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2A12铝合金在模拟溶液中的周浸腐蚀行为 总被引:1,自引:1,他引:1
采用干湿周浸实验、失重法和电化学阻抗谱研究了2A12铝合金在0.6mol/L NaCl和0.6mol/L NaCl 0.02mol/L NaHSO3两种溶液中的腐蚀行为与规律, 利用扫描电镜(SEM)、能谱(EDX)和红外光谱(FTIR) 观察分析腐蚀产物表面形貌、结构和组成,测试了材料的力学性能.研究表明,随腐蚀时间的延长,腐蚀产物不断增多,失重增加,力学性能下降,阻抗模值逐渐减小;腐蚀产物形貌以团状和块状为主,在0.6mol/L NaCl溶液中腐蚀产物主要为铝的氯化物和氧化铝,在0.6mol/L NaCl 0.02mol/L NaHSO3溶液中腐蚀产物主要为氧化铝、铝的硫酸盐水合物和铝的氯化物;由于NaCl和NaHSO3共同作用,2A12合金在0.6mol/L NaCl 0.02mol/L NaHSO3溶液中腐蚀电流密度高,阻抗模值相对较小,腐蚀速率较高,腐蚀后失重大,力学性能下降幅度较大,腐蚀更严重. 相似文献
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J. J. Jesudason R. H. Marchessault T. Saito 《Journal of Polymers and the Environment》1993,1(2):89-98
The synthetic analogue of a bacterially produced polyester, poly(-hydroxybutyrate) (PHB) was synthesized from racemic -butyrolactone using anin situ trimethyl aluminum-water catalyst. The polymer was fractionated into samples differing in molecular weight and isotactic diad content. The latter was closely related to degree of crystallinity. The biodegradation of these fractions were examined by monitoring mass loss over time in the presence of anAlcaligenes faecalis T1 extracellular bacterial poly(-hydroxybutyrate) depolymerase. The fraction with high isotactic diad tacticity content showed little or no degradation over a 50 hour incubation period, whereas the fraction of intermediate isotactic diad content degraded in a continuous steady fashion at a rate that was less than that for bacterial PHB. The low isotactic diad fraction underwent a rapid initial degradation, followed by no further mass loss. The presence of stereoblocks in the polymer structure of the various fractions was an influence on the degree of susceptibility towards degradation and is related to sample crystallinity. 相似文献
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Tohru Kamo Kanji Takaoka Junichiro Otomo Hiroshi Takahashi 《Journal of Material Cycles and Waste Management》2006,8(2):109-115
Steam gasification of dehydrochlorinated poly(vinyl chloride) (PVC) or activated carbon was carried out in the presence of
various alkali compounds at 3.0 MPa and 560°C–660°C in a batch reactor or in a semi-batch reactor with a flow of nitrogen
and steam. Hydrogen and sodium carbonate were the main products, and methane and carbon dioxide were the minor products. Yields
of hydrogen were high in the presence of sodium hydroxide and potassium hydroxide. The acceleration effect of the alkali compounds
on the gasification reaction was as follows: KOH > NaOH > Ca(OH)2 > Na2CO3. The rate of gasification increased with increasing partial steam pressure and NaOH/C molar ratio. However, the rate became
saturated at a molar ratio of NaOH/C greater than 2.0. 相似文献
