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611.
阐述了新型SXD水力旋流沉淀器的工作原理及结构特点,并从理论和实际应用两方面分析了影响水力旋流器处理效果的因素,评价了其在精对苯二甲酸废水处理中的性能。 相似文献
612.
铬渣中Cr(Ⅵ)制取铬黄颜料的资源化技术研究 总被引:3,自引:0,他引:3
用蒸馏水在直径52 mm和80 mm的有机玻管中淋浸风化铬渣,在渣水比为250 g/200mL、500 g/400 mL和750 g/600 mL的3种方案中,750 g/600 mL的效果最佳.在2种不同管径装置中,可分别得到Cr(Ⅵ)总溶出率为94.0%、98.7%的良好淋浸效果.将含Cr(Ⅵ)的淋滤液替代商品重铬酸钠成功地制备出柠檬铬黄、中铬黄、浅铬黄,PbCrO4含量指标符合国标要求.相对于铅盐、Na2CrO4的理论反应用量,Cr(Ⅵ)浓度为26.21 g/L时,不仅可获取理想的铬黄生成量,而且可使沉淀分离液中检不出Cr(Ⅵ)残留量,但高于此浓度则会出现Cr(Ⅵ)残留.理论值1.15倍的铅盐用量可使Cr(Ⅵ)沉淀完全,铬黄达最高产率.廉价矿物材料改性磷灰石等可用于外排废液中Pb2+的吸附去除,以控制二次污染.利用铬渣中Cr(Ⅵ)溶出液直接制取铬黄颜料,可为铬渣资源化处理开辟一条新途径并获得明显的经济效益. 相似文献
613.
Yun Heejeong Kang Dongjin Kang Youngeun 《Environment, Development and Sustainability》2022,24(1):502-526
Environment, Development and Sustainability - Since demand for outdoor recreation in forests has been increasing, a structural planning framework for sustainable use while minimizing ecosystem... 相似文献
614.
615.
Herein,palygorskite(PAL)was activated via a simple hydrothermal process in the presence of ammonium sulfide,and the effects of activation on the microstructure,physico-chemical feature and adsorption behaviors of PAL were intensively investigated.The hydrothermal process evidently improved the dispersion of PAL crystal bundles,increased surface negative charges and built more active –Si–O-groups served as the new"adsorption sites".The adsorption property of the activated PAL for Methyl Violet(MV)was systematically investigated by optimizing the adsorption variables,including p H,ionic strength,contact time and initial MV concentration.The activated PAL exhibited a superior adsorption capability to the raw PAL for the removal of MV(from 156.05 to 218.11 mg/g).The kinetics for MV adsorption followed pseudo second-order kinetic models,while the isotherm and thermodynamics results showed that the adsorption pattern well followed the Langmuir model.The structure analysis of PAL before and after adsorption demonstrated that electrostatic interaction and chemical association of –X–O-are the prominent driving forces for the adsorption process. 相似文献
616.
617.
Three study areas of Kwanak campus (Seoul National University), Boeun (Choongbuk) and Gapyung (Kyonggi) were selected and classified according to their bedrock types in order to investigate soil–gas radon concentrations. The mean values of radon concentrations decreased in the order of Gapyung (40BqL–1) > Kwanak campus (30BqL–1) > Boeun (22BqL–1), and decreased in the order of granite gneiss > banded gneiss > granite > black slate–shale > mica schist > shale–limestone > phyllite schist according to bed rock types. Variation in radon emanation with water content in soils and with soil grain size was assessed by the modified Morse (1976) 3min method. Soil–gas radon concentrations increased with increasing water content in the range of less than about 6–16wt.%, but decreased above 6–16wt.%. Radon concentrations also increased with decreasing soil grain size. Radioactivity analysis of radionuclides of 238U series in some soil samples indicated their possible radioactive disequilibrium between 226Ra and 238U due to the differing geochemical behaviour of intermediate radionuclides. Thus, a radioactive isotope geochemical approach should be necessary for soil–gas radon study. 相似文献
618.
Junhua Li Shoufang Kang Lixin Fu Jiming Hao 《Frontiers of Environmental Science & Engineering》2007,1(2):143-146
A highly effective Ag-Al2O3 catalyst was prepared using the in-situ sol-gel method, and characterized by surface area using nitrogen adsorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The catalyst performance was tested on a real lean-burn gasoline engine. Only unburned hydrocarbons and carbon monoxide in the exhaust were directly used as reductant (without any external reductant), the maximum NO x conversion could only reach 40% at 450°C. When an external reductant, ethanol was added, the average NO x conversion was greater than 60%. At exhaust gas temperature range of 350–500°C, the maximum NO x conversion reached about 90%. CO and HC could be efficiently oxidized with Pt-Al2O3 oxidation catalyst placed at the end of SCR converter. However, NO x conversion drastically decreased because of the oxidation of some intermediates to NO x again. The possible reaction mechanism was proposed as two typical processes, nitration, and reduction in HC-SCR over Ag-Al2O3. 相似文献
619.
Xiaofeng Guo Hongsheng Zhang Ling Kang Jinlin Du Wanbiao Li Yuanjing Zhu 《Environmental Fluid Mechanics》2007,7(5):421-437
Micrometeorological measurements were made over an irrigated rice paddy during the Huaihe River Basin Experiment (HUBEX) in
1999. This study addresses the quality control and gap filling strategy for the heat fluxes with the Bowen ratio energy balance
(BREB) method. It also endeavors to benefit future studies through comparing five methodologies to estimate the net water
exchange. First, a three-step quality control strategy is constructed. Its first two steps guarantee the correct flux directions
and reject suspicious data, respectively. The third step forbids supersaturation by considering the Bowen ratio ranges for
different flux combinations (termed as “scenarios”). The quality-controlled latent heat (LE) and sensible heat (H) fluxes fall in three scenarios, namely I (LE > 0, H > 0), II (LE > 0, H < 0), and IV (LE < 0, H < 0). Second, the Priestley–Taylor evaporation model (PTEM) is applied to fill the gaps of LE, while the energy balance relationship is used to gap-fill H, namely H = R
N
− G − LE (R
N
: net radiation; G: soil heat flux). Central to the success of this strategy is the idea to calibrate the Priestley–Taylor parameter (α) in
a scenario-specific manner. On average, α values are calibrated as 1.20 and 1.35 for scenario I and II, respectively. For
scenario IV, most α values lie in a narrow range, namely from 0.9 to 1.0. Then, α is calibrated as 0.97 to extend the applicability
of the PTEM to condensation (negative LE). The scenario-specific treatment explicitly explains the diurnal variation of α derived without distinguishing the scenarios.
Third, five methodologies are compared in the calculation of net water exchange, including PTEM-gap-filled BREB method (M1),
energy-balance-based eddy covariance method (M2), and three simplified models to estimate LE, respectively as R
N
− H, R
N
− G, and R
N
. A major finding is that G and H have a similar effect of about 3% in the net water exchange. Thus, if either is neglected, the net evaporation should be
slightly lowered to avoid overestimate, by 3% as a rule of thumb from this work. 相似文献
620.