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61.
The adsorption behaviors of heavy metals onto novel low-cost adsorbent, red loess, were investigated. Red loess was characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectra. The results indicated that red loess mainly consisted of silicate, ferric and aluminum oxides. Solution pH, adsorbent dosage, initial metal concentration, contact time and temperature significantly influenced the efficiency of heavy metals removal. The adsorption reached equilibrium at 4 hr, and the experimental equilibrium data were fitted to Langmuir monolayer adsorption model. The adsorption of Cu(II) and Zn(II) onto red loess was endothermic, while the adsorption of Pb(II) was exothermic. The maximum adsorption capacities of red loess for Pb(II), Cu(II) and Zn(II) were estimated to be 113.6, 34.2 and 17.5 mg/g, respectively at 25°C and pH 6. The maximum removal efficiencies were 100% for Pb(II) at pH 7, 100% for Cu(II) at pH 8, and 80% for Zn(II) at pH 8. The used adsorbents were readily regenerated using dilute HC1 solution, indicating that red loess has a high reusability. All the above results demonstrated that red loess could be used as a possible alternative low-cost adsorbent for the removal of heavy metals from aqueous solution. 相似文献
62.
Chemical forms of Zn, Ni, Cu, and Pb in municipal sewage sludge were investigated by adding humus soil to sludge and by
performing sequential extraction procedures. In the final sludge mixtures, Zn and Ni were mainly found in Fe/Mn oxide-bound (F3) and
organic matter/sulfide-bound (F4) forms. For Zn, exchangeable (F1), carbonate-bound (F2), and F3 forms were transformed to F4 and
residual forms (F5). For Ni, F1 and F2 forms were transformed to F1, F2, and F3 forms. Both Cu and Pb were strongly associated with
the stable forms F4 and F5. For Cu, F2 and F3 forms were major contributors, while for Pb, F3 and F4 forms were major contributors to
F5. Humus soil dosage and pH conditions in the sludge were strongly correlated with the forms of heavy metals. Five forms were used
to evaluate metal mobilities in the initial and final sludge mixtures. The mobilities of the four heavy metals studied decreased after 28
days. The metal mobilities in the final sludge mixtures were ranked in the following order: Ni > Zn > Cu = Pb. Leaching tests showed
that the mobilities of Zn and Ni in lower pH conditions (pH 4) were higher than those in higher pH conditions (pH 8). 相似文献
63.
Remediation of copper polluted red soils with clay materials 总被引:2,自引:0,他引:2
Attapulgite and montmorillonite were utilized to remediate heavy metal polluted red soils in Guixi City, Jiangxi Province, China.
The e ects of clay minerals on availability, chemical distribution, and biotoxicity of Cu and Zn were evaluated. The results provided
a reference for the rational application of clay materials to remediate heavy metal contaminated soils. From the sorption experiment,
the maximum adsorbed Cu2+ by attapulgite and montmorillonite was 1501 and 3741 mg/kg, respectively. After polluted red soil was
amended with attapulgite or montmorillonite and cultured at 30 and 60 days, soil pH increased significantly compared to the control. An
8% increase in the amount of montmorillonite in soil and 30 days incubation decreased acid exchangeable Cu by 24.7% compared to the
control red soil. Acid exchangeable Cu decreased with increasing amounts of attapulgite and montmorillonite, with best remediation
e ect reached at a dose of 8%. Results also showed that the Cu poisoning e ect on earthworms was reduced with the addition of
attapulgite and montmorillonite. Montmorillonite showed the best e ect, with the addition of a 2% dose the mortality of earthworms
decreased from 60% to zero compared to the control. Our results indicated that the bioavailability of Cu in soils was reduced more
e ectively with the application of montmorillonite than attapulgite. 相似文献
64.
Siriprapha Jangkorn Sinchai Kuhakaew Suwapee Theantanoo Harit Klinla-or Tongchai Sriwiriyarat 《环境科学学报(英文版)》2011,23(4):587-594
A coagulation-flocculation process is typically employed to treat the industrial wastewater generated by the consumer products
industry manufacturing detergents, soaps, and others. The expenditure of chemicals including coagulants and chemicals for pH
adjustment is costly for treating this wastewater. The objective of this study was to evaluate the feasibility of reusing the aluminum
sulfate (alum) sludge as a coagulant or as a coagulation aid so that the fresh alum dosage can be minimized or the removal e ciency can
be enhanced. The experiments were conducted in a jar-test apparatus simulating the coagulation-flocculation process for simultaneous
removals of organic matters, anionic surfactants, suspended solids, and turbidity. At the optimum initial pH value of 10 and the fresh
alum concentration of 400 mg/L, the total suspended solids (TSS), total chemical oxygen demand (TCOD), total anionic surfactants,
and turbidity removal e ciencies were 71.5%, 76.4%, 95.4%, and 98.2%, respectively. The addition of alum sludge as a coagulant
alone without any fresh alum addition could significantly remove the turbidity, TCOD, and anionic surfactants. The TSS was left in the
supernatants after the settling period, but would subsequently be removed by adding the fresh alum. The TSS, TCOD, and turbidity
removal e ciencies were also enhanced when both the alum sludge and the fresh alum were employed. The TCOD removal e ciency
over 80% has been accomplished, which has never fulfilled by using the fresh alum alone. It is concluded that the alum sludge could
be reused for the treatment of industrial wastewater generated by the consumer products industry. 相似文献
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68.
藻类代谢对地表水中含氧量和pH均产生影响。藻类光合作用放出氧气,导致地表水中的含氧量增加。藻类光合作用吸收二氧化碳,影响地表水中碳酸及碳酸盐的平衡,导致地表水中pH偏向碱性。地表水中存在的弱酸及弱酸盐也会影响地表水中pH的变化。在同样的光合作用条件下,如果地表水中碳酸及碳酸盐浓度高,则pH变化小;如果地表水中碳酸及碳酸盐浓度低,则pH变化大。 相似文献
69.
城市有机垃圾间歇厌氧消化pH控制动力学研究 总被引:3,自引:0,他引:3
对厌氧消化系统的物料及电离平衡进行分析,利用底物降解和微生物生长动力学建立城市有机垃圾间歇厌氧消化pH值控制模型,并研制开发了间歇厌氧消化过程pH值与产气量最优化计算机软件.运用该模型可预测不同厌氧消化过程的最佳pH值,从而通过控制厌氧系统的pH值使系统产气量达到最大,通过2组对比实验验证模型的有效性.结果表明,在相同的实验条件下厌氧系统的pH控制在最佳值时系统产气较未对pH值控制时稳定,且总产气量平均提高20%左右. 相似文献
70.
西天山科其喀尔冰川消融径流的水化学分析 总被引:7,自引:5,他引:2
为了研究西天山科其喀尔冰川融水径流的基本化学特征,2003-06~2003-09在研究区取样(冰面径流、冰面湖水、河水及大气降水),结果表明:①本区各类水体都呈碱性,pH值大小顺序为:河水>冰面径流>冰面湖水>大气降水>7.②各类样品总离子浓度的顺序为:河水>大气降水>冰面湖水>冰面径流.冰面径流中的各项离子浓度均低于其它3类样品的相应值,平均仅是河水的24%;阴、阳离子分别以SO42-和Ca2+为最大.③由于降水过程中有物理变化和化学反应的作用,不同降水形式中降雨的各项离子浓度(NO3-除外)均比冰雹和雪中的相应离子浓度大;④对不同海拔高度水样分析表明,各项离子浓度“高程效应”十分明显,3 900m以上区域,冰面径流中各阳离子浓度逐渐向冰川冰中各相应离子浓度逼近. 相似文献