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合成了一种高吸附容量的磁性生物炭负载Mg-Fe水滑石复合材料(L-BC),并用于去除水中的Cd2+和Ni2+。表征结果表明,采用浸渍联合热解法成功制备了磁性生物炭(M-BC),水热合成法成功地将Mg-Fe水滑石负载在M-BC上。动力学研究结果表明,Cd2+和Ni2+吸附符合伪二级动力学模型,化学吸附为速率控制步骤。等温吸附研究结果表明,L-BC对Cd2+和Ni2+的吸附符合Langmuir模型,为单分子层化学吸附,最大吸附量分别为263.156 mg/g和43.291 mg/g。吸附机理主要为Mg-Fe水滑石层间CO32-和表面羟基与Cd2+和Ni2+产生表面共沉淀。L-BC具有良好的吸附和重复利用性能,是一种很有前景的去除Cd2+和Ni2+的吸附材料。 相似文献
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在未来相当长的一段时间内,煤气化仍是大规模制取氢气的主要途径。目前,常规煤气化过程得到的是H2、CO和CO2为主的混合气,需要通过净化、变换和分离工艺才能得到洁净的氢气,工艺过程复杂。采用连续式超临界水反应装置,以质量分数为20%的水煤浆为反应原料,考察了Ca/C摩尔比和温度对褐煤制氢系统的影响。试验结果表明:Ca(OH)2不仅可以很好地固定气相中的CO2和硫化物,而且对煤气化过程也表现出较好的催化作用。反应温度600℃,压力为25MPa的条件下,与未加Ca(OH)2相比,Ca/C摩尔比为0.45时,气体中CO2的体积分数由50.7%降至1.0%,趋于完全固定;硫化物浓度由10 878mg/m3降至807mg/m3;H2的体积分数由32.4%增至73.3%。Ca(OH)2对煤气化的催化作用在高温下更加明显。 相似文献
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粒状羟基氧化铁对废水中硝酸盐的吸附 总被引:2,自引:0,他引:2
本实验研究了粒状羟基氧化铁(GFH)对人工配制含氮废水中NO3--N吸附的影响因素、吸附等温线和吸附动力学。结果表明,GFH的吸附平衡时间为80 min,增加NO3--N溶液的初始浓度,去除率下降;pH值为5时GFH对NO3--N的吸附能力最强,pH值升高和降低,吸附能力均下降;GFH对NO3--N的吸附能力随着温度的升高略有降低;在25℃下,以Langmuir方程和Freundlich方程分别对GFH吸附NO3--N的等温线进行拟合,拟合效果以Langmuir方程较好,相关性达到0.9930。GFH吸附NO3--N的过程符合拟二级动力学方程,初始时刻的吸附速率h在35℃时最大,为1.653 mg/(g.mg),吸附速率常数随温度的升高而增大;吸附反应的活化能Ea为54.72 kJ/mol。本研究结果表明,GFH在饮用水脱氮和含氮浓度较低的污水再生回用领域有实际应用的潜力。 相似文献
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Simultaneous removal of Cu(II) and Cr(VI) by Mg–Al–Cl layered double hydroxide and mechanism insight
Mg–Al–Cl layered double hydroxide (Cl-LDH) was prepared to simultaneously remove Cu(II) and Cr(VI) from aqueous solution. The coexisting Cu(II) (20 mg/L) and Cr(VI) (40 mg/L) were completely removed within 30 min by Cl-LDH in a dosage of 2.0 g/L; the removal rate of Cu(II) was accelerated in the presence of Cr(VI). Moreover, compared with the adsorption of single Cu(II) or Cr(VI), the adsorption capacities of Cl-LDH for Cu(II) and Cr(VI) can be improved by 81.05% and 49.56%, respectively, in the case of coexisting Cu(II) (200 mg/L) and Cr(VI) (400 mg/L). The affecting factors (such as solution initial pH, adsorbent dosage, and contact time) have been systematically investigated. Besides, the changes of pH values and the concentrations of Mg2+ and Al3+ in relevant solutions were monitored. To get the underlying mechanism, the Cl-LDH samples before and after adsorption were thoroughly characterized by X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. On the basis of these analyses, a possible mechanism was proposed. The coadsorption process involves anion exchange of Cr(VI) with Cl− in Cl-LDH interlayer, isomorphic substitution of Mg2+ with Cu2+, formation of Cu2Cl(OH)3 precipitation, and the adsorption of Cr(VI) by Cu2Cl(OH)3. This work provides a new insight into simultaneous removal of heavy metal cations and anions from wastewater by Cl-LDH. 相似文献