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21.
柠檬酸对重金属复合污染土壤的浸提效果研究 总被引:4,自引:1,他引:3
以浙江富阳某炼铜厂附近受Cd、Cu、Pb和Zn复合污染的土壤为研究对象,采用振荡、静置和超声3种不同浸提方式,通过研究柠檬酸在不同浸提方式下对重金属的去除效果,筛选出最佳柠檬酸浓度、处理时间及功率,并采用Tessier连续提取法分析浸提前后4种重金属形态变化.结果表明,柠檬酸对4种重金属均具有较好的去除效果,其中对Zn的去除效果最好,Cd的去除效果最差,而Cu和Pb的去除效果相当.Pb和Zn的去除率均随着柠檬酸浓度的增加而增加,但增幅随之减小,Cu的去除率则先增加后基本保持不变,而Cd的去除率变化不明显.综合考虑成本和浸提效果后,选用0.2 mol·L-1柠檬酸浸提2次为最优条件,最佳振荡时间和静置时间分别为4 h和24 h,最佳超声时间和功率分别为30 min和500 W.柠檬酸能够在很大程度上改变土壤中重金属的形态分布,主要去除以可交换态和碳酸盐结合态形式存在的Cd及以碳酸盐结合态和铁锰氧化物结合态形式存在的Cu、Pb和Zn.通过对比3种浸提方式,在同等去除效果的前提下,静置浸提相比振荡浸提需要更长的时间,而将超声波应用于重金属污染土壤淋洗,所需时间较少,因此,超声波辅助浸提土壤中重金属是可行的,具有良好的应用前景. 相似文献
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Research on the micro- and macrocharacteristics of different metamorphic degrees of coal helps improve the control and protection techniques used during spontaneous combustion. Nine coals with different properties were thoroughly investigated in this study. Fourier transform infrared spectroscopy and a self-designed temperature-programmed oil bath experimental system were adopted to analyze the molecular structure and macrocharacteristic parameters of the spontaneous combustion of coal. Additionally, the influence of particle size on spontaneous combustion was considered. Various functional groups were employed as microcharacteristic parameters to capture the principal active groups in oxidation. The gas production rate, oxygen consumption rate, gas concentration, heat energy release rate, and characteristic temperatures were evaluated as macrocharacteristic parameters to investigate the changes in coal during oxidation. The results establish that the microcharacteristics of coal molecules determine the degree of spontaneous combustion based on intrinsic properties and that changes in the macrocharacteristics of the spontaneous combustion of coal reflect the microstructural changes. The contents of the hydroxyl groups, carbonyl groups, alkyl ether and aryl ether in the coal molecules gradually decrease with the metamorphic increase. Oxygen-containing functional groups have higher reactivities and easily react with oxygen, causing the macroparameters, such as the oxygen consumption rate, the gas generation rate and the heat energy release rate, to consistently decrease with the increase of the metamorphic degree. Small-particle-size coal molecules have more active aliphatic hydrocarbons, oxygen-containing functional groups and a larger specific surface area, increasing the chances of adsorbing the oxygen of active groups and promoting the reaction between coal and oxygen. The experimental results indicate that coal samples with higher metamorphic degrees or larger sizes exhibit lower tendencies toward spontaneous combustion. Evaluation of the spontaneous combustion of coal based on a temperature-programmed oil bath experimental system is of great practical importance for preventing the spontaneous combustion of coal during storage, processing and utilization and can serve as a convenient reference for production safety in mining applications. 相似文献
23.
污泥超声破解效应及厌氧消化性能研究 总被引:6,自引:0,他引:6
针对超声破解污泥的可行性进行了实验研究,重点考察了超声频率、比能耗、作用时间等因素对破解效应的影响,探讨了破解污泥的厌氧消化性能。结果表明,超声作用的施加可使污泥固体有效破解,污泥细胞内的活性有机物被释放至水相并形成溶解性有机物,表现为SCODCr的显著增加;采用低频、高比能耗及延长作用时间有利于获取高的SCODCr增加值;污泥在频率25kHz、比能耗2.0W/mL、作用时间30min条件下破解,其厌氧消化累计产气量可从破解前的268mL提高到473mL,相应TCODCr去除率、VS去除率分别从39.1%、33.5%提高至54.3%、61.7%。研究结果表明采用超声破解技术提高污泥的厌氧消化性是可行的。 相似文献
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超声波预处理对牛粪与玉米秸秆混合厌氧发酵特性的影响 总被引:1,自引:0,他引:1
为了探索超声波预处理提高厌氧发酵产气量的机理、优化超声波预处理工艺及分析超声波预处理的能量效益,利用因子分析法和通径分析研究不同发酵阶段各环境因子对发酵过程的影响,以及发酵初始环境与甲烷产量之间的关系.同时,用响应面优化法优化超声波预处理工艺,并且分析了超声波预处理的能量效益.结果表明,在40 k Hz和0.20 k W下,适宜的超声波预处理能显著提高厌氧发酵总产气量(p0.05),牛粪预处理17.68 min后与玉米秸秆预处理19.94 min混合发酵,甲烷产量最高为177.20 L·kg-1(以TS计),显著高于CK(未经预处理组,p0.05),其能量效益也最高,为1835.14 k J·kg-1(以TS计).超声波预处理通过改变发酵初始环境之间的相互关系和发酵过程环境的主要影响因素来使发酵系统更加稳定从而提高产气量.超声波预处理是一种能量输入的预处理方式,产气量高于CK处理组,但其能量效益不一定大于零.因此,在优化超声波预处理条件时必须对其能量效益进行分析.研究结果能为超声波预处理条件的优化方式提供理论依据. 相似文献
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Alkaline and ultrasonic sludge disintegration can both be used as pretreatments of waste activated sludge (WAS) for improving the subsequent anaerobic or aerobic digestion. The pretreatment has been carried out using different combination of these two methods in this study. The effect was evaluated based on the quantity of soluble chemical oxygen demand (SCOD) in the pretreated sludge as well as the degradation of organic matter in the following aerobic digestion. For WAS samples with combined pretreatment, the released COD was in high level than those with ultrasonic or alkaline treatment. When combined with the same ultrasonic treatment, NaOH treatment resulted in more solubilization of WAS than Ca(OH)2. For combined NaOH and ultrasonic treatments with different sequences, the released COD were in the order: simultaneous treatment > ultrasonic treatment following NaOH treatment > NaOH treatment following ultrasonic treatment. For simultaneous treatment, low NaOH dosage (100 g/kg dry solid), short duration (30 min) of NaOH treatment, and low ultrasonic specific energy (7 500 kJ/kg dry solid) were beneficial for sludge disintegration. Using combined NaOH and ultrasonic pretreatment with the optimium parameters, the degradation efficiency of organic matter was increased from 38.0% to 50.7%, which is much higher than with ultrasonic (42.5%) or with NaOH pretreatment (43.5%) in the subsequent aerobic digestion at the same retention time. 相似文献
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超声波预处理-生物降解复合工艺处理含油污泥 总被引:1,自引:0,他引:1
以超声辐照和生物降解复合工艺处理油田含油污泥,辐照30 min后,连续曝气4 h的污泥中COD去除率比未经辐照的污泥COD去除率增幅85.7%,除油率增幅为66.7%;超声辐照强度对含油污泥处理效果影响较大,输出电压从50 V增至250 V时,COD去除率从10%增至70%,除油率则先增加后降低,在200 V左右时除油率最高达60%。 相似文献