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高硫煤矸石中的FeS2在水中氧化分解为Fe2+,能将废水中的Cr6+还原为Cr3+,高硫煤矸石中的C对Cr6+具有较好的吸附、还原作用,从而表现出对含铬(Ⅵ)废水具有较好的净化作用。在处理含铬(Ⅵ)废水过程中,废水的pH值、反应时间、高硫煤矸石粒度、加入量对Cr6+的去除率影响较大。高硫煤矸石对含铬(Ⅵ)废水的吸附行为符合Langmui等温方程,在3 50℃～4 00℃高温处理后对Cr6+的去除效果明显提高,且反应速度加快。 相似文献
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张志刚 《福建工程学院学报》2014,(6):557-561
采用柚子皮制备生物吸附剂用于去除水中的Cr(VI),考察了p H值、柚子皮投加量、柚子皮粒径、溶液离子强度、反应温度等因素对吸附效果的影响。结果表明,当溶液中Cr(VI)离子初始浓度15mg/L、p H 1.5、反应温度25℃、柚子皮投加量1.0g/100 m L、吸附时间7 h时,Cr(VI)离子去除率可达90%以上。柚子皮对Cr(VI)离子的吸附过程可以用Langmuir和Freundlich吸附等温模型来描述,吸附等温线线性相关性均较显著,吸附过程符合准二级动力学方程。柚子皮对水中Cr(VI)离子吸附性能较好,且运行成本低,可推广应用于水中重金属离子的治理。 相似文献
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Some laboratory diffusion tests were conducted with diffusion device to determine the diffusion coefficient of Cr(Ⅵ) ion passing through Dalian red clay samples. The concentrations of Cr(Ⅵ) at different places of the samples were then measured spectrophotometrically after a standing time of 1 000 d. A one-dimensional solute transport equation was used to simulate the transport of Cr(Ⅵ) through clay samples. Back-calculation of diffusion coefficient of Cr(Ⅵ) was made with finite difference method. Parametric analysis was conducted to simulate variations in soil dry density, temperature, pH and standing time. The results show that the method used in this paper is simple and effective. The diffusion coefficient of Cr(Ⅵ) in Dalian red clay varies from 1.50×10-7 cm2/s to 2.08×10-7 cm2/s. After 1 000 d diffusion, the concentration of the source solution drops down to 1.27 mg/L from 62.5 mg/L, and the diffusion distance is only 3.5 cm. Under the assumption that diffusion coefficient is constant, the diffusion effect becomes more obvious with lower density, lower temperature, higher pH value, and much more time. 相似文献
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实验研究了酸枝锯末对模拟含铬废水中的Cr（VI）的吸附性能,静态吸附结果表明,酸枝锯末对Cr（VI）具有较好的吸附效果．锯末对Cr（VI）的吸附率随着锯末用量的增加而增大;随着溶液初始pH的增大,吸附效果降低;随着吸附温度的上升,吸附效果升高．酸枝锯末对Cr（VI）的吸附符合拟二级吸附动力学模型（R2〉0．99）,吸附平衡前,颗粒内扩散为吸附速率的主要控制步骤;吸附过程可用Langmuir吸附等温线（砰〉0．99）来描述．吸附热力学研究表明,酸枝锯末对Cr（VI）的吸附为自发的吸热反应过程． 相似文献
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Groundwater remediation by nanoparticles has收稿日期increasing interest in recent years. This report presents a thorough evaluation of hexavalent chromium removal in aqueous solutions using iron (Fe0) nanoparticles. Cr(Ⅵ) is a major pollutant of groundwater. Zero-valent iron, an important natural reductant of Cr(Ⅵ), is an option in the remediation of contaminated sites, transforming Cr(Ⅵ) to essentially nontoxic Cr(Ⅲ). At a dose of 0.4 g/L, 100% of Cr(Ⅵ) (20 mg/L) was degraded. The Cr(Ⅵ) removal efficiency decreased significantly with increasing initial pH. Different Fe0 type was compared in the same conditions. The reactivity was in the order starch-stabilized Fe0 nanoparticles＞Fe0 nanoparticles＞Fe0 powder＞Fe0 filings. Electrochemical analysis of the reaction process led to the conclusion that Cr(OH)3 should be the final product of Cr(Ⅵ). Iron nanoparticles are good choice for the remediation of heavy metals in groundwater. 相似文献
