分析多种情景下园区在基准年(2017年)7—10月气象条件下对惠州市及周边城市O3影响程度.研究表明,重化工园区增产而增加VOCs排放4101.96 t,“VOCs倍量替代”综合减排余量7298.97 t;“VOCs倍量替代”政策可有效解决重化工园区增产对O3浓度的不利影响,其中7月最为显著,主导东南风下风向的深圳市及惠州市大亚湾管委会站点O3浓度降幅最大,分别为3.9μg·m-3(下降率2.97%)和7μg·m-3(下降率4.95%);... 相似文献
138.
Lo Chen-Chen Liu Wen-Te Lu Yueh-Hsun Wu Dean Wu Chih-Da Chen Ting-Chieh Fang Yu-Ting Lo Yu-Chun Chen You-Yin Kang Lo Tsai Cheng-Yu Lee Yueh-Lun Chuang Kai-Jen Ho Kin-Fai Chang Ta-Yuan Chuang Hsiao-Chi 《Environmental science and pollution research international》2022,29(35):52355-52366
Environmental Science and Pollution Research - The effects of air pollution on sleep and dementia remain unclear. The objective of this study was to investigate the effects of air pollution on... 相似文献
139.
北京市凉水河表层沉积物中砷含量及其赋存形态 总被引:3,自引:2,他引:1
选择北京市典型的非常规水源补给城市河流(凉水河)为研究对象,采用王水水浴消解法和BCR三步提取法分析了表层沉积物中砷含量及其形态,并利用富集系数法、风险评估指数法和沉积物重金属质量基准法对表层沉积物中砷进行评价.结果表明,凉水河表层沉积物中总砷含量范围是2.18~22.5 mg·kg~(-1),均值为6.01 mg·kg~(-1),多数样点低于北京市土壤中砷的背景值;沉积物中砷主要以残渣态(B4态)存在,平均含量为3.93 mg·kg~(-1);沉积物中各形态砷所占的平均比例顺序为:残渣态(B4态)可还原态(B2态)可氧化态(B3态)弱酸可溶解态(B1态),其中生物有效态砷占总砷的平均比例为39.61%.富集系数法分析结果显示凉水河表层沉积物中砷基本未出现富集;风险评估指数法分析结果显示凉水河60%的采样点表层沉积物中砷含量呈中度风险,40%的采样点呈低风险;沉积物重金属质量基准法分析结果显示凉水河55%的采样点表层沉积物中砷含量低于阈值效应水平(TEL),40%的采样点处于可能效应水平(PEL)和阈值效应水平(TEL)之间. 相似文献
140.
采用Fenton法对垃圾渗滤液膜滤浓缩液进行预处理,探讨了pH值、FeSO4/H2O2用量及比例、以及反应时间对CODcr及色度去除率的影响.研究结果表明:当pH =4.0,FeSO4/H2O2用量0.75/7.5 (g/ml),反应时间2.5h,垃圾渗滤液膜滤浓缩液的CODcr浓度从4 416 mg/L降低至630.7 ml/L,CODcr去除率达85.7%;色度从1 250倍降低至200倍以下,色度去除率达84%.因此,本工艺对垃圾渗滤液膜滤浓缩液的CODcr及色度具有较好的去除效果,作为垃圾渗滤液膜滤浓缩液的预处理工艺具有可行性. 相似文献