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INTRODUCTION Chromium is a commonly identified soils andgroundwater contaminant. Cr(VI) is toxic, carcino-genic, and has great subsurface mobility. In contrast,Cr(III) is relatively non-toxic and immobile. Muchresearch focused on the remediation of Cr(VI) such asadsorption by zeolites (Bowman, 2003) or silicas(Hideaki et al., 2002), chemical reduction by ferrousiron (Buerge and Hug, 1999; Fendorf and Li, 1996) orzero-valent iron (Powell and Puls, 1997; Alowitz andScherer, 2002), b… 相似文献
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The effectiveness of vitamin C in treating Cr(Ⅵ)-contaminated water is being evaluated. Cr(Ⅵ) is an identified pollutant of some soils and groundwater. Vitamin C, an important biological reductant in humans and animals, can be used to transform Cr(Ⅵ) to essentially nontoxic Cr(Ⅲ). The removal efficiency was 89% when the mass concentration of vitamin C was 80 mg/L in 60 min, and nearly 100% Cr(Ⅵ) was removed when the mass concentration was 100 mg/L. Our data demonstrated that the removal efficiency was affected by vitamin C concentration, the reaction temperature and the dissolved oxygen concentration.The reaction mechanism of Cr(Ⅵ) by vitamin C was presented. Our study opens the way to use vitamin C to remediate Cr(Ⅵ)-contaminated soils and groundwater. 相似文献
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吴其华 《湖州师范学院学报》1989,(5)
本文研究了D_(252)树脂(?)对Cr(Ⅵ)吸附的最佳酸度、螯合容量、作用时间、温度及用量。结果表明,D_(252)树脂用作Cr(Ⅵ)的交换树脂是合宜的。 相似文献
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Cr(VI) and phenol are toxic contaminants that need to be treated, and different methods have been researched to simultaneously remove these two contaminants from industrial wastewater. In this study, Cr(VI) was used as a novel Fenton-like catalyst in phenol degradation by H2O2. In the pH range of 3.0‒11.0, the degradation efficiency of phenol decreased with elevated pH. At pH = 3.0, 100 mg/L phenol was effectively degraded by 2 mmol/L Cr(VI) and 20 mmol/L H2O2. At pH = 7.0 and the same conditions as those of pH = 3.0, 79% of 100 mg/L phenol was removed within 6 h, which was an improvement in pH limitation compared with the Fe(II)-mediated Fenton reaction. Quenching experiments indicated that ·OH generated from the catalysis of H2O2 by Cr(V) instead of Cr(VI) was the primary oxidant that degraded phenol. When pyrophosphate was added in the Cr(VI)/H2O2 system, complexes with the Cr(V) intermediate rapidly formed and inhibited H2O2 decomposition, implying that the decomposition of H2O2 to ·OH was catalyzed by Cr(V) instead of Cr(VI). The presence of anions such as chloride and sulfate had insignificant effect on the degradation of phenol. TOC and UV analyses suggest that phenol could not be completely oxidized to CO2 and H2O, and the intermediates identified by high performance liquid chromatography further indicates that maleic acid and benzoquinone were intermediates which may be further degraded into short chain acids, primarily maleic, formic, acetic, and oxalic acids, and eventually into CO2 and H2O. Considering that more than 50% Cr(VI) can also be removed during this process, the Cr(VI)/H2O2 system is more appropriate for the simultaneous removal of Cr(VI) and phenol contaminants from industrial wastewater.
相似文献11.
Azo dyes discharged in the environment are persistent organic pollutants （POPs）, which are very difficult to remove. We developed a microwave-assisted Fenton-like process to degrade methyl orange （MO）, an azo dye, with hydrogen peroxide （H2O2） catalyzed by chromium compounds coexisting with MO in the solution. Comparison between the Cr（Ⅲ）-H2O2 and Cr（Ⅵ）-H2O2 systems shows＂ that Cr（Ⅵ） has a stronger and more stable catalytical activity than Cr（Ⅲ）, and Cr（Ⅲ） is more susceptible to a change in the acidity or alkalinity of the reaction system. With a Cr（Ⅵ） concentration of 10 mmol L^-1 or a Cr（Ⅲ） concentration of 12 mmol L^-1 in the solution under the microwave irradiation of a power larger than 300 W for 3 min, 10 mmol L^-1 H2O2 can degrade more than 95% of 1 000 mg L^-1 methyl orange; when the microwave power is increased to 700 W, the same amount of H2O2 can degrade all methyl orange in the solution with the same amount of Cr（Ⅵ ） catalyst. Ultraviolet-visible spectrography indicates the cleavage of the azo bond in methyl orange after treatment, suggesting the potential o of this Fenton-like process to degrade azo dye POPs. Reusing waste chromium compounds coexisting with dyestuff in wastewater to catalyze the degradation of azo dyes could be a cost-effective technique for azo dyes and chromate manufacturers and/or users to treat their wastewater and prevent POPs from endangering the environment. This is of particula importance to controlling the water quality of the Three Gorges Reservoir. 相似文献
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目的及方法:采用室内模拟试验,研究木炭不同粒径和用量及不同吸附时间对水溶液中Cd2+和Cr3+质量浓度的影响。结果:木炭粒径为0.25 mm时,溶液中的Cd2+、Cr3+质量浓度最高;粒径大于0.25 mm时,Cd2+、Cr3+质量浓度随着粒径增大而减小;粒径小于0.25 mm时,Cd2+、Cr3+质量浓度随着粒径减小而减小,表明只有在粒径小于0.25 mm时,粒径越小,吸附效果越好。木炭用量达到20 g.L-1时,水溶液中Cd2+、Cr3+剩余质量浓度显著低于对照,且随着用量增加,Cd2+、Cr3+剩余质量浓度有所降低;木炭用量为40 g.L-1时,第1天至第4天,4种不同浓度Cr3+水溶液中,Cr3+质量浓度随着时间的递增而递减,随后随着时间的推移,Cr3+质量浓度呈小幅增长趋势。结论:使用木炭对水溶液中的重金属离子浓度进行吸附,需要对粒径大小、用量、吸附时间等因素进行优化,才能保证吸附效果。 相似文献
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对乙酰基偶氮羧光度法测定痕量铬的研究 总被引：1，自引：0，他引：1
研究了对乙酰基偶氮羧与Cr_2O_7~(2-)的褪色反应,建立了一种新的测定痕量Cr(Ⅵ)的光度方法,发现其在高氯酸介质中具有高灵敏的褪色反应,摩尔吸光系数达到3.0×10~6 L·mol~(-1)·cm~(-1)Cr(Ⅵ),量在0～50μg范围内符合比耳定律. 相似文献
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1 Ｉｎｔｒｏｄｕｃｔｉｏｎ Ａｑｕｅｏｕｓｅｆｆｌｕｅｎｔｓｄｉｓｃｈａｒｇｉｎｇｆｒｏｍｍｉｎｉｎｇａｎｄｏｔｈ ｅｒｉｎｄｕｓｔｒｉｅｓｃｏｎｔａｉｎｈｅａｖｙｍｅｔａｌｓｓｕｃｈａｓｌｅａｄ ,ｃａｄ ｍｉｕｍａｎｄｃｈｒｏｍｉｕｍｉｎｄｉｓｓｏｌｖｅｄａｎｄ ｐａｒｔｉｃｕｌａｔｅｆｏｒｍｓ[1] .Ｔｈｅｉｍｐａｃｔｏｆｕｎｔｒｅａｔｅｄｉｎｄｕｓｔｒｉａｌｅｆｆｌｕｅｎｔｓｏｎｔｈｅａｑｕｅｏｕｓｅｎｖｉｒｏｎｍｅｎｔｈａｓｂｅｅｎｅｘｔｅｎｓｉｖｅｌｙｓｔｕｄｉｅｄ[2 ] .Ｃｏｎｖｅｎｔｉｏ… 相似文献
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实验室含铬废液处理方法的对比研究 总被引：2，自引：0，他引：2
实验室含铬废液不能直接排放,必须进行回收处理。采用化学还原法处理含Cr（VI）废液,对比研究了以亚硫酸钠、亚硫酸氢钠、抗坏血酸、硫酸亚铁为还原剂还原Cr（VI）的酸度条件、还原剂用量、反应时间等影响因素．结果表明：在最佳参件下,四种还原剂处理含Cr（VI）废液的去除率都在99．9％以上,处理后出水的Cr（VD浓度分别为0．048mg·L^-1、0．018mg·L^-1,0．038mg·L^-1,0．018mg·L^-1,均小于0．5mg·L^-1,达到了国家排放标准,取得了良好的处理效果。综合分析Cr（VI）~除率和经济效益得出亚硫酸氢钠为最佳还原剂。 相似文献
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Schedule-induced polydipsia was studied using a behavioral contrast paradigm. Food pellets were delivered to food-deprived rats on a response-independent FT 1-min schedule. Licking on a tube produced water on a MULT FR 10 FR 10, MULT FR 10 EXT, or MIXED FR 10 EXT for three rats (Experiment 1) and on a MULT VI VI, MULT VI EXT, or MIXED VI EXT schedule for three other rats (Experiment 2). On the FR schedules, rats could drink more water by increasing lick rates, but on the VI schedules the amount of drinking was fixed by the schedule parameters and was relatively unaffected by lick rates. Relative to MULT FR FR, positive polydipsia contrast was clearly demonstrated on MULT and MIXED FR EXT; but relative to MULT VI VI, contrast was not demonstrated on MULT and MIXED VI EXT. These data suggest that polydipsia contrast occurs only if increased licking permits increased drinking. 相似文献
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Pigeons' keypecking was reinforced by food on baseline schedules of multiple variable interval (VI) x VI x and on contrast schedules of multiple VI x VI y. Deprivation of food was varied by maintaining subjects at 75%, 85%, and 95% (+/- 2%) of their free-feeding weights. Positive and negative behavioral contrast were observed. The size of the contrast was not systematically altered by changes in deprivation. Positive and negative contrast were both larger later in the session than they were earlier. Within-session decreases in responding were steeper for the baseline than for the contrast schedules for positive contrast. Within-session decreases were steeper for the contrast than for the baseline schedules for negative contrast. These results were predicted by the idea that different amounts of habituation to the reinforcer during the baseline and contrast schedules contribute to behavioral contrast. The results show that contrast occurs under conditions that reduce the effect of the following component. The results support the assumption that positive and negative contrast are produced by symmetrical theoretical variables. 相似文献
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SAENGHAENGTHAM Nida KANONGCHAIYOS Pizzanu 《浙江大学学报(A卷英文版)》2006,7(7):1225-1232
INTRODUCTION Collision detection is an important task in many fields such as robotics, computer games, computa- tional geometry (Gottschalk et al., 1996), computer simulation, virtual reality, etc. Most collision detec- tion algorithms work efficiently only with solid and rigid objects, so collision detection between de- formable objects is a challenge. A number of re- searches on non-rigid objects are proposed such as cloth simulation (Bridson et al., 2003; Teschner et al., 2004) and bi… 相似